MEIOSIS Flashcards
- reduces # of chromosomes in gametes
- results in sperm and egg cells
- haploid gametes in diploid organisms
Meiosis
1 set of chromosomes
Haploid
2 sets of chromosomes
Diploid
How many phases of meiosis are there?
8
- sperm enters with diploid chromosomes and tetraploid DNA
- chromosomes duplicated to produce sister chromatids / homologous dyads
Interphase / Diploid Cell
most complex stage of meiosis (90%)
Prophase I
dyad pairs align to create tetrads
Prophase I
structure containing 4 chromatids
tetrad
stage of Meiosis I where synapsis occurs
Prophase I
Synapsis is mediated by __________.
synaptonemal complex
homologous chromosomes come together as pairs
synapsis
stage of Meiosis I where crossing over occurs
Prophase I
non-sister chromatids connect and trade sections at a chiasma
crossing over
- chromosomes condense
- tetrads move towards center
crossing over
- x-shaped structure
- point of contact
chiasma
Substages of Prophase I (5)
- Leptotene
- Zygotene / Zygonema
- Pachytene / Pachynema
- Diplotene
- Diakinesis
substage of Prophase I wherein synapsis occurs
Zygotene / Zygonema
substage of Prophase I wherein chromosomes condense and become visible
Leptotene
substage of Prophase I
- chromosomes crossover
- chromosomes become shorter and thicker
Pachytene / Pachynema