L20 Yeast as a Human Disease Model

Question 1

Human genetic diseases start at the cellular level, therefore…

Answer 1

Cellular models can help us understand these defects

Question 2

Yeast is a good model for human disease as:

…

Answer 2

There are fundamentally conserved processes between yeast and human cells which are affected by these diseases.

Question 3

The two main types of yeast are…

Answer 3

1. Saccharomyces cerevisiae (budding)

2. Schizosaccharomyces (fission)

Question 4

Humans, budding yeast and fission yeast are all separated by around 600myrs of evolution. Thus, any cell similarities between the two types of yeast are:

a) unlikely to be conserved in humans
b) likely to be disadvantageous
c) unlikely to be conserved between the yeast types
d) likely to be conserved in humans

Answer 4

d) likely to be conserved in humans

Question 5

5 advantages of yeast as a model organism…

Answer 5

1. Sequenced genome
2. Easy gene deletion
3. East to grow ( unicellular and grow in defined media)
4. Both haploid and diploid life cycles
5. Conserved fundamental processes

Question 6

The cell cycle is regulated by…

Answer 6

Cyclin-dependent kinase (CDK)

Question 7

To regulate the cell cycle, CDK interacts with:

a) phase specific cyclins
b) phase independent cyclins
c) phase specific kinases

Answer 7

a) phase specific cyclins

Question 8

Cell cycle checkpoints regulate the levels of…

Answer 8

Cyclin

Question 9

Cell cycle checkpoints act as a…

Answer 9

Quality control mechanism which is highly sensitive to defects

Question 10

The main cell cycle checkpoints are at (4)…

Answer 10

• G0
• G1
• G2/ M
• M

Question 11

Cancer can be viewed as a…

Answer 11

Disease of the cell division cycle

Question 12

Spontaneous mutations are ( sufficient / insufficient ) to account for the prevalence of cancer

Answer 12

Insufficient

Occurs roughly 1 in a billion times, which is much lower than the cancer rate

Question 13

Environmental factors can influence the speed of…

Answer 13

Damage accumulation in DNA

Question 14

Failure of quality control mechanisms may lead to…

Answer 14

Higher mutation rates

Question 15

Damage to p53 means DNA damage…

Answer 15

Cannot be repaired

Question 16

Mutations at cell cycle checkpoints are a…

Answer 16

Possible target for cancer treatments

Question 17

The majority of cancers have a mutation affecting the G1 checkpoint, which controls…

Answer 17

Entry into the cell cycle

Question 18

S. Pompey has 5000 genes. Of these…

Answer 18

141 are associated with human cancers

Question 19

Examples of cancer associated genes conserved between yeasts and humans are (2)…

Answer 19

MSH2 (DNA repair gene)

ATM (cell cycle checkpoint gene)

Question 20

MSH2 dna repaid gene is associated with

Answer 20

Non polyposis hereditary colon cancer

Question 21

Mutation of the ATM gene is associated with the condition…

Answer 21

Ataxia telasiectasia, which increase sensitivity to UV light, raising cancer risk by x100

Question 22

The genes MEC1 and TEL1 in S. Cerevisiae have high hologram with…

Answer 22

ATM (cell cycle checkpoint gene) in humans

Question 23

We may be able to identify targets for cancer treatments using…

Answer 23

Yeast as a model system

Question 24

Radiation therapy kills cancer cells more readily than normal cells as cancer cells have…

Answer 24

Defective repair mechanisms

Question 25

A synthetic lethal screen for lethal pair wise combinations of gene mutations allows identification of…

Answer 25

Mutations that are lethal only In combination with cancer mutations (so able to differentiate between cancer and normal cells)

Question 26

6-7% of S. pombe genes are associated with a variety of human diseases in addition to cancer. For example (2):

Answer 26

1. SGS1 (WRN/BLM genes in humans associated with premature ageing, also shown in yeast model)
2. IRA1, IRA2 (associated with NR1 gene in humans, complex cognitive symptoms that begin on a cellular level)