20.4 Phenotypic Ratios Flashcards
What is an autosome? (1 mark)
A chromosome that is not a sex chromosome.
What is autosomal linkage? (3 marks)
When genes on the same chromosome are linked, they are inherited as one unit, independent assortment does not happen during meiosis.
What are recombinant offspring? (1 mark)
Offspring who have different combinations of alleles than their parent.
What affects how likely the genes (in linked autosomes) are separated during crossing over? (2 marks)
How close the genes are, the closer they are, the less likely they are to be separated.
The closer the genes are on a chromosome the less likely they are to be separated during crossing over and the fewer ……… (1 mark)
Recombinant offspring produced.
What is the recombination frequency? (1 mark)
The measure of the amount of crossing over that has happens in meiosis.
What is the equation for recombination frequency? (2 marks)
= number of recombinant off spring/ total number of offspring
What does a recombination frequency of above 50% indicate? (1 mark)
That there is no linkage and the genes are on separate chromosomes.
What does a recombination frequency of less 50% indicate? (1 mark)
That there is gene linkage
What is epistasis? (1 mark)
The interaction of genes at different loci.
What is gene regulation? (1 mark)
A form of epistasis with regulatory genes controlling the activity of structural genes.
What is dominant epistasis? (1 mark)
When a dominant allele results in a gene having an effect on another gene.
What is recessive epistasis? (1 mark)
When the phenotype of one alleles masks or prevents the phenotype of another.
What is the chi-squared test? (2 marks)
A statistical test that measures the size of the difference between the results you actually get and those you expected to get.
What is the null-hypothesis is the chi-squared test? (1 mark)
That there is no significant difference between what we expect and what we observe/ that the differences we do see are due to chance.
