Lecture 47. Recombination - Birth of Linkage Mapping Flashcards
What was the chromosome theory of hereditary?
Chromosomes were the units of heredity, heredity could be explained by what’s on a chromosome
What are non-parental phenotypes known as?
Recombinant
What was interesting about all pairwise combinations of Mendel’s seven traits?
They were all assorted independtly
What experimental model did Hunt-Morgan and Sturtevant experiment on?
Drosophila melanogaster
What hypothesis did Hunt-Morgan reach?
For two genes on the same chromosome the frequency of recombination will depend on the physical distance between them
What did Sturtevant discover?
How to map genes on same chromosome
What are the units of heredity?
Genes not Chromosomes
How are genes located on a chromosome?
Genes are ‘physically’ located in a linear manner along a chromosome
What does 0% recombination mean?
Two genes are very tightly linked or possibly the same gene
What does 50% recombination mean?
Independently assorting, unlinked or on different chromosome or far apart on same chromosome
What are the units of recombination?
Centimorgan (cM)
1% recombination = 1 map unit = 1 centimorgan
What are the steps taken to identify a gene responsible for a Mendelian trait through map-based cloning?
Step 1. Identify the genes location (locus) from a genome-wide search of linkage to markers.
Step 2. Sequence the DNA across the locus, in both wild type and mutant variants.
Step 3. Verify function of the causal gene.
What is a molecular marker?
A difference in DNA sequence (DNA polymorphism) between two individuals
How to verify whether a candidate gene is casual?
Mutational analysis - Loss-of-function experiment
Genetic transformation - Gain-of-function experiment
