Genetics: Basic Concepts

A unit of heredity determining characteristics passed from parents to offspring.

A thread-like structure in a cell's nucleus carrying genetic information (genes).

The molecule that carries genetic information and makes up chromosomes in most living organisms.

One version of a gene, arising through mutation, found at the same location on a chromosome.

Having two identical alleles for a particular gene.

Having two different alleles for a particular gene.

One allele masking the expression of another allele.

An allele's expression is masked by a dominant allele, only showing up if both alleles are recessive.

A trait's inheritance pattern determined by genes located on sex chromosomes, typically the X chromosome, resulting in different inheritance patterns in males and females.

A genetic pattern where one allele isn't completely dominant over another, producing an intermediate phenotype.

Chromosome pairs with the same genes at the same locations, but possibly different alleles (versions of the gene).

Cell division process reducing chromosome number by half to form gametes (sperm or egg).

Having half the usual number of chromosomes, like in gametes.

Having the full set of chromosomes, normal body cells.

Genetic condition with an extra copy of a chromosome.

Genetic condition with missing chromosome.

The first stage of meiosis I where homologous chromosomes pair up and exchange genetic material.

The exchange of genetic material between homologous chromosomes during meiosis, leading to genetic variation.

Reproductive cells (sperm and egg) that contain half the number of chromosomes.

A fertilized egg, containing the full set of chromosomes received from parent cells.

A visual arrangement of an individual's chromosomes, showing their number, size, and structure.

During meiosis, the number of chromosomes is reduced by half, resulting in daughter cells with only one set of chromosomes.

Meiosis leads to the creation of genetically unique offspring by shuffling the alleles of the parent chromosomes.

The pairing up of homologous chromosomes during prophase I of meiosis.

The random orientation of homologous chromosomes during metaphase I, leading to various combinations of maternal and paternal chromosomes in gametes.

The failure of homologous chromosomes or sister chromatids to separate properly during anaphase I or II, resulting in gametes with abnormal chromosome numbers.

A condition caused by trisomy 21, meaning three copies of chromosome 21.

A condition caused by monosomy X, meaning only one copy of the X chromosome.

A prenatal test that involves extracting amniotic fluid containing fetal cells to analyze for genetic abnormalities.

A prenatal test where a sample of cells from the placenta (chorion) is taken to analyze for genetic abnormalities.

A method of breeding plants or animals to select and enhance desirable traits.

The introduction of sperm into a female's reproductive tract, often using processed semen from selected males.

A technique where fertilized eggs are transferred into a recipient female, enabling the production and transport of embryos.

A scientist known for his groundbreaking work on inheritance patterns using pea plants.

An allele that will always be expressed in the phenotype, regardless of the other allele present.

An allele that is only expressed in the phenotype if two copies of it are present.

States that during meiosis, the two alleles of a gene separate and are packaged into different gametes.

Describes how one allele can mask the expression of another allele in a heterozygote.

States that the alleles of different genes segregate independently of one another during meiosis.

The genetic makeup of an individual, represented by the combination of alleles they possess.

The observable characteristics of an individual, resulting from their genotype.

A grid used to predict the possible genotypes and phenotypes of offspring from a cross.

A cross between an individual of unknown genotype and an individual that is homozygous recessive for the trait.

A cross between two individuals that differ in two traits.

States that genes are located on chromosomes and that the behaviour of chromosomes during meiosis explains Mendel's laws of inheritance.

A scientist who proposed the Chromosome Theory of Inheritance.

A diagram used to trace inheritance patterns of traits within a family across generations, displaying relationships and phenotypes.

Inheritance of traits governed by genes on autosomes (chromosomes 1-22), excluding sex chromosomes.

A genetic disorder where a single copy of the dominant disease-causing allele leads to the condition.

A genetic disorder where two copies of the recessive disease-causing allele are needed for the condition to manifest.

A technique that uses fluorescent probes to detect specific DNA sequences in chromosomes, illuminating abnormalities.

When a trait is controlled by more than two alleles for one gene, leading to diverse phenotypes.

Inheritance of traits determined by multiple genes, leading to continuous variation in the phenotype.

Genes located on the same chromosome that are inherited together, deviating from independent assortment.

A disorder passed on through the X chromosome, requiring two copies (for females) or one copy (for males) of the recessive allele for the condition to appear.

A tightly condensed, inactive X chromosome found in the cells of females. This inactivation ensures that females only express one X chromosome's genes.

Males inherit only one X chromosome, so if they inherit a recessive allele on that X chromosome, they will express the disorder. Females have two X chromosomes, so they need two recessive alleles to express the disorder, making it less common.

Heterozygous females, carrying one dominant and one recessive allele for an X-linked trait, will exhibit a mosaic pattern. Some cells will express the dominant trait, while others will express the recessive trait.

An example of X-linked inheritance. The alleles for black or orange coat color in cats are carried on the X chromosome. Heterozygous females exhibit a mosaic pattern, showcasing both black and orange patches due to random X inactivation.