Lecture Notes on Mendelian Genetics

This collection of flashcards covers various key terms and principles associated with Mendelian genetics, providing definitions and explanations relevant to the topic.

Mendelian Genetics

The study of how traits are transmitted from one generation to the next through genetic inheritance.

Dominant Trait

A trait that is expressed when at least one dominant allele is present in the genotype.

Recessive Trait

A trait that is only expressed in the absence of a dominant allele (i.e., when two copies of the recessive allele are present).

Genotype

The genetic constitution of an organism; the alleles present at a particular genetic locus.

Phenotype

The observable characteristics or traits of an organism, determined by the genotype and environment.

Homozygous

Having two identical alleles for a specific gene.

Heterozygous

Having two different alleles for a specific gene.

Monogenic Trait

A trait determined by a single gene.

Dihybrid Cross

A genetic cross between individuals that differ in two traits.

Random Segregation

The process through which alleles segregate independently during the formation of gametes.

Independent Assortment

The principle that genes for different traits are inherited independently of each other.

Test Cross

A genetic cross between an individual with an unknown genotype and a homozygous recessive individual to determine the unknown genotype.

Incomplete Dominance

A genetic situation in which one allele does not completely dominate another allele, resulting in a third phenotype.

Codominance

A condition in which both alleles in a heterozygote are fully expressed, resulting in a phenotype that is neither dominant nor recessive.

Epistasis

An interaction between genes, where one gene can affect the expression of another gene.

Penetrance

The proportion of individuals with a specific genotype that actually expresses the expected phenotype.

Expressivity

The degree to which a genotype is expressed in an individual.

Dosage Compensation

The process by which organisms equalize the expression of genes between individuals with different sex chromosome complements.

Autosomal Dominant Trait

A trait that requires only one copy of the allele to be expressed in the phenotype.

Autosomal Recessive Trait

A trait that manifests only when an individual has two copies of the recessive allele.

X-linked Trait

A genetic trait associated with a gene on the X chromosome.

Y-linked Trait

A genetic trait associated with a gene on the Y chromosome.

Pedigree

A diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors, often used to trace inheritance patterns.

Punnett Square

A diagram that predicts the genotype and phenotype combinations of a genetic cross.

Variation in Traits

Differences in characteristics among individuals, often influenced by both genetic and environmental factors.