Molecular Bio Exam IV

Polycistronic

A single mRNA encoding several different polypeptide chains

Monocistronic

A single mRNA that includes a single polypeptide chain

Peptidyl Transferase Center

Component of the large ribosome sub unit that is responsible for the formation of peptide bonds

Decoding Center

Components of the small ribosome subunit, which is responsible for the interaction of tRNA with codons on the mRNA

Svedberg

A unit used to measure sedimentation velocity

Translocation

The movement of mRNA and associated tRNA's through the E, P, and A site of the ribosome

Translational coupling

An increase in translation efficiency due to the association of ribosome with a ribosomal binding site on an upstream open reading frame in polycistronic mRNA

Degeneracy

The ability of elements that are structurally different to perform the same function or yield the same output

Sigma Factor

A bacterial transcription initiation factor that enables specific binding of RNA polymerase gene promoters

Alternative Sigma Factor

A sigma factor that initiates transcription of specific genes under specific conditions, and does not allow for a constitutive expression of a large set of genes like a housekeeping factor

Allostery

The influencing of an enzyme activity, or the binding of a ligand to a protein, by a change in the confirmation of the protein, about the binding of a substrate or other effect at a site (allosteric sites) other than the active site of the protein

Basal Level

The low level of constitution gene expression that occurs in the absence of regulatory proteins or when a promoter element is missing

Cooperative Binding

An interaction between molecules that results in their stable association

Riboswitches

A riboswitch, which is a regulatory segment of an mRNA molecule that binds a small molecule, resulting in a change in the production of the proteins encoded by the mRNA

Aptamer

Oligonucleic acid or peptide molecules that bind to a specific target molecule

Attenuation

A regulatory feature found throughout archaea and bacteria, causing premature termination of transcription

Small RNA (sRNA)

Non-coding RNA molecules produced by bacteria that modify the function of bound protein, or bind mRNA and modify gene regulation

Small Interfering RNA (siRNA)

A class of synthetically generated double-stranded RNA molecules that participate in RNA interference (RNAi) pathways, where it interfere with the expression of specific genes with complementary nucleotide sequences

MicroRNA (miRNA)

A small, non-coding RNA, found in implants, animals, and some viruses, which functions in transcriptional and post-transcriptional regulation of gene expression

Precursor RNA (Pre-RNA)

An unprocessed, immature, single strand of mRNA synthesis from a DNA template in the cell nucleus by transcription

Primary Transcript (Primary RNA or Pri-RNA)

A single-stranded RNA product is synthesized by transcription of DNA, and processed to yield various mature RNA products such as mRNA, tRNA, and rRNA