Meiosis Keypoint 1 Mitosis and Meiosis are two

Meiosis

Keypoint #1: Mitosis and Meiosis are two different kinds of cell DIVISION Mitosis vs. Meiosis • Mitosis creates two identical cells from one original cell. Meiosis creates FOUR unique daughter cells from one original cell • All of your SOMATIC cells do MITOSIS Only to make SEX CELLS (GAMETES) • The two cells after division Each daughter cell has half (n) as many chromosomes as have the same number (2 n) of the original cell chromosomes as the original cell

simple vocab Parent Cell = original cell before division Daughter Cells = cells after division (mitosis or meiosis) Review: Gamete/Sex Cell = sperm and egg cells Somatic Cells = all other body cells Haploid = only one set of chromosomes (n) Diploid = pair of each chromosome (2 n)

Keypoint #2: Mitosis is cell division that results in two diploid cells identical to the original one 1) The diploid parent cell (2 n) replicates its DNA to go from I to X shaped chromosomes 2) The parent cell divides (splitting X shapes back into I shapes) to create two identical cells that still have 2 n. you don’t want all of your skin cells to be different do you? 2 n 2 n

Check For Understanding 1. If a skin cell with 46 chromosomes undergoes mitosis, how many chromosomes will each daughter cell have? a. 46 b. 23 if it is mitosis, the daughter cells are IDENTICAL (the same c. 47 as the original. start with 46, end with 46 d. 92 2. If two daughter cells in a cabbage leaf end up with 18 chromosomes, how many chromosomes did the original cell have? a. 36 b. 18 c. 9 d. 17

Keypoint #3: Meiosis is two cell divisions that result in the creation of four HAPLOID daughter cells 2 n Step 1: Diploid parent cell replicates (copies) its own DNA to go from I to X shaped chromosomes. Still diploid. Step 2: Parent Cell divides to make 2 haploid cells (the pairs of X shaped chromosomes split up) n Step 3: those 2 daughter cells each divide with the X shapes splitting up to make I shaped chromosomes to make a total of 4 haploid daughter cells.

Keypoint #4: Meiosis only happens in reproductive / sex organs to create sex cells In FEMALES meiosis happens in the OVARIES to make EGG CELLS In MALES meiosis happens in the TESTES to make SPERM CELLS Egg and sperm are called GAMETES Testes Ovary

The Meiosis Diagram • You HAVE to know these diagrams Diploid = two of each chromosome 2 n DNA copies but still just diploid 2 n Parent cell divides with one chromosome from each pair going to each cell = haploid n n Each haploid cell divides to make 4 haploid cells. Still haploid because both I and X shapes are considered ONE chromosome n n

Filling in the Diagram In human cells, this is the number of chromosomes during Meiosis What about in frogs? If we know there are 26 in somatic cells. . . 46 26 23 23 23 13 13 13

Check For Understanding Finish this Meiosis diagram for Coyotes: 76 76 38 38 38

Check For Understanding 1. If a somatic human cell has 46 chromosomes, how many chromosomes would a human cell have after Meiosis? a. 46 Key Info: somatic = 46 b. 23 cell after meiosis = gamete c. 47 gamete = 1/2 somatic = 46 / 2 = 23 = B d. 92 2. If a gamete produced during meiosis in a Goat has 30 chromosomes, how many chromosomes would a skin cell of the goat have? Key Info: gamete = 30 a. 30 skin cell = somatic b. 15 c. 60 Somatic is = 2 x gamete d. 10 Somatic = 60! = C