Mendelian Genetics and Pedigree Analysis - Vocabulary Flashcards

Vocabulary flashcards covering key genetics concepts and terms from the lecture notes.

Genetics

The study of the laws and processes of biological inheritance and the transfer of traits from parents to offspring.

Gene

A basic unit of heredity; a segment of DNA that determines a trait.

Allele

Alternative forms of a gene that occupy the same gene locus on homologous chromosomes.

Trait

A characteristic that can be inherited and expressed by an organism.

Phenotype

The observable physical appearance or trait of an organism resulting from its genotype.

Genotype

The genetic makeup of an organism; the specific combination of alleles (e.g., TT, Tt, tt).

Dominant

An allele that expresses its trait in the phenotype when present in one or two copies.

Recessive

An allele that expresses its trait only when two copies are present (homozygous recessive).

Homozygous

Having two identical alleles for a gene (e.g., TT or tt).

Heterozygous

Having two different alleles for a gene (e.g., Tt).

Punnett square

A grid used to predict the possible genotypes and phenotypes of offspring from parental alleles.

Monohybrid cross

A cross analyzing the inheritance of a single trait.

Dihybrid cross

A cross analyzing the inheritance of two traits simultaneously.

Particulate Inheritance

Mendel’s concept that inheritance occurs via discrete factors (genes) rather than blending.

Law of Dominance

Some alleles are dominant over others, determining the phenotype in heterozygotes.

Law of Segregation

During gamete formation, paired alleles separate so each gamete carries one allele.

Law of Independent Assortment

Genes for different traits assort independently during gamete formation.

Epistasis

One gene masks or interferes with the expression of another gene.

Incomplete dominance

Neither allele is completely dominant; heterozygotes show an intermediate phenotype.

Codominance

Both alleles contribute to the phenotype, with neither being recessive.

Multiple alleles

More than two allele forms exist for a gene within a population (e.g., ABO blood groups).

Blood type alleles

ABO system: IA, IB, and i; IA and IB are codominant with each other and dominant over i.

Sex-linked traits

Traits controlled by genes on the sex chromosomes (X or Y).

X-linked inheritance

Traits located on the X chromosome; inheritance patterns differ by sex.

Y-linked inheritance

Traits located on the Y chromosome; passed from father to all sons.

Mitochondrial inheritance

Inheritance of genes in mitochondria, transmitted exclusively through the mother.

Pedigree

A family tree used to study inheritance patterns across generations.

Autosomal dominant

Dominant allele on an autosome; vertical transmission with equal affected males and females.

Autosomal recessive

Recessive allele on an autosome; horizontal transmission; carriers are common.

Carrier

An individual who is heterozygous for a recessive allele and does not show the trait but can pass it on.

Gamete

A reproductive cell (sperm or egg) that carries one allele for each gene.

Genotypic ratio

The ratio of genotypes among offspring (e.g., 1:2:1 in a monohybrid cross).

Phenotypic ratio

The ratio of observable traits among offspring (e.g., 3:1 in a monohybrid cross).