Genetics

Missense Mutation

A genetic mutation in which a point mutation of a single nucleotide changes the existing code to a sequence that codes for a different amino acid, which results in a nonfunctional protein.

Duplication Mutation

A genetic mutation in which a region that contains a gene or an entire chromosome is duplicated, which results in multiple copies of that region or nucleotide.

Insertion Mutation

A genetic mutation in which one or more nucleotides are inserted into a genetic sequence.

Deletion Mutation

A genetic mutation in which one or more nucleotides are removed from a section of DNA.

Inversion Mutation

A genetic mutation in which the order of a segment of genetic material is reversed. This type of mutation can involve a small number of nucleotides as well as larger sections of a chromosome containing more than one gene.

Silent Mutation

A genetic mutation that results in a codon that does not change the amino acid sequence that occurs, codes for the same amino acid, or codes for a different amino acid that does not cause any functional change in the proteins that are produced.

Nonsense Mutation

A genetic mutation, which is typically the result of a point mutation, that causes the sequence of nucleotides to code for a premature stop codon. This type of mutation usually results in a protein product that is shortened, incomplete, and often nonfunctional.

Protein

A macromolecule that contains the principal components of organisms: carbon, hydrogen, oxygen, and nitrogen; performs a variety of structural and regulatory functions for cells.

Nucleus

A membrane-bound organelle in eukaryotic cells functioning to maintain the integrity of the genetic material and, through the expression of that material, controlling and regulating cellular activities.

Gene Recombination

A natural process in which a nucleic acid molecule (usually DNA but can be RNA) is broken and then joined to a different molecule; a result of crossing-over.

Mitosis

A nuclear division resulting in the production of two somatic cells having the same genetic complement as the original cell.

Dominant Inheritance

A pattern of inheritance in which the phenotypic effect of one allele is completely expressed within a homozygous and heterozygous genotype.

Recessive Inheritance

A pattern of inheritance in which the phenotypic effect of one allele is only expressed within a homozygous genotype. In a heterozygous condition with a dominant allele, it is not expressed in the phenotype.

Co-dominance

A pattern of inheritance in which the phenotypic effect of two alleles in a heterozygous genotype express each phenotype of each allele fully and equally; a phenotype which would not be expressed in any other genotypic combination.

Incomplete Dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

Gene Mutation

A permanent alteration that changes a segment of DNA within a gene.

Mutation

A permanent transmissible change of genetic material (e.g., chromosomal mutations and gene mutations).

Cloning

A process in which a cell, cell product, or organism is copied from an original source.

Gene

A sequence of nucleotides composing a segment of DNA that provides a blueprint for a specific hereditary trait.

Chromosomes

A single piece of coiled DNA and associated proteins found in linear forms in the nucleus of eukaryotic cells and circular forms in the cytoplasm of prokaryotic cells; contains genes that encode traits. Each species has a characteristic number of these.

Point Mutation

A single-base substitution causing the replacement of a single-base nucleotide with another nucleotide (e.g., silent mutation, missense mutation, and nonsense mutation).

Gamete

A specialized cell (egg or sperm) used in sexual reproduction containing half the normal number of chromosomes of a somatic cell.

Genetic Engineering

A technology that includes the process of manipulating or altering the genetic material of a cell resulting in desirable functions or outcomes that would not occur naturally.

Sex-linked Trait

A trait associated with a gene that is located on one of the sex chromosomes (e.g., color blindness, hemophilia).

Polygenic Trait

A trait in which the phenotype is controlled by two or more genes at different loci on different chromosomes.

Meiosis

A two-phase nuclear division that results in the eventual production of gametes with half the normal number of chromosomes.

Gene Splicing

A type of gene recombination in which the DNA is intentionally broken and recombined using laboratory techniques.

Allele

A variation of a gene's nucleotide sequence (an alternative form of a gene).

Crossing-over

An exchange of genetic material between homologous chromosomes during prophase I of meiosis; contributes to the genetic variability in gametes and ultimately in offspring.

Genetically Modified Organism

An organism whose genetic material has been altered through some genetic engineering technology or technique.

Biotechnology

Any procedure or methodology that uses biological systems or living organisms to develop or modify either products or processes for specific use. This term is commonly associated with genetic engineering, which is one of many applications.

Plasmid

Circular DNA molecules that are separate from chromosomal DNA and can replicate independently.

Multiple Alleles

More than two forms of a gene controlling the expression of a trait.

Frame-shift Mutation

The addition (insertion mutation) or removal (deletion mutation) of one or more nucleotides that is not divisible by three, therefore resulting in a completely different amino acid sequence than would be normal. The earlier in the sequence that nucleotides are added or removed, the more altered the resulting protein will be.

Genotype

The genetic composition of an organism with reference to a single trait, a set of traits, or the entire complement of traits of an organism.

Gene Therapy

The intentional insertion, alteration, or deletion of genes within an individual's cells and tissues for the purpose of treating a disease.

Interphase

The longest-lasting phase of the cell cycle in which a cell performs the majority of its functions, such as preparing for nuclear division and cytokinesis.

Phenotype

The observable expression of a genotype.

DNA Replication

The process in which DNA makes a duplicate copy of itself.

Gene Expression

The process in which a nucleotide sequence of a gene is used to make a functional product such as protein or RNA.

Translocation

The process in which a segment of a chromosome breaks off and attaches to another chromosome.

Transcription

The process in which a strand of messenger RNA (mRNA) is synthesized by using the genetic information found on a strand of DNA as a template.

Protein Synthesis

The process in which amino acids are arranged in a linear sequence through the processes of transcription of DNA to RNA and the translation of RNA to a polypeptide chain.

Inheritance

The process in which genetic material is passed from parents to their offspring.

Nondisjunction

The process in which homologous chromosomes or sister chromatids fail to separate during meiosis.

Translation

The process in which the messenger RNA (mRNA) molecule on a ribosome is decoded to produce a sequence of amino acids for protein synthesis.

Selective Breeding

The process of breeding organisms that results in offspring with desired genetic traits.

Forensics

The science of tests and techniques used during the investigation of crimes.

Genetics

The scientific study of inheritance.

Locus (gene locus)

The specific location of a gene or DNA sequence on a chromosome or linkage map.

Therapeutic cloning

the process of taking undifferentiated embryonic cells [STEM cells] for use in medical research).

DNA cloning

the transfer of a DNA fragment from one organism to a self-replicating genetic element such as a bacterial plasmid.

Reproductive cloning

the transfer of genetic material from the nucleus of a donor adult cell to an egg cell that has had its nucleus removed for the purpose of creating an embryo that can produce an exact genetic copy of the donor organism.

Nucleic Acid

A biological macromolecule (DNA or RNA) composed of the elements C, H, N, O, and P that carries genetic information.

Deoxyribonucleic Acid (DNA)

A biological macromolecule that encodes the genetic information for living organisms and is capable of self-replication and the synthesis of ribonucleic acid (RNA).

Haploid Cell

A cell containing one chromosome (n) from each homologous pair, typically observed in somatic cells.

Diploid Cell

A cell containing two homologous pairs of chromosomes (2n).

Ribosome

A cellular structure composed of RNA and proteins that is the site of protein synthesis in eukaryotic and prokaryotic cells.

Chromosomal Mutation

A change in the structure of a chromosome (e.g., deletion, duplication, Inversion, and translocation)