Quantitative Genetics And Multifactorial Traits

Front 1

What are polygenetic traits

Back 1

controlled by more than one gene; ususally a complex character such as skin color, cancer cells

Front 2

continuous variation is also known as

Back 2

quantitative inheritance

Front 3

What is a continuous trait often the result of?

Back 3

polygenic ingeritance and is frequent multifactorial-multiple genes contributing to a trait and the environmental impact on the degree of expression. Example anger, addition.

Front 4

multifactorial trait

Back 4

phenotype that results from gene action and environmental influences

Front 5

meristic traits

Back 5

polygenic traits in which the phenotype is recorded by counting whole number. They are quantitative traits but do not have an infinite range of phenotypes. example; – eggs per clutch- you will not have 6.5 eggs-not infiniate range

Front 6

What is a threshold traits

Back 6

are polygenic and often multifactorial but have a small number of discrete phenotypic classes, an increasing number of diseases show this pattern of polygenic inheritance

Front 7

Cancer is result of what kind of trait?

Back 7

Threshold trait

Front 8

How can quantitative traits be explained in Mendelian terms?

Back 8

by many genes, each behaving individually in mendelian fashion, contributing to the phenotype in a cumulative or quantitative way

Front 9

corolla length in Nicotiana and grain color Triticum demonstrate what?

Back 9

Multifactorial hypothesis

Front 10

If you have a corolla length with one ranging 37-44mm and 91-97mm and you crossed them and get 61-67. What is the reasoning for this result in the F1? What happens in the F2?

Back 10

In the F1 population is it contribution of multiple genes influencing the trait, In the F2 population the variance increases and the mean is similar to what we started with however the spread is changed (variability changes). This show's Mendel's fist law of segregation of alleles

Front 11

What happens when you cross small with smalls, meds with meds, and large and large, overtime with the F3 generation?

Back 11

In the F3 generation the range is limited therefore the distribution is narrower and over time they become reproductively isolated from each other and diverge farther apart which can be speciation.

Front 12

In oncolor in wheat the contribution is noe the same as Mendel's dihybrid cross. Why?

Back 12

in this cross both of the alleles contribute to the same trait in the same way

Front 13

AABB has how many contributions? (oncolor in wheat)

Back 13

Has 4 contributions to the color and is most intense because it has 4 additive alleles the genotypic ratio is 1:4:6:4:1 and is approaching a bell shaped curve

Front 14

1 gene pair

Back 14

1:2:1

Front 15

2 gene pair

Back 15

1:4:6:4:1

Front 16

3 gene pair

Back 16

1:6:15:20:15:6:1

Front 17

4 gene pair

Back 17

1:8:28:56:70:56:28:8:1

Front 18

5 gene pair

Back 18

1:10:45:120:210:252:210:120:45:10:1

Front 19

For a low number of polygenes the number of additive loci can be estimated low?

Back 19

From the total number of possible phenotypes. These estimates assume that all of the additive alleles contribute equally and additively and that there are no significant environmental effects on the trait

Front 20

Number of phenotypic

Back 20

2n+1

Front 21

Polygenetic traits are usually measured how?

Back 21

sample of individuals that are large and representative of the population from which it is drawn from?

Front 22

How are the variences between F1 and F2 different?

Back 22

broader variance and is more spread out

Front 23

What does Hertatibility estimate?

Back 23

The genetic contribution to the phenotypic variability

Front 24

heritability describes what?

Back 24

the proportion of total phenotypic variation in a population due to genetic factors, but it does not indicate how much of a trait is genetically determined or the extent to which an individual’s phenotype is due to genotype

Front 25

Phenotypic variation has

Back 25

Genotypic variation
Environmental variation
Genotype-by-environment interaction varience components

Front 26

Broad sense heritability

Back 26

Measure the contribution of genotypic variance to the total phenotypic varience. The genotyic variance to the total phenotypic varience. The genotypic varience component includes all types of genetic variation in the population and assumes that the genotype-by environment varience component is negligible.

Front 27

Narrow sense heritability

Back 27

is the proportion of phenotypic varience due to the additive genotypic varience alone.

Front 28

Artificial selection

Back 28

the process of choosing specific individuals with preferred phenotypes from an initially heterogeneous population for future breeding. The purpose is to develop a population containing a high frequency of individuals with the desired traits.

Front 29

Give an example of artificial selection

Back 29

Dog species

Front 30

Realized heritability

Back 30

in selective breeding estimates the potential for artificial selection to be successful. An example is artificial selection for increased oil content in corn (figure in book).

Front 31

Twin studies allow what?

Back 31

An estimation of heritability in human. They are useful when they are maintained in the family, so the genetic variance should be 0 and the environmental should be similar so there is no dramatic differences between them. They are also useful subjects for examining genotypic vs. environmental varience for a multifactorial trait

Front 32

For monozygotic twins (identical) phenotypic variance equals what?

Back 32

environmental variance, since there is no genotypic variance.

Front 33

For dizygotic twins (fraternal) phenotypic variance differences represent what?

Back 33

both environmental variance and approximately half the genotypic variance.

Front 34

Comparison of phenotypic variances for the same trait in identical and fraternal twin sets provides what?

Back 34

estimate of broad-sense heritability for that trait. The difference in concordance for a given trait in identical versus fraternal twins suggests whether there is a strong genetic component involved in the determination of the trait