Allele and Gene interactions

Incomplete dominance

Heterozygote has neither the recessive or dominant phenotype, they show a unique mix. Aka PINK

Complementation Test

Test mutants on same gene or different genes. Figure out if the genes restore wild type.

• Mutants must be recessive to WT

• True breed parents

When breeding 2 true breeding mutants with the same mutant phenotype, and you restore WT, what does that mean?

The mutant alleles are of different genes, so they complement each other.

Ex) mom AA bb dad aa BB

When breeding 2 true breeding mutants with the same mutant phenotype, and you get mutant, what does that mean?

The mutant alleles fail to complement because they are on the same gene.

Ex) aaBB mom and aaBB dad, fail to make WT for aa because they have the same gene that’s mutated

Mendelian inheritance

Meiosis and independent assortment

Codominance

Heterozygotes show the phenotype of both alleles equally

Lethal alleles

Just one recessive allele causes an affected genotype. We cannot have two recessive alleles, or else we die.

Leaky

Some expression or function

Temp sensitive alleles/ conditional

At restrictive temperature the protein to activate WT is inactive. At permissive temperatures, the protein to activate WT is active.

Hierarchy of dominance

Some alleles may be more dominant than others, causing a heirachy. Ex brown >grey>white rabbits

Haploinsufficient

One WT allele is not enough to show the WT genotype

G/g small or B/b medium

Haplosufficient

One WT allele of the gene is enough to get the phenotype WT

Gain of function

Inc gene expression or new function

Loss of function

Null allele. No expression or function.

Pleiotropy

One gene affects multiple characteristics ex gene influences the eye and the hands

Epistasis

Two genes interact to get the same trait, but one gene is more powerful or hides the visible output, or phenotype of another gene. Ex) gene 4 overrules/ is epistatic to gene 2, because even though gene 2 helps activate to get a color, gene 4 not working will determine the fate of the color.

Recessive epistasis

Epistasis is when a homozygous mutation in one gene hides the homozygous mutation in another gene. The gene whose mutation is visible in the double mutant is said to be 'epistatic' over the other gene. Genes working in the same pathway are often epistatic to each other.

Substrate dependent pathway

Compound leads to gene , gene leads to another compound/ of a gene is off it can no longer produce the next compound

Regulatory pathway

May turn genes on or off which changes their function: either can’t inhibit anymore, or can’t activate anymore.

How do we know if a gene in a regulatory pathway is a positive regulator or negative regulator to our desired outcome?

Determine what the gene’s function is, and how that affects the rest of the pathway to either get our desired outcome or our undesired outcome.