Exam 2 Flashcards
(93 cards)
Haplosufficient
Promote a wild type function or full expression in only one copy
Dominant negative
As a heterozygote wipes out a gene function by a spoiler effect on the protein
Incomplete or partial dominance
Intermediate phenotype
Temperature Sensitive mutants
Allele can be expressed as both permissive and restrictive temperature, protein only encoded if permissive
Pleiotropic
When a single gene has multiple effects
Archibald Garrod
Discovered that many diseases show defects in metabolism
Beadle and Tatum
Used Neurospora to discover that one gene will lead to the production of one protein (one-gene-one-polypeptide)
Inferring Gene Interactions
1) Obtain and select a mutant, confirm single gene inheritance and asses phenotype
2) Test mutant for allelism and confirm the total number of genes involved
3) Combine the mutants into pairs to form double mutants to see if the genes interact
Complementation Test
Distinguishes if two mutant alleles are on the same gene/enzyme
Recessive Epistasis
A mutant allele of one gene masks the expression of the mutant allele of another gene and expresses its own phenotype
Suppressor Screens
Mutate the mutant and look for WT phenotype, looks for a return to an original state
Penetrance
Percentage of individuals with a given allele who shows the phenotype
Expressivity
Degree to which an allele is expressed, the intensity of the phenotype
Fredrick Griffith
1928, worked with pneumonia in mice to assume there had to be some biological matter transferring
Oswald Avery
1944, continued Griffith’s experiment with mice and found evidence of DNA
Hershey-Chase
1952, confirmed evidence of DNA by using phage and T2 virus
Key Properties of DNA
1) Makes copies of itself
2) Encodes information
3) Is able to mutate
Structure of DNA
Phosphate, deoxyribose, and the four nitrogenous bases
Purines
Adenine and Guanine
Pyrimidines
Cytosine and Thymine
Chargaff’s Rules
Amount of A = T and amount of C = G
Double Helix
Discovered by Watson and Crick with the help of x-ray differentiation images done by Rosalind Franklin and Maurice Wilkins
Semi-Conservative Replication
Some parental and some new DNA
Conservative Replication
Parental is used as a template