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Reproduction!!!. 2 Types. If both parents replicated cells using mitosis, a child would receive 46 chromosomes from dad & 46 from mom given a grand total of…? 92! (Way too many) So…if dad could give 23 + 23 from mom = 46! (Bingo !). Examples of Asexua l !!!!. Binary Fission Budding
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Reproduction!!! 2 Types
If both parents replicated cells using mitosis, a child would receive 46 chromosomes from dad & 46 from mom given a grand total of…? • 92! (Way too many) • So…if dad could give 23 + 23 from mom = 46! (Bingo!)
Examples of Asexual!!!! • Binary Fission • Budding • Fragmentation
Better when the environment is not favorable or becomes unstable
Meiosis • Def: 2 successive cell divisions that produce gametes • What does that mean? • Successive one right after the other • Gametes a haploid reproductive cell, either an egg or a sperm • Haploid containing only 1 of every chromosomes (n) • Diploid containing 2 of every chromosome (2n)
Some More Vocabulary • Body Cells • AKA somatic cells • Ex skins cells, nerve cells, blood cells • Diploid 46 chromosomes (23 pairs) • Sex Cells • AKA germ cells • Ex egg & sperm • Haploid 23 chromosomes (all single) Q: A mutation in which type of cell would be worse?
Meiosis = 2 Mitosis P1M1A1T1 P2M2A2T2 With a few slight differences!
Meiosis = 1st Division Prophase 1 Crossing Over Metaphase 1 chromosomes line up randomly2 by 2 forming a tetrad (4 across) Anaphase 1 homologous chromosomes are pulled to opposite poles (sister chromatids do not separate!) Prophase I Metaphase I Anaphase I Telophase I
Anaphase 2 Telophase 2 Prophase 2 Metaphase 2 Single Chromosomes line up Sister Chromatids are pulled apart Meiosis II 2nd Division
Mitosis vs. Meiosis • Cells divide twice! (Mitosis divide only once) • End result is 4 different cells instead of 2 genetically identical cells! • Chromosome number is cut in half! • 2n (diploid) n (haploid) = Meiosis • 2n 2n = Mitosis • Crossing Over!
The purpose of meiosis is…? • To produce gametes which are necessary for sexual reproduction. • Allows for new mixtures of combinations called genetic recombination • VARIATION!