Chapter 6: 6.3 Mendel and heredity, 6.4 Traits, Genes and Alleles and 6.5 Traits and Probability

Trait

Characteristics that are inherited

Genetics

Study of heredity patterns and variation of organisms

Cross

the mating of two organisms in the context of genetics

Law of segregation

the principle, originated by Gregor Mendel, stating that during the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent.

Gene

A piece of DNA that provides a set of instructions to a cell to make a certain protein and is located at a particular on a chromosome.

Allele

one of a number of different forms of a gene (round or wrinkled for pea shape)

Homozygous

Alleles that are identical to each other

Heterozygous

Alleles that are different from each other

Genome

All of an organisms genetic material

Phenotype

Physical characteristics of the person or organism

Dominant

The stronger version of a pair of alleles.

Recessive

Describes a allele that is covered over, or dominated, by another form of that trait and seems to disappear.

Punnett square

A grid system for predicting all possible genotype a resulting from a cross

Monohybrid cross

Cross that examines how the inheritance of only one specific trait

Dihybrid cross

Crosses that examine the inheritance of two specific traits

Probability

The likelihood that a particular trait will even happen

purebred

An organism that always produces offspring with the same form of a trait as the parent.

law of independent assortment

alleles of different genes separate independently of one another during meiosis.

test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Genotype

the set of alleles an organism has for a trait. TT, Tt, tt

DNA

Deoxyribonucleic Acid