Genotype, phenotype And Inheritance Flashcards
What is an allele?
A variant form of a gene
Define homozygous
When the two alleles of a gene are the same - may be dominant or recessive
Define heterozygous
The two alleles of a gene are different
Define hemizygous
When only one copy of the gene is present - for example genes on the X chromosome in males
What is codominance?
When neither of two alleles show dominance, so when both are seen in the genotype a (new) codominant phenotype is seen
E.g. Blood groups - A and B are codominant so show AB phenotype
What is recombination frequency?
How often a single chromosomal crossover takes place between two genes (measure of genetic linkage)
Your mitochondria is inherited from ___________
Your mother
What does polygenic mean?
More than one gene is involved in producing the phenotype
What are linked genes?
Genes on the same chromosome
Genes closer together are ________________ linked
More tightly
What are some of the symptoms of huntingtons disease?
Seizures
Abnormal gait
Personality change
Dementia
What is the function of huntingtons protein?
Unknown
What is the mutation causing huntingtons disease?
Mutation in short tandem CAG repeats in HTT gene.
10-25 normal
37-80 HD
More CAG repeats in HD may cause _____________ and _______________
Early onset
More severe symptoms
Deleted genes in what pathway have been shown to prevent HD in mice
The kynurenine biochemical pathway
