13.1 Prokaryotic Diversity

• Two of the three domains--bacteria and Archaea--lack both a nucleus and true membrane bound organelles.
• They are now considered to be as different from each other as they are from the third domain.
• The first inhabitants on Earth were prokaryotes.
• They live in the most extreme environments on the planet, from boiling hot springs to permanently frozen environments in Antarctica, as well as more benign environments such as compost heaps, soils, ocean waters, and the guts of animals.
• The kingdoms of animals, plants, and fungi are included in the Eukarya.
• A diverse group of kingdoms used to be grouped together as protists.

• By the end of this section, you will be able to: They live on and inside of other living things because they cover every surface with enough water.
• There are more prokaryotes in the human body than there are human cells.
• Some prokaryotes thrive in inhospitable environments.

• Carbon and nitrogen are recycled by prokaryotes and they drive the evolution of new ecosystems, some of which are natural while others are man-made.
• Since long before multicellular life appeared, prokaryotes have been on Earth.

• The relationships and origins of prokaryotes that were not possible using traditional methods of classification were provided immense insight by the advent of DNA sequencing.
• Two groups of prokaryotes were found to be very different from each other.
• A new understanding of the classification of all life and the fundamental relationships of all living things was brought about by this recognition.

• The first forms of life on Earth were prokaryotes, which existed for billions of years before plants and animals appeared.
• The planet is 4.54 billion years old.

• Evidence from the dating of meteorite material shows that the surface rocks on Earth are not as old as the Earth itself.
• Rocks on Earth have undergone geological changes that make them younger than they are.
• The original material in the solar disk that formed the objects of the solar system is what makes some meteorites.
• The age of meteorites is a good indicator of the age of Earth.
• The original estimate is 4.54 billion years.
• According to ages determined from other sources, the Earth is 4.54 billion years old.

• The atmosphere on Early Earth was different than it is today.
• Within one billion years of the formation of Earth, phototrophic organisms needed an organic source of carbon.
• Carbon dioxide can be used as a source of carbon.
• The oxygenation of the atmosphere began with the help of the cyanobacteria.
• The evolution of other life forms was aided by the increase in oxygen concentration.

• There is a hot spring in the park.
• The intensity of the green color in the spring is due to the cell density increasing.

• The edges of the stream appear green because the water is cooler at the edges than in the center.

• The first organisms would have flourished where they were more protected, such as in ocean depths or beneath the surface of Earth, because before the atmosphere became oxygenated, the planet was subjected to strong radiation.
• It is likely that these first organisms were adapted to very high temperatures because of the volcanic activity on Earth.
• We can conclude that the first organisms that appeared on Earth were able to survive harsh conditions, because these are not the typical environments in which most life thrives today.

• Microbial mats are thought to be the earliest forms of life on Earth, and there is fossil evidence of them.
• Microbial mats are a few centimeters thick and grow on moist surfaces.

• Different types of prokaryotes carry out different pathways and reflect different colors.

• The prokaryotes are held together by a gummy-like substance.

• The first mats probably got their energy from the vent.
• About 3 billion years ago, some prokaryotes in the mats came to use a more widely available energy source--sunlight--whereas others were still dependent on chemicals from the vent for food.

• The arrow shows a chimney that allows gases to escape.

• Fossilized mats are the earliest record of life on Earth.
• Stromatolites are rocks made of carbonate or silicate.
• There are places on Earth where stromatolites are still forming, even though most stromatolites are artifacts from the past.
• There are living stromatolites in the Anza-Borrego Desert State Park.

• Some prokaryotes can grow and thrive in conditions that would kill a plant or animal.
• Extreme environments include the depths of the oceans, hot springs, thearctic, and very dry places, as well as harsh chemical environments and high radiation environments.
• The discovery of new therapeutic drugs or industrial applications can be made with the help of extremists.
• They have made it possible to find life in other places in the solar system, which have harsher environments than on Earth.
• Moderate environments are not suitable for many of these extremophiles.

• The Director of the Planetary Science Division of NASA talks about the possibility of finding life on other planets in our solar system in a video.

• Microbiologists used to think of prokaryotes as separate entities.
• The model does not reflect the true ecology of prokaryotes, who prefer to live in communities where they can interact.

• Films grow on surfaces.
• Some of the best-studied biofilms are composed of prokaryotes.

• Almost everywhere there are biofilms.
• They cause the pipes to fail and cause problems in industrial settings.
• They played a role in the recent large-scale outbreak of food-borne illnesses.
• Kitchen countertops, cutting boards, sinks, and toilets are all colonized by biofilms.

• These communities are more robust because of the interactions among the organisms that populate them.
• biofilms are resistant to many forms of sterilizing, so they are difficult to destroy.

• There are differences between the two types of cells.
• All cells have four structures that are 888-609- 888-609- 888-609- 888-609- 888-609-

• There are three categories of prokaryotes: cocci, bacilli, and spirilla.

• There are three basic categories for prokaryotes: cocci, bacilli, and spirilla.
• Prokaryotes are unicellular organisms that don't have any organelles.
• They don't have a nucleus but instead have a piece of circular DNA located in an area of the cell called the nucleoid.
• Most prokaryotes have a cell wall.
• The cell wall is responsible for the shape of the organisms.

• Some structures are present in some species, but not in others.
• Some species have flagella used for locomotion and pili used for attachment to surfaces.
• Many species ofbacteria have plamids, which consist of small, circular pieces of DNA outside of the main chromosomes.

• The features of a bacterium cell are shown.

• There are two types of prokaryotic cells.
• They differ in the composition of their cell walls.
• The basic structures of both types of prokaryotes are the same, but they are built from different chemical components.
• Some archaeal membranes are not phosopholipid bilayers as compared to the bacterial one.

• The cell wall surrounds some prokaryotic cells and gives them shape and rigidity.
• It is located outside the cell's outer shell and prevents osmotic lysis.
• The composition of the cell walls are different betweenbacteria and Archaea.
• Cell wall structure is the cause of the different responses to the staining procedure.

• Gram-positive and Gram-negative are the major groups of the bacterium.
• Both groups have a cell wall composed of peptidoglycans.
• In Gram-negativebacteria, the cell wall is surrounded by a protective barrier.

• The Archaeal cell walls do not contain peptidoglycan.
• There are different types of archaeal cell walls.
• S-layers are found in the other three types of cell walls.

• Asexual reproduction is the main method of reproduction in prokaryotes.
• The prokaryote's DNA is usually a single, circular chromosome.
• Contrary to popular belief, prokaryotes don't undergo mitosis.
• The chromosomes loop is duplicated and the two resulting copies are separated as the cell grows.
• The prokaryote is pinched inward at its equator and the two resulting cells are clones.
• Prokaryotes can alter their genetic makeup in a number of ways.

• If a nonpathogenic bacterium takes up a pathogen's genes and puts them in its own, it may become a problem.
• There are different types of viruses that Archaea have that can cause genetic material to be transferred from one person to another.
• The chromosomes can be moved if the plasmid is transferred.

• On the order of minutes for some species, there can be a rapid cycle of binaries fission.
• The rapid evolution of prokaryotes is possible because of the short generation time and mechanisms of genetic recombination.

• Prokaryotes are diverse.
• There are many niches on Earth, including being involved in the nitrogen and carbon cycles, decomposing dead organisms, and growing and multiplying inside living organisms, including humans.
• The OpenStax book is free and can be found at http://cnx.org/content/col11487/1.9.
• Phototrophs get their energy from the sun.
• Chemotrophs get their energy from chemical compounds.

• Humans have been affected by diseases and plagues in nature.
• There are no known pathogenic Archaea in humans or any other organisms.
• Humans and pathogenic organisms evolved together.
• The true cause of these diseases was not understood in the past, and some cultures thought that diseases were a spiritual punishment or were mistaken about material causes.

• Staying apart from people who are sick, improving Sanitation, and properly disposing of corpses and personal belongings of sick people reduced their own chances of getting sick.

• There were infectious diseases as far back as 3000 B.C.
• The decline of cities and cultures was caused by some of the largest pandemics.

• In the case of Tuberculosis, many were zoonoses that appeared with the domestication of animals.
• A zoonosis is a disease that can be transmitted from animals to humans.

• The leading causes of death are infectious diseases.
• They are important determiners of mortality in developing countries, even though their impact is less in developed countries.
• The development of antibiotics reduced the mortality rates from infections, but access to antibiotics is not universal, and the use of antibiotics has led to the development of resistant strains ofbacteria.
• Public Sanitation efforts that dispose of sewage and provide clean drinking water have done more to prevent deaths caused bybacteria than medical advances.

• The plague of Athens killed 25% of the Athenian troops that were fighting in the Great Peloponnesian War.
• A quarter of the population of Athens was killed by the disease over the course of four years.

• The source of the plague may have been identified recently when researchers from the University of Athens were able to analyze DNA from teeth recovered from a mass grave.

• One-quarter to one-half of the human population was wiped out by the plague of Justinian from 541 to 750 A.D. Europe's population declined by 50 percent during this outbreak.

• Europe would be ravaged by the plague more than once.

• Black rats carry a bacterium that is carried by fleas.

• The world's population was reduced from 450 million to about 350 million by the Black Death.
• The plague hit London again in the 1600s.
• Approximately 1000 to 3000 plague cases are reported each year.

• The mortality rates from plague are low because the bacterium responds to several types of modern antibiotics.

• There is a video about the Black Death in Europe during the 14th century.

• Europeans developed resistance to many infectious diseases.

• An antibiotic is hostile to the growth of other organisms.

• The healthcare community is challenged by all of these questions.

• Not completing a full course of antibiotics is one of the main reasons for resistantbacteria.
• Most of the infectingbacteria are killed by the antibiotic.
• There is an increase in the proportion of resistant forms over non-resistant ones.

• The excessive use of antibiotics in livestock is a problem.
• The use of antibiotics in animal feed promotes resistance to them.
• 70 percent of the antibiotics produced in the US are fed to animals.
• The antibiotics are used to increase the production of their products.

• There is a recent news report on the problem of routine antibiotic administration to livestock.

• MRSA is more common in healthy people who live or work in dense groups than in people in healthcare facilities.

• Society is facing an antibiotic crisis.
• After years of being protected from infections by antibiotics, some scientists think we may be going back to a time when a simple bug could kill the population.
• It takes a long time to get an effective and approved drug, even though researchers are working on developing new antibiotics.

• Food is not an exception as prokaryotes colonize the surface of any type of material.

• Infections related to food consumption are common.

• Over time, the characteristics of foodborne illnesses have changed.
• The incidence of this disease has been reduced by proper canning procedures.

• Most cases of food poisoning are linked to produce contaminated with animal waste.

• Several antibiotic resistance genes and specific genetic sequence have been acquired.

• All types of food can be contaminated.

• Epidemiology studies the occurrence, distribution, and determinants of health and disease in a population.
• It is related to public health.

• Epidemiologists track the spread of a disease to identify the original mode of transmission.
• They work with historians to try to understand the evolution of a disease and the natural history of pathogens.
• They gather information from a variety of sources.
• Public health policies are designed to reduce the incidence of a disease or to prevent its spread.
• Epidemiologists conduct rapid investigations in case of an outbreak to recommend measures to control it.

• Epidemiologists usually have a graduate degree.
• A master's degree in public health is one of the degrees an epidemiologist might have.
• Many epidemiologists have both an MD and a PhD in an associated field, such as biology or epidemiology.

• Not all prokaryotes are bad.
• Our life and all life on this planet would not be possible without prokaryotes.

• Specific use is a type of commercial application.
• Genetics, artificial selection, antibiotic production, and cell culture are some of the current topics of study.
• Humans have been using prokaryotes to create products for a long time.
• Some of the goods and services are as simple as cheese, yogurt, sour cream, vinegar, cured sausage, sauerkraut, and fermented seafood that contains bothbacteria and archaea.

• Some of the products derived from the use of prokaryotes include cheese, yogurt, and fish sauce.

• Humans started to breed animals and process their milk 4,000 years ago.
• Evidence shows that yogurt has existed for at least 4,000 years.

• The removal of agricultural chemicals from the soil is called bioremediation.
• Toxic metals can be removed from water by bioremediation.
• Reduction of SeO2 to SeO2 and to Se0 is a method used to remove selenium from water.

• The active ingredient in pesticides is mercury, which is also used in industries such as battery production.
• Mercury is toxic because it accumulates in living tissues in low concentrations in natural environments.
• The biotransformation of toxic mercury can be carried out by several species ofbacteria.

• Oil spills are one of the most useful and interesting examples of the use of prokaryotes for bioremediation purposes.
• There have been several oil spills in recent years, such as the Exxon Valdez spill in Alaska (1989), the Prestige oil spill in Spain 2002), and the spill into the Mediterranean from a Lebanon power plant.
• bioremediation is a way to clean up spills because it helpsbacteria already present in the environment to grow.
• The oil droplets are broken into compounds by the hydrocarbon-degrading bacteria.
• Natural bioremediation tends to occur in the case of oil spills in the ocean, as there are oil- consumingbacteria in the ocean prior to the spill.
• It has been reported that up to 80% of the nonvolatile components in oil can be degraded within a year of the spill.

• It is more difficult to remove aromatic and highly branched hydrocarbon chains from other oil fractions.
• The first patent application for a bioremediation application in the U.S. was for a genetically modified oileating bacterium.