The Cell Cycle

Question 1

Three checkpoints of the cell cycle

Answer 1

1. G1/S checkpoint
   - the cell “decides” to divide
2. G2/M checkpoint
   - the cell makes a commitment to mitosis
3. late metaphase (spindle) checkpoint
   - the cell ensures that all chromosomes are attached to the spindle

Question 2

G1/S checkpoint

Answer 2

Division can be halted by DNA damage, starvation, and lack of growth factors

Question 3

G2/M checkpoint

Answer 3

Division can be halted by DNA damage or incomplete DNA replication

Question 4

Metaphase checkpoint

Answer 4

Division can be halted by sister chromatids not being properly attached to the mitotic spindle

Question 5

cyclins

Answer 5

proteins produced at different times in the cell cycle

Question 6

cyclin-dependent kinases (Cdks)

Answer 6

enzymes that drive the cell cycle (always present but activate only when bound by a cyclin)

Question 7

Growth factors:

Answer 7

• influence the cell cycle
• trigger intracellular signaling systems
• can override cellular controls that otherwise inhibit cell division

Question 8

Platelet-derived growth factor (PDGF) triggers what?

Answer 8

Cells to divide during would healing

Question 9

Cancer cells

Answer 9

• reproduce in defiance to normal restraints on cell growth and division
• invade and colonize territories normally reserved for other cells

Question 10

benign tumor

Answer 10

overgrown cells, but they stay in the area the cell type is normally found

Question 11

malignant tumor

Answer 11

cells have acquired ability to invade other tissues

Question 12

metastasis

Answer 12

when a tumor breaks open and spreads to other sites in the body

Question 13

viruses

Answer 13

• contains genes that promotes cell division
• contain nucleic acid
• insert genetic material

Question 14

Cancer can arise from:

Answer 14

• loss of function mutations in tumor suppressor genes

- gain of function mutations in proto-oncogenes

Question 15

epidermology

Answer 15

analysis of disease frequency in populations