Template:Genetics glossary

A-F

Adenine One of the four nucleotide bases in DNA or RNA; pairs with thymine in DNA or uracil in RNA.

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.

Base pair A pair of nucleotide bases on complementary DNA or RNA strands organized in a double helix.

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.

Cytosine One of the four nucleotide bases in DNA or RNA; pairs with guanine.

DNA A polymeric molecule made of deoxyribonucleotides, hence then name deoxyribonucleic acid. 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.

G-Z

Gene The unit of heredity in living organisms, typically encoded in a sequence of nucleotide monomers that make up a long strand of DNA, or deoxyribonucleic acid. A particular gene can have multiple different forms, or alleles, which are defined by different sequences of DNA.

Gene expression The process in which the infomation 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 pool The sum of all the alleles shared by members of a single population.

Genetics The field of biology that studies genes and their inheritance.

Genome The total complement of genetic material contained in an organism or cell.

Genotype The complement of alleles present in a particular individual's genome that give rise to the individual's phenotype.

Guanine One of the four nucleotide bases in DNA or RNA; pairs with cytosine.

Locus A location on a chromosome where a particular gene resides.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">Phenotype The observable physical or behavioral traits of an organism, largely determined by the organism's genotype.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">Protein A linear polymeric molecule made of of amino acids linked by peptide bonds. Proteins carry out the majority of chemical reactions that occur inside the cell.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">RNA A polymeric molecule made of ribonucleotides, hence the name ribonucleic acid, similar to but less stable than DNA. One type, messenger RNA, plays an important role in gene expression. Ribosomes are also made largely of RNA.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">Thymine One of the four nucleotide bases in DNA; pairs with adenine. In RNA, thymine is replaced with uracil.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">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.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">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.

<div class="NavHead" style="padding:2px 2px 2px 30px; background-color:#BBDDFF; text-align:left; font-size:normal;">Uracil One of the four nucleotide bases in RNA; pairs with adenine. In DNA, uracil is replaced with thymine.