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Why do some scientist feel that diarrhea is hereditary?. It runs in our “genes”/jeans. Cell Cycle including Meiosis (known as Gametogenesis). Purpose :. To create germ cells, gametes or sex cells. - cells with ½ the number of chromosomes - known as 1N cells -two types of germ cells
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Why do some scientist feel that diarrhea is hereditary? It runs in our “genes”/jeans
Purpose: To create germ cells, gametes or sex cells. - cells with ½ the number of chromosomes - known as 1N cells -two types of germ cells -sperm -egg / ova -in humans 1N/monoploid # =23 -contains 1 chromosome from each of the 23 pairs.
Two types of gametes Spermatogenesis: -meiosis that takes place in the testicles -produces sperm -made starting at puberty and ends at death -occurs everyday at a rate of 120 to 200 million/day Male Reproduction
Oogenesis: -meiosis that takes place in the ovaries -produces ova/eggs -occurs: -during 2nd month of fetal development -ova stored and released once a month during menstrual cycle -starting at puberty and ending with menopause -each ovary contain approximately 300,000 eggs. Female Reproductive
Gametogenesis 1 parent cell divides twice creating four cells with ½ the number of chromosomes. Parent cell is either a testicle or an ovary cells each starting with 46 chromosomes. Meiosis I Meiosis II
Interphase I Occurs in testicle or ovary cell, 2N cells DNA replicates
Prophase I • Chromatin supercoils into chromatid • Centrioles split and form spindle fibers • Nucleus and nucleolus disassemble • Homologous pairs of chromosomes pair up
Homologous Chromosomes Chromosomes that carry the same set of genes. One is from your mom and one from your dad.
Metaphase I • Homologous pairs of chromosomes move to the middle of the cells, each pair lines up on one spindle fiber. • Chromosomes line up randomly
Anaphase I • Homologous pairs of chromosomes split apart and move away to opposite sides of the cell. • Asters push against cell membrane causing the cell to elongate.
Telophase I with cytokinesis • Nucleus and nucleolus reform • Cell divides into two/cytokinesis • End result is now 2 cells each with 23 replicated chromosomes each.
Interphase II DNA does not replicate The rest of meiosis II is identical to mitosis.
End result is four cells each with ½ the number of chromosomes.