2 - mitosis / cell cycle Flashcards
Phases of Cell Cycle
interphase
nuclear division (mitosis)
cell division (cytokinesis)
Interphase
G1 phase
-increase in protein content
-number of organelles such as mitochondria and ribosomes increase and they grow in size
S-phase
-DNA is replicated
G2 phase
-ATP is produced, DNA checked for errors
Binary Fission
the circular DNA and plasmids replicate
the cytoplasm replicates to produce two daughter cells.
Each of these cells has a single copy of the circular DNA but the number of plasmids may vary
Mutagens
physical or chemical agents that increase the frequency of mutations
Mutation
change in the base sequence of DNA during replication
Examples:
Base deletion and base substitution
Formation of Tumour
Rate of cell division is controlled by:
-proto-oncogenes (stimulate cell division)
-tumour suppressor genes (slow cell division)
Mutated proto-oncogene (oncogone) stimulates cells to divide uncontrollably
mutated tumour suppressor gene is inactivated
Malignant vs Benign Tumour
Benign
-Does not spread from original site
Malignant
-spread through the body, invading and destroying other tissues
-interfere with the normal functioning of the organ / tissue in which they have started to grow (eg. they may block the intestines, lungs or blood vessels