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Receptor (Cell Receptor)

A protein molecule, embedded in either the plasma membrane or the cytoplasm of a cell, to which a mobile signaling (or signal) molecule may attach. A molecule that binds to a receptor is called a ligand, and may be a peptide (such as a neurotransmitter), a hormone, a pharmaceutical drug or a toxin, and when such binding occurs, the receptor goes into a conformational change, which usually initiates a cellular response.

Recombinant DNA

A form of DNA that does not exist naturally and is created by combining DNA sequences that would not normally occur together.

Recombinant Proteins

Proteins created by recombinant DNA technology.

Regenerative Medicine

Research into treatments that restore damaged cells with healthy, disease free cells.

Restriction Enzymes

Enzymes having the ability to cut DNA at a certain location. Scientists use these enzymes to isolate certain types of DNA and place them into new environments. Where DNA ligase is the glue of recombinant DNA technology, restriction enzymes are the scissors.

Reverse Transcriptase

An enzyme used by retroviruses to form a complementary DNA sequence (cDNA) from an RNA template, usually the genome of the retrovirus. The enzyme then performs a complementary template of the cDNA strand such that a double-stranded DNA molecule is formed. This double-stranded DNA molecule is then inserted into the chromosome of the host cell, which has been infected by the retrovirus. 

Ribonucleic Acid (RNA)

A molecule similar to DNA, which helps in the process of decoding the genetic information carried by DNA. RNA is a nucleic acid transcribed from DNA; mRNA is then translated into proteins.

Ribosome

The cell structures within which protein synthesis occurs.

RNA Interference

A mechanism that inhibits gene expression at the stage of translation (see translation) or by hindering the transcription (see transcription) of specific genes. This method has been referred to as posttranscriptional gene silencing and is an important tool for gene-expression research.