Meiosis Flashcards
1
Q
Mitosis
A
Division os the nucleus through the separation of sister chromatids (2 identical daughter nuclei)
2
Q
Meiosis
A
2 successive divisions of nucleus (part I & II)
Produces 4 haploid unique nuclei
3
Q
Meiosis produces genetic variability in 2 ways:
A
- Genetic recombo. = exchange of material b/w homologous chromosomes
2.
4
Q
Meiosis I
A
Separation of homologous chromosomes = 2 haploid nuclei
5
Q
Meiosis II
A
Separation of sister chromatids = 4 haploid nuclei
6
Q
Prophase I
A
Leptotene (thin thread) Zygotene (zipper thread) Pachytene (thick thread) Diplotene (double thread) Diakinesis (movement apart)
7
Q
Leptotene
A
- Chromosomes uncondensed
- Ends of chromosomes attached to nuclear evelope
8
Q
Zygotene
A
- Homologous chromosomes pair up & zipper together (Synapsis)
- Homologs held tightly together by protein core (Synaptonemal complex)
9
Q
Pachytene
A
- Chromosomes condense
- Genetic recombination/crossing-over = genetic exchange of chromatic segments b/w homologs –> sister chromatids no longer identical
10
Q
Diplotene
A
- Synaptonemal complex dissolves
- Chromosomes decondense
- Homologs separate from each other except at points of cross-over = chiasmata
- Transcription of chromosomes can occur
11
Q
Diakinesis
A
- Chromosomes condense
- Chromosomes detach from nuclear envelope
- Nuclear envelope breaks down & spindle starts to form
12
Q
Metaphase I
A
- Nuclear envelope is gone
- Tetrads/Bivalents line up (orientation is random)
- Spindle MTs attach to kinetochores
13
Q
Anaphase I
A
- Homologs separate
14
Q
Telophase
A
- Formation of 2 Haploid nuclei
- Cytokenesis may or may not occur
- Chromosomes are decondensed at this stage
15
Q
Prophase II
A
- Chromosomes condense
- Nuclear envelope breaks down
- Spindle starts to form
