Inheritance Flashcards
(14 cards)
What is a genotype?
A genotype is the genetic constitution of an organism.
What is a phenotype?
A phenotype is the expression of the genotype and its interaction with the environment.
What are alleles?
Alleles are different forms of the same gene. Most plants and animals only carry two alleles of each gene (one from each parent). The order of bases in each different allele is slightly different.
What are dominant alleles?
Dominant alleles are expressed in the phenotype even when there’s only one copy present. These are represented using an uppercase letter (R).
What are recessive alleles?
Alleles whose characteristics only appear in the phenotypes when both copies are present. These are represented using a lowercase letter (r).
What are co-dominant alleles?
Co-dominant alleles are both expressed in the phenotype (neither one is recessive).
What is meant by the term homozygous?
Homozygous refers to when both alleles are the same (both dominant or both recessive).
What is monohybrid inheritance?
Monohybrid inheritance is the inheritance of one single character, controlled by a single gene. Usually, there are two alleles of each gene.
What is dihybrid inheritance?
Dihybrid inheritance is the inheritance of 2 characteristics controlled by 2 genes. This involves 2 genes on 2 different chromosomes.
What is meant by sex-linkage?
A gene that is found on a sex chromosome is said to be sex-linked. Most genes on sex chromosomes are carried by the X chromosome.
Since males only have 1 x chromosome, they often only have 1 allele for sex-linked genes. Because they only have 1 copy of the gene, they express the characteristic of this allele even if it’s recessive.
As a result, males are much more likely to show recessive phenotypes for sex-linked genes.
What are autosomal genes?
Autosomal genes are genes that aren’t found on sex chromosomes.
What is meant by autosomal linkage?
Genes on the same autosome are said to be linked and they will stay on the same chromosome during independent segregation in meiosis 1, and offspring will inherit these alleles together.
However, they won’t stay on the same chromosome if they’re separated during crossing over. The closer together two genes are on the same chromosome, the less likely they’ll be split by crossing over.
What is epistasis?
Epistasis is the effect of one gene upon another. The two genes interact, so that one may be masked (prevented from being expressed) by another.
How to use the chi-squared test?
1) Find X2
2) Compare with critical value which is the degrees of freedom which is the number of classes -1
If the result exceeds or is equal to the critical value, we reject the null hypothesis.
