Biology 1111 - Chapter 8 Patterns of Inheritance Flashcards

Comprehensive vocabulary flashcards covering Mendelian genetics, inheritance patterns, and complex genetic interactions as described in the Chapter 8 lecture notes.

Genetics

The study of heredity.

Pisum sativum

The scientific name for the garden pea plant used by Mendel to study inheritance.

True-breeding

Plants that always produce offspring that look like the parent.

Hybridizations

The process of mating two true-breeding individuals that have different traits.

P generation

The parental generation; the plants used in first-generation crosses.

F1 generation

The first filial generation, or offspring from the P generation plants.

F2 generation

The second filial generation, or offspring from the F1 generation plants.

Trait

A variation in the physical appearance of a heritable characteristic.

Dominant traits

Traits that are inherited unchanged in a hybridization, such as purple flowers in pea plants.

Recessive traits

Traits that become latent or disappear in the offspring of a hybridization but reappear in the progeny of the hybrid offspring.

Genes

Specific nucleotide segments located on homologous chromosomes that determine specific characteristics by coding for specific proteins.

Locus

The specific physical location of a gene on a chromosome.

Alleles

Gene variants that arise by mutation and exist at the same relative locations on homologous chromosomes.

Phenotype

The physical appearance or observable traits expressed by an organism.

Genotype

An organism’s underlying genetic makeup, represented by letters like $YY$ or $yy$.

Homozygous

A genotype consisting of two identical alleles ($YY$ or $yy$) on homologous chromosomes.

Heterozygous

A genotype consisting of one dominant allele and one recessive allele ($Yy$).

Law of Dominance

States that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic.

Monohybrid cross

A fertilization occurring between two true-breeding parents that differ by only one characteristic.

Punnett square

A tool that predicts all possible outcomes of all possible random fertilization events and their expected frequencies.

Law of Segregation

States that alleles must segregate equally into gametes during meiosis so that offspring have an equal likelihood of inheriting either allele.

Test cross

A technique where a dominant-expressing organism is crossed with a homozygous recessive organism to determine if the dominant parent is a heterozygote or a homozygote.

Law of Independent Assortment

States that genes do not influence each other regarding the sorting of alleles into gametes, and every combination of alleles is equally likely.

Incomplete Dominance

A pattern of inheritance where the heterozygote expresses an intermediate phenotype between the dominant and recessive phenotypes, such as pink flowers in snapdragons.

Codominance

A condition where both alleles for the same characteristic are simultaneously expressed in the heterozygote, such as the $AB$ blood type in humans.

Wild type

The most common phenotype or genotype in the natural population ($+$, while all others are considered variants or mutants.

X-linked

A gene being examined that is present on the X chromosome but not the Y chromosome.

Hemizygous

A term describing males who have only one allele for any X-linked characteristic since they lack a second X chromosome.

Carrier

A heterozygous individual who possesses a recessive allele for a disease but does not exhibit any phenotypic effects.

Linkage

A phenomenon where genes located physically close to each other on the same chromosome are more likely to be inherited as a pair.

Polygenic inheritance

When characteristics depend on the combined effects of numerous genes, such as skin color and human height.

Epistasis

An interaction where the expression of one gene masks or interferes with the expression of another gene.