Bio Lecture Notes

Bio Lecture Notes - LECTURE NOTES Tuesday No Discussion...

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I I I I I I I I I I I I X X X X X X X X X X X X I I I I I I I I I I I I LECTURE NOTES Tuesday, January 17, 2006 No Discussion this week! www.unm.edu/~khowe/202.html ~Study Guides ~Class Questions ~Homework Turn in unofficial transcript!! Genetics : the study of inheritance Structure & Function of Genes- 1. Meiosis: cell division producing cells with ½ the genetic information Inheritance 7. Eukaryotic chromatin and genomes 8. Multi-cellular development Mitosis : production of 2 identical cells that are the same as each other and the parent Prophase Metaphase M Anaphase Telophase G 1 G 2 Interphase Cytokinesis S G 1 Nucleus G 1 G 2 dsDNA G 1 (making up chromosomes) multiple: linear diploid # = 2N = 4 ALWAYS! 2 homologous pairs [same size, shape, order/type of genes] Humans – 2N = 46 Meiosis G 1 G 2 Meiosis II S phase Meiosis I Meiotic products are haploid ~1 copy of every chromosome ~1 copy of every gene Mitosis Meiosis - 2 cells produced - 4 cells produced
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- 1 round of cell division - 2 rounds of cell division - cells are identical to each other - cells have ½ the genetic information and the parent cell (not identical to each other) - used for growth, cell replacement, - used for sexual reproduction and asexual reproduction Asexual Reproduction : 1 parent producing offspring genetically identical to itself Sexual Reproduction : 2 parents producing offspring ~each parent contributes ½ of the genetic information ~haploid cells produced in meiosis are called gametes - sperm and eggs 2N parent 1N gamete Meiosis 2N Offspring 2N parent 1N gamete ~ somatic cells (non sex cells) go through meiosis ~ germline cells go through meiosis to produce gametes Meiosis I – separate homologous chromosomes Meiosis II – separate sister chromatids Thursday, January 19, 2006 Meiosis I – homologous pairs separate Meiosis II – sister chromatids separate [produce haploid cells – contain one copy of every chromosome] 2 n = 4 (2 pairs) paternal chromosome comes from father maternal chromosome comes from mother Meiosis Figure online at website Meiosis I Prophase I ~chromosomes condense ~nuclear envelope disintegrates and formation of spindle apparatus ~homologs pair up and find each other ~ crossing over occurs between homologs [ genetic variation ] - chiasma : location of crossing over Metaphase I ~homologs line up in pairs along the metaphase plate ~ random (independent) assortment occurs Anaphase I ~homologs pulled to opposite ends of cell [sister chromatids not separated] Telophase I ~constriction in center of cell ~chromosomes de-condense ~nuclear envelopes reappear -homologous chromosomes have separated -sister chromatids of one chromosome are still connected -2 sister chromatids connected by a centromeres are haploid ~cells are now haploid! Homologous chromosomes
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Bio Lecture Notes - LECTURE NOTES Tuesday No Discussion...

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