McGraw-Hill Ryerson Biology 11 Chapter 5- patterns of inheritance definitions

Trait

A specific characteristic or feature exhibited by an organism.

True breeding

Organisms that exhibit the same traits generation after generation.

Cross

Fertilizing a female gamete of a specific origin with a male gamete of another genetic origin.

P-Generation

In breeding, the organisms initially crossed and are typically true breeding.

F1- Generation

The offspring of a cross of the P-Generation

Monohybrid cross

The cross of individuals that differ by one trait

F2- Generation

The offspring of a cross between the F1-Generation

Dominant

The form of a trait that always appears when an individual has an allele for it.

Recessive

The form of a trait that only appears if an individual has both alleles for it.

Law of segregation

Traits are determined by pairs of alleles that segregate during meiosis so that each gamete receives one allele.

Genotype

The combination of alleles for any given trait

Phenotype

The physical and physiological traits of an organism

Homozygous

An organism that has two identical alleles of a gene

Heterozygous

An organism that has two different alleles of a gene.

Punnet square

A grid used to illustrate all possible genotypes and phenotypes of offspring from genetic crosses

Test cross

A cross between a parent of unknown genotype and a homozygous recessive parent

Dihybrid cross

A cross of two individuals that differ in two traits due to different genes

Law of independent assortment

During gamete formation, the two alleles of one gene segregate or assort independently of the alleles for the other genes.

Chromosome theory of inheritance

Traits determined by genes are inherited throough the movement of chromosomes during meiosis

Pedigree

A flowchart that uses symbols to show the inheritance patterns of traits in a family over many generations

Autosomal inheritance

The inheritance of traits determined by genes on the autosomal chromosomes

Autosomal dominant

The inheritance of a dominant phenotype who’s gene is on an autosomal chromosome

Autosomal recessive

The inheritance of a recessive phenotype whose gene is on an autosomal chromosome

Genetic counsellor

A health care professional with specialized training in medical genetics and counselling

Gene therapy

Technique aimed at treating genetic disorders by introducing the correct form of the defective gene into the patients genome.