3.7.1 Inheritance Flashcards
(27 cards)
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 (position) 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 characteristic 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?
Both alleles are dominant, or both alleles are recessive.
What is meant by 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 parent 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 on the trait on.
What is meant by autosomal linkage?
Where two or more genes are located on the same (non-sex) 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.
What is recessive epistasis?
Where two homozygous recessive alleles mask the expression of another allele.
What is dominant epistasis?
Where one dominant allele masks the expression of multiple other alleles.
What is a chi-squared test?
A statistical test to find out whether the difference between observed and expected data is due to chance or a real effect.
What type of data is required for a chi-squared test?
Data must be placed in discrete categories.
What is the minimum sample size requirement for a chi-squared test?
A large sample size is required.
What type of data is not allowed in a chi-squared test?
Percentages are not allowed; only raw count data is permitted.
What is a restriction regarding data values in a chi-squared test?
No data values can equal zero.
What is the result of performing a chi-squared test?
The formula results in a number.
