MOD

Question 1

What is the difference b/w hyperplasia + hypertrophy? (2)

Answer 1

Hyperplasia is an increase in cell numbers

Hypertrophy is an increase in cell size

Question 2

What does growth of a population of cells depend on? (2)

Answer 2

Integration of intracellular + extracellular signals

Checks on cellular physiology, growth + inhibitory factors, cell adhesion

Question 3

What does cell growth at a cellular level occur to? (1)

Answer 3

Increase in size (+ sometimes cell division)

Question 4

What are the phases of the cell cycle + how is progression controlled? (2)

Answer 4

G1, S, G2, M

3 key checkpoints (restriction points)

Question 5

What is apoptosis? (3)

Answer 5

Programmed cell death
A coordinated program of cell dismantling ending in phagocytosis
Distinct from necrosis

Question 6

When does apoptosis happen? (3)

Answer 6

During normal development - separation of digits, involution, immune + NS dev
In response to DNA damage + viral infection

Question 7

What are GFs, cytokines + ILs? ()

Answer 7

Proteins that

• stimulate proliferation (mitogens) + maintain survival
• stimulate differentiation + inhibit proliferation
• induce apoptosis

Question 8

What are the three broad classes of GFs, cytokines + ILs? (4)

Answer 8

Paracrine - produced locally to stimulate proliferation of a diff. cell type with appropriate cell surface receptor
Autocrine - produced by cell that also expresses apropriate cell surface receptor
Endocrine - like conventional hormones, released systemically for distant effects

Question 9

Outline the process of DNA replication (4)

Answer 9

1. DNA is replicated semi-conservatively (daughter cells inherit one parental + one new strand)
2. New DNA is synthesised in 5’ to 3’ direction from deoxynucleotide triphosphate precursors at a replication fork by a multienzyme complex
3. Fidelity is determined by base pairing + presence of proof reading enzyme in DNA polymerase
4. Synthesis of new DNA strand uses an RNA primer occurs continuously on the leading strand + discontinuously on the trailing stand = gives rise to Okazaki fragments which are ligated together after removal of RNA primer

Question 10

What happens if the growth factors are removed? (1)

Answer 10

A normal cell will undergo growth arrest

Question 11

What are the main stages of mitosis? (6)

Answer 11

Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Cytokinesis

Question 12

What happens at the prophase stage? (3)

Answer 12

Nucleus becomes less definite
Microtubular spindle apparatus assembles
Centrioles migrate to poles

Question 13

What happens at the prometaphase stage? (2)

Answer 13

Nuclear membrane breaks down

Kinetochores attach to spindle in nuclear region

Question 14

What happens at the metaphase stage? (1)

Answer 14

Chromosomes align in equatorial plane

Question 15

What happens in anaphase stage? (1)

Answer 15

Chromatids separate + migrate to opposite poles

Question 16

What happens at the telophase stage? (1)

Answer 16

Daughter nuclei form

Question 17

What happens at the cytokinesis stage? (2)

Answer 17

Division of cytoplasm

Chromosomes decondense

Question 18

What are examples of S-phase active drugs? (2)

Answer 18

5-fluoroacil = an analogue of thymidine block thymidylate synthesis
Bromodeoxyuridine = another analogue that may be incorporated into DNA + detect by Abs to identify cells that have passed through S-phase

Question 19

What are examples of M-phase active drugs? (3)

Answer 19

Colchicine stabilises free tubulin, preventing microtubule polymerisation + arresting cells in mitosis (used in karyotype analysis)
Vinca alkaloids (similar action)
Paclitaxel (stabilises microtubules, prevents depolymerisation)

Question 20

What drugs acting on the cell cycle are used in treatment of cancer? (4)

Answer 20

5-fluorouracil
Paclitaxel
Vinca alkaloids
Tamoxifen

Question 21

How is strict alternation of mitosis + DNA replication ensure? (2)

Answer 21

Via cell cycle checkpoints

Controls involving specific protein kinases + phosphatases