Term
| What are the 4 roles of apoptosis? |
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Definition
1. sculpting tissue
2. Tissue homeostasis
3. Controlling cell numbers
4. Eliminating abnormal or harmful cells |
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Term
| Describe the mechanism of apoptosis in mammals |
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Definition
| Bcl-2 is an inhibitor of Apaf-1. Apaf-1 promotes Caspase, which causes apoptosis. When apoptosis is triggered, BH3-only inhibits Bcl-2, removing its inhibitory effect on Apaf-1. |
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Term
| How do caspases function? |
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Definition
1. They are originally expressed as inactive pro-caspases
2. They cleave and destroy proteins essential for structure and survival
3. They also activate DNAse |
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Term
| how does the apoptosome form and what does it do? |
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Definition
BH3 causes mitochondria to release Cytochrome C which binds to Apaf-1, which combines with other dimers to make the apoptosome.
The apoptosome is what cleaves pro-caspase to activate their apoptic functions |
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Term
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Definition
Genes that when activated promote excess cellular number or growth
Require one mutational event and are dominant gain of function |
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Term
| What are tumor suppressor genes? |
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Definition
Genes that when inactivated can lead to excess cell number or growth
Require two mutational events (both alleles), recessive loss of function |
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Term
| What are caretaker genes? |
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Definition
| Genes responsible for maintaining the integrity of the genome. Their inactivation can lead to an increase in the mutation of other genes. |
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Term
| What are the 6 characteristics of cancer? |
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Definition
1. Evading apoptosis
2. Self-sufficiency in growth signals
3. Insensitivity to anti-growth signals
4. Tissue invasion and metastasis
5. Sustained angiogenesis
6. Limitless replicative potential |
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Term
| What is the mechanism of Rous activation? |
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Definition
| The oncogene v-src (normally found in animal cells) is incorporated into the RSV (a virus) genome. When the virus invades a cell, it leads to overexpression of this gene leading to uncontrolled mitosis. |
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Term
| What are the mechanisms by which oncogenes become activated? |
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Definition
1. Point mutation
2. Amplification of the gene
3. Translocation of the gene toward a strong promoter
4. Translocation to create fusion with a new protein
5. Proviral insertion |
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Term
| How do anti-oncogenes work? |
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Definition
| Anti-oncogenes are genes whose protein expression serve to inhibit the function of oncogenes |
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Term
| What is Knudson's "two-hit" hypothesis? |
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Definition
| Retinoblastoma is the outcome of mutated tumor suppression genes which are inherited from parents. In familial cases, one mutant allele is passed down, meaning only 1 more mutation is needed for cancer to proliferate. In sporadic cases, 2 mutations are needed (This is an example of a "loss of function" mutation, so a mutation on both alleles is necessary). |
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Term
| Mutations in what gene are likely involved in all forms of cancer? |
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Definition
Rb (a tumor suppression gene)
Mutations lead to rapid cell proliferation |
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