3.2.2 All cells arise from other cells Flashcards
(13 cards)
1
Q
what is interphase?
A
longest stage of cell cycle
- DNA replication (synthesis)
- growth of cell and new organelles + proteins made (G phases)
2
Q
why is mitosis important?
A
growth + repair
3
Q
what happens in prophase?
A
- chromatin condenses
- nuclear envelope breaks down
- centrioles move to opposite poles
4
Q
what happens in anaphase?
A
- spindle fibres contract
- chromatids separated and pulled apart
- centromere divides
5
Q
what happens in metaphase?
A
- chromosomes line up at equator
- spindle fibres attach to centromere
6
Q
what happens in telophase?
A
- nuclear envelope reforms
- 2 nuclei forms
- chromosomes decondense
7
Q
how is cancer caused?
A
by uncontrolled cell division leading to a tumour. genes controlling cell division are mutated
8
Q
how can cancer be treated?
A
- control rate of cell division
- G1 phase = some chemical drugs prevent synthesis of enzymes needed for DNA replication so cell unable to enter synthesis stage causing it to kill itself
- synthesis = radiation/ some drugs damage DNA. At cell checkpoints, cell checks DNA for damage, will kill itself
9
Q
how does meiosis cause genetic variation
A
- crossing over of homologous chromosomes
- independent segregation
- random nature of fertilisation
10
Q
what does meiosis create?
A
2 nuclear divisions lead to 4 genetically unique cells (haploid)
11
Q
what is the point in meiosis 1
A
to separate homologous pairs
12
Q
what is the point in meiosis 2
A
to separate chromatids
13
Q
A
