10.1 Meiosis Meiosis Section 10.1 ody ells & Gametes somatic = body do NOT pass on N to offspring 46 chromosomes (23 pairs) gametes = sex eggs (females) and sperm (males) pass on N to offspring 23 chromosomes, NO pairs lick for Meiosis nimation Homologous hromosomes a.k.a. homologues matching chromosomes (same length and genes) 1 from mom and 1 from dad carry genes that control the same inherited traits duplicated during "S" phase of interphase To see what the homologous pairs look like after the "S" stage. Homologous hromosomes and hromatids How many chromatids in a pair of duplicated homologous chromosomes? (instant math question) utosomes & Sex hromosomes autosomes chromosome pairs 1-22 sex chromosomes chromosomes pair 23 X + X = female X + Y = male controls the development of sexual characteristics
1 MT: ells in your stomach, liver, or heart are considered 2 Which of the following describes gametes? sex sperm and egg body sex somatic gametes have 23 chromosomes to pass on to offspring all of the above describe gametes 3 Homologous chromosomes contain genes for the same traits. You get one from mom and one from dad. fter the "S" phase they contain only 2 sister chromatids. 4 The first 22 pairs of chromosomes are called, pair 23 are called chromosomes. (separate terms with a space) True False 5 What is the sex/gender of this person? Sexual Reproduction fusion of 2 gametes (egg and sperm) results in offspring that are genetic combinations of mom and dad (genetically unique) fertilization - fusion of egg and sperm
iploid and Haploid IPLOI diploid = 2n 2 copies of each chromosome 1 from mom 1 from dad body HPLOI haploid = n 1 copy of each chromosome gametes (sex ) egg & sperm 6 MT: Fertilization is the fusion of egg and sperm results in genetically unique offspring requires 2 gametes can happen sexually or asexually 7 iploids (n) contain 2 copies of each chromosome and are found in gametes. True False My, oh my, Meiosis form of nuclear division that creates 4 haploid (n) from one diploid cell (2n) "reduction division" reduces the number of chromosomes (2n to n) then divides into 4 (1 cell becomes 4) essential for sexual reproduction ensures the same # of chromosomes in each generation creates genetic diversity requires 2 rounds of cell division meiosis I and meiosis II GOL: to produce 4 genetically unique daughter gametes (egg & sperm) Mitosis Vs. Meiosis Mitosis 1 cell becomes 2 Meiosis 1 becomes 4 n + n = 2N genetically identical two set of chromosomes diploid (2n) genetically unique one set of chromosomes haploid (n) body
Meiosis I PURPOSE: homologous chromosomes separate creating 2 each with duplicated chromosomes #1-23 (haploid) Interphase - 46 chromosomes replicate Prophase I homologous chromosomes find each other (synapsis) tetrads form tetra = four 4 chromatids crossing over occurs portions of chromatids break and change places like wearing two different socks Metaphase I tetrads line up in the center of the cell spindle fibers attach to chromosomes independent assortment occurs homologous chromosomes line up randomly 8,388,608 possibiliites naphase I & telophase I naphase I homologous chromosomes separate Telophase I results in 2 each with chromosomes #1-23 (haploid) 8 What is the purpose of MEIOSIS? 9 What is the purpose of MEIOSIS I? to produce 4 genetically unique daughter to produce 4 genetically unique daughter to separate homologous chromosomes to separate homologous chromosomes to separate sister chromatids to separate sister chromatids to produce 4 genetically identical daughter to produce 4 genetically identical daughter
10 MT: What happens during Prophase 1? 11 Homologous chromosomes separate during independent assortment synapsis triplets form crossing over 12 t the end of meiosis I, chromosomes are (diploid or haploid). Meiosis II PURPOSE: sister chromatids separate creating 4 unique no Interphase between meiosis I and meiosis II PMT II Prophase II chromosomes still replicated Metaphase II sister chromatids line up in the center of the cell naphase II sister chromatids separate 13 What is the purpose of MEIOSIS II? to create 4 genetically unique daughter to separate homologous chromosomes to separate sister chromatids to create 4 genetically identical Telophase II 4 haploid daughter
omplete the venn diagram. nuclear growth 1 cell genetically reduction 2 Label sets becomes of haploid sexual diploid PMT & division repair chromosomes reproduction identical unique division 42 Mitosis Meiosis