mitosis and the cell cycle 3.2.2 Flashcards
what does mitosis produce
2 genetically identical daughter cells
what does meiosis produce
4 daughter cells with half the number of chromosomes
order of cell cycle
interphase
prophase
metaphase
anaphase
telophase
cytokinesis
what happens during prophase
chromatin condenses
spindle fibres start to develop
nucleolus disappears
nuclear envelope breaks down
what happens during metaphase
chromosomes pulled along spindle apparatus and arranged across equator of the cell
what happens during anaphase
centromeres divide in 2
spindle fibres pull chromatids to opposite poles of the cell
what happens during telophase
chromosomes return to chromatin state
spindle fibres disintegrate
nuclear envelope + nucleolus reforms
what happens during cytokinesis
cytoplasm and cell membrane divides to form 2 daughter celld
what happens during interphase
synthesis of DNA
synthesis of protein
synthesis of ATP
growth of cytoplasm and organelles
what happens during binary fission
DNA replicates
cell membrane grows and pinches inwards
dividing cytoplasm
new cell wall forms between
produces 2 daughter cells
what is the process of replication of viruses
attach to host cell
inject nucleic acid into cell
this instructs host cell to produce viral components, nucleic acid, enzymes and proteins
new viruses are made inside host cell
host cell bursts to release new viruses
what is it called when the host cell bursts
lysis
what causes cancer
mutation in a gene that controls the cell cycle causing damage to genes leading to the development of a tumour
what can the rate of mitosis be affected by
the environment of the cell
growth factors
proto oncogenes
tumour suppressor factors
what can a mutation to a proto oncogene / tumour suppressor factors cause
uncontrolled mitosis
what are the features of a malignant tumour
very uncontrolled division
less compact
more likely to be life threatening
can be carried by the blood steam or lymphatic system to invade other tissues
what are the features of a benign tumour
do not spread from point of origin
do not cause cancer
less life threatening
three treatments for cancer
surgery - removal of tumour
radiotherapy
chemotherapy
what is radiotherapy
radiation damages DNA and causes cells to kill themselves
what is chemotherapy
drugs used to treat cancer
how does chemotherapy work (2 ways)
- prevents DNA from replicating
- inhibits the metaphase stage of mitosis by interfering with spindle formation
what is the issue with cancer drugs
they also disrupt cell cycle of normal cells
why does chemotherapy cause hair loss
drugs are more effective against rapidly dividing cells - hair cells are rapidly dividing
describe binary fission in bacteria (3 marks)
- DNA replicates
- replication of plasmids
- division of cytoplasm
