Inheritance Flashcards
Diploid
Cell or organisms with a pair of homologous chromosomes and hence two alleles of each gene
Allele
A variation of version of a gene
Genotype
Combination of all genes that an organism produces
Phenotype
Physical expression of the genotype and its interaction with the environment
Dominant allele
An allele that is always expressed in the phenotype
Recessive allele
An allele that is only expressed when homozygous
Codominant allele
When both alleles are always expressed in the phenotype, and is usually intermediate between the two
Homo/heterozyguous
When alleles are the same, not the same
Monohybrid inheritance
Inheritance of a characteristic controlled by a single gene
Dihybrid in inheritance
Inheritance of two characteristics that are controlled by separate genes
Epistasis
An interaction between genes, where the expression of one gene suppressed the expression of another gene
When can epistasis occur?
When a phenotype is controlled by more than one gene
What are the phenotypic ratios for a recessive epistatic allele, and dominant epistatic allele
(9:3:4) and (12:3:1)
Autosome
Any chromosome that is not a sex chromosome
Autosomal linkage
Genes on the same chromosome so stay together during independent assortment so inherited together
What is the phenotypic ratio for autosomal linkage
(3:1)
What does autosomal linkage mean
More offspring have the same genotype and phenotype as parents UNLESS crossing over occurs
What does a closer loci on autosomal linkage mean
Gene more closely linked
Homologous pair
Same gene loci
Sex linkage
Expression of alleles located on sex chromosomes depending on the sex of the individual
Why are males susceptible to sex linked disease
Only one X chromosome so cannot be carrier
What is the normal phenotypic ratio for MHC F2
3:1 Dominant to recessive
What is the normal phenotypic ratio for DHC F2
9:3:3:1 9 Dominant both 3 Dominant, then recessive 3 Recessive, then dominant 1 Recessive both
What is the normal phenotypic ratio for codominance F2
1:2:1
Homozygous 1
2 Heterozygous
Homozygous 2
What is the phenotypic ratio in epistasis for a recessive epistatic allele and dominant epistatic allele F2
9: 3:4
12: 3:1
What is the phenotypic ratio for hetero dominant and recessive Sex Linkage
3: 1
1: 1
