Complementation testing

Question 1

Why do we do complementation testing?

Answer 1

Identify alleles of the same gene so we don’t waste time and resources mapping different alleles for the same gene

Question 2

What are allelic mutations?

Answer 2

Mutations in the same gene, they don’t complement

Question 3

What are non-allelic mutations?

Answer 3

Mutations in different genes, they do complement

Question 4

What are the two things that can happen to cause allelic mutations to complement each other?

Answer 4

Intragenic complementation and transvection

Question 5

What type of genes can show intragenic complementation?

Answer 5

Genes that encode multidomain proteins

Question 6

Why do genes encoding multi-domain proteins able to show intragenic recombination?

Answer 6

If one mutation knocks out one domain, and another mutation knocks out another domain, each chromosome can supply a functional domain and create a functional protein with a WT phenotype

Question 7

What is transvection?

Answer 7

Type of intragenic complementation that specifically involves an enhancer acting in trans

Question 8

What are the two specific mutations that cause transvection to occur?

Answer 8

One mutation knocks out the promotor of one allele, and the other mutation knocks out an enhancer

Question 9

How does transvection work?

Answer 9

The functional enhancer from the allele with the knocked out promotor acts in trans on the functional promotor from the allele with the knocked out enhancer, and the gene gets transcribed and gives us a WT phenotype

Question 10

How does the Yellow gene in flies show transvection?

Answer 10

The Y2 allele has an insertion right after the enhancer for body tissues, which pushes it too far away to be able to do anything. The Y1#8 allele has a deletion in the promotor. A compound heterozygote has a WT body colour. But if one of those two alleles is with the Y1 allele, which has a point mutation in the coding region, they don’t complement