BIO306 Exam 1 Review

Vocabulary flashcards for key concepts covered in the BIO306 lecture notes.

Monohybrid Cross

A cross between true-breeding parents (homozygous) that results in an F1 generation with a heterozygous genotype and a specific phenotype. The expected F2 generation has specific genotypic and phenotypic ratios.

Dihybrid Cross

A cross between true-breeding parents (homozygous) that results in an F1 generation with a heterozygous genotype and a specific phenotype. The expected F2 generation exhibits a specific phenotypic ratio.

Law of Segregation

Mendel's law stating that allele pairs separate or segregate during gamete formation, and randomly unite at fertilization.

Law of Independent Assortment

Mendel's law stating that the alleles of two (or more) different genes get sorted into gametes independently of one another.

Chromosome Theory of Inheritance

The theory stating that genes are located on chromosomes.

Homologous Chromosomes

Chromosomes that pair during meiosis; they are similar in size, centromere position, banding patterns, and genes, but may have different alleles for the genes.

Nonhomologous Chromosomes

Chromosomes that have different sizes, centromere positions, banding patterns, and genes.

Mitosis

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

Meiosis

A type of cell division that results in four daughter cells each with half the number of chromosomes as the parent cell, as in the production of gametes and plant spores.

Incomplete Dominance

A form of inheritance in which the phenotype of a heterozygote is intermediate between the phenotypes of the two homozygous parents.

Codominance

A form of inheritance in which neither allele is dominant or recessive, and both are expressed in the heterozygote.

Heterozygous Advantage (Overdominance)

A condition where the heterozygous genotype has a higher fitness than either of the homozygous genotypes.

Multiple Alleles

The presence of more than two alleles for a gene within a population.

Sex-linked Traits

Traits that are determined by genes located on the sex chromosomes (e.g., X chromosome).

Sex-limited Traits

Traits that are expressed in only one sex, even though the genes are present in both sexes.

Sex-influenced Traits

Traits in which the phenotype expressed by a heterozygote is influenced by the sex of the individual.

Lethal Alleles

Alleles that cause death when present in certain genotypes.

Epistasis

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

Complementation

The production of a wild-type phenotype when two haploids with recessive mutations in different genes are crossed together.

Penetrance

The proportion of individuals with a particular genotype that actually express the expected phenotype.

Variable Expressivity

The range of phenotypes expressed by individuals with the same genotype.

Allele Frequency

The proportion of all copies of a gene in a population that are of a specific allele type.

Gene Pool

The total collection of genes in a population at any one time.

Hardy-Weinberg Equilibrium

A principle stating that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

Genetic Drift

Random changes in allele frequencies in a population due to chance events.

Gene Flow

The transfer of genetic variation from one population to another.

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Quantitative Traits

Traits that show continuous variation and are influenced by multiple genes (polygenic) and environmental factors.

Heritability

The proportion of phenotypic variation in a population that is attributable to genetic variation.

Linkage

The tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.

Recombination Frequency

The proportion of offspring of a genetic cross that have a phenotype different from either parent.

Mitotic Recombination

A type of genetic recombination that may occur in somatic cells during either mitosis or meiosis.

Genetic Mosaics

An individual that has different genotypes in its different cells.

Eugenics

The pseudoscientific belief in the possibility of improving the qualities of the human population, especially by means of discouraging reproduction by persons having genetic defects or presumed to have inheritable undesirable traits.