Inheritance Flashcards
What is a genotype?
The genetic constitution of an organism
What is a 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
How many alleles per gene do diploid organisms carry?
2
What is meant by dominant allele?
An allele whose characteristic will always appear in the phenotypes whether one or two are present
What is meant by a recessive allele?
An allele whose characteristic only appears in the phenotype if two alleles are present
What is meant by codominant alleles?
Two dominant alleles that both contribute to the phenotype
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
What is monohybrid inheritance?
Where one phenotypic characteristic is controlled by a single gene
What is dihybrid inheritance?
Where 2 phenotypic characteristics are determined by 2 different genes present on 2 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 so males only get one copy of the allele meaning it will express this characteristic even if it’s recessive - since females get 2 alleles it’s less likely
Which parent do males inherit sex-linked characteristics from?
Their mother, since the Y chromosome can only come from their father so if the mother is heterozygous for sex-linked alleles she is a carrier and may pass the trait on
What is meant by autosomal linkage?
Where 2 or more genes are located on the same chromosome so only one homologous pair is needed for all four alleles to be present
If genes are not linked two homologous pairs are needed
What is meant by epistasis?
Where 2 non-linked genes interact with one gene either masking or suppressing the other gene
What are the 2 types of epistasis?
Recessive and dominant
What is recessive epistasis?
Where 2 homozygous recessive alleles mask expression of another allele
What is dominant epistasis?
Where one dominant allele masks expression of multiple other alleles
What is the 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 are the criteria for the chi-squared test?
- data place in discrete categories
- large sample size
- only raw count data allowed
- no data values equal 0
How is a chi-squared test performed?
- the formula results in a number which is then compared to a critical value
- if the number is greater than or equal to the critical value we conclude there is a significant difference between the observed and the expected data and that the results did not occur due to chance
How can we use a chi-squared test in relation to the content of this topic?
We can compare expected phenotypic ratios with observed ratios to test our understanding of how different genes and alleles are inherited
