Mendelian Genetics

These flashcards cover key terms and concepts related to Mendelian genetics, including definitions of critical terms and principles of inheritance.

Mendelian Laws

The principles of inheritance formulated by Gregor Mendel, which include the Law of Segregation and the Law of Independent Assortment.

Phenotypic Ratio

The ratio of different phenotypes produced in offspring, typically observed in genetic crosses.

Dominance

The relationship between alleles, where one allele masks the expression of another in the phenotype.

Recessive

An allele that is masked by a dominant allele and is only expressed in a homozygous state.

Genotype

The genetic makeup of an organism, including all alleles present at a specific locus.

Phenotype

The observable traits or characteristics of an organism resulting from the interaction of its genotype with the environment.

Homozygous

An organism with two identical alleles at a locus.

Heterozygous

An organism with two different alleles at a locus.

Locus

The specific location of a gene on a chromosome.

Test Cross

A genetic cross performed to determine the genotype of an individual with a dominant phenotype by crossing it with a homozygous recessive individual.

Epistasis

A phenomenon where one gene masks or modifies the expression of another gene.

Pleiotropy

The ability of a single gene to affect multiple phenotypic traits.

Co-dominance

A type of inheritance where both alleles in a heterozygote are fully expressed, resulting in a phenotype that shows both traits.

Polygenic Inheritance

The additive effect of multiple genes on a single phenotypic trait, leading to continuous variation.

Law of Segregation

Mendel's first law stating that allele pairs segregate during gamete formation, resulting in gametes that carry only one allele for each gene.

Law of Independent Assortment

Mendel's second law which states that genes assort independently of one another in the formation of gametes.

Genetic Recombination

The process by which alleles are shuffled during meiosis, leading to genetic variation in offspring.

Dominant Allele

An allele that expresses its trait even in the presence of a recessive allele.

Wild Type Allele

The allele that is most common in natural populations, typically associated with the normal phenotype.

Mutant Allele

An allele that has undergone a mutation and typically results in a non-functional version of the protein.

Incomplete Dominance

A form of inheritance where the heterozygous phenotype is an intermediate blend between the two homozygous phenotypes, such as pink flowers produced from red and white parents.

Punnett Square

A diagrammatic tool used to predict the genotypes and phenotypes of offspring resulting from a genetic cross by mapping possible gamete combinations.

P Generation

The parental generation in a genetic cross, usually consisting of true-breeding individuals used as the starting point for study.

F1 Generation

The first filial generation; the hybrid offspring resulting from the crossing of the P generation.

F2 Generation

The second filial generation; the offspring produced by crossing or self-fertilizing members of the F_{1} generation, often revealing recessive traits.

Monohybrid Cross

A genetic cross between two individuals that focuses on the inheritance of a single pair of contrasting traits at one locus.

Dihybrid Cross

A genetic cross between two individuals that tracks the inheritance of two different traits governed by two different genes at separate loci.

Multiple Alleles

A condition where three or more alternative forms of a gene (alleles) exist within a population, even though an individual only possesses two at a given locus.

Lethal Alleles

Alleles that cause the death of the organism that carries them, typically expressed in the homozygous recessive state, which can alter expected Mendelian ratios.

True-breeding

Organisms that, when self-fertilized or crossed with those of the same phenotype, produce offspring with the same traits over many generations; they are homozygous for those traits.