lec 5 Flashcards
How is variance calculated?
s^2 = (xi - mean)^2 / n - 1
What is the equation for total phenotypic variance?
VP = VG + VE + VGE
(genetic + environmental + interaction variance)
What is broad-sense heritability (H²)?
The ratio of total genetic variance to total phenotypic variance
H^2 = VG / VP
What is narrow-sense heritability (h²)?
The ratio of additive genetic variance to total phenotypic variance
h^2 = VA / VP
What are the three components of genetic variance (VG)?
Additive (VA), dominance (VD), and epistatic (VI) variance.
What is additive genetic variance (VA)?
The cumulative effect of individual loci (inheritance of an allele).
What is dominance genetic variance (VD)?
Variation due to interaction between alleles at the same locus (intragenic).
What is epistatic genetic variance (VI)?
Variation due to interaction between alleles at different loci (intergenic)
What are three methods to estimate heritability?
- Estimation of variance components (lab animals)
- Mid-parent offspring regressions
- Degree of genetic relatedness (twin studies)
What is the Falconer model for estimating heritability from twin studies?
H^2 = 2(rmz - rdz)
What is a founder animal in genetic modification?
A transgenic animal that carries the modified gene in its germline DNA.
What is the Cre-LoxP recombinase system used for?
Creating conditional gene knockouts by cutting and recombining DNA at specific LoxP sites.
What is the role of sgRNA in CRISPR?
It guides the Cas9 enzyme to the target DNA sequence for cutting.
What is CRISPR-Cas9 used for?
Genome editing by creating double-strand breaks in DNA.
How can negative selection be introduced in homologous recombination?
Using HSV-tk or diphtheria toxin gene to kill cells with random integration.
How does the fearless mouse experiment show gene function?
Removing olfactory neurons made the mouse unafraid of cat smells, revealing the genetic basis of fear.
How can promoter sequences be used to direct gene expression to a specific cell type?
By using cell type-specific promoters, the gene of interest can be expressed only in the target cell type.
What is the construct used to direct gene expression to a specific cell type?
The construct consists of a cell type-specific promoter, the gene of interest, and a reporter gene.
What is PAX6 (paired box 6)?
A protein transcription factor involved in the development of the eye, brain, and spinal cord (including olfactory bulbs).
