Review - Genetics and Modes of Gene action Flashcards
In terms of breeding, how do you define a gene?
Basic unit of heredity.
A chromosome is:
A long strand of DNA and associated proteins present in the nucleus of all cells.
Chromosomes are found in ________ in all animals.
pairs
Locus (singular)/loci (plural) is a site of a particular region/gene on a __________.
Chromosome
An allele is:
an alternative form of a gene.
Epistasis is:
How one gene is affecting the expression of another gene.
What are the five types of gene action/dominance?
- Partial dominance
- Codominance
- Complete dominance
- Overdominance
- No dominance
How is genetic information transferred?
DNA
_______________ pieces of DNA carry the same genes.
Homologous
A(n) ____________ is an alternative form of a gene.
allele
___________ genes ARE functionally the same, while ________________ genes ARE NOT functionally the same.
Homozygous ; heterozygous
True of False. A genome is most of the genes in a cell or organism.
False! A genome consists of ALL genes in a cell or organism.
A ___________ allele has an effect on the phenotype when it is homozygous AND heterozygous.
dominant
A ____________ allele has an effect on phenotype ONLY when it is homozygous.
recessive
Additive effect is:
the combined effects of genetic alleles at two or more gene loci are equal to the sum of their individual effects.
For complete dominance, what two genotypes have the same phenotype?
AA
aa
Aa
AA and Aa
True or False. Incomplete dominance has a heterozygous genotype (Aa) express a phenotype in between the homozygous genotypes (AA and aa), except it is NOT exactly midway.
True!
No dominance has the heterozygous genotype’s (Aa) phenotype exactly in between the homozygous genotypes (AA and Aa) or partially toward one end?
Exactly in between
What is the difference between No Dominance and Partial Dominance?
For heterozygous genotypes, No Dominance phenotypes lay exactly in between the homozygous genotypes.
Partial dominance lays toward one end or the other. NOT exactly in the middle.
In Codominance, how many phenotypes will there be with a simple genotype
(example: AA, Aa, aa)
3
In Overdominance, where does the heterozygous genotype’s expression land in comparison to the homozygous genotypes?
HIGHER than the average of both homozygous genotypes.
Define gene interaction:
The interactions between two or more genes result in a phenotype that differs from the phenotype expected if the genes were independent of each other.
Define epistasis in your own words.
When the expression of one gene affects the expression of another on another loci.
What does G, in P = G + E, expand into? And what do each letter stand for?
G = D + I + A
D = dominance
I = epistasis
A = additive effect
What are two types of gene-trait relationships that we mentioned in class?
Pleiotropy and Lethal Genotypes
What is the difference between epistasis and pleiotropy?
Epistasis is one gene expression affecting another gene expression (of the same trait).
Pleiotropy is one single gene affecting multiple traits.
Define genomic imprinting.
The ability of a gene to be expressed depends on the sex of the parent that the gene is coming from.
What are the three kinds of sex-related inheritance?
What is an example of each?
Sex-linked - Color blindness in males only
Sex-limited - milk and egg production in females only
Sex-influenced - Scurs are more frequent in males
What is an example of a non-additive effect?
Any form of dominance.
