Lecture 11 - Quantitative Genetics

Question 1

Gene expressing a range a values (e.g.: height)

Answer 1

Quantitative Trait Loci

Question 2

Interplay of genotype and environment (X gene better in environment a but less in b and vice versa for Y gene)

Answer 2

Genotype-by-environment interaction

Question 3

Heritability (square) formula (H2) of a phenotypic trait

Answer 3

Genetic variance / (Genetic variance + Phenotypic variance)

Question 4

Contributions to Genetic variance (3 elements)

Answer 4

1. Additive contributions of different alleles (A = +10, B= -5…)
2. Dominant/Recessive allele interactions
3. Epistatically interacting genes

Question 5

Explain slide 30?

Answer 5

Covariance/Correlation coefficient etc…

Question 6

How do we call the fact F1 generation generated by crossing inbred lines is superior to both parental lines?

Answer 6

Hybrid vigor or heterosis

Question 7

What does the Lod score stands for

Answer 7

Log of the odds

Question 8

What is the Lod score used for?

Answer 8

Answer the question about how much more likely it is that the allele transmission pattern seen in a pedigree will occur if the loci are linked at a given recombination frequency less than 50% than if they are not linked

Question 9

What is the Lod equation?

Answer 9

Log( P(Obtaining observed results if loci are linked at a given RF) /
P(Obtaining observed results if loci are unlinked) )

Question 10

Definition of fate for a cell

Answer 10

Terminally differentiated cell type(s) that a stem/progenitor cell can become

Question 11

Definition of potency for a cell

Answer 11

The number of fates that a cell has (totipotent, pluripotent, unipotent, differentiated)

Question 12

Definition of determination for a cell

Answer 12

Whether a cell has made a decision to choose a certain fate (determined)

Question 13

Four classes of genes responsible for formation of segments

Answer 13

• Maternal genes
• Gaps
• Pair-rule genes
• Segmentation polarity genes

Question 14

What is the segmentation hierarchy?

Answer 14

1) Products of maternal-effect genes establish morphogenic gradients in the egg - Gradients ensure that gap genes are expressed only in certain broad regions of the embryo
2) Gap genes activate pair-rule genes in a series of seven stripes
3) Levels of pair-rule gene products restrict the expression of segment polarity genes to a series of 14 stripes, one per segment
4) Embryo is divided into 14 segment-sized units

Question 15

What is the maternal effect?

Answer 15

Mother’s egg cytoplasm will determine the phenotype. The genotype of the zygote will not affect it. (see dextral/sinistral example)

Question 16

Homeosis

Answer 16

transformation of one organ into another, arising from mutation in or misexpression of certain developmentally critical genes, specifically homeotic genes

Question 17

Homeotic genes

Answer 17

Homeotic genes are
transcription factors
controlling gene expression
in different segments
and directing differentiation
of cells as they take on
their final cell fate