WSU MBIOS 301 Practice Exam 3
correctly answered to pass
Wild type allele - correct answer ✔✔The most prevalent version of a gene in wild populations
Mutant allele - correct answer ✔✔A less common version of a gene
Polymorphism - correct answer ✔✔When there is more than one common allele considered to
be wild type
Recessive allele - correct answer ✔✔Al allele masked by a dominant allele and is displayed
when homozygous
Dominant allele - correct answer ✔✔Alleles that effect phenotype as just one copy
Homozygous - correct answer ✔✔When one gene has 2 identical alleles
Heterozygous - correct answer ✔✔When one gene has 2 different alleles
Gain of function mutation - correct answer ✔✔When a gene gains a new or abnormal function
Dominant-negative mutation - correct answer ✔✔When a mutant protein acts to antagonize a
normal protein
Haploinsufficiency - correct answer ✔✔Mutant is loss-of-function allele
One wild type copy is not enough to provide function
,Incomplete penetrance - correct answer ✔✔A situation in which an allele is expected to cause a
particular phenotype, but does not in a given individual
Population based
Variable expressivity - correct answer ✔✔How affected an individual is by a mutation
Example is more than 5 fingers
Incomplete dominance - correct answer ✔✔When heterozygotes exhibit a phenotype
intermediate between the phenotypes of the homozygotes
Codominance - correct answer ✔✔When 2 alleles are expressed at the same time, usually when
there is a gene with 3 or more alleles
Overdominance - correct answer ✔✔Also known as heterozygote advantage
When a heterozygote is more vigorous, has greater reproductive success, than the two
homozygotes
Disease resistance - correct answer ✔✔Microorganism infects a cell only if cellular proteins
function optimally
Heterozygotes have one altered copy of a gene that is enough to prevent infections
Homodimer formation - correct answer ✔✔Two different alleles = two slightly different proteins
and may be able to function in a wider range of conditions or have wider range of functions
Functional variation - correct answer ✔✔When a gene encodes for different metabolic enzymes
depending on conditions and lead to varied phenotypes
, Multiple alleles - correct answer ✔✔Many genes have more than two alleles
Example is blood type alleles
Sex-influenced traits - correct answer ✔✔An allele is dominant in one sex, but recessive in the
other
Is autosomal
Sex-limited traits - correct answer ✔✔Traits that occur in only one of the two sexes resulting in
sexual dimorphism
Essential genes - correct answer ✔✔Genes that are required for an organism to survive
Make up about 1/3 of genes
Nonessential genes - correct answer ✔✔Genes not required for survival but may still benefit
the organism
Lethal alleles - correct answer ✔✔An allele that has the potential to cause death
Conditional lethal alleles - correct answer ✔✔Only lethal under certain environments
Semi-lethal alleles - correct answer ✔✔Lethal in some but not all
Pleiotropy - correct answer ✔✔When one gene has 2+ phenotypic effects
Gene interactions - correct answer ✔✔Occurs when 2+ different genes influence the outcome
of a single trait
correctly answered to pass
Wild type allele - correct answer ✔✔The most prevalent version of a gene in wild populations
Mutant allele - correct answer ✔✔A less common version of a gene
Polymorphism - correct answer ✔✔When there is more than one common allele considered to
be wild type
Recessive allele - correct answer ✔✔Al allele masked by a dominant allele and is displayed
when homozygous
Dominant allele - correct answer ✔✔Alleles that effect phenotype as just one copy
Homozygous - correct answer ✔✔When one gene has 2 identical alleles
Heterozygous - correct answer ✔✔When one gene has 2 different alleles
Gain of function mutation - correct answer ✔✔When a gene gains a new or abnormal function
Dominant-negative mutation - correct answer ✔✔When a mutant protein acts to antagonize a
normal protein
Haploinsufficiency - correct answer ✔✔Mutant is loss-of-function allele
One wild type copy is not enough to provide function
,Incomplete penetrance - correct answer ✔✔A situation in which an allele is expected to cause a
particular phenotype, but does not in a given individual
Population based
Variable expressivity - correct answer ✔✔How affected an individual is by a mutation
Example is more than 5 fingers
Incomplete dominance - correct answer ✔✔When heterozygotes exhibit a phenotype
intermediate between the phenotypes of the homozygotes
Codominance - correct answer ✔✔When 2 alleles are expressed at the same time, usually when
there is a gene with 3 or more alleles
Overdominance - correct answer ✔✔Also known as heterozygote advantage
When a heterozygote is more vigorous, has greater reproductive success, than the two
homozygotes
Disease resistance - correct answer ✔✔Microorganism infects a cell only if cellular proteins
function optimally
Heterozygotes have one altered copy of a gene that is enough to prevent infections
Homodimer formation - correct answer ✔✔Two different alleles = two slightly different proteins
and may be able to function in a wider range of conditions or have wider range of functions
Functional variation - correct answer ✔✔When a gene encodes for different metabolic enzymes
depending on conditions and lead to varied phenotypes
, Multiple alleles - correct answer ✔✔Many genes have more than two alleles
Example is blood type alleles
Sex-influenced traits - correct answer ✔✔An allele is dominant in one sex, but recessive in the
other
Is autosomal
Sex-limited traits - correct answer ✔✔Traits that occur in only one of the two sexes resulting in
sexual dimorphism
Essential genes - correct answer ✔✔Genes that are required for an organism to survive
Make up about 1/3 of genes
Nonessential genes - correct answer ✔✔Genes not required for survival but may still benefit
the organism
Lethal alleles - correct answer ✔✔An allele that has the potential to cause death
Conditional lethal alleles - correct answer ✔✔Only lethal under certain environments
Semi-lethal alleles - correct answer ✔✔Lethal in some but not all
Pleiotropy - correct answer ✔✔When one gene has 2+ phenotypic effects
Gene interactions - correct answer ✔✔Occurs when 2+ different genes influence the outcome
of a single trait
