Chapter 3.2: Extensions to Mendel for Multifactorial Inheritance Flashcards
Define permissive conditions
range of temperature organism remains viable
Continuous traits are usually __genic?
polygenic
Define pentrance
how many members of a population with a particular genotype showed the expected phenotype
What is redundant gene action?
Redundant gene action is when proteins encoded by the dominant alleles function in parallel, redundant pathways
Define phenocopy
a change in phenotype due to chemical/environmental agent exposure
What is complementary gene action?
Complementary gene action is when two genes work together to produce a trait and the dominant allele of each gene must be present
What are factors that alter the phenotypic expression of genotype? (3)
o Factors that alter the phenotypic expression of genotype include modifier genes, the environment, and chance
What are continuous traits also called?
qualitative traits
Define restrictive conditions
lethal temperatures organism is unviable
What does dominant epistasis often indicate?
• Dominant epistasis often indicates that alleles of the two genes have antagonistic functions
What is range of temperature organism remains viable?
permissive conditions
What is the presence or absence of the dominant alleles of two genes?
genotype class
What is lethal temperatures organism is unviable?
restrictive conditions
What are continuous traits?
o Continuous traits (also called qualitative traits) vary over a range of values and can usually be measured
What is a complementation test?
The method of discovering whether a particular phenotype arises from mutations in the same or separate genes is a naturally occurring version of an experimental genetic tool called the complementation test
What are modifier genes?
Modifier genes alter phenotypes produced by the alleles of other genes
Define heterogeneous trait
a mutation at anyone of a number of genes that can give rise to the same phenotype
Define epistasis
a gene interaction in which the effects of an allele at one gene hide the effects of alleles at another gene
What is the degree of intensity with which a particular genotype is expressed in a phenotype?
expressivity
Define polygenic
controlled by multiple genes
Define conditional lethal
allele is lethal only under certain conditions
What is a gene interaction in which the effects of an allele at one gene hide the effects of alleles at another gene?
epistasis
What is an allele is lethal only under certain conditions?
conditional lethal
What is dominant epistasis?
Epistasis in which the dominant allele of one gene hides the effects of another gene is called dominant epistasis
What is epistatic?
The allele that is doing the masking is epistatic to the gene that is being masked
What is controlled by multiple genes?
polygenic
Define genotype class
the presence or absence of the dominant alleles of two genes
What is recessive epistasis?
Recessive epistasis is when the allele causing the epistasis is recessive
Why do Humans require pedigree analysis instead of breeding experiments to determine how a trait is inherited?
o Breeding experiments cannot be done for ethical reasons
Define expressivity
the degree of intensity with which a particular genotype is expressed in a phenotype
What is how many members of a population with a particular genotype showed the expected phenotype?
penetrance
The majority of traits are what? (gene number)
multifactorial
What is a change in phenotype due to chemical/environmental agent exposure?
phenocopy
What is a mutation at anyone of a number of genes that can give rise to the same phenotype?
heterogeneous trait
What do the phenotypic ratios resulting from dominant epistasis depend on?
• The phenotypic ratios resulting from dominant epistasis depend on the specific functions of the different alleles and the particular biochemical pathways in which the genes participate
What type of proteins do redundant genes often specify?
• Often, redundant genes specify nearly identical proteins that perform the same function
