Complex (non-mendelian) inheritance Flashcards
What is penetrance?
The frequency with which a trait is manifested by individuals carrying a gene.
What is incomplete penetrance?
When not every individual in a populations with a gene expresses the trait.
Define precision/personalised medicine?
Checking someones DNA mutations could be used to tell their risk of developing a disease (e.g. breast cancer) based on the penetrance amonst othe people with the same genes,
What are genetic modifiers in terms of penetrance?
Genes with a small quantitative effect on the level of expression of another gene.
What else effects penetrance?
Enviromental factors like lifestyle, air polutions, alcohol, diet etc.
What is an imprinted gene?
An imprinted gene is silenced or deactivated.
How does genomic imprinting effect inheritance?
An epigenetic phenomonon.
If the gene inherited from one of the aprents is imprinted then only the gene from the other is expressed leading to a mono-allelic child.
Why do imprinted genes has a higher risk of mutation?
Because they only have one active allele so they are more susceptible to mutations.
From which parent does mitochondrial DNA come?
Mitochondrial DNA is entirely Maternal
Why does mitochondrial DNA have a much higher mutation rate than the nuclear genome?
- LAcks efficient DNA repair system
- Lacks protective proteins like histones
- Is damaged by reactive oxygen species (ROS) such as free radicals
What is Homoplasmy?
When the mtDNA is uniform within a cell
What is heteroplasmy?
When the mtDNA in the mitochondria of a cell is different (i.e. some are mutated)
What is the effect on disease of mitochondiral inheritance?
Diseases cuased by mutated mtDNA are more serious the higher the percentage of mutated mtDNA
Why is a cell’s mtDNA often polyploidy?
Each cell has thousands of mitochondria and 2-10 copies of DNA in each.
What does anticipation mean?
Diseases that present younger or more severely in succeeding generations.
