The Cell Cycle Flashcards
1
Q
What are the phases of the cell cycle?
A
- Interphase
- G1
- S
- G2
- M
- Mitosis
- Cytokinesis
2
Q
What happens in G1
A
- replicate mitochondria, robosomes, ER
- increase cell size
- Includes a restriction point
3
Q
What happens in S
A
Clone DNA to create 2 chromatids joined at the centromere
4
Q
What happens in G2
A
- Checkpoint
- enough organelles?
- correctly replicated DNA?
5
Q
What happens in M
A
- Prophase
- Metaphase
- Anaphase
- Telophase
6
Q
Prophase
A
- Chromatin condenses into chromosomes
- centrioles go to poles
- spindle fiber and aster formation
- nuclear membrane dissolves
- kinetochore fibers attach to kinetochores
7
Q
Metaphase
A
microtubles align the chromosomes at the metaphase plate
8
Q
Anaphase
A
sister chromatids are pulled apart by shortening of the kinetochore fibers
9
Q
Telophase
A
- spindle apparatus disappears
- nuclear membranes form
- chromosomes relax
- cytoplasm and organelles are split in cytokinesis
10
Q
What are the phases of meiosis
A
- Prophase I and II
- Metaphase I and II
- Anaphase I and II
- Telophase I and II
11
Q
General discription of meiosis I
A
reductional division: homologous chromosomes are separated creating 2 haploid daughter cells
12
Q
prophase I
A
- chromatin condenses into chromosomes
- spindle apparatus forms
- nuclear membrane breaks down
-
synapsis
-homologous chromosomes (maternal and parental) form a tetrad held together by the synaptonemal complex
-crossing over can occur at chiasmata
13
Q
Why is crossing over important
A
- can unlink linked genes which increases genetic variability of gametes
- explains Mendel’s 2nd law of independent assortment
14
Q
metaphase I
A
- tetrads align at the metaphase plate
- each homologous pair attaches to its own kinetorchore fiber
15
Q
anaphase I
A
- disjuction: the maternal and paternal chromosomes separate
- accounts for Mendel’s 1st law of segregation
16
Q
telophase I
A
- nuclear membranes form
- cells now haploid
19
Q
prophase II
A
- nuclear membranes dissolve
- centrioles go to the poles
- spindle apparatus forms
20
Q
metaphase II
A
chromosomes align at the metaphase plate
21
Q
anaphase II
A
sister chromatids are pulled apart
22
Q
telophase II
A
nuclear membranes form
