Mendelian Genetics and Chromosomal Disorders Flashcards
What is polymorphism
It is a variant or a change that occurs commonly in a population and is not associated with a disease
How does polymorphism contribute to human diversity
Results in variation in the expression of proteins and their associated functions
How can silent mutation be deleterious
A silent mutation may preserve and record for the same amino acid but it may disrupt the normal splicing site, resulting in splicing ratios that maybe associated with disease.
What is Loss of function mutation
When a mutation results in the
- loss of protein or
- reduced amount of the useful protein being made or
- the reduced activity of the protein that has been made
What is a null allele
A copy of the gene at a specific locus that completely lacks the function of that gene
How can 1 null allele influence the function of a gene
It can result in 50% reduction of the protein level expressed
Haploinsufficiency
50% product of a gene result in altered phenotype, usually in the dominant gene, can be associated with a disease
Dominant negative
LOF mutation where the normal function is lost and the mutant protein interferes with the normal product, rendering its function useless aswell
Gain of function mutation
Produce either an increased amount or a protein that has an increased activity
What kind of mutation is usually a GOF mutation
Missense
Can LOF and GOF mutation occur at the same gene at the same time?
Yes
Non penetrance
Failure to manifest a disease even when you have the genotype is defined as non pentrance
Variable expressivity
People with the same genotype express the phenotypes to variable extents. This is called variable expressivity
de novo mutation
A mutation that occurs spontaneously.
First define what is mosacisim and then differentiate between germ line and somatic mosacisim
Mosaicism is the occurrence of cells that differ in their genetic material from other cells of the body. Germ line mosaicism arrises when there is a mutation in the germ line cells, this form of mutation can be passed on to the offsprings.
Somatic mosaicism occurs in somatic cells and it is not passed on to the offsprings. It can occur for example shortly after fertilization, in 1 of the cells when the zygote consists of only 4 cells.
