fertilization - aka syngamy; fuses gametes to form a new cell
- gametes - eggs, sperm
- somatic cells - nonreproductive cells
- has twice as many chromosomes as gametes
- never form gametes
- zygote - formed by 2 gametes fusing together
- meiosis produces cells w/ 1/2 the normal number of chromosomes
- sexual reproduction - uses meiosis/fertilization to give chromosomes from 2 parents to offspring
- 23 maternal homologues from mother, 23 paternal homologues from father in humans
- life cycles of organisms w/ sexual reproduction alternate between diploid/haploid periods
- germ-line cells - will eventually produce gametes
- undergoes meiosis, not mitosis
synapsis - close association of chromosomes during prophase I of meiosis
- synaptonemal complex - homologues paired closely along a protein lattice between them
- pairs of homologues come together during metaphase I
- homologues, not sister chromatids, go towards opposite poles during anaphase I
- meiosis I - aka “reduction division”
- crossing over - genetic recombination
- homologues can exchange chromosomal information
- chiasmata - sites of crossing over, maintained until anaphase I
- continued association of chromosome pairs until anaphase is needed to ensure accurate separation
2 divisions - genetic material only replicated once
- produces cells w/ 1/2 the number of chromosomes
- meiosis II - like mitosis, but without chromosome duplication
Subject:
Subject X2:
