cell division

Question 1

euchromatin

Answer 1

• lightly packed chromatin
• in parts of chromosome that contain many genes
• can be transcribed
• found close to nuclear pore

Question 2

heterochromatin

Answer 2

• densely packed chromatin
• found in parts of chromosome where there are few inactive or no genes
• not transcribed
• replicated during s phase

Question 3

cell cycle regulation

Answer 3

G1 and G2/M
- whether or not to continue in cell cycle
- cycling dipendent kinases (cdks) are protein kinases activated by formation of a complex with cyclin
- regulates cell cycle and signals the cell is ready to pass into the next stage of cell cycle

Question 4

carcinogenesis

Answer 4

• Retinoblastoma rare form of cancer which develops in retina
• due to mutations of RB1 gene in chromosome 13
• RB1 is tumour suppressor gene and normally regulates cell growth
• At G1/S checkpoint pRb is phosphorylated by cyclins