Lecture 18 – Meiosis

Lecture 18 – Meiosis - Lecture 18 Meiosis...

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Lecture 18 – Meiosis A. Function 1. Reduction division - Chromosome number (2N to 1N; diploid to haploid) - All organisms have a set number of chromosomes (46) - Without meiosis, humans would double in chromosomes every generation - Chromosome number Humans alternate between o Diploid (2n) 46 chromosomes o Haploid (1n) 23 chromosomes - Because we sexually reproduce, we n e e d to m aintain our chromoso m e nu mb ers Onions have 16 chromoso m es - Diploid nu m b er (46)– so m atic cells Epithelial cells Muscle cells Nerve cells - Haploid nu m b er – g a m et es Sperm Eggs (Ova) - Homologous p airs – e ach ga m et e has a similar set of chromoso m es Differ in size, sh ap e, and gen etic m at erial - Fertilization – restores 2N nu m b er Egg a nd sperm unite and form a zygote (first cell of the diploid stag e) - Meiosis – s ep arates ho mologous chromoso m es 1 of e ach chromoso m e B. Mitosis vs. Meiosis
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- Mitosis is an equational division – 1 2N cell to 2 2N cells
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Lecture 18 – Meiosis - Lecture 18 Meiosis...

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