General Biology Genetics Vocabulary

Allele

An alternative form of a gene.

Gene

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

Dominant

An allele that is always expressed

Recessive

A gene that is only show in the phenotype when homozygous.

Sex-Linked

gene located on the X or Y chromosome

Linked Trait

A trait that is co-inherited with another trait

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Co-Dominant

When both phenotypes appear in heterozygous individuals; Examples: red camellia and white camellia breed to create red and while flowers.

Incomplete dominance

When both phenotypes appear in heterozygous individuals blended together; Examples: red snapdragons and white snapdragons breed to create pink flowers.

Phenotype

An organism's physical appearance, or visible traits.

Genotype

genetic makeup of an organism

Heredity

Passing of traits from parents to offspring

Fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell

Gametes

sex cells- sperm and egg

Monohybrid Cross

A cross between individuals that involves one pair of contrasting traits

Heterozygous

An organism that has two different alleles for a trait

Homozygous

An organism that has two identical alleles for a trait

Hemophilia

An X-linked recessive disorder in which blood fails to clot properly, leading to excessive bleeding if injured.

Huntington's Corea

Autosomal dominant genetic disorder that results in muscle impairment that does not typically occur until after age 40

Chromosome

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Haploid

An organism or cell having only one complete set of chromosomes.

Colorblind

a recessive x-linked disorder in which an individual cannot distinguish between certain colors, usually red and green

Autosomal Dominant

inheritance pattern of a dominant allele on an autosome

Autosomal Recessive

Inheritance pattern of a recessive allele on an autosome.

Sex-linked Dominant

gene causing the trait is located on a sex chromosome; one copy necessary in females and males

Sex-linked Recessive

recessive gene carried on X chromosome

Ex: hemophilia and color blindness

Sex Chromosomes

X and Y chromosomes.

True Breeding

term used to describe organisms that produce offspring identical to themselves if allowed to self-fertilize or to fertilize another true breeding individual.

P Generation

Parental generation, the first two individuals that mate in a genetic cross

F1 Generation

the first generation of offspring obtained from an experimental cross of two organisms (Offspring of the P Generation)

F2 Generation

offspring of the F1 generation

Cystic Fibrosis

A genetic disorder that is present at birth and affects both the respiratory and digestive systems. Autosomal Recessive

Sickle Cell Disease

Autosomal Recessive Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape.

Muscular Dystrophy

group of hereditary diseases characterized by degeneration of muscle and weakness (Sex-linked Recessive)

Hybridization

Breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms

Diploid

containing two complete sets of chromosomes, one from each parent. (This is normal and is why you have two alleles for all genes unless it it is a sex-linked trait)

Polygenic Trait

trait controlled by two or more genes