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7 Cards in this Set

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What is Heredity?
What is Variation?
The transmition of traits from one generation to the next.
Variation is differing in appearence form parents or siblings.
What is genetics?
the study of heredity and hereditary variations. Genes program cells to synthesize specific enzymes and proteins. DNA is a polymer of 4 kinds of monomers (nucleotides). Gene's locus= location. Humans= 46 chromosomes.
Asexual
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Asexual reproduction
Sexual Reproduction
asexual- a single individual is the sole parent and passes copies of all its genes to its offspring (dna is copied equally into two daughter cells).
Sexual- two parents give rise to an offspring. Life cycle= generation to generation sequence of stages in the reproductive history of an organism.
Human Life Cycle
Human= each somatic cell(diploid) has 46 chromosomes.
Karyotype=when chromosomes are arranged in pairs(homologous)starting with the longest to the shortest.X Y are sex chromosomes, the others are autosomes.
Reproductive cells are gametes which have a single set of 22 autosomes and a single chromosome either X or Y. Fertilization= syngamy= union of gametes =zygote(resulting egg)are diploid cells(two sets of chromosomes)
Meiosis and Mitosis(General)
Meiosis-process that halvs the chromosome number in the gametes, compenstationg for the doubling that occurs at fertilization (restores the diploid condition by combining two haploid sets of chromosomes.
Mitosis: DNA replication occurs during interphase before nuclear division begings...in meiosis it occurs once, during the interphase before meiosis I begins.
Mitosis has one division and meiosis has two, each including prophase, metaphase, anaphase, and telophase. synapsis doesnt occur in mitosis, but it occurs in meiosis.Mitosis has two daughter cells (2n-diploid), and meiosis has four daughter cells (n-haploid). Mitosis- ebables multicellular adult to arise from zygote;produces cells for growth and tissue repair. Meiosis produces gametes and reduces the number of chromosomes in half.
Meiosis I and Meiosis II
Interphase: chromosomes replicated, result in two identical sister chromatids attached at the centromeres.
Prophase: in a process called synapsis, a protein sturcture(synaptonemal complex) attaches the homologous chromosomes tightly together. The longer chromosomes are are crossed twice, and the shorter ones are crossed once.These crossings are called chismata. Centrosomes move away from each other and spindle microtubules form between them, nuclear envelope disappears.
Metaphase I: chromosomes arranged on metaphase plate, still in homologus pairs, kinetochore microtubules form poles at each end of the cell.
Anaphase I: sister chromatids remain attached and two sister chromatids are pulled to each end of the cell. One short pair and one long pair.
Telophase I and cytokinesis: They get separated into two different cells.
Crossing Over
Independent Assortment
crossing over produces recombinant chromosomes, which combine genes inherited from our two parents. This vegins early in prohase.