Meiosis (Sexual) chpt 13

1. Asexual--> 1 parent passes a copy of its entire genome to offspring

(offspring=Clones)

2. Sexual--> Not a Clone, but a mixture

2 Parents each pass a copy of hlf their genome to offspring

(offspring= Genetic Recombinants)

1. Diploid--> contain 2 sets of chromosomes (Contain Homolgous Chromosomes)

• All somatic cells
• 46 total chromosomes
• 23 Pairs of Homologous chromosomes (code for same inherited traits)
• Most cells are Diploid
• 1 Diploid  ( 2 divisions) = 4 Haploid

Humans- 22 pairs of autosomes

1 pair of sex chromosomes = Homologous - XX  or NON Homologous  XY

= 46

1. (Animals)  Haploid gametes-->fertilization-->diploid zygote-->mitosis-->multicellualar diploid organism-->gametes formed by meiosis

2. Fungi,ushrooms, molds, mildew) Haploid gametes-->fetilization-->diploid zygote--> MEIOSIS-->mitosis-->multicellular HAPLOID organism-->gametes formed by MIOTOSIS

3. Alternation of Generations  (Most Complex) --> Plants  and Algae

Sporophyte (Plants)

Sporophyte=multicellular haploid stage (Meiosis)

Gametophyte (Animals)

Gametophyte=multicellular haploid stage (Mitosis)

Prophase 1 is much longer and more complex tha in Mitosis

• Synapsis (snapping together) happens = the pairing up of homolgous chromosomes
• Chiasmata = points where non-sistr chromatids connect

• Homologous pairs (Tetrads) separate
• Spindle shortens pulling chromosomes to OPPOSITE poles of the cell

• Chromooms concentrate at opposie poles of cell
• Cell completely devides
• 1 Diploid cell--> 2 Haloid cells
• resting period

Prophase II

• spindle attaches to each individual chromosome from BOTH sides (NO synapsis)

• chromosomes line up along Metaphase plate
• Chromosomes split and sister chromatids seperate

Centromeres split and sister-chromatids separate

• chromoatids concentrate at opposite poles of cell
• nuclear enelpes reform
• chromaids-->chromatin
• cells completely divide
• 2 Haploid cells-->4 Haploid cells

MITOSIS    vs.    MEIOSIS

1 Division  vs.  2 Divisions

NO synapsis    vs.  Synapsis Occurs

NO Chiasmata  vs.  Chiasmata Form

Individual chromosmes line up    vs.    Hmo. airs line up in Metaphase I

1 Diploid--> 2 Diploids Or    vs.      1 Diploid--> 4 Haploids

1 Haploid--> 2 Haploids

1) Independent Assortment--50% chance of getting mom or dad's

2) Cross Over--> Synapses

3) Random Fertilizatin--> 8 million possible comos