BIOL212 Ch14

Comprehensive vocabulary flashcards covering the key genetic terms, principles, inheritance patterns, and disorders from Campbell Biology Chapter 14: Mendel and the Gene Idea.

Character

A heritable feature that varies among individuals, such as flower color in pea plants.

Trait

Each variant for a character, such as purple or white color for flowers.

True-breeding

Referring to organisms that produce offspring of the same variety over many generations when they self-pollinate.

Hybridization

The mating or crossing of two contrasting, true-breeding varieties.

P generation

The true-breeding parental generation from which $F_1$ hybrid offspring are derived in studies of inheritance.

$F_1$ generation

The first filial, hybrid offspring resulting from a cross between true-breeding parents of the P generation.

$F_2$ generation

The second filial generation of offspring produced when $F_1$ hybrids self-pollinate or cross-pollinate with other $F_1$ hybrids.

Alleles

Alternative versions of a gene that account for variations in inherited characters.

Locus

The specific physical position or site on a chromosome where a particular gene resides.

Dominant allele

An allele that determines the organism's appearance when two different alleles are present at a locus.

Recessive allele

An allele that has no noticeable effect on an organism's appearance when present alongside a dominant allele.

Law of segregation

Mendel's first law of inheritance, stating that the two alleles for a heritable character separate during gamete formation and end up in different gametes.

Punnett square

A diagrammatic representation used to calculate and predict the possible combinations of alleles resulting from a genetic cross.

Homozygote

An organism that possesses a pair of identical alleles for a gene controlling a character.

Heterozygote

An organism that possesses two different alleles for a gene controlling a character.

Phenotype

The observable physical appearance or physiological traits of an organism, determined by its genetic makeup.

Genotype

The genetic makeup or set of alleles possessed by an organism.

Testcross

Breeding an individual of dominant phenotype but unknown genotype with a homozygous recessive individual to determine the unknown genotype.

Monohybrids

Organisms that are heterozygous for the single specific character being tracked in a genetic cross.

Monohybrid cross

A cross between two organisms that are each heterozygous for the single character being followed.

Dihybrids

Individuals that are heterozygous for two different characters being followed simultaneously.

Dihybrid cross

A cross between two dihybrids used to determine whether two characters are transmitted to offspring together as a unit or independently.

Law of independent assortment

Mendel's second law of inheritance, stating that each pair of alleles segregates independently of any other pair of alleles during gamete formation.

Complete dominance

A pattern of inheritance in which the phenotypes of the heterozygote and the dominant homozygote are identical.

Incomplete dominance

A pattern of inheritance in which the phenotype of $F_1$ hybrids is an intermediate phenotype between the two parental varieties.

Codominance

A situation in which the phenotypes of both alleles are exhibited because both alleles affect the phenotype in separate, distinguishable ways.

Pleiotropy

The ability of a single gene to have multiple phenotypic effects, such as responsible for multiple symptoms in certain hereditary disorders.

Epistasis

A type of gene interaction wherein the phenotypic expression of a gene at one locus alters the expression of a gene at a second locus.

Polygenic inheritance

An additive effect of two or more genes on a single phenotypic character, often resulting in a continuous spectrum of variation.

Pedigree

A family tree diagram that describes the traits and inheritance patterns of parents and children across multiple generations.

Carriers

Heterozygous individuals who carry a recessive allele for an inherited disorder but are phenotypically normal.

Consanguineous matings

Matings between close relatives, which significantly increase the chance that both parents carry the same rare deleterious recessive allele.

Polydactyly

A condition characterized by extra fingers or toes caused by a rare dominant allele present in approximately $1$ out of $400$ babies in the United States.

Cystic fibrosis

The most common lethal genetic disease in the United States among individuals of European descent ($1$ in $2,500$), caused by defective or absent chloride transport channels.

Sickle-cell disease

A human genetic disorder caused by the substitution of a single amino acid in hemoglobin, which distorts red blood cells into a sickle shape at low oxygen levels.