Summary
Summary Interactions between genes
- Course
- Institution
Detailed notes on Interactions between genes
[Show more]
Seller
Follow
7joshlyons7
Content preview
BLGY1232 Interactions between genesEpistatic interactions
Most common
Epistasis – an interaction between 2 different genes so that an allele of one of them
(epistatic gene) interferes with or inhibits the phenotypic expression of the other
(hypostatic gene)
Recessive epistasis – the action of one gene is required for the expression of another
coat colour in mice 9:4:3 Aa cc and AA cc mice have the same phenotype as aa
cc mice, Epistasis of cc over A-, white hairs produced irrespective of the genotype at
locus A C is epistatic to A Not a single gene trait (not 3:1), probably 2 genes
(9+6+1=16), probably epistasis (9+6+1 = 9+4+3) 1/16 probably double recessive
Duplicate recessive epistasis – the phenotype requires both genes for its expression
probably 2 genes (9+7=16), probably 2 epistatic interacting genes (9+4+3=9+7)
you cannot get a wildtype phenotypes when grossing 2 parents with mutants in the
same gene (GENETIC COMPLEMENTATION)
Complementation testing is routinely carried out to determine how many genes
control a phenotype;
1. Collect a population of independently isolated mutants showing the same
mutant trait
2. Cross them, in pairwise combinations
3. Count how many crosses produce mutant offspring (mutations in the same
gene) and how many crosses produce wildtype offspring (mutants in different
genes)
4. If the progeny of such a cross show restoration of the wild-type phenotype
the mutations carried by the parents are in different genes – the mutants are
said to complement each other
5. If the progeny still exhibit the mutant phenotype the mutations are in the
same gene – individuals that don’t complement one another form a
complementation group – the number of complementation groups defines
the number of different genes that control the trait in question
Lethal alleles
Recessive lethal – absence of a gene product leads to death in homozygotes
Dominant lethal – both homozygotes and heterozygotes carrying the allele will die
Sex linked lethal – homozygotes of the homogametic sex will die and heterozygotes
will survive, however individuals of the heterogametic sex will die if they inherit the
lethal allele
Usually loss-of-function mutations are recessive
Segregation patterns
Co-dominance and Intermediate dominance F2 generation has 1:2:1
Two alleles are said to display intermediate dominance (also sometimes called
incomplete dominance) when the heterozgote offspring of two true-breeding
parents shows a phenotype that is not identical to either of the parents, but is “in-
between” blending inheritance
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller 7joshlyons7. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.88. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79223 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now