meiosis Flashcards
1
Q
meiosis produces…
A
gametes (sex cells) with 23 chromosomes
2
Q
define meiosis
A
division process that prevents “doubling” of genetic material from occurring
3
Q
fertilization
A
fusion of 2 gametes (male + female) to create a diploid cell (develops into new individual)
4
Q
stages of meiosis
A
- S phase/interphase
- meiosis I
- meiosis II
5
Q
interphase/S-phase
A
- DNA replication
- each chromosome made of sister chromatids held with centromere
6
Q
meiosis I
A
number of chromosomes reduced from diploid 2n to haploid n
7
Q
meiosis II
A
cells are haploid
8
Q
prophase I
A
- chromosomes condense/shorten
- spindle fibers form
- centrioles move to poles
- homologous chromosomes form tetrad and do synapsis
9
Q
synapsis
A
- also called crossing over
- chromatids swap ends
- location is called chiasma
10
Q
metaphase I
A
- tetrads line up at equator (two rows)
- spindle fibers attach to a whole chromosome
11
Q
independent assortment
A
- random alignment of maternal/paternal chromosomes during metaphase I
- daughter cell can receive either chromosome (maternal or paternal) of each pair
12
Q
anaphase I
A
- entire pairs of chromosomes pulled to separate sides (sister chromatids do not break apart)
13
Q
telophase I
A
- chromosomes condense slightly
- cytokinesis forms two genetically diff. daughter cells
- each daughter cell has haploid chromosome (n=2)
14
Q
differences between meiosis I and II
A
- meiosis II more similar to mitosis but w/o chromosome duplication during a short interphase
- meiosis II: sister chromatids split apart
- meiosis II: final 4 daughter cells
15
Q
prophase II
A
- nuclear envelope begins to break down
- spindle fibers form
- centriole move to opposite poles
