Glossary of genetics

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This is a glossary of terms and concepts commonly used in the study of genetics and related disciplines in biology.[1] It is intended as introductory material for novices; for more specific and technical detail, please see the article corresponding to each term.


A[edit]

adenine
One of the four nucleotide bases in DNA or RNA; pairs with thymine in DNA or uracil in RNA.
affected relative pair
An affected relative pair consists of two organisms related genetically that are both affected by the same trait. For example, two cousins who both have blue eyes are an affected relative pair since they are both affected by the allele coding for blue eyes.
allele
one of multiple alternative forms of a single gene, each of which is a viable DNA sequence occupying a given position, or locus on a chromosome. For example, in humans, one allele of the eye-color gene produces blue eyes and another allele of the eye-color gene produces brown eyes.
allosome
Any chromosome that differs from an ordinary autosome in size, form, or behavior and which is responsible for determining the sex of an organism. In humans, the X chromosome and the Y chromosome are sex chromosomes.
amino acid
An organic compound containing amine and carboxyl functional groups, as well as a side chain specific to each individual amino acid. Out of nearly 500 known amino acids, a set of 20 are coded for by the standard genetic code and incorporated in sequence as the building blocks of polypeptides and hence proteins. The sequences of amino acids in polypeptide chains that form proteins determine the proteins' structure and function.
anaphase
aneuploidy
anticodon
autosome
Any chromosome that is not an allosome and is hence not involved in the determination of the sex of an organism. Unlike the sex chromosomes, the autosomes in a diploid cell exist in pairs, with the members of each pair having the same structure, morphology, and genetic loci.

B[edit]

bacterial artificial chromosome (BAC)
base pair
A pair of nucleotide bases on complementary DNA or RNA strands organized in a double helix.

C[edit]

canalisation
candidate gene
carrier
centimorgan (cM)
A unit for measuring genetic linkage defined as the distance between chromosomal loci for which the expected average number of intervening chromosomal crossovers in a single generation is 0.01. Though it is not an actual measure of physical distance, it is used to infer the distance between two loci based on the apparent likelihood of a crossover occurring between them. Also called a map unit (m.u.).
centriole
centromere
The part of a chromosome that links a pair of sister chromatids. During mitosis, spindle fibers attach to the centromere via the kinetochore.
centrosome
chromatid
One copy of a newly copied chromosome which is still joined to the original chromosome by a centromere.
chromatin
chromosomal crossover
chromosomal duplication
chromosome
A molecular "package" for carrying DNA in cells, organized as two double-helical DNA molecules that encode many genes. Some simple organisms have only one chromosome made of circular DNA, while most eukaryotes have multiple chromosomes made of linear DNA.
classical genetics
cloning
codominance
codon
A series of three nucleotides in a coding region of a nucleid acid sequence which code for a particular amino acid or stop signal during protein synthesis. DNA and RNA molecules are each written in a language using four "letters" (four nucleotide bases), but the language used to construct proteins includes 20 "letters" (20 different amino acids). Codons provide the key that allows these two languages to be translated into each other. In general, each codon corresponds to a single amino acid (or stop signal), and the full set of codons is called the genetic code. The vast majority of living organisms use what is called the "standard" genetic code, which includes 64 possible permutations, or combinations, of three-letter nucleotide sequences that can be made from the four nucleotides. Of the 64 codons, 61 code for amino acids, and the remaining three code for stop signals. For example, the codon CAG represents the amino acid glutamine, and TAA is a stop codon. The genetic code is described as degenerate, or redundant, because a single amino acid may be coded for by more than one codon. When codons are read from the nucleotide sequence, they are read in succession and do not overlap with one another.
copy number variation (CNV)
CRISPR
cytogenetics
cytosine
One of the four nucleotide bases in DNA or RNA; pairs with guanine.

D[edit]

deletion
deoxyribose
diploid
DNA
An acronym for deoxyribonucleic acid, a polymeric molecule made of deoxyribonucleotides. Most often has the form of a "double helix", which consists of two paired DNA molecules and resembles a ladder that has been twisted. The "rungs" of the ladder are made of base pairs, or nucleotides with complementary hydrogen bonding patterns.
DNA condensation
DNA fingerprinting
DNA polymerase
DNA replication
The process by which a DNA molecule copies itself, producing two identical copies of one original DNA molecule.
DNA sequencing
dominant
double helix
duplication

E[edit]

electrophoresis
endoplasmic reticulum (ER)
epigenetics
episome
epistasis
evolution
The change in the heritable characteristics of biological populations over successive generations. In the most traditional sense, it occurs by changes in the frequencies of alleles in a population's gene pool.
exome
exon
Any part of a gene that encodes a part of the final mature mRNA produced by that gene after introns have been removed by splicing. The term refers to both the sequence as it exists within a DNA molecule and to the corresponding sequence in RNA transcripts.
extrachromosomal DNA

F[edit]

fluorescence in situ hybridization (FISH)
frameshift mutation
A mutation caused by insertions or deletions of a number of nucleotides in a nucleic acid sequence that is not divisible by three. Because of the triplet nature by which nucleotides code for amino acids, a mutation of this sort causes a shift in the reading frame of the nucleotide sequence, resulting in a grouping of codons completely different from the original downstream of the mutation site. The earlier in the sequence the deletion or insertion occurs, the more altered the final gene product.

G[edit]

gene
A set of segments of a nucleic acid molecule that contains the information necessary to produce a functional RNA transcript in a controlled manner. In living organisms, it is a unit of heredity and typically encoded in DNA. A particular gene can have multiple different forms, or alleles, which are defined by different sequences of DNA.
gene dosage
gene drive
gene duplication
gene expression
The process in which the information encoded in a gene is converted into a form useful for the cell. The first step is transcription, which produces a messenger RNA molecule complementary to the DNA molecule on which a gene is encoded. For protein-coding genes, the second step is translation, in which the messenger RNA is read by the ribosome to produce a protein.
gene mapping
gene pool
The sum of all of the alleles shared by members of a single population.
gene regulation
gene silencing
gene therapy
gene trapping
genealogy
genetic code
The set of rules by which information encoded within nucleic acids is translated into proteins by living cells. These rules define how sequences of nucleotide triplets called codons specify which amino acid will be added next during protein synthesis. The vast majority of living organisms use the same genetic code (sometimes referred to as the "standard" genetic code) but variant codes do exist.
genetic counseling
genetic disorder
genetic drift
genetic engineering
genetic marker
gene product
genetic screening
genetic testing
genetics
The field of biology that studies genes and their inheritance.
genome
The entire complement of genetic material in the chromosome set of an organism, virus or organelle.
genomics
genotype
The complement of alleles present in a particular individual's genome, which give rise to the individual's phenotype.
genotyping
germ line
guanine
One of the four nucleotide bases in DNA or RNA; pairs with cytosine.

H[edit]

haploid
haplodiploid
haplotype
haplogroup
HapMap
hemizygous
heredity
The passing on of phenotypic traits from parents to their offspring, either through sexual or asexual reproduction. Offspring cells or organisms are said to inherit the genetic information of their parents.
heritability
heterozygous
In a diploid organism, having two different alleles of a gene at a given genetic locus. Heterozygous genotypes are represented by a capital letter (indicating the dominant allele) and a lowercase letter (indicating the recessive allele), such as "Aa" or "Bb".
histone
homologous chromosomes
A set of two matching chromosomes, one maternal and one paternal, that pair up with each other inside the nucleus during meiosis. They have the same genes at the same loci, but may have different alleles.
homologous recombination
homozygous
horizontal gene transfer (HGT)
Human Genome Project (HGP)
hybridization

I[edit]

in situ hybridization
incomplete dominance
indel
A term referring to either an insertion or a deletion of bases in a nucleic acid sequence.
insertion
intron

J[edit]

K[edit]

karyotype
knockin
knockout

L[edit]

linkage
linkage disequilibrium
locus
(pl. loci) A location on a chromosome where a particular gene resides.
LOD score
lyonization

M[edit]

map unit (m.u.)
See centimorgan.
medical genetics
meiosis
Mendelian inheritance
messenger RNA (mRNA)
metagenomics
metaphase
microRNA (miRNA)
microsatellite
missense mutation
mitochondrial DNA (mtDNA)
mitosis
mobile genetic element
monosomy
mosaic
mutagen
mutation
Any change in the base pair sequence of DNA or RNA.

N[edit]

nitrogenous base
non-coding DNA
non-coding RNA
nondisjunction
nonsense mutation
Northern blotting
nuclear membrane
nucleic acid
A long polymeric macromolecule made up of smaller monomers called nucleotides which are chemically linked to one another in a chain. Two specific nucleic acid molecules, DNA and RNA, are used in biological systems to encode the genetic blueprint of living organisms: the order, or sequence, of the nucleotides in DNA and RNA molecules encodes information that is translated into proteins which direct all of the chemical reactions necessary for life. DNA differs from RNA by its inclusion of thymine (T) as a nitrogenous base, whereas RNA includes uracil (U) instead. In DNA, the nucleotides are referred to in shorthand as A, C, T, and G; in RNA, the nucleotides are A, C, U, and G.
nucleolus
nucleopore
nucleosome
nucleotide
An organic molecule that serves as the monomer, or subunit, of nucleic acids like DNA and RNA. The nucleotides relevant to biology include adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U).
nucleus
(pl. nuclei) A membrane-enclosed organelle found in eukaryotic cells. The nucleus contains most of a cell's genetic material, organized as chromosomes, and directs the activities of the cell by regulating gene expression.
nullizygous

O[edit]

Okazaki fragments
oncogene
open reading frame (ORF)
The part of a reading frame that has the ability to be translated from DNA into protein; a continuous stretch of codons that contains a start codon and a stop codon.
operon

P[edit]

pedigree chart
peptide
A short chain of amino acid monomers linked by peptide bonds.
pharmacogenomics
phenotype
The observable physical or behavioral traits of an organism, largely determined by the organism's genotype.
phosphate backbone
phylogenetics
plasmid
pleiotropy
ploidy
point mutation
A mutation where a single nucleotide base is changed, inserted, or deleted from a sequence of DNA or RNA.
polygenic trait
polymerase chain reaction (PCR)
polymorphism (disambiguation)
polypeptide
polyploidy
population genetics
positional cloning
primer
proband
A term used in medical genetics and genealogy to denote a particular subject being studied or reported on. Often prosposito for a male subject and prosposita for a female subject.
promoter
prophase
protein
A linear polymeric molecule made of amino acids linked by peptide bonds. Proteins carry out the majority of chemical reactions that occur inside cells.
proteome
pseudogene
Punnett square
purine
pyrimidine

Q[edit]

quantitative genetics
quantitative trait locus (QTL)

R[edit]

reading frame
A way of dividing the nucleotide sequence in a DNA or RNA molecule into a set of consecutive, non-overlapping triplets which is "read" by proteins during transcription and replication. In coding DNA, each triplet is referred to as a codon that is paired with a particular amino acid during translation. In general, only one reading frame (the open reading frame) in a given section of a nucleic acid is biologically relevant, but there are exceptions in a few organisms. A mutation that results in a shift in the normal reading frame affects all downstream codons and is called a frameshift mutation.
recessive
recombinant DNA (rDNA)
repressor
restriction enzyme
restriction fragment length polymorphism (RFLP)
reverse transcriptase
ribose
ribosomal RNA (rRNA)
ribosome
RNA
RNA interference
RNA polymerase

S[edit]

Sanger sequencing
scaffolding
sex linkage
shotgun sequencing
silent mutation
single nucleotide polymorphism (SNP)
sister chromatids
small interfering RNA (siRNA)
solenoid fiber
somatic cell
somatic cell nuclear transfer (SCNT)
Southern blotting
spectral karyotype (SKY)
splicing
split-gene
start codon
stem cell
Any biological cell which has not yet differentiated into a specialized cell type and which can divide through mitosis to produce more stem cells.
stop codon
structure gene
substitution
See point mutation.
swivel point

T[edit]

tandem repeat
telomere
telophase
thymine
One of the four nucleotide bases in DNA molecules; pairs with adenine. In RNA, thymine is replaced with uracil.
transcription
The first step in gene expression, in which a messenger RNA molecule complementary to particular gene encoded in DNA is synthesized by enzymes called RNA polymerases. To produce a functional protein, transcription is followed by translation.
transcription factor
transfer RNA (tRNA)
transgenic
translation
The second step in gene expression, in which a messenger RNA molecule is read by the ribosome to produce a functional protein. Translation is always preceded by transcription.
translocation
transcriptome

U[edit]

uracil
One of the four nucleotide bases in RNA molecules; pairs with adenine. In DNA, uracil is replaced with thymine.

V[edit]

W[edit]

Western blotting
wild type (WT)
A term referring to the phenotype of the typical form of a species as it occurs in nature, a product of the standard "normal" allele at a given locus as opposed to that produced by a non-standard mutant allele. In genetics shorthand, wild-type alleles are often indicated by a "+" superscript.

X[edit]

X chromosome
X-linked trait

Y[edit]

Y chromosome
yeast artificial chromosome (YAC)

Z[edit]

zygosity
zygote

See also[edit]

Further reading[edit]

Budd, A. (2012). "Introduction to genome biology: features, processes, and structures". Methods in Molecular Biology (855): 3–4. 

References[edit]

  1. ^ "Talking Glossary of Genetic Terms". genome.gov. 8 October 2017. Retrieved 8 October 2017.