L20 Yeast as a Human Disease Model Flashcards
Human genetic diseases start at the cellular level, therefore…
Cellular models can help us understand these defects
Yeast is a good model for human disease as:
…
There are fundamentally conserved processes between yeast and human cells which are affected by these diseases.
The two main types of yeast are…
- Saccharomyces cerevisiae (budding)
2. Schizosaccharomyces (fission)
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
d) likely to be conserved in humans
5 advantages of yeast as a model organism…
- Sequenced genome
- Easy gene deletion
- East to grow ( unicellular and grow in defined media)
- Both haploid and diploid life cycles
- Conserved fundamental processes
The cell cycle is regulated by…
Cyclin-dependent kinase (CDK)
To regulate the cell cycle, CDK interacts with:
a) phase specific cyclins
b) phase independent cyclins
c) phase specific kinases
a) phase specific cyclins
Cell cycle checkpoints regulate the levels of…
Cyclin
Cell cycle checkpoints act as a…
Quality control mechanism which is highly sensitive to defects
The main cell cycle checkpoints are at (4)…
- G0
- G1
- G2/ M
- M
Cancer can be viewed as a…
Disease of the cell division cycle
Spontaneous mutations are ( sufficient / insufficient ) to account for the prevalence of cancer
Insufficient
Occurs roughly 1 in a billion times, which is much lower than the cancer rate
Environmental factors can influence the speed of…
Damage accumulation in DNA
Failure of quality control mechanisms may lead to…
Higher mutation rates
Damage to p53 means DNA damage…
Cannot be repaired
Mutations at cell cycle checkpoints are a…
Possible target for cancer treatments
The majority of cancers have a mutation affecting the G1 checkpoint, which controls…
Entry into the cell cycle
S. Pompey has 5000 genes. Of these…
141 are associated with human cancers
Examples of cancer associated genes conserved between yeasts and humans are (2)…
MSH2 (DNA repair gene)
ATM (cell cycle checkpoint gene)
MSH2 dna repaid gene is associated with
Non polyposis hereditary colon cancer
Mutation of the ATM gene is associated with the condition…
Ataxia telasiectasia, which increase sensitivity to UV light, raising cancer risk by x100
The genes MEC1 and TEL1 in S. Cerevisiae have high hologram with…
ATM (cell cycle checkpoint gene) in humans
We may be able to identify targets for cancer treatments using…
Yeast as a model system
Radiation therapy kills cancer cells more readily than normal cells as cancer cells have…
Defective repair mechanisms
A synthetic lethal screen for lethal pair wise combinations of gene mutations allows identification of…
Mutations that are lethal only In combination with cancer mutations (so able to differentiate between cancer and normal cells)
6-7% of S. pombe genes are associated with a variety of human diseases in addition to cancer. For example (2):
- SGS1 (WRN/BLM genes in humans associated with premature ageing, also shown in yeast model)
- IRA1, IRA2 (associated with NR1 gene in humans, complex cognitive symptoms that begin on a cellular level)
