GENETICS

Monogenic
Click the card to flip 👆
1 / 11
Terms in this set (11)
Monogenic
Disease due to mutation or defect In a single gene
polygenic
Disease due to mutation at 2+ loci
Homologous recombination
repair of DNA break.
Has 3 steps.
1. Strand invasion
- Initiated by RAD51 and expose the 3' end and invades sister chromatid
2. Branch migration
- DNA repair from both 3' ends using homologous template
3. Holliday junction formation - junction formed by RESOLVASES
DNA mismatching repair
Corrects DNA replication errors
Mismatch recognised by MSG
Binding MLH activates exonuclease and continues along strand till mismatch removed
nucleotide excision repair
Protects against damage from UV
Repairs DNA from 24-32 nucleotides
damage recognised by XPC that recruits XP proteins
Damage removed by XPG
base excision repair
Protects against DNA damage by endogenous mutagens
Repairs DNA from 1-13 nucleotides
Steps in DNA breaks and chromosome abnormalities
1. Cell enters S phase and replicates DNA despite break
2. One daughter cell inherits chromosome lacking telomere
3. Cell enters S phase and replicates dna
4. Sister chromatid ends fuse together
5. Fused ends pulled apart in mitosis making new break site
6. One daughter cell inherits chromosome with duplicate gen. But lacking telomere
Function of Care taker gene
maintain genomic integrity
Inactivation of gene leads to accumulation of DNA mutations
function of gate keeper genes
Prevent growth of potential cancer cells and prevent accumulation of mutations
* induces cell death or cycle arrest to potentially inorganic cells
* if cell damaged then p53 induced in cycle phase and cause cell arrest
* if damage repaired the cycle continues. If not repaired then cell dies
5 things to distinguish cancer cells
1. uncontrolled cell proliferation
2. Have mechanisms to avoid apoptosis
3. Able to invade tissues by loosing cell adhesion molecules
4. Acquire increased mobility
5. Secrete factors to induce New vvessel fformation
Functions of cancer genes1. Cell cycle regulators 2. DNA repair 3. Apoptosis 4. Senescence