ch3 - Ch 3 Chromosomes and Cellular Reproduction Eukaryotic...

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Ch 3 Chromosomes and Cellular Reproduction Eukaryotic Chromosomes Multiple, linear; # of chrom. is charact. of species (rare exceptions) Diploid = 2N; fusion of 2 haploid gametes diploid zygote Genome – complete compendium of genetic info in a haploid chromosome set Homolog – member of a pair of chromosomes that contain the same genes and that pair during meiosis; one from each parent; opposite is nonhomologous chromosome Sex chromosomes – represented differently in the 2 sexes, opposite of autosome; one sex has a matched pair of sex chromosomes and the other sex has an unmatched pair of sex chrom. or a single sex chrom. Centrometre – constriction along the length of each chromosome – important for behavior of chrom. during cellular division Metacentric – about the center (2 = arms) Submetracentric – one arm longer than the other Acrocentric - one arm w/ a stalk and often w/ a “bulb” (called a satallite) on it Telocentric – only one arm b/c centromere is at the end Chrom. can vary in size; length and centromere position constant for each chrom. and help identify individ. chrom. karyotype – complete set of all the metaphase chrom. in a cell (2 chromatids per chrom.) species specific wide range of #s, sizes, and shapes metaphase chrom. ( most condensed chrom. in mitosis) used for identification b/c most compact form during cell division cycle and therefore are easy to see under microscope after staining customary to arrange chrom. in order to size and position of centromere; largest pair = 1 stain band patterns are specific to each chrom. G banding – chrom. treated w/ mild heat/proteolytc enzymes to digest chrom. proteins partially; then stained w/ Giemsa stain to produce G bands p = small arm of chrom., q = other arm; numbered regions then assigned from the centromere outwards ex: 17q31.2 – chrom. 17, on long arm, region 21, subregion 2 Mitosis cellular reproduction = mitosis and cytokinesis then interphase (growth) (whole thing is called cell cycle) Interphase S – DNA & chrom. replication; creates sister chromatids (held by replicated but unseparated centromeres; when they separate, they become daughter chrom.) G2 – cell prepares for cell division G0 – nondividing state function individ. chrom. elongated (difficulat to see under light microscope) relative time spent in each of 4 stages of mitosis varies among cell types length of cell cycle depends on G1 b/c S+G2+M is almost the same in all the same cell types occurs in haploid and diploid cells phases
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prophase at beginning, chomatids are very elongated they begin to coil tightly (look shorter and fatter) mitotic spindle assembles outside nucleus o centrioles (in pairs; replicates before S phase) are focal points for spindle assembly o centriole pair is focus of aster (radial array of microtubules) - which develop
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This note was uploaded on 02/09/2010 for the course BIOL 3301 taught by Professor Hannig/miller during the Spring '10 term at Dallas.

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ch3 - Ch 3 Chromosomes and Cellular Reproduction Eukaryotic...

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