2 - mitosis / cell cycle

Question 1

Phases of Cell Cycle

Answer 1

interphase

nuclear division (mitosis)

cell division (cytokinesis)

Question 2

Interphase

Answer 2

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

Question 3

Binary Fission

Answer 3

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

Question 4

Mutagens

Answer 4

physical or chemical agents that increase the frequency of mutations

Question 5

Mutation

Answer 5

change in the base sequence of DNA during replication

Examples:
Base deletion and base substitution

Question 6

Formation of Tumour

Answer 6

Rate of cell division is controlled by:
-proto-oncogenes (stimulate cell division)
-tumour suppressor genes (slow cell division)

Mutated proto-oncogene (oncogone) stimulates rapid cell division

mutated tumour suppressor gene is inactivated so doesn’t suppress cell division

Question 7

Malignant vs Benign Tumour

Answer 7

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

Question 8

how to make temporary mount of root tissue for mitosis practical

Answer 8

Place end section of root in HCL

Wash end section of root in water

Cut tip from root section and place on slide

Add stain

Break up the tissue with a mounted needle

Cover with a coverslip and squash