Chapter 12, 13, week 9 vocab

Alleles

Alleles

Different forms of a gene that occupy the same position (locus) on homologous chromosomes.

Amniocentesis

A medical procedure used to collect amniotic fluid from a pregnant woman to test for genetic abnormalities in the fetus.

Aneuploidy

A condition where the number of chromosomes is not the typical set for a species, such as an extra or missing chromosome.

Barr body

The inactivated X chromosome in the cells of female mammals, visible as a dense structure in the nucleus.

Blending inheritance

An outdated theory that offspring are a blend of the traits of their parents.

Chromosomal theory of inheritance

The theory that genes are located on chromosomes, which are the basis for inheritance.

Chorionic villi sampling (CVS)

A prenatal test where a small sample of placental tissue is collected for genetic testing.

Continuous variable

A variable that can take on an infinite number of values, such as height or weight.

Cross-fertilization

Fertilization between two different individuals, leading to genetic variation.

Crossing over (recombination)

The exchange of genetic material between homologous chromosomes during meiosis, leading to new combinations of alleles.

Codominant

A genetic scenario where both alleles in a heterozygous individual are fully expressed, without one being dominant over the other.

Dominant pedigree

A pedigree in which a dominant trait appears in every generation.

Dosage compensation

A mechanism that balances the dose of X chromosome gene expression in males and females.

Dihybrid cross

A genetic cross that follows two traits simultaneously, involving organisms heterozygous for both traits.

Dominant

An allele that masks the effect of a recessive allele in a heterozygous organism.

Epigenetic inheritance

Inheritance of traits that are controlled by factors other than changes in the DNA sequence, such as DNA methylation.

Epistasis

Interaction between gene pairs where one gene can mask or modify the expression of another gene.

First filial (F1) generation

The first generation of offspring from a cross between two parental individuals.

Genetic mapping

The process of determining the location of genes on a chromosome.

Genome-wide association study (GWAS)

A study that looks for associations between specific genetic variations (SNPs) and particular diseases across a population.

Genomic imprinting

A form of inheritance where certain genes are expressed differently depending on whether they are inherited from the mother or father.

Genotype

The genetic makeup of an organism, specifically the combination of alleles it carries.

Heterozygous

Having two different alleles for a particular gene.

Homozygous

Having two identical alleles for a particular gene.

Human genome maps

Charts that show the location of genes on human chromosomes.

Incomplete dominance

A genetic scenario where the phenotype of a heterozygote is intermediate between the phenotypes of the two homozygotes.

Maternal inheritance

Inheritance of traits specifically from the mother, often associated with mitochondrial DNA.

Multiple alleles

The existence of more than two alleles for a particular gene within a population.

Multiple crossovers

When more than one crossover event occurs between homologous chromosomes during meiosis, leading to greater genetic variation.

Monohybrid cross

A genetic cross that involves one trait, where organisms are heterozygous for that trait.

Monosomy

A condition where an individual has only one copy of a particular chromosome instead of the typical two.

Nondisjunction

An error in cell division where chromosomes fail to separate properly, leading to an abnormal number of chromosomes in the resulting cells.

Parental generation

The original individuals in a genetic cross from which offspring are derived.

Pedigree analysis

A diagram used to track the inheritance of traits across generations in a family.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by both genetics and the environment.

Phenotype-wide association study (PheWAS)

A study that investigates the association between a genetic variant and multiple phenotypes across a population.

Phenotypic plasticity

The ability of an organism to change its phenotype in response to environmental conditions.

Pleiotropy

When a single gene affects multiple, seemingly unrelated traits.

Polygenic inheritance

Inheritance of a trait that is controlled by multiple genes, each contributing a small effect.

Principle of independent assortment

Mendel's law stating that the alleles of different genes are distributed independently of one another during gamete formation.

Principle of segregation

Mendel's law stating that the two alleles for a gene segregate during gamete formation and are reunited at fertilization.

Punnett square

A diagram used to predict the outcome of a genetic cross by considering all possible combinations of alleles.

Recessive

An allele whose effects are masked by a dominant allele in a heterozygous organism.

Recessive pedigree

A pedigree in which a recessive trait may skip generations and reappear when two carriers have offspring.

Rule of addition

The probability rule used to calculate the likelihood of one event or another occurring (when events are mutually exclusive).

Rule of multiplication

The probability rule used to calculate the likelihood of two independent events occurring together.

Second filial (F2) generation

The offspring of the F1 generation in a genetic cross.

Sex chromosomes

Chromosomes that determine the sex of an organism (e.g., X and Y chromosomes in humans).

Self-fertilize

When an organism fertilizes itself, commonly seen in plants.

Sex-linked (X-linked) inheritance

The pattern of inheritance for genes located on the X chromosome, which often results in different traits being expressed in males and females.

Short tandem repeats (STR)

Short sequences of DNA that are repeated in a row and vary in length between individuals, often used in genetic profiling.

Single-nucleotide polymorphisms (SNPs)

Variations at a single nucleotide position in the DNA sequence among individuals.

Testcross

A cross between an individual with a dominant phenotype but unknown genotype and a homozygous recessive individual to determine the unknown genotype.

Trisomy

A condition where an individual has an extra copy of a chromosome, resulting in three copies instead of the typical two.

Three-point testcross

A genetic cross involving three genes to map their relative positions on a chromosome.

True-breeding

Organisms that, when self-fertilized, produce offspring with the same traits over many generations.

X inactivation

The process by which one of the two X chromosomes in female mammals is randomly inactivated to prevent overexpression of X-linked genes.