Fundamentals of Biology - Lecture Outlines: Chapter 10 - Meiosis
Asexual Reproduction
Sexual Reproduction
Meiosis halves the chromosome number.
- two divisions
Diploid (2n) - cells that have a pair of each chromosome
Haploid (n) - cells that have only
Meiosis resembles mitosis in that:
- chromosomes duplicated
- chromosomes moved
Meiosis differs from mitosis:
In meiosis:
- two divisions
- only in germ cells
- produce haploid
- shuffle the genes
Key Events during Meiosis I:
PROPHASE I
- chromosomes condense
- homologues pair = synapsis
- crossing-over
- chiasmata
- chromosomes attach to microtubules
METAPHASE I
- microtubules
- homologues align at random
Possible combinations
How many possible for 23 pairs of homologues?
ANAPHASE I
- homologues separated
= reduction division
TELOPHASE I
- cytoplasm divides
- resulting in 2 haploid cells
PROPHASE II
- transition phase occurs first
- new spindles
- chromosomes attach
METAPHASE II
- chromosomes are lined up at equator
ANAPHASE II
- sister chromatids separate
- move to opposite poles
TELOPHASE II
- have four daughter nuclei
- each cell has
New combinations of alleles occur because of:
Gamete Formation in Animals
Spermatogenesis:
Oogenesis:
Germ cell (2n) --->
Fertilization restores diploid number
Review Chapter 10
Review questions 1-7 (for # 6 just do the animal section)
Self quiz 1-9
Critical thinking #2