6 Cell division Flashcards
1
Q
What is DNA?
A
Polynucleotide made of two anti-parallel strands of sugar phosphate backbone with nitrogenous bases
2
Q
What is gene?
A
A section of DNA which codes for a particular sequence of amino acids
3
Q
What is allele?
A
Different types of the same gene
4
Q
What is chromosome?
A
Length of DNA that contains multiple genes
5
Q
What is chromatid?
A
Chromosome connected to the replicated chromosome by a centromere
6
Q
What happens at G1?
A
- protein synthesis
- organelle replication
- increase in cell size
7
Q
What happens at S phase?
A
DNA replication in the nucleus
8
Q
What happens at G2?
A
- increase in cell size
- increased storage of energy containing molecules
- DNA checked for errors
9
Q
What happens at G0?
A
Cell leaves the cell cycle and becomes senescent
10
Q
Describe “interphase”
A
- cell carries out its specialised function
- cell organelles synthesised
- chromosomes replicate
- errors are checked
11
Q
Describe “prophase”
A
- chromosomes thicken and supercoil, making them now visible as a pair of sister chromatids
- nucleolus disappears
- centrioles divide and move to opposite poles of the cell ready for spindle formation
- nuclear envelope breaks down
12
Q
Describe “metaphase”
A
- chromosomes attached to spindle fibres by the centrioles
- chromosomes are moved by the spindle fibres and line up on them centre of the spindle on an area called the metaphase plate
13
Q
Describe “anaphase”
A
- sister chromatids separate at the centromere as it divides and are now individual chromosomes again
- the spindle fibres shorten, pulling the chromosomes further away from each other
14
Q
Describe “telophase”
A
- when the chromosomes have reached the poles new nuclear envelopes form
- the spindle breaks down and disappears
- chromosomes will uncoil and become less visible
15
Q
Describe “cytokinesis”
A
- a cleavage furrow forms and the cell membrane is pulled inwards by the cytoskeleton
- the two new daughter cells will be genetically identical
