6.1.2 Patterns of inheritance Flashcards
Define genotype
The genetic constitution of an organism (alleles it has for a gene)
Define phenotype
expression of genes and their interaction with the environment
Define homozygous
A pair of homologous chromosomes carrying the same alleles for a single gene
Define heterozygous
A pair of homologous chromosomes carrying two different alleles for a single gene
Define recessive allele
An allele which is only expressed if no dominant allele is present
Define dominant allele
An allele that will always be expressed in the phenotype
Define codominance
Both alleles are expressed in the heterozygote resulting in a different phenotype
Multiple alleles
More than two alleles for a single gene
Sex-linkage
A gene whose locus is on an X chromosome
Autosomal linkage
Genes that are located on the same chromosome (but not the sex chromosome)
Epistasis
When one gene influences (affects or masks) the expression of another
Monohybrid
Genetic inheritance cross of a characteristic determined by one gene
Dihybrid
Genetic inheritance cross of a characteristic determined by two genes
In a dihybrid cross, if two heterozygous parents are crossed what phenotypic ratio would you expect in offspring?
9:3:3:1
Unless there is autosomal linkage, crossing over in meiosis or epistasis.