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11-4 Meiosis – Sex Cell Division
I.
II.
Chromosomes – contain genes encoded in DNA
A. Gametes – reproductive cells
1. Pollen cells and egg cells in plants
2. Sperm cells and egg cells in animals
B. Haploid vs Diploid
1. Diploid – a double set of chromosomes
a. Cell with a full set and their copies
b. 46 chromosomes + 46 copies = 92
chromosomes
c. Represented with 2n
2. Haploid – contain just 1/2 set of
chromosomes
a. Cell contains ½ of somatic (body) cell
chromosomes
b. 23 chromosomes
c. Haploid = n =23
Phases of Meiosis – meiosis takes place in….
A. 2 stages called Meiosis 1 and Meiosis 2
B. Meiosis 1 – diploid = 46 and copies to 23
C. Meiosis 2 - 23 and copies to Haploid 23
D. Crossing over occurs during meiosis 1 in
metaphase 1 when homologous
chromosomes exchange information
Interphase – Prophase – Metaphase –
Anaphase – Telophase (Meiosis 1)
Prophase – Metaphase – Anaphase –
Telephase – Cytokinesis (Meiosis 2)
Chapt. 11-5 Gene Linkage
I.
Individual genes can stick together in
sets called Linkage Groups.
A. Crossing over can sometimes
separate different linkage groups.
B. The farther two genes are on
opposite ends of a chromosomes,
the more likely they are to be
separated
C. Close genes separate less
frequently
D. Gene Maps use this information to
place genes on a position on each
chromosome.