Key Genetic Terms and Concepts

DNA

A nucleic acid molecule that stores information and contains instructions for cell functions, carried by nearly every cell in all living organisms, and unique to each person. It serves as a universal language for building all structures in living organisms.

Nucleotide

A unit that makes up DNA, consisting of a sugar, a phosphate group, and a nitrogen-containing base.

Genome

An organism's full set of DNA.

Gene

A sequence of bases in a DNA molecule that holds the information to produce a functional product, such as a polypeptide or an RNA molecule, and serves as a storehouse of information.

Transcription

The process in the nucleus of eukaryotic cells where a single copy of a specific gene's base sequence is created in the form of a messenger RNA (mRNA) molecule. The mRNA then leaves the nucleus and enters the cytoplasm.

Translation

The process in the cytoplasm where the information encoded in the mRNA's nucleotide sequence is read and used to produce a protein, using ingredients available in the cytoplasm.

Mutation

Alterations in a single base pair or changes in large DNA segments that can include multiple genes.

Biotechnology

The application of technology to modify organisms, cells, and their molecules to gain practical benefits, particularly in agriculture, human health, and forensic science.

CRISPR

A precise and efficient gene-editing tool that can target and cut the DNA of almost any species at a specific sequence, allowing for extensive genetic modification.

Telomere

In eukaryotic cells, telomeres track the number of cell divisions by shortening with each division; if they become too short, further divisions lead to loss of essential DNA and cell death.

Mitosis

The process by which cells duplicate themselves, allowing organisms to grow and replace old or dead cells. It results in two genetically identical daughter cells from a single parent cell.

Cancer

Unrestrained cell growth and division, often caused by mutations in genes that control the cell cycle.

Meiosis

The process that produces reproductive cells (gametes) in sexually reproducing organisms. It results in four genetically dissimilar haploid gametes with half the genetic material of the parent cell.

Karyotype

A visual display of a complete set of chromosomes, used as a diagnostic tool to check for abnormalities.

Allele

One of the two copies of a gene an individual inherits, which determines their observed trait.

Genotype

An organism's genetic makeup.

Phenotype

An organism's outward appearance.

Segregation

The process where each gamete receives only one of the two copies of a gene that an individual carries.

Test-Cross

Mating an individual with a dominant trait but unknown genotype with a homozygous recessive individual to determine the unknown parent's genotype based on the offspring's phenotypes.

Pedigree

Charts that help determine the genes individuals carry and the probability that their offspring will have a certain trait.

Incomplete Dominance

A pattern of inheritance where the phenotype of a heterozygote is an intermediate blend of the two homozygous phenotypes.

Codominance

A pattern of inheritance where a heterozygote's phenotype displays characteristics of both homozygotes.

Multiple Allelism

A condition where a single gene has more than two alleles existing within the population, though an individual still carries only two alleles.

Polygenic Trait

A trait influenced by multiple genes, such as height and eye color.

Pleiotropy

Occurs when one gene influences multiple, unrelated traits.

Sex-Linked Trait

A trait whose gene is located on a sex chromosome, leading to different expression patterns between males and females.

Gene Linkage

When the alleles for two genes are located close together on the same chromosome, causing them to tend to be inherited together as a package.