Extending Mendel's Laws: More Patterns and Probabilities (Section 17.2)

Linked Genes

Genes found on the same chromosome

Crossing Over

The process by which non-sister chromatids exchange genes during prophase I of meiosis, allowing for the recombination of genes

Chromosome Mapping

Process for determining the relative position of genes on a chromosome

Map Unit

Distance between points on a chromosome where a crossover is likely to occur in 1% of all meiotic events

Recombinant Type

Describes offspring that have a different combination of alleles than the chromosomes of their parents

Parental Type

Describes offspring that have chromosomes that are identical to those of their parents

Recombination Frequency

Percentage of times that a crossover occurs as gametes are formed

Sex-Linked Trait

Trait controlled by genes on either the X or Y chromosome (most times only on the X chromosome)

Barr Body

Structure formed when the inactive X chromosome condenses tightly

Multiple Alleles

Pattern of inheritance in which a gene has more than two alleles for any given trait

Order of Dominance

The sequence that indicates which alleles are dominant to other alleles

Continuous Trait

A trait for which the phenotypes vary smoothly from one extreme to another

Polygenic Trait

A trait that is controlled by many genes