Take a few moments to review the discussions before you start this chapter.

A T4 cell with HIV is used in a criminal case.

Problems in agriculture, medicine, and forensic science have been addressed thanks to the ability to identify the genetic profile of an organisms. A gastroenterologist was found guilty of attempted murder of his girlfriend when he injected her with HIV and hid it in a B12 shot.

One of the doctor's patients with HIV/AIDS was traced to the girlfriend's HIV. The doctor's victim's HIV lineages are nested within the doctor's patient's in the image above. The doctor was sentenced to 50 years in prison for attempted murder because of this evidence.

In this chapter, we look at how biologists classify organisms based on ancestry.

The Linnaean classification hierarchy has levels.

The scientific name of the organisms should be identified.

Section 17.3 examined macroevolution, evolutionary Page 338 change that results in the formation of new species.

The source of the past and present is macroevolution.

The study of biodiversity helps us understand the evolutionary relationships between species. The relationships among organisms are inferred through the use of traits of living and fossil organisms.

"usage, law" is a branch of systematic biology that identifies, names, and organizes biodiversity into related categories. The taxon has organisms with a spine column.

Classifying organisms. Taxonomy describes the classification of organisms. Throughout history, the methods used to classify living organisms have changed. The ancient Greek philosopher was interested in Taxonomy, and he sorted organisms into groups based on a set of shared traits.

The method was problematic because many features of organisms were similar not because they shared a common ancestor, but because of convergent evolution. Birds, bats, and beetles, all of which have wings, are different in many other ways.

Natural groups are groupings of organisms that represent a shared evolutionary history.

Natural groups are classified by using a set of traits to create a family tree that represents the evolutionary history of taxa. The evolutionary history is used to classify taxa.

Modern biologists are able to compare trait other than external features to classify organisms. Birds, bats, and beetles are not related to wings. As a result of convergent evolution, wings originated on three different branches of the tree of life.

Carolus Linnaeus, considered to be the father of modern taxonomy, created the classification hierarchy that taxonomists use today. The way to organize biodiversity was developed by Linnaeus. Europeans traveled to distant parts of the world and described, collected, and sent back to Europe examples of plants and animals they had never seen before.

The binomial system of naming and classification was created by Linnaeus. His original name was Karl von Linne, but he latinized it because of his fascination with scientific names. Linnaeus wanted to classify plants.

Sometimes the specific epithet tells us something about the organisms. The scientific name is in italics. Without a street name and a specific epithet, it's useless to find an address. The group of related species can be referred to with the genus name alone.

There are many ways in which scientific names are derived.

Latin is used to describe organisms for a variety of reasons.

People who speak the same language sometimes use different names for the same organisms. The common name is sometimes given to different organisms. Latin is a universal language that is well known by many of the same people who were physicians or clerics. Common names can cause confusion when used by scientists.

Linnaeus used a binomial system to classify species.

Taxonomists use a set of categories to classify organisms. The organisms that fill a particular classification category have the same set of traits as other organisms.

Organisms are classified into categories. The species is the most nested.

Many genera can be in the same family, and several species can share the same name. The number of boxes depends on the amount of diversity in the group. Depending on the study, the family Muridae can be divided into 150 to 250 genera and up to 1,000 species.

Organisms in the same domain have general characteristics in common with those in the same species. All animals are included in the kingdom Animalia. There are only animals with a spine in the kingdom Animalia. There are animals within the class that have mammary glands and have spine cords. The species is the most exclusive of the categories as it only contains one type of organisms.

The classification hierarchy is useful because it allows scientists to organize the diversity of life, but it is important to remember that the hierarchy was created by scientists and does not represent any special relationship among organisms in nature. Being in the same order does not mean much to the genetics or behavior of monkeys or apes. The best working hypothesis of evolutionary relationships is the classification hierarchy.

With the addition of new information, the hierarchy and placement of organisms are revised. You can find the same thing in older textbooks or among taxonomists. One of the greatest principles of science is uncertainty.

There were no official rules for classification of organisms until the 1800s.

The International Code of Zoological Nomenclature (ICZN) was accepted as the universal guide for naming animals in 1961.

Nomenclature is the keeper of the ICZN and all scientists use its rules to classify animal groups.

Nomenclature is in charge of establishing the policies for the naming of plants.

Only a fraction of the millions of species now living on Earth have been classified despite a universal set of rules. The naming of the birds and mammals may be complete, but there are millions of insects and microorganisms that remain to be discovered and classified.

It is difficult to identify and name the world's species. A large database of sequence from known organisms is compared with a short fragment of DNA from an unknown organisms. The similarities and differences between the sequence of the unknown organisms and the sequence in the database can help determine which group the organisms belong to or if they are new to science.

Some taxonomists think that DNA barcoding is too simplistic because it doesn't always get the taxonomy correct. It is possible to quickly and cheaply catalog at least a portion of the world's biodiversity.

There are two characteristics that define each of the three domains.

The kingdoms Plantae and Animalia were only recognized by biologists from the middle of the twentieth century. Plants and animals were both mobile organisms that were planted. The kingdom Protista (protists) was proposed in Page 341 by a German scientist.

The Monera, Protista, Fungi, Plantae, and Animalia were added to the classification system in 1969.

Organisms were placed in the kingdoms based on their type of cell, complexity, and type of nutrition. Kingdom Monera contained all the prokaryotes, which are organisms that don't have a nucleus. Thebacteria were singlecelled organisms. The kingdoms have different types of eukaryotes.

In the late 1970s, Carl and his colleagues at the University of Illinois were studying the relationships among the prokaryotes. The rRNA sequence of prokaryotes that lived at high temperatures or produced methane are different from the other types of prokaryotes. He proposed that there are two groups of prokaryotes, rather than one group, the Monera. The rRNA sequence of the two groups of prokaryotes is so different that they should be classified in a different category than the kingdom.

The archaea lineage separated from the eukarya. The archaea, the oldest of the living organisms on Earth, is more closely related to the eukaryotes than to the bacteria.

There is a tree of life. The shaded areas depict representatives of each domain. The tree shows that both domain Archaea and domain Eukarya are related to each other.

Taxonomists used to rely on anatomical traits to tell species apart. The only way to define a species is through physical features. The help of experts who specialize in a particular group of organisms is needed for the identification of anatomical traits. The number of species has vastly exceeded the number of experts. The rate at which our natural areas are disappearing is much slower than the cataloging of the world's biodiversity.

The Consortium for the Barcode of Life wants taxonomists to use a sample of DNA to identify any organisms on Earth.

It would be possible to use the base sequence in DNA to create a barcode for each living organisms, according to the CBOL. The store barcode's sequence of numbers would be filled by the order of DNA nucleotides within a particular gene common to the organisms in each kingdom.

It would be a boon to catalog a rapidly disappearing biodiversity and also have practical applications. Farmers with a pest attacking their crops, doctors having to choose the correct antivenin for snakebite victims, customs agents noting the illegal trade in rare species are some of the benefits of rapid identification. The CBOL has hundreds of thousands of barcodes representing species across the diversity of life.

They collected 60 fish samples from four restaurants and ten grocery stores in Manhattan, which they sent off to have the DNA segment, barcode, and compared to a global library of fish barcodes. Two of the four restaurants and six of the ten grocery stores sold fish that had been mislabeled. The fish were being sold as more expensive species.

If you want to help manage modern societal problems, you should propose additional ways that DNA barcoding can be used.

A barcode can be used to identify a can of soup, but a DNA barcode can be used to identify a species. This is possible because the barcodes are unique to each product and the species they are based on.

bacteria can be found in large numbers in almost every environment on Earth The archaea are similar tobacteria but have differences in their chemistry. Sections 20.3 and 20.4 detail the differences.

The prokaryotes of the cyanobacteria are large. In the same way that plants use solar energy to convert carbon dioxide and water into water and oxygen, they do it the same way. The first organisms to contribute oxygen to early Earth's atmosphere may have been the cyanobacteria. They may have made the environment hospitable for the evolution of oxygen-using organisms, including animals.

Heterotrophicbacteria have a wide variety of means for getting food. Heterotrophicbacteria break down organic remains. They keep chemical cycling going so that plants always have a source of nutrition.

Archaea are prokaryotic single-celled organisms that reproduce asexually. bacteria under the microscope look the same as Archaea. It is difficult to grow many species in the laboratory because of the extreme conditions they live in. Their unique place among living organisms went unrecognized for a long time because of Page 343.

The archaea are different frombacteria by their rRNA sequence and cell wall chemistry.

The cell wall structure of archaea might help them live in extreme conditions. The branched nature of diverse lipids in the archaeal plasma membrane is different from that of thebacterial plasma membrane.

The archaea thrive in environments that are similar to those of the early Earth. The methanogens live in environments where methane is abundant, such as swamps, marshes, and the guts of animals. The halophiles thrive in salty environments like the Great Salt Lake in Utah.

Eukaryotes are single-celled to multicellular organisms. They also have a variety of different parts, some of which came from other single-celled organisms. Sexual reproduction is common in the eukaryotes.

We will look at the individual kingdoms that occur within the domain Eukarya later in this text. The protists are a diverse group of single-celled eukaryotes that are hard to classify and define. Some protists have colonies.

There are true tissues on Page 343. Heterotrophic by ingestion or absorption is one of the differences in nutrition. Green algae, paramecia, and slime molds are protists. The protists are placed in six super groups.

Fungi have cell walls with chitin and form spores that lack flagella. They are multicellular with a few exceptions.

The saprotrophic nature of the Fungi is due to their absorption of vitamins and minerals from decaying organic matter. Representative fungi include mushrooms, molds, and yeasts.

Plants are mostly adapted to a land environment. They are related to an aquatic protist. Land plants have true tissues and have a level of organization. The examples include cacti and cypress trees.

Animals are multicellular organisms that evolved from a protist. Animals have true tissues and an organization similar to land plants. Heterotrophs are animals.

The worms, whales, and insects are examples.

List the differences between the Archaea and other single-celled organisms.

All multicellular organisms are included in the domain.

There are types of traits used to make a phylogeny.

The sequence, structure, and function of RNA and DNA are used by Systematic Biologists to construct a phylogeny. The evolutionary history of biodiversity is studied by systematic biologists.

A phylogeny is the visual representation of the evolutionary history of biodiversity, and systematic biology is the study of the evolutionary history.

A taxon and their common ancestor are two of the many characteristics that are unique to and shared by the taxon and their line of descent. Each branch is a descendant of a common ancestor. A new evolutionary path can be formed when a new character is created, as well as a new branch of the family tree.

All descendants of a clade have red-numbered traits such as deer with antlers, cattle with horns, monkeys with tails, and apes with full shoulder rotation. The evolutionary history of a few members of the class Mammalia is depicted in the phylogeny. All of the descendants of the common ancestor have the same trait. New derived traits give greater resolution to the classifications as you move towards the tips of the tree. The mammary glands are found in mammals.

Artiodactyls have hooves. There are even toed hooves and mammary glands in deer.

The deer, cattle, monkeys, and apes are all examples of mammals. This trait is not helpful for understanding how deer, cattle, monkeys, and apes are related to each other because all mammals have mammary glands. Derived traits are the most important for clarifying evolutionary relationships. Both monkeys and apes have an opposable thumb, a trait not found in mammals. The trait places monkeys and apes on a different line of mammals.

Whether a trait is derived or ancestral depends on the location of the common ancestor. An opposable thumb is a trait that all monkeys and apes have. The opposable thumb is an ancestral trait of the primate. Both deer and cattle have even-toed hooves, a trait not found in mammals or primates. The trait of even-toed hooves is an ancestral trait of artiodactyls. The evolutionary history of artiodactyls and primate became independent as each group differed from the mammal common ancestor, according to the hooves and thumb.

A fully rotating shoulder joint, which allows apes to swing from branch to branch in trees, and the prehensile tail of monkeys are derived traits that define separate ape and monkey branches within the primate. The cattle and deer are divided into two individual artiodactyl branches by their horns and antlers.

Linnaeus defined species as closely related to other species within the same group. From order to class to kingdom to domain, a genera is related to other genera in the same family. The pattern of branching is used by taxonomists to classify taxa into natural groups.

All mammals with even-toed hooves form a single lineage that is assigned to the order Artiodactyla.

Artiodactyla is classified as a family.

During the breeding season, males grow antlers and they can grow large and branched. Artiodactyls with horns form a lineage within the order Artiodactyla that is classified as the family Bovidae. Horns are found on both males and females, although they are smaller in females.

The order Primates is a group of mammals with opposable thumbs. The Hominidae and family Cebidae are two separate families of monkeys and apes that are classified in the order Primates.

Multiple characteristics from a variety of organisms are compared at the same time. This approach can produce various evolutionary trees, because not all traits are equally useful to the study of evolutionary history. The best hypothesis of evolutionary history is being determined.

A cladogram is a representation of the data. The lancelet is in an outgroup with all the other species. A lancelet does not have a trait that is shared by certain species in the study group. All of the species in the ingroup have four limbs. The derived traits show which species are distantly related and which are closely related.

A human is more distantly related to a fish than to an iguana, with which it shares only one trait--vertebrae, four limbs, and an amniotic egg.

The principle of parsimony is used to construct a cladogram. Parsimony considers the simplest solution to be the best solution. The cladogram that requires the least number of evolutionary changes is considered the best hypothesis. When new traits are discovered and incorporated into the construction of a cladogram, it may change.

Our understanding of evolutionary history is constantly changing as we learn more about organisms' lifestyles.

The science is subject to rigorous testing.

A table that summarizes the derived traits of the taxa being compared is the first step in developing a cladogram.

Derived traits are used to determine ancestry. In cladistics, the taxon that is used to determine the ancestral and derived states of characters in the ingroup is the taxa for which the evolutionary relationships are being determined. The outgroup is the lancelet, and the ingroup is all other animals.

Derived traits are those that are present in the ingroup but not in the lancelet. The lancelet is an ancestral trait because it has a dorsal or spine nerve cord.

Each of the clades has a unique trait.

One of the protective layers surrounding a growing embryo is a clade within the chordates that does not include fish. Amniotes are a clade of organisms that have an amnion.

A cladogram is a tree. Each clade has a common ancestor that is shared by all clade members.

The principle of parsimony is applied once derived and ancestral traits have been identified.

Systematic biologists used to rely on morphological data to study evolutionary relationships between taxa. Morphology can be misleading. Birds and crocodiles are more related to each other than lizards, according to recent studies. Linnaeus used wings and feathers to classify birds as different from crocodiles.

We have a wide range of different sources of traits to assist with understanding the evolutionary history of organisms.

Fossil turtles may indicate that they are distantly related to crocodiles.

Rieppel of the Field Museum of Natural History in Chicago is challenging the conventional interpretation that turtles are not related to crocodiles but are related to a common ancestor. His interpretation is supported by data showing turtles and crocodiles to be closely related.

There might be less controversy about the interpretation of fossils if the fossil record was more complete. Most fossils are formed from harder body parts, such as bones and teeth. Soft parts are usually eaten before they have a chance to be buried and preserved. It has been difficult to discover when angiosperms first evolved.

The appearance of the earliest flowering plants may be described by the fossil found recently. The fossil record will reveal more characteristics useful to systematic biologists as paleontologists discover new fossils.

Structural similarity stems from having a common ancestor. Page 347 contains information regarding homology.

The bones of the forelimbs of animals are the same as they were in the common ancestors. Even though a horse has a single digit and toe, a bat has four longer digits that support its wing, a horse's forelimb and a bat's forelimb have the same bones.

Because of convergent evolution,ciphering homology can be difficult. The wings of an insect and a bat are similar.

Analogous structures have the same function in different groups, but they don't have a common ancestry. Both cacti and spurges are adapted to a hot, dry environment, and both are succulent with modified leaves. The flower structure of these plants indicates that they are not related.

The construction of a tree is dependent on discovering and avoiding structures that are similar to each other.

Some dinosaurs cared for their young in a similar way to crocodilians and birds. The data shows that dinosaurs, crocodilians, and birds are related. The leopard frog's mating calls are an example of a behavioral trait that has been used to decipher evolutionary history.

Systematic biologists assume that the more closely related the species, the less changes there will be in their base-pair sequence.

The evolutionary relationships among some mammals are determined by the alignment of a small section of a gene. Each nucleotide is assigned a number and aligned in columns. Information about how organisms are related is provided by individual nucleotides. The sixth nucleotide is a T shared by all mammals.

Chimpanzees and humans have a close relationship thanks to these two genes. Computers are used to perform comparisons of long alignments.

A recent common ancestor for humans and Chimpanzees is supported by a primate phylogeny. The more closely species are related, the less differences there will be in the amino acid sequence.

The phylogeny was determined from the data. The relationship of primate species is based on their genomes. The length of the branches shows the number of differences between groups. It is possible to suggest a date for the other divergences in the tree with the data and knowledge of the fossil record.

It's very easy and inexpensive to collect nucleotides for many different taxa thanks to the advances in biology.

Software has made it possible to analyze a sequence quickly and accurately. Anyone can access the archives of the genes from thousands of organisms.

Nuclear DNA is ten times faster than mtDNA. When determining the phylogeny of closely related species, investigators often choose to sequence mtDNA instead of nuclear DNA. There was a study about North American songbirds.

Birds diverged from each other due to retreating glaciers over 100,000 years ago, according to Ornithologists. The two groups of North American songbirds differed an average of 2.5 million years ago.

Evolutionary theory can be applied to all areas of biology. Human society has been helped by this information. Agriculturalists have used phylogenies of insects to design effective controls of crop pests.

Immunology used to be used to judge the similarity of the different types of cells. The cells of one species are transfused with the rabbit's cells. The degree of the reaction is observed when cells of the second species are exposed to the antibodies.

In the past, it was customary to use a certain method to determine the number of amino acid differences.

We can conclude from the data that chickens and ducks are more closely related to humans. Differences in individual nucleic acids have become a powerful tool for examining evolutionary relationships.

Some nucleic acid changes are neutral and accumulate at a constant rate.

A timeline of evolutionary history can be constructed using these neutral mutations. There are 5.1% differences in the nucleic acid of songbird subspecies. The average rate at which mtDNA changes occur is called the mutation rate, and is measured in the number of mutations per unit of time.

The researchers used their data as a clock to show the difference between songbird subspecies.

The researchers used their data to show how long the different types of primate have been separate. The fossil record for one divergence shows how long it takes for each pair to change. Researchers have more confidence in the proposed tree when the fossil record and clock data agree.

Take a look at the various traits used to make a phylogeny.

Taxonomy uses a set of categories to classify organisms.

New information has been included in the classification system over time. The system was expanded in the late 1970s.

A taxon's unique characteristics are shared by their common ancestor in the form of phylogenies.

The one with the lowest number of evolutionary steps is the most parsimonious cladogram. Systematic biologists study evolutionary relationships with the help of fossil, morphological, and behavioral traits.

We can sometimes trace a lineage through time if the fossil record is complete.

Multiple lines of evidence can provide more confidence in the tree.

Pick the best answer for the question.

There is a class below the level of family.

The dates of divergence are always given.

Descendants are given rise to by common ancestors.

The discovery of common ancestors in the fossil record helps scientists classify organisms.

Some plant taxonomists believe that the traditional way of classifying flowering plants is not correct, and that they need to be completely reclassified. It would be foolish to ignore the historical classification groups according to other botanists. Keep traditional classification schemes.

The classification of Chimpanzees and Humans has been changed because of the similarity of their genomes and the differences between them.

Humans and Chimpanzees are placed in the same family. They are in a category that is rarely used.

Tell us why you prefer one method over the other.

It's richly populated because it includes the viruses, the prokaryoticbacteria and archaea, and the eukaryotic protists and fungi. These organisms can be found anywhere from the highest mountain peaks to the deepest ocean trenches.

We use microbes in many ways, even though some cause diseases in plants and animals. Gene cloning and genetic engineering, making foods and antibiotics, and disposing of sewage and environmental pollutants can all be accomplished by the help ofbacteria. The biosphere is dependent on the services of organisms.

Plants can absorb all the nutrition they need because their roots are covered with friendly fungi. Some protists are the producers of food in the oceans because they put oxygen in the atmosphere.

Microbes are our ancestors.

Even though we can't see the organisms without a microscope, this unit talks about them.

Take a few moments to review the discussions before you start this chapter.

The workers are trying to stop the spread of the disease.

It is believed that a 1-year-old boy contracted the disease while playing near a tree that housed a species of bat that is known to carry the virus. The outbreak became the largest in history as it spread to other countries and cases were recorded in Nigeria, Africa.

According to the CDC, there have been over 11,000 confirmed deaths from the disease in West Africa. The complete toll from this outbreak may never be known because most agencies believe the numbers are underestimates.

The fear of the disease is that it belongs to a family of viruses that cause a disease that targets several different cell types in the body, including the immune system and the blood vessels. Most deaths are due to fluid loss, organ failure, or an overall failure of the immune system, not the disease that causes widespread bleeding.

The virus can be transmitted by direct contact with a person's body fluids.

There are many myths about the Ebola virus. You can get the disease from contact with cats and dogs, antibiotics are an effective treatment, and the virus is airborne. In order to make more copies of itself, it must invade specific cells of the body and hijack the cell's metabolism.

We will look at viruses along with other members of the microbial world.

The basic structures of a virus can be identified.

There is a Page 354 number of plant, animal, and human diseases. The mere mention of the term brings to mind diseases such as AIDS, as well as diseases that used to be common in childhood. It is estimated that the average person catches a cold several times a year because of the viral diseases.

Viruses are a mystery. The ability to evolve and replicate is one of the characteristics of living organisms. They do not have a metabolism, they do not respond to stimuli, and they use the metabolism of a host cell to replicate.

It is difficult to study the history of Viruses because they do not fossilize. There are a number of hypotheses regarding their origin and evolution. Hypotheses about the origin of life suggest that the two organic molecule present in viruses were the first to evolve. It is possible that living cells and viruses came from the same place at the same time. An alternative hypothesis suggests that the viruses came from living cells.

Tobacco mosaic disease, which causes damage to the leaves and fruit of tobacco plants, was studied by a Russian microbiologist in 1892. He noticed that an infective extract still caused disease even after it was removed from a fine-pore porcelain filter. Pasteur believed that the disease-causing agent was smaller than any known one.

Viruses were seen for the first time in the twentieth century. By the 1950s, the study of viruses and prions has contributed to our understanding of disease, genetics and the characteristics of living organisms.

Viruses are not living organisms and are difficult to classify. The classification system used for living organisms has been developed by the International Committee on Taxonomy of Viruses. The higher levels of kingdom, class, and order are not included in viral classification.

When a new type of virus emerges within a single species of virus, additional classification levels are required for clear identification. The type of two glycoprotein spikes in the envelope, hemagglutinin (H) and neuraminidase (N), are what determines the type of influenza A.

The size of a large macromolecule is 10 to 400 nm. Viruses can be studied through electron microscopy. Many viruses can be stored in the same way as chemicals are. When viral particles are given the chance to invade a cell, they become infectious.

The outer capsid of all viruses is composed of only one type of DNA orRNA, but not both. Some viruses have a membranous envelope.

Viruses can be threadlike or polyhedral. All viruses have the same basic structure, consisting of an outer capsid and an inner core of nucleic acid.

The virus is said to be naked if the viral capsid is the outermost structure. The viruses are surrounded by membranous glycoprotein spikes. Each virus has a different set of molecules that allow it to bind to a new cell. A viral particle's genome is not the only part of it's structure that is important to produce viral DNA and/orRNA.

Viruses have the same genetic material as prokaryotic and eukaryotic cells. A virus cannot duplicate its genetic material or any of its other components on its own because a cell can. A living cell is the only way a virus can be reproduced. Once inside a living cell, the virus hijacks the cell's synthesis machinery to replicate the nucleusc acid and other parts of the virus, including the capsid, viral enzymes and the envelope.

Cells that are killed or damaged by a replicating virus can cause symptoms associated with viral infections. When adenoviruses are complete, cells in the respiratory tract are lysed, which leads to conditions such as bronchitis and pneumonia.

Only plants in the tobacco family are affected by the tobacco mosaic virus. Human viruses can be specific to a particular tissue. The human immunodeficiency virus only enters certain blood cells and the other viruses only enter certain nerve cells.

Host specificity is determined by the structure of the naked capsid. Attaching these in a lock-and-key manner with a receptor on the host cell's outer surface. A cell that doesn't have a receptor to match a virus can't be infections because it won't be able to enter. The lock-and-key attachment of viruses to host cells is interfered with by many antiviral medications.

Viruses hijack the metabolism of a host cell during their reproduction cycle, which consists of five steps. A virus binding to a specific host cell is based on the host specific match between the virus surface molecule and the host cell receptors.

The virus injects its genome into the host cell.

The host's ribosomes, tRNA, and energy are used to synthesise new viral components.

New viruses are made from viral components.

New viruses exit the host cell through lysis or budding.

There are exceptions to the reproductive cycle of different types of viruses.

"To eat" are viruses that attackbacteria. Scientists can use the model to study the reproductive cycle of viruses.

The cell is broken open in the lytic cycle. In the lysogenic cycle, host and viral DNA are integrated. The lytic cycle can be followed by the lysogenic cycle in the future.

The lytic cycle is named because the host is lysed at the end of the cycle. Several hundred new viral particles are released after the cell dies.

When a virus enters the lysogenic cycle instead of the lytic cycle, reproduction may take place in the future.

Sometime in the future, certain environmental factors, such as ultraviolet radiation, can induce the prophage to re-enter the lytic stage of biosynthesis, followed by maturation and release.

There are prophage genes that lysogenicbacterial cells carry. The presence of a prophage can cause a cell to make a toxin. If the Page 358 bacterium that causes strep throat carries a prophage that causes a red skin rash, then it will cause scarlet fever, which is named because the toxin causes a widespread red skin rash as it spreads through the body.

The cause of diphtheria is caused by a bacterium. The lining of the upper respiratory tract is damaged by the diphtheria toxin.

Different animal viruses have different ways of introducing their genetic material into their host cells. The process of attachment and fusion of the envelope with the host cell is as simple as it gets. Endocytosis is the process of taking nude and nude viruses into host cells. The capsid and envelope are removed if necessary after the virus enters. The viral genome is no longer covered and the virus can enter the lysogenic cycle.

The rapid and severe destruction of host cells is caused by Viruses that enter directly into the lytic cycle. 50% of people die from the disease within 2-21 days of being exposed to it. HIV enters first into the lysogenic cycle and can be inactive for many years before AIDS symptoms emerge.

The penetration for animal viruses is variable. Some mature viruses are released.

Some animal viruses take envelopes from other parts of the cell, such as the nuclear envelope or Golgi apparatus.

Host celllysis releases naked animal viruses.

Figure 20.3 shows the reproduction of HIV.

HIV uses reverse transcription and double-stranded DNA to make a copy of the genes in the cell. It is unique to retroviruses.

Before a retroviruses can integrate into the host's genome, or use the host cell's machinery to translate its proteins, it must first convert its RNA to DNA. The reverse transcriptase is able to synthesise from itsRNA genome a single DNA strand, called cDNA, which is a complement to the viral RNA. The single strand of cDNA is used as a template.

The double-stranded virus DNA is integrated into the host genome. When host DNA is replicated, the viral DNA remains in the host genome. In the case of HIV, the new viruses are produced by the steps already cited: biosynthesis, maturation, and release. HIV can remain undetected for a long time. The median survival time after HIV is 9-11 years without treatment.

The emergence of AIDS can be delayed by treatment with antiretroviral drugs, which interfere with one or more of the steps of HIV reproduction. One type of antiretroviral drug, AZT, consists of reverse transcriptase inhibitors, which bind to reverse transcriptase and interfere with its function. Acyclovir is a drug that is used to treat a variety of diseases.

It is difficult to find a cure for HIV, which is a rapidly evolving virus. HIV is engaged in an "arms race" with an animal's immune system. Although a new drug or vaccine may work against some, it is very likely that one type within the billions of virus copies will evolve resistance and continue the infection. There is no cure for HIV because of the rapid evolution of resistance.

Emerging diseases are caused by viruses that are able to cause large numbers of humans to get sick.

There are several types of events that can cause a viral disease to arise and cause a widespread human illness.

There are emerging diseases. Emerging diseases are new or have increased prevalence.

The agents may have acquired new virulence factors or the environment may have encouraged their spread.

West Africa and Southeast Asia were the only places where the virus was found before 2007. There was an outbreak in Brazil in 2015.

An individual with the strain from Southeast Asia was brought to the region. The outbreak was caused by a suitable environment that included high populations of mosquitoes and a susceptible human population. This outbreak could spread across the Americas, including the United States, as was discussed in the Biological Systems feature.

The H spike allows the virus to bind to itsreceptor, and the N spike allows mature viruses to exit the cell. There are at least 16 types of H and 9 types of N spikes. The type of spike is what determines the codes assigned to the flu viruses. The H5N1 virus has a variety of H5 spikes and N1 spikes.

Our immune systems can only distinguish between the different types of H and N spikes they have been exposed to in the past. There is little or no immunity in the human population to a new flu virus that can cause a global outbreak.

The H7N9 and H5N1 strains of flu virus have the potential to reach epidemic proportions. The ability of these viruses to spread from birds to humans has led to severe illness and death.

Humans become infections because the H spikes can attach to both a bird flu and a human flu. The virus has rarely been transmitted from one human to another, and close contact between domestic poultry and humans is necessary for this to happen.

Bird flu can be transmitted by coughing or sneezing, but it's rare at this time.

The new virus would be lethal in both cases. Half of the people who get the H5N1 or H7N9 virus die, and there is no vaccine for it.

The H5N1 and H7N9 viruses have the same names.

The human upper respiratory tract could be affected by bird flu. A combination of bird flu and human spikes could allow the virus to enter the human upper respiratory tract.

Between 2015 and 2016 Brazil experienced a dramatic increase in the number of babies born with microcephaly or abnormal smallness of the brain.

Health officials were investigating an outbreak of an illness that caused rash, inflammation, and pain. Microcephaly, a condition in which babies are born with small heads, was caused by the Zika virus and researchers concluded that it could be passed from a mother to a fetus.

When a person is bitten by a mosquito, the virus can be passed on to new mosquitoes.

It can also be spread through sexual contact with an individual who has the disease.

Researchers were able to trace the genetic code of the virus in Brazil and conclude that it arrived in the country during a soccer tournament.

A mosquito extinction gene is being pursued as a permanent approach to prevention. The solution may lie in the organisms that spread the disease.

The offspring will not survive if they mate with a female.

The population will decline eventually. Within several months, small-scale trials have reduced populations by 80%.

Microcephaly is a condition caused by the spread of the mosquito-borne disease, and can be contracted from a pregnant mother to her infant.

The virus can jump to other species, including humans. It is necessary to have a flu shot every year because the antibodies generated from last year's shot are not expected to be effective this year.

There are many different viruses that cause diseases in plants. A number of diseases of crops, including potatoes, coconuts, and citrus, have been attributed to the fact that they are not viruses. The cell can produce more viroids.

Prions are normally found in an animal but have a different structure. Like viruses, prions can't replicate on their own but can cause infections by interacting with a normalprotein. As simple as changing a chemical bond, the process of changing the structure of the normalprotein to the prion can be done. Once a prion enters a body, a chain reaction begins that converts normal proteins to prions.

Small holes in the brain are created by clusters of prion proteins that break down normal brain tissue. TSEs are fatal and untreatable. Mad cow disease, or bovine spongiform encephalopathy, is a neurodegenerative disease of cattle that is transmissible to humans by eating cattle brains or meat contaminated with prion-infected brain tissue. The discovery of prions began when it was observed that members of a primitive tribe in the highlands of the country died from a disease. The cannibalistic practice of eating a dead person's brain caused the disease.

The lytic and lysogenic cycles of viral reproduction are compared.

Why is it beneficial to a virus if its host is dead?

bacteria and archaea are fully functioning, living, single-celled organisms. The prokaryotes were not discovered until the 17th-century Dutch microscopist Antonie van Leeuwenhoek described them.

He believed that the "little animals" he observed could arise spontaneously. When the meat was spoiled, it was thought that the flies came from it.

Scientists have conducted various experiments to determine the origin of organisms in laboratory cultures.

It showed that a previously sterile soup can't become cloudy with microorganism growth if it's exposed to the air.

Pasteur performed these types of experiments to disprove the theory of Spontaneous generation of microbes.

Today, we know that there are lots ofbacteria in the air, water, and soil and that newbacteria arise from the division of existingbacteria. We know a lot about the structure ofbacteria, how and where they live, where they get their nutrition, and how they coordinate their replication. First, we will look at the general characteristics of prokaryotes, then we will look at the specific characteristics of domain Bacteria and domain Archaea.

Prokaryotes range in size from 1 to 10 um in length and from 0.7 to 1.5 um in width. The average human is about 1.5 m tall, or 1 million times longer than a bacterium. According to the fossil record, the prokaryotes were alone on Earth for 2.5 billion years. They became very diverse in structure and metabolism during that time. Prokaryotes are adapted to living in most environments because they have a wide variety of ways to get and use energy.

Page 362 has a cell wall outside of the membrane.

Depending on the type of prokaryote, there may be another layer outside the cell wall.

The flagellum of a bacterium has a hook and a body.

A well-organized glycocalyx is called a capsule, whereas a poorly organized one is called a slime layer. These outer coverings help protect the cell from the host defenses.

The flagellum has a helix with strands of the flagellin wound. The hook is anchored by a body. The rotation of the flagellum causes the cell to spin. The archaeal flagellum is more slender and lacks a body.

Short, bristlelike fibers extending from the surface.

The membranous organelles of a eukaryotic cell is absent in a prokaryotic cell.

ribosomes are smaller than eukaryotic ribosomes and are used to synthesise prokaryotic cells.

Imagine becoming a scientist. The image of a scientist is changing. For about $250, you can purchase materials to perform a sophisticated experiment to create a glowing plant in your own home.

A project like this is part of a movement called do-it-yourself biology, where amateurs are doing modern biology experiments in their kitchens, garage, and community lab spaces.

The project requires a gene that codes for green fluorescent protein, which glows when exposed to ultraviolet light.

It isn't a mechanical device to get the genes into the plant. The plant transformation is done by themediated plant transformation.

Some of the seeds produced by the original plant will grow into glowing plants if the procedure is done correctly.

In prokaryotes, it is not possible to form a spindle apparatus.

Prokaryotes divide to reproduce when conditions are favorable. The daughter cells have the same genetic material as the parent cells, so this is a form of asexual reproduction.

As the cell enlarges, the two copies separate as the single circular chromosome replicates. The cell is separated into two cells by a wall. Under favorable conditions, prokaryotes can have a generation time as short as 12 minutes. The offspring are passed on more quickly than in otheryotes. Natural selection determines any possible adaptive benefit in the particular environment because prokaryotes are haploid.

Sexual reproduction results in genetic recombination. There are three ways of genetic recombination that have been observed in prokaryotes.

A conjugate pilus is used to link two bacteria temporarily. The donor cell passes its genetic material to the recipient cell.

A portion of a cell's genetic material is carried from one cell to another.

There are three ways in which prokaryotes can recombine their genetic material.

There are similarities and differences in the cell wall structure of Gram-positive and Gram-negativebacteria.

Understand the three types ofbacteria and how they get their nutrition.

The more common type of prokaryote is the bacterium.

They are found in almost every environment on Earth. In this section, we look at the bacteria's characteristics, metabolism, and lifestyle.

The structure of the cell wall is what distinguishes Gram-positive and Gram-negativebacteria.

It is difficult to treat Gram-negative infections because they are surrounded by a second cell wall, which blocks antibiotics.

The thick peptidoglycan layer traps crystal violet dye so the Gram positivebacteria appear purple after the Gram stain. Gram negativebacteria do not retain the crystal violet dye and so exhibit the red counterstain, because they have less peptidoglycan between the outer and the plasma membranes. A micrograph shows the results of a Gram stain.

All rights belong to the person. After the Gram stain process, Gram-positive and Gram-negativebacteria appear red and dark purple, providing a useful first step for identifying the cause of an infection.

In addition to cell wall type and shape,bacteria can be characterized by their growth arrangement.

bacteria are diverse in their lifestyles

bacteria are not different from other organisms The need for oxygen is one of the differences. Like animals, mostbacteria need a constant supply of oxygen to function. facultative anaerobes can grow in either the presence or absence of oxygen. Some obligate anaerobes can't grow in the presence of free oxygen.

A few serious illnesses, such as botulism, gas gangrene, and tetanus, are caused by the same type ofbacteria that can be found in the gut or deep puncture wounds.

The photoautotrophs are calledbacteria. For a review of photosynthesis, "food" are photosynthetic. They use solar energy to reduce carbon dioxide. There are two types of photoautotrophicbacteria, Page 366 those that perform anoxygenic photosynthesis and those that perform oxygenic photosynthesis.

Some purplebacteria carry out anoxygenic photosynthesis. The muddy bottom of a marsh is where thesebacteria live. They don't emit oxygen and can't photosynthesize in the presence of it.

There is a type ofbacteria called chemoautotrophs. "food" is used to carry out chemosynthesis. They oxidize compounds such as hydrogen gas, hydrogen sulfide, and ammonia to get the necessary energy to reduce CO2 to an organic compound.

nitrites to nitrates.

Otherbacteria oxidize sulfur compounds. They live in environments that are 2.5 km below sea level.

The growth of a community of organisms found at deep-sea vents is supported by the organic compounds produced by suchbacteria and archaea. The discovery supports the idea that the first cells came from these vents.

Thebacterial called chemoheterotrophs. "different" obtain carbon and energy from other living organisms. The living host's tissues and fluids are fed by parasites.

There is no natural organic molecule that can be eaten by at least one prokaryotic species and this plays a critical role in recycling matter.

Humans have been exploiting the metabolism of chemoheterotrophicbacteria for a long time. ethyl alcohol, acetic acid, butyl alcohol, and acetones are some of the chemicals produced by the bacterium.

The production of butter, cheese, sauerkraut, rubber, silk, coffee, and cocoa are all done by the same organisms. Antibiotics are produced by some organisms.

Two different species live together in an intimate way.

Both species benefit from the association.

We can use K and B to make blood components. In the stomachs of cows and goats, mutualistic prokaryotes digest cellulose, which allows the animals to feed on grass. Nitrogen fixation is a process in whichmutualisticbacteria reduce atmospheric nitrogen to ammonia in the root nodules of soybean, clover, and alfalfa plants. Plants can't fix atmospheric nitrogen, sobacteria are the only source of usable nitrogen.

The plant can use atmospheric nitrogen as an organic nitrogen.

Commensalism occurs when one population modifies the environment in a way that benefits another population.

There are some parasites that cause diseases and are listed in Table 20.2. The growth of microbes does not cause disease in some cases.

The result could be a high temperature and a drop in blood pressure that could lead to death.

The tetanus toxin produced by the bacteria moves throughout the body. The relaxation of muscles is prevented by this toxin.

The page contorts because the muscles have contracted.

Fimbriae allow a pathogen to bind to certain cells, and their specificity determines which organs or cells of the body are its host. Invasive mechanisms that allow a pathogen to move through tissues and into the bloodstream result in a more medically significant disease. A life-threatening disease can result from this.

When faced with unfavorable environmental conditions. A portion of the cytoplasm and a copy of the chromosomes are encased in a protective endospore coat after they become dehydrated. The endospore is released when the rest of the cell degrades.

bacteria that produce a neurotoxin can be released if a wound is gained access to. tetanus can be fatal if the patient develops it, and immunization can prevent it.

Desert heat and dehydration, boiling temperatures, polar ice, and extreme ultraviolet radiation are just some of the environments in which elastophytes survive. They live for a long time. Animals and sheep can get a severe infection from the 1,300 year old anthrax. Humans fear a deadly type of food poisoning called botulism, which is caused by the growth of parasites inside cans of food. The endospore grows out of the endospore coat. In a few hours' time, it becomes a typical bacterial cell, capable of reproducing once again. It's not a means of reproduction, but it allows the survival and dispersal ofbacteria to new places.

Many antibiotic compounds are widely prescribed. There are two classes of antibacterial compounds, those that affect the cell wall and those that don't. Two types of antibiotics, erythromycin and tetracyclines, work differently than eukaryotic ribosomes. Antibiotics that block the formation of peptidoglycan are necessary to maintain the integrity of the cell walls. Penicillin, ampicillin, and fluoroquinolone do not harm animal cells.

When not needed, antibiotics are often prescribed to treat infections. Increased use of antibiotics has led to increased resistance to antibiotics. Genes that confer resistance to antibiotics can be transferred. A lot of people are resistant to penicillin and methicillin because of the advantage that comes with it.

People with open wounds and weakened immune systems are more likely to be affected by MRSA in hospitals and nursing facilities.

There are a number of unusual features of the conobacteria. They are believed to be the first to introduce oxygen into the primitive Page 368 atmosphere. The cyanobacteria were once called bluegreen algae, but now they are classified as prokaryotes. The blue-green color of chlorophyll can be masked by other pigments that make them appear red, yellow, brown, or black.

There is no visible means of locomotion for the organisms, although some glide when in contact with a solid surface and others oscillate.

Heterocysts, which are thick-walled cells without nuclei, are an advantage for some cyanobacteria. Their nutrition requirements are minimal because of their ability to fix atmospheric nitrogen. They can be used as food for Heterotrophs.

In fresh and marine waters, in soil, and on moist surfaces, but they are also found in harsh habitats, such as hot springs. They are symbiotic with a number of organisms. They can grow on rocks. In a lichen, the cyanobacterium provides organic nutrition to the fungus, while the fungus may protect and give up some of the nutrition to the cyanobacterium. It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 Other forms of life may follow after Lichens transform rocks into soil. It is thought that the first colonizers of land were the cyanobacteria.

In another way, cruciobacteria are important.

Light cannot penetrate the surface of the water. The fish die from lack of oxygen when a portion of the cyanobacteria die off.

The atmosphere of early Earth may have been affected by cyanobacteria.

At one time, archaea were considered to be a unique group ofbacteria.

As evolution occurs, any changes in rRNA sequence probably occur at a slow, steady pace.

Section 19.2 states that the tree of life contains three different parts. Archaea and somebacteria are found in extreme environments such as hot springs and thermal vents, which may have caused them to differ from a common ancestor. The archaeal line of descent gave way to the eukarya. The archaea are more closely related to the eukarya. Both Archaea and Eukarya share some of the same ribosomal proteins, initiate transcription in the same way, and have similar types of tRNA.

Archaea have biochemical characteristics that distinguish them from other organisms. Many of the unusual lipids in the archaea plasma are able to function at high temperatures. The lipids of archaea are linked to branched chain hydrocarbons, while the lipids ofbacteria are linked to fat.

Diverse cell wall types allow Archaea to survive under extreme conditions. The cell walls of archaea do not contain peptidoglycan. In some archaea, the cell wall is mostly made of polysaccharides, and in others, it is mostly made of proteins.

The Archaea were found living in extreme environmental conditions. The three main types of archaea are methanogens, halophiles, and thermoacidophiles.

There are salt lakes where halophilic archaea can live. There are hot springs in the park. They live in swamps and in the guts of animals.

The need for high salt concentrations is usually 12-15%.

These archaea are able to survive in environments that are high in salt. To prevent osmotic water loss to the hypertonic environment, halophiles increase solutes such as chloride ion, potassium ion, and organic molecule within the cell, creating an internal environment more isotonic to the outside salt water. The halophiles don't have to compete with as many organisms as they would in a more moderate environment.

Some of these organisms can carry out a unique form of photosynthesis if their oxygen supply becomes scarce, but they are aerobic chemoheterotrophs.

The halophiles use a purple color called bacteriorhodopsin to capture solar energy for use in synthesis.

halophiles are adapted to a high-saline environment and will die if placed in a solution with a low salt concentration.

They use hydrogen and sulfur as terminal electron acceptors for their electron transport chains.

It is not surprising that thermoacidophiles grow best at extremely low pH levels.

The methanogens are obligate anaerobes found in environments such as swamps and marshes. Methanogenesis is a type of metabolism performed by some archaea. H2 is used by methanogens to reduce carbon dioxide and methane to methane and to couple the energy released to ATP production.

The greenhouse effect and climate change are caused by methane being released into the atmosphere. Methane is produced by the methanogenic archaea.

Methanogenic archaea can help us anticipate what life will be like on other bodies. In eastern Idaho, there is an unusual microbial community in the Lidy Hot Springs. The springs are rich in H2 but lacking in organic nutrients. The majority of the springs are inhabited by methanogens and archaea. Similar methanogenic communities may one day be found beneath the surface of Mars and one of Jupiter's moons. The most abundant element in the universe is hydrogen, which is readily available for use by methanogens.

archaea are found in all moderate environments, even though they are capable of living in extremely stressed conditions. Some archaea have been found living with sponges and sea cucumbers.

The roles of archaea are still being explored. A group of nitrifying marine archaea has recently been discovered. Some scientists think that the archaea may contribute to the supply of nitrite in the oceans. Plants and other producers can use nitrate, a form of nitrogen that can be used to make nucleic acids, by converting nitrite to nitrate. The Archaea have also been found in the soil and in the rice paddies.

There are differences between archaea andbacteria.

The three types of archaea are distinguished by their unique habitats.

The Archaea are thought to be related to the eukaryotes.

Viruses are non living and can change quickly.

Some contain an outer membranous envelope with spikes used for attachment to host cells.

Viruses can only attach to the cells of certain organisms. The host cell is forced to make new virus copies when a virus hijacks it.

The spikes lock the capsid to the cell.

The cell has a viral genome.

New viral components are created by using host cell and ribosomes.

New viruses are made from viral components.

The host cell is the exit point for new viruses.

The lytic cycle of the viral genome will continue for a long time.

The genomes of animal cells need to be free from the capsid of the viruses that cause them, either budding or lysis.

The first living cells did not have a nucleus and did not have a cytoplasm.

The difference between cell wall types is highlighted by gram staining. Gram-positive and Gram-negativebacteria have different cell wall densities, with Gram-positivebacteria having a thick peptidoglycan cell wall and Gram-negativebacteria having a thinner cell wall. The three basic shapes ofbacteria are spiral-shaped, rod-shaped and round.

Prokaryotes have differing needs for oxygen.

The archaea appear to be more related to the eukarya than to the bacteria.

The Archaea do not have peptidoglycan in their cell walls, while thebacteria do.

Moderate environments are where Archaea are found.

Pick the best answer for the question.

Viruses do not live.

The host cell is the source of the animal virus envelope.

They are not dead.

They don't have a nucleus.

The lytic cycle is used to reproduce prokaryotes.

The peptidoglycan cell wall is thinner.

The cell wall ofbacteria is made of lipopolysaccharide.

A constant supply of oxygen is required for cultivateative anaerobes.

There are prokaryotes.

A prokaryote that gains organic molecule from other living organisms is called a photoautotroph.

Methanogens are Gram-negativebacteria that first introduced oxygen into the atmosphere.

Some archaea form methane.

Most viral infections are untreatable. Severe side effects on the patient are possible with few antiviral drugs.

Antibiotics work by targeting specific structures and functions. The side effects on the patient are usually minimal because their cells do not have the same structures and characteristics.

The consumption of organic waste and carbon dioxide and the creation of oxygen, alcohol, methane, nitrates, and antibiotics are just some of the things that archaea andbacteria can do. The known capabilities come from only a small portion of prokaryotes.

Scientists theorize that at least 10% of the population are undiscovered and have the potential to benefit human life.