Biology 2C03- week 8 flashcards

Question 1

What is a polygenetic trait

Answer 1

results from the influence of many genes

Question 2

What is a multifactorial trait

Answer 2

Both genetic and non-genetic factors can influence phenotypic variation of traits

Question 3

qualitative phenotypes

Answer 3

corresponds to a specific genotype and are distinctly different from each other (eg: blood type A vs blood type B)

Question 4

Quantitative traits

Answer 4

Continuous variation along a phenotypic scale. Traits are frequently described using units of measure

Question 5

Quantitative genetics

Answer 5

analysis of quantitative traits

Question 6

What types of traits display continuous variation

Answer 6

Polygenetic and multifactorial traits usually display continuous variation

Question 7

What is phenotypic variation is controlled by

Answer 7

allelic variation at single genes

Question 8

Genes that have a predominant effect are called?

Answer 8

major genes

Question 9

Give an example of major genes

Answer 9

Although human eye colour is determined by 15 genes, OCA2 and HERC2 are major genes

Question 10

What does the OCA2 gene do vs the HERC2 gene

Answer 10

OCA2: reduces the amount of melanin production
HERC2: regulates expression of OCA2

Question 11

How does continuous phenotypic distribution happen

Answer 11

the polygenetic traits has to be made of additive genes (genes that have no major/predominant effect)

Question 12

When can we add the values of the alleles together to determine a phenotype

Answer 12

When there is no environmental influence present

Question 13

Is it possible for more than one genotype to correspond to a certain phenotype?

Answer 13

Yes, since traits controlled by additive genes have a phenotype that is the sum of allelic contributions across multiple genes

Question 14

What is the multiple gene hypothesis

Answer 14

alleles of each of the contributing genes obeys the principles of segregation and independent assortment and had an additive effect in the production of phenotypic variation.

Question 15

What happens when the number of additive genes contributing to a phenotypic trait increases?

Answer 15

phenotype categories increase

Question 16

What happens when the number of phenotypic classes increase (due to increases in additive genes)

Answer 16

The classes are more tightly packed, blending into a continuous phenotypic distribution

Question 17

How do we calculate the number of distinct phenotype categories in diploid organisms?

Answer 17

2n+1

Question 18

In which generation for corolla plant length can we see both genetic and environmental factors influence length

Answer 18

The f2 generation. The f1 generation, the variance is due to environment

Question 19

how can non-genetic factors (environmental factors) effect phenotype

Answer 19

Environmental factors can make it difficult to identify genotype (the phenotypes blend in more as more environmental factors are involved, especially in the f2 generation), more overlap

Question 20

What is a threshold trait

Answer 20

a trait in which a person can be classified as “affected” or “unaffected”

Question 21

What is genetic liability

Answer 21

a term conveying that certain alleles can push the phenotype toward the “affected” end od the continuous distribution

Question 22

what are the 2 components of the genetic liability model

Answer 22

• follow menders law of independent assortment
• transition from unaffected to affected occurs when a sufficient number of “liability alleles” are present in the genotype

Question 23

If 2 parents have a family history of a threshold trait, what does that say for the child?

Answer 23

Trait will most likely be in the child

Question 24

if unaffected parents then have an affected child with a threshold trait, what does that say for future children?

Answer 24

The rick of recurrence in future children increases

Question 25

If you are the first degree relative of someone with a polygenetic trait or threshold trait, what is ur chance of also being affected?

Answer 25

higher than average chance

Question 26

what are the components of phenotypic variance

Answer 26

genetic variance (VG) and environmental variance (VE)

Question 27

When does vg=0 (no genetic variance)

Answer 27

In highly inbred populations, in which all individuals are homozygous for alleles

Question 28

examples of environmental variance?

Answer 28

differences in sun exposure, water, and nutrient content in soil, exposure to pests between the different plants

Question 29

how much genetic variance is there in an f1 population?

Answer 29

0, genetically uniform, no genetic variation among the individuals (VP=VE)

Question 30

What are the components of genetic variance

Answer 30

additive variance, dominance variance, interactive variance

Question 31

What is additive variance

Answer 31

variance due to incomplete dominance of alleles at a locus, causes heterozygotes to have a phenotype intermediate between the homozygous phenotypes

Question 32

What is dominance variance

Answer 32

variance due to dominance relationships in which alleles of a heterozygote produce a phenotype that is not intermediate between those of homozygotes

Question 33

Interactive variance

Answer 33

drives from epistatic interactions

Question 34

What is the formula that depicts the components of genetic variance

Answer 34

VG=VA+VD+VI

Question 35

What does heribitibility measure

Answer 35

the extent to which phenotypic variation is due to genetic variation

Question 36

What is the difference between broad and narrow sense heritability

Answer 36

broad sense: proportion of phenotypic variation due to total genetic variation H2=VG/VP
Narrow sense: due to additive variance
h2=VA/VP