MolBio14-15 - 22 Flashcards
What are the three steps in general forward genetics?
Randomly mutate the genome, look for interesting phenotypes, identify the gene that causes it
Outline forward genetics
Function > gene
Outline backward genetics
Gene > function
What does complementation analysis try to prove?
Whether different mutations with the same phenotype are in fact different alleles of the same gene
What does linkage analysis try to prove?
Whether two alleles are linked
How does linkage analysis work?
Analysis of the occurrence of recombination between our allele and a known marker - further away = more frequent crossing over during meiosis; R/T x 100 = centimorgan (R = recombinant genes; T = total gametes)
What are SNPs?
Single Nucleotide Polymorphisms - markers of possible disease, easy to compare between individuals
How many SNPs have been placed on the human chromosome?
> 1 million
What is the premise of SNPs?
If an SNP is always present in diseased children, but not in healthy ones, then we know the gene is linked to the SNP
How do mutations affect gene function?
Changes in regulatory sequence, changes in non-coding sequence, changes in the coding sequence
What can changes in non-coding sequence result in?
Alterations in RNA splicing, stability or translation
What can changes in the coding sequence result in?
Folding or truncation
What is meant by an amorphic mutation?
Missense mutation that inactivated function, completely haplosufficient (enough normal), recessive
What is meant by a hypomorphic mutation?
Missense mutation that weakens function, mostly haplosufficient (some may interrupt normal function), recessive
What is meant by an antimorphic mutation?
Missense resulting in deletion, dominant negative, rare functioning (requires correct WT combination), almost dominant
What is meant by a hypermorphic mutation?
Over-reactive, constituently active, dominant
What makes anti-body purification easy?
Epitope tagging
What are epitope tags?
Peptides for which antibodies are already available
How are anti-bodies purified?
Small beads coated with antibody for their epitope tag, then the crude extract of bacterial farm is pass through them
How are some anti-bodies detected?
Fluorescence, enzyme conugates, antibody conjugates
Examples commonly used enzyme conjugates
Alkaline phosphatases (blue); horseradish peroxidase (brown); betagalactosidase (blue)
How can the antibody signal be amplified?
Use antibody for antibody (more than one binds)
