X/Y Chromosome : In males the sex chromosomes have a different appeaance. Males have an XY chromosome combination while Females have XX chromosome combinations. The XX chromosome is bigger than the Y chromosome.

Alleles : Alternate versions of a gene for a particular trait

Meiosis : A reduction division. Invlves 2 divisions which result in 4 daughter cells. Haploid Cells.

Gametes : sex cells - sperm and egg that fuse during fertilization.

Stem cells : Special human cells that are able to develop into many different cell types. This can range from muscle cells to brain cells. In some cases, they can also fix damaged tissues.

Germ cells : Any biological cell that gives rise to the gametes of an organism that reproduces sexually.

Differentiation : Cellular differentiation, or simply cell differentiation, is the process through which a cell undergoes changes in gene expression to become a more specific type of cell. The process of cell differentiation allows multi-cellular organisms to create uniquely functional cell types and body plans

Synapsis : When Homologues come together and line up side by side, much like two dancing partners who will stay together until the dance ends. The Homologues are held in place by a protein lattice that develops between them. Crossing-over happens in Synapsis as well.

Interkinesis : The period of time between meiosis I and meiosis II.

Crossing-over : When the homologues randomly exchange genetic material.

Tetrad : Each set of four chromatids

Independent assortment : The random assortment of the maternal and paternal chromosomes aligning at the equator. Because of Independent assortment genetic variation has increased and crossing over increases the genetic variation even more of the chromosomes.

Zygote : The union of a male and female gametes during fertilization.

Pro, meta-, ana-, telophase I/II :

Prophase I - Chromosomes have duplicated. Homologues pair during synapsis and crossing over occurs. The nuclear envelope fragements as well and the nucleolus dissapears as the spindle appears.

Metaphase I - Homologues randomly align at the equator

Anaphase I - Homologues seperate and are pulled towards the poles

Telophase I - Spindle dissapears and nuclei re-form around seperated homologues

Interkinesis - Chromosomes still consist of two chromatids

Prophase II - Cells have one chromosome from each pair of homologues

Metaphase II - Chromosomes align at the equator

Anaphase II - Sister Chromatids seperate and become daughter chromosomes

Telophase II - Spindle dissapears, nuclei re-form, and cytokinesis takes place.

Daughter cells - Meiosis results in four haploid daughter cells.

Gametogenesis : the process in which cells undergo meiosis to form gametes.

Tri-, Polyploid :

triploid - A eukaryote that has three of each kind of chromosomes

Polypoid - When a eukaryote has three or more complete sets od chromosomes

Nondisjunction : ccurs during Meiosis I, when homologues fail to seperate and both homologues go into the same gamete or during meiosis II when the didter chromatids fail to seperate and both daughter chromsomes go into the same gamete.

Aneuploidy : An individual with a chromosome anomaly

Monosomy : The abcense of a chromosome

Trisomy : A condition created by an extra chromosome

Syndrome : When an individual inherits an Aneuploidy , certain characteristics commonly appear that together are called a syndrome.

Down syndrome : The most common autosomal trisomy amon humans in trisomy 21. It is recognized by short stature, eyelid fold, flat face, stubby fingers, wide gap between the first and second toe, large, fissured tongue, round head, distinctive palm crease, heart problems, and intellectual disability.

Turner syndrome :Females only have one X chromosome, is recognized if they are short, with a broad chest and widely spaced nipples,. Also have a low posterior hairline and neck webbing. Their ovaries, oviducts, and uterus are very small and underdeveloped.

Klinefelter syndrome : A male with this syndrome has two or more X chromosomes in addition to a Y chromosome. The testes and prostate gland are underdeveloped and facial hair is lacking.

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