Ch 15 AP Bio

Wild Type

The wild type is the typical form of a species, which is often used as a standard in genetic analysis. It denotes the most common phenotype or genotype found in natural populations.

Sex-Linked Gene

A gene located on a sex chromosome, often influencing traits that are inherited differently in males and females.

X-Linked Genes

Genes located on the X chromosome that are responsible for determining specific traits and can exhibit different inheritance patterns in males and females.

Duchenne Muscular Dystrophy

A severe X-linked disorder characterized by progressive muscle degeneration and weakness due to the absence of dystrophin.

Hemophilia

A genetic disorder that affects the blood's ability to clot, primarily due to deficiencies in clotting factors, often linked to X-linked inheritance.

Barr Body

An inactivated X chromosome in female mammals, which condenses into a dense structure to prevent gene expression, ensuring dosage compensation between sexes.

Linked Genes

Genes that are located close together on the same chromosome and tend to be inherited together during meiosis, resulting in a violation of Mendel's law of independent assortment.

Genetic Recombination

The process by which genetic material is rearranged during meiosis, leading to the formation of new allele combinations on chromosomes, which increases genetic diversity.

Parental Types

The offspring that inherit the same combination of alleles as their parents, resulting in no recombination of genes during gamete formation.

Recombinant types

Offspring with new allele combinations that differ from those of the parents, resulting from genetic recombination during meiosis.

Crossing Over

The exchange of genetic material between homologous chromosomes during meiosis, leading to genetic diversity in offspring.

Genetic Map

A diagram that shows the relative positions of genes on a chromosome, determined by the frequency of recombination between them.

Linkage Map

A genetic map that shows the relative positions of genes on a chromosome based on the frequency of recombination between them. It helps in estimating the distance between genes.

Map Units

A unit of measurement used in genetics to express the distance between genes on a chromosome, based on the frequency of recombination, where one map unit corresponds to a 1% recombination frequency between two genes.

Nondisjunction

An error during meiosis or mitosis in which homologous chromosomes or sister chromatids fail to separate properly, resulting in daughter cells with an abnormal number of chromosomes.

Aneuploidy

A chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number, typically resulting from nondisjunction during cell division.

Monosomic

Referring to a diploid cell or organism that is missing one chromosome from a homologous pair, resulting in a chromosomal count of 2n−1

Trisomic

Referring to a diploid cell or organism that has three copies of a particular chromosome instead of the normal pair, resulting in a chromosomal count of 2n+1

Polyploidy

a condition in which an organism has more than two complete sets of chromosomes

common in plants not animals

Deletion

 removes a chromosomal segment

Duplication

repeats a segment

Inversion

reverses orientation of a segment within a chromosome

Translocation

moves a segment from one chromosome to another

Down Syndrome

an aneuploid condition that results from three copies of chromosome 21

Genomic Imprinting

involves the silencing of certain genes depending on which parent passes them on

thought to affect only a small fraction of mammalian genes

critical for embryonic development