Cellular Biology

Question 1

Mention the phases of the cell cycle and the most important event of each of them.

Answer 1

• G1 phase: synthesis of proteins and organelles.
• S phase: synthesis of DNA.
• G2: growth in preparation for mitosis.
• M phase: cell divide into two daughter cells.

Question 2

What’s the difference between a Mitogen and a Growth factor?

Answer 2

A Growth Factor stimulates growth in size and a Mitogen (function via Cyclin dependant kinases) stimulates growth via cell division.

Question 3

Three examples of “labile cells” that rarely/never enter the G0 state.

Answer 3

1. Bone marrow cells.
2. GI epithelial cells.
3. Hair follicle cells.

Question 4

Neurons and skeletal muscles cells are in permanent __ state.

Answer 4

G0

Question 5

Mention the phases of Mitosis and the most important event of each of them.
“Pee on the MAT”

Answer 5

1. Prophase: chromosomes condense, spindle fibers form.
2. Prometaphase: chromosomes organize on mitotic spindle.
3. Metaphase: chromosomes lined up on the metaphase plate.
4. Anaphase: chromosomes separate.
5. Telophase/Cytokinesis: cells divide.

Question 6

Explain the function of CDK’s.

Answer 6

Kinase enzymes lead to phosphorylation of other proteins, regulating the cell cycle

Question 7

Which disease is caused by a mutation in Rb1 gene?

Answer 7

Retinoblastoma.

Question 8

Which disease is caused by a mutation in the gene TP53?

Answer 8

Li-Fraumeni syndrome. (Sarcoma, Breast, Leukemia, Adrenal gland)

Question 9

Explain the main function of P53 protein.

Answer 9

P53 induces transcription of P21 protein, this protein binds to CDK’s, inhibiting it’s activity and blocking cell progression through cell cycle.