Biology Chapter 11 Study Guide

Allele
one of the alternative forms of a gene that governs a characteristic, such as hair color

Trait
A characteristic that an organism can pass on to its offspring through its genes.

Hybrid
an organism that is the offspring of genetically dissimilar parents or stock

Dominant
observed trait of an organism that masks the recessive form of a trait

Recessive
trait that will only appear in the phenotype if organism inherits two of them; covered up by the dominant gene

Homozygous
Having two identical alleles for a particular gene

Heterozygous
Having two different alleles for a particular gene

Genotype
genetic makeup of an organism

Phenotype
what an organism looks like as a consequence of its genotype

Gametes
A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

What is the principle of dominance?
The principle of dominance states that some alleles are dominant and others are recessive

What is the principle of segregation?
holds that each pair of factors of heredity separate during gamete formation so that each gamete receives one member of a pair.

What is independent assortment?
holds that during gamete formation, alleles in one gene pair segregate into gametes independently of the alleles of other gene pairs.

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

F2 Generation
the second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation

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

Incomplete Dominance
one allele is not completely dominant over the other allele

Codominance
situation in which both alleles of a gene contribute to the phenotype of the organism

Multiple alleles
Three or more forms of a gene that code for a single trait

Polygenic Traits
traits controlled by two or more genes

Pedigree Chart
A chart which shows several generations of related families and how traits are passed down through the offspring.

Probability
Likelihood that a particular event will occur