Module 8

If an organism has a cerain characteristic that is always passed on to all of its offspring, we say that this organism bred true with respect to that chatacteristic.

One of a pair of genes that occupies the same position on homologous chromosomes.

Two-letter set that represents the allels an orgamism possesses for a certain trait.

The observable expression of an organism's genes.

A genotype in which both alleles are indentical.

A genotype with two different alleles.

An allele that will determine phenotype if even one is present in the genotype.

An allele that will not determine the phenotype unless the genotype is homozygous with that allele.

• 1. The traits of an organism are determined by its genes.
• 2. Each organism has two alleles that make up the genotype of a given trait.
• 3. In sexual reproduction, each parent contributes ONLY ONE of its alleles to the offspring.
• 4. In each genotype, there is a dominant allele. If it exists in an organism, the phenotype is determined by that allele.

A diagram that follows a particular species' phenotype through several generations.

A cross between two individuals concentrating on only one definable trait.

A cross between two individuals concentrating on two definable traits

Chromosomes that do not determine the sex of an individual

Chromosomes that determine the sex of an individuals

Inheritance of a genetic trait not on a sex chromosomes

A person who is heterozygous in a recessive genetic disorder

Inheritance of a genetic trait located on the sex chromosomes

A radical chemical change in one or more alleles

A situation in which the chromosomes loses or gains genes during meiosis

A situation in which abnormal cellular events in meiosis lead to eather none of a particular chromosome in in the gamete or more than one chromosome in the gamete