Lecture #12 Flashcards
What is the most common allele and how is it identified?
the wild type, usually identified with a superscript +
What is a polymorphism?
Any allele found at appreciable frequencies (at least 1%) in the population
What alleles are considered mutant alleles?
any alleles other than the wild type or any polymorphisms
What are 5 factors that mendel did not account for in his expeirements?
genes have more than 2 alleles, different alleles may affect the phenotype in different ways, a single gene may control several traits, multiple genes may control a single trait, environmental factors can influence phenotypes
What is incomplete dominance?
When the heterozygotes have a phenotype of the two homozygotes mixed
Why may incomplete dominance happen?
the homozygotes have twice as much enzyme as heterozygotes
What is co-dominance?
When the phenotype expresses the phenotype of both homozygotes
What is an allelic series?
describes the dominance hierarchy of multiple alleles
What is the genotype for blood type A?
I^A I^A or I^A i
What is the genotype for blood type B?
I^B I^B or I^B i
What is the genotype for AB blood type?
I^A I^B
What is the genotype for O blood type?
ii
What is penetrance?
the percentage of individuals having a particular genotype that expresses the expected phenotype
What is expressivity?
the degree to which a character is expressed
What is incomplete penetrance?
When individuals do not express a trait even though they have the genotype
What is a lethal allele?
causes death at an early stage of development, and so some genotypes may not appear among the progeny
What is the results of a null mutation in either the cyclin gene or the CDK gene?
it will inhibit the phosphorylation of the target protein and generate the same mutant phenotype
What are discontinuous characteristics?
relatively few phenotypes
What are polygenic characteristics?
characteristics influenced by genes at many loci
What is a temperature sensitive allele?
an allele whose product is only functional at certain temperatures
What are multifactorial charcteristics?
refers to the continuous characteristics that are both polygenic and influenced by environmental factors
