Cell Divison, Diveristy, Differentiation Flashcards
1
Q
What’s in interphase
A
G1
S
G2
2
Q
G0
A
Cell has left cell cycle:
To differentiate
Apoptosis
Senescence
3
Q
Senescence
A
Cells no longer divide
4
Q
Check points in cell cycle
A
At G1
At G2
5
Q
Why are there
checkpoints
A
To prevent uncontrolled division that would lead to tumours To detect and repair damage to DNA
6
Q
M phase
A
Checkpoint chemical triggers condensation of chromatin Cell growth stops 4 stages of mitosis Cytokinesis then occurs
7
Q
G1
A
Cells grow Transcription of genes to make RNA occurs Synthesis of biological molecules occur e.g. protein synthesis
8
Q
S phase
A
DNA replicates (doubles) Each chromosome has two sister chromatids Once the cell has entered this phase, it is committed to completing the cell cycle
9
Q
Why does S phase
happen very rapidly
A
Exposed DNA base pairs are more susceptible to mutagens so this phase happens quickly to reduce the chances of mutations
10
Q
G2
A
Cells grow Chemicals stimulate histones and formation of the spindle Organelles duplicate
11
Q
Prophase
A
Chromosomes
condense- chromatids shorten, thicken and DNA supercoils
Centrioles duplicate and move to opposite
poles
Cytoskeleton protein (tubulin)threads form a spindle between centrioles.
Nuclear envelope
breaks down
Nucleolus no
longer visible
12
Q
Metaphase
A
Chromosomes align at equator and attach by their centromeres Two sister chromatids of each chromosome are attached to spindle fibres
13
Q
Anaphase
A
Centromere splits Sister chromatids of a pair are pulled towards opposite poles and directions of the cell by motor proteins walking along tubulin threads to spindle fibres shortening (now chromosomes)
14
Q
Telophase
A
Chromosomes decondense Spindle disappears Nuclear envelope reforms and a nucleolus reappears cells contain two nuclei each genetically identical to one an other
15
Q
Cytokinesis in an
animal cell
A
plasma membrane folds inwards the middle of the cell pinches inwards, creating an indentation called the cleavage furrow
