MBG 3060 Final Exam Questions and Answers Graded A+
Qualitative trait; give an example - Answers - phenotypes directly associated with specific genotype
- eg, coat colour
Quantitative trait; give an example - Answers - phenotypes controlled by many different loci (polygenic)
& display a range of expression
- eg. litter size, racing speed, growth rate
What makes up the phenotype? (short version) - Answers genotype + environment
what makes up the genotype? - Answers addition + dominance + interaction
Addition; give an example - Answers - measure of the sum of effects of individual alleles
- passed on in gametes
- inbreeding is an additive gene effect
Dominance - Answers measure of combined dominance effects of individual loci
interaction - Answers - combined effect of different loci on one phenotype
- is typically ignored due to difficulty isolating its affects
- form of epistasis
- dominant interaction effects are NOT inherited
what makes up enviroment? - Answers Epermenant + Etemporary
- phenotype may change from day by day, we can determine which parts of phenotype have been perm.
changed by environment vs temporary
what is the phenotypic equation normally used? - Answers = A + Ep + Et
- deom. & interaction are not inherited, so represent under umbrella of Ep
What is phenotypic variance? - Answers measure of range of a phenotype
What is genotypic variance? - Answers measure of a range of underlying genotype
what is additive genetic variance? - Answers - measure of a range of additive genetic component of
variance
-eg, variance passed on from parents to offspring
, what is dominant genetic variance? - Answers - measure of range of dominant genetic component of
variance
what is hertitability? what is the equation used? - Answers - is a ratio of genotypic variance &
phenotypic variance
- how much of the phenotype that we observe is due to the underlying genotype
= O^2A / O^2P
Estimation of heritability is based on.. - Answers covariances among relatives
what is covariance? give an example - Answers - means independent variables are linked
- eg, variance of one individual increases, the other one also increases
what is the equation for covariance between individuals i & j? - Answers = aij x O^2A
for unrelated individuals, what does a equal? - Answers a = 0
- so covariance would be 0, no influence of each others variances
what can heritablity be estimated by? - Answers linear regression & ANOVA
what is linear regression? - Answers - used to predict the value of the dependant variable based on the
value of the independant variable
how can heritability be estimated from linear regression? - Answers estimated from the slope b, of the
line when plotting phenotype of offspring (dependant) against one parent (independant)
what is the equation used for offspring-parent regression slope? - Answers bO.P = Cov(OP) / O^2P = 1/2
( O^2A/O^2P) = 1/2 (h^2)
mid-parent variance - Answers average of parental phenotype variance ( 2 parents)
why is offspring-mid-parent regression preferred over offspring-parent regression? - Answers since it
provides more info than variance of a single parent
what is the equation for offspring-midparent regression slope? - Answers bO.MP = Cov(OP) / O^2P
= (O.S(O^2A)/O.S (O^2P) = h^2
heritability predicts.. - Answers degree of genetic resemblance between relatives & generations
- defines how much genetic change will result from selection; predicts pace of change in population
selection differential (S) - Answers - average of selected parents deviated from original population mean
selection differential (S) equation - Answers S = Xs-Xp
Qualitative trait; give an example - Answers - phenotypes directly associated with specific genotype
- eg, coat colour
Quantitative trait; give an example - Answers - phenotypes controlled by many different loci (polygenic)
& display a range of expression
- eg. litter size, racing speed, growth rate
What makes up the phenotype? (short version) - Answers genotype + environment
what makes up the genotype? - Answers addition + dominance + interaction
Addition; give an example - Answers - measure of the sum of effects of individual alleles
- passed on in gametes
- inbreeding is an additive gene effect
Dominance - Answers measure of combined dominance effects of individual loci
interaction - Answers - combined effect of different loci on one phenotype
- is typically ignored due to difficulty isolating its affects
- form of epistasis
- dominant interaction effects are NOT inherited
what makes up enviroment? - Answers Epermenant + Etemporary
- phenotype may change from day by day, we can determine which parts of phenotype have been perm.
changed by environment vs temporary
what is the phenotypic equation normally used? - Answers = A + Ep + Et
- deom. & interaction are not inherited, so represent under umbrella of Ep
What is phenotypic variance? - Answers measure of range of a phenotype
What is genotypic variance? - Answers measure of a range of underlying genotype
what is additive genetic variance? - Answers - measure of a range of additive genetic component of
variance
-eg, variance passed on from parents to offspring
, what is dominant genetic variance? - Answers - measure of range of dominant genetic component of
variance
what is hertitability? what is the equation used? - Answers - is a ratio of genotypic variance &
phenotypic variance
- how much of the phenotype that we observe is due to the underlying genotype
= O^2A / O^2P
Estimation of heritability is based on.. - Answers covariances among relatives
what is covariance? give an example - Answers - means independent variables are linked
- eg, variance of one individual increases, the other one also increases
what is the equation for covariance between individuals i & j? - Answers = aij x O^2A
for unrelated individuals, what does a equal? - Answers a = 0
- so covariance would be 0, no influence of each others variances
what can heritablity be estimated by? - Answers linear regression & ANOVA
what is linear regression? - Answers - used to predict the value of the dependant variable based on the
value of the independant variable
how can heritability be estimated from linear regression? - Answers estimated from the slope b, of the
line when plotting phenotype of offspring (dependant) against one parent (independant)
what is the equation used for offspring-parent regression slope? - Answers bO.P = Cov(OP) / O^2P = 1/2
( O^2A/O^2P) = 1/2 (h^2)
mid-parent variance - Answers average of parental phenotype variance ( 2 parents)
why is offspring-mid-parent regression preferred over offspring-parent regression? - Answers since it
provides more info than variance of a single parent
what is the equation for offspring-midparent regression slope? - Answers bO.MP = Cov(OP) / O^2P
= (O.S(O^2A)/O.S (O^2P) = h^2
heritability predicts.. - Answers degree of genetic resemblance between relatives & generations
- defines how much genetic change will result from selection; predicts pace of change in population
selection differential (S) - Answers - average of selected parents deviated from original population mean
selection differential (S) equation - Answers S = Xs-Xp
