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