Lecture 6: Gene mapping File Flashcards
What is independent assortment ?
The probability of inheriting an allele at one locus is independent of the probability of inheriting an allele at the second locus
what is parental alleles?
Combination of alleles inherited from a parent
what is recombinant alleles?
A different combination of alleles than that possessed by a parent
When does homologous recombination (crossing over) occur ?
Meiosis metaphase 1
What does crossing over generate ?
Gametes with recombinant genotypes
What is the probability of crossing over between two genes which are FAR APART
High
What is the probability of crossing over between two genes which are CLOSE TOGETHER
Low
both vestigal wings and purple eyes mutations in flies are _______
recessive
What makes two genes ‘linked’
If they are on the sam echromosome and their alleles tend to be transmitted in the parental configuration
Why is map distance higher than RF when genes are far apart ?
Because double (or higher) recombinatino ‘hides’ the number of crossovers that have occurred
can RF be 64% ?
No, RF is never more than 50%
What is recombination frequency ?
measure of genetic distance between two genes
RF = ?
RF= (number of recombinants/total number of chromosomes) x 100
What happens if cross over frequency is too low ?
Chromosome is inherited unchanged from generation to genration
What happens if cross over frequency is too high ?
all genes are inherited independantly, therefore no linkage and no mapping
