Inherited Change Flashcards
Define genotype
The genetic constitution of an organism
Define phenotype
The expression of an organism’s genetic constitution combined with its interaction with the environment
What is an allele?
Different forms of a particular gene, found at the same locus on a chromosome. A single gene could have many alleles
How many alleles per gene do diploid organisms carry?
Two
What is meant by a dominant allele?
An allele whose characteristics will always appear in the phenotype whether one or two are present
What is meant by a recessive allele?
An allele whose characteristic only appears in the phenotype if no dominant allele is present, meaning two must be present
What is meant by codominant alleles?
Two dominant alleles that both contribute to the phenotype, either by showing a blend of both characteristics or the characteristics appearing together
What is meant by homozygous and heterozygous?
Homozygous = both alleles are dominant or both alleles are recessive
Heterozygous = one allele is dominant, the other is recessive
Define monohybrid inheritance
Where one phenotypic characteristic is controlled by a single gene
Define dihybrid inheritance
Where two phenotypic characteristics are determined by two different genes present on two different chromosomes at the same time
What is meant by sex-linkage?
Where an allele is located on one of the sex chromosomes meaning its expression depends on the sex of the individual
Why are males more likely to express a recessive sex-linked allele?
Most sex-linked alleles are located on the X chromosome. Therefore males only get one copy of the allele so will express this characteristic even if it’s recessive. Since females get two alleles this is less likely
Which parents do males inherit sex linked characteristics from?
Their mother, since the Y chromosome can only come from their father. Therefore if the mother is heterozygous for sex linked alleles, she is a carrier and may pass the trait one
What is meant by autosomal linkage?
Where two or more. genes are located on the same chromosome. In this case only one homologous pair is needed for all four alleles to be present. For genes that aren’t linked, two homologous pairs are needed
What is meant by epistasis?
Where two non linked genes interact with one gene either masking or suppressing the other gene
