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What is Meiosis Exactly?. Meiosis is a form of cell division that __________ the number of chromosomes when forming specialized reproductive cells such as gametes or spores There are ___ stages of meiosis, Meiosis 1 and meiosis 2 Meiosis 1 and 2 create 4 _________ cells all together.
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What is Meiosis Exactly? • Meiosis is a form of cell division that __________ the number of chromosomes when forming specialized reproductive cells such as gametes or spores • There are ___ stages of meiosis, Meiosis 1 and meiosis 2 • Meiosis 1 and 2 create 4 _________ cells all together
MITOSIS VS. MEIOSIS • Mitosis- process that happens during 1) _________ 2) asexual reproduction 3) __________4)regeneration • AFTER 4 STAGES (P-M-A-T) and 1 cell division IT PRODUCES 2 CELLS ___________ (CLONES) TO THE PARENT CELL- SAME DNA VS. • Meiosis- process that happens to make sex cells (egg and sperm) • AFTER __ STAGES (PMAT-P2M2A2T2) and 2 cell divisions, IT PRODUCES 4 CELLS WITH DIFFERENT GENETIC INFO FROM PARENT
REMEMBER CHROMOSOMES • IN ALL BODY CELLS THEY COME IN PAIRS (2N) CALLED THE ________________. ONE OF THE PAIR IS FROM MOM/DAD. • We have 46 chromosomes in body cells- 23 pairs. • SINCE IN SEX CELLS THERE NEEDS TO BE ½ THE # OF CHROMOSOMES, THEY ARE NO LONGER IN PAIRS…THEY ARE ALONE. THIS IS CALLED THE HAPLOID (HALF) NUMBER (1N) • We have 23 chromosomes in egg/sperm.
Prophase I:Prophase II: Metaphase I:Metaphase II: Anaphase I:Anaphase II: Telophase I:Telophase II:
I. Meiosis (Reduction Division) A. Meiosis I 1. Prophase I a. _____________ become distinct b. nucleolus and nuclear membrane disappear and spindle fibers appear
Prophase I c. spindle fibers appear d.____________–homologous chromosomes . Line up together
Prophase I e. _________________may occur 1) portions of chromatid from one parent break off and attach to a homologous chromatid from the other parent 2) results in ____________________
2. Metaphase I a. chromosomes line up along the midline b. sister chromatids___________separate
3. Anaphase I a. at random, one member of each homologous pair moves to the opposite poles (_____________- ____________)
4. Telophase I and Cytokinesis I a. chromosomes reach opposite poles b. cytokinesis begins
Telophase I c. resulting cells have the n or ____________number of chromosomes 1) one member of each homologous pair with two attached chromatids d. each new cell contains ½ the the number of chromosomes as the original cell
B. Meiosis II 1. Prophase II a. spindle form and chromosomes begin to move toward the mid-line of the cell
. Metaphase II a. chromosomes move to the ______________of the dividing cell
3.Anaphase II a. ____________ separate and move to the opposite poles of the cell
4. Telophase II a. nuclear membrane forms around the nucleus in each cell b. each resulting cell contains the _______________of chromosomes
D. Genetic Recombination and Variation 1. independent assortment 2. __________ over 3. _____________ fusionof sperm and egg
E. Formation of Gametes 1. spermatogenesis – results in 4 viable sperm 2. oogenesis – results in 1 egg and 3 ________ ____________
Karyotype 1. picture of homologous chromo- somes and sex chromosomes 2. used to detect chromosome abnormalities
Work on the karyotyping project • www.biology.Arizona.edu/