Module 5 Flashcards
5’ cap
in eukaryotes the RNA transcript destined to become mRNA are modified by addition of a 7-methylguanosine ‘cap’ at the 5’ end during the process of maturation from pre-mRNA to mRNA. This cap structure is required for efficient recognition by the ribosome.
Activator protein
a transcriptional regulatory protein that binds to a specific site on DNA (activator binding site) and enhances transcription initiation.
Activator binding site
the site where an activator protein binds to enhance transcription initiation.
Alternate sigma factors
a mechanism of global regulation in bacteria. Similar to the sigma factor that allows RNA polymerase to recognize the promoter that dictates the start of transcription, these have their own specific promoter sequences that they specifically bind to promote transcription initiation.
Attenuation
a mechanism for regulating transcription of some bacterial operons by changes in RNA folding to allow or prevent the formation of a transcriptional terminator stem-loop signal dependent on the availability of charged tRNAs for co-translation of the transcript.
AUG initiation codon or start codon
the first A-U-G sequence in an mRNA’s coding region; it is where translation into protein begins.
cAMP
cyclic adenosine monophosphate formed by adenosine cyclase. Functions as a ‘second messenger’ to regulate cellular physiology and transcription.
Catabolite repression
inhibition of the synthesis of several catabolic enzymes by a preferred carbon source (note, for E. coli, the actual mechanism is due to a lack of functional activator protein when glucose is present).
Chaperone proteins
proteins that assist in the folding and stabilization of other proteins.
Chemotaxis
the pattern of cellular behavior in which the cell moves toward chemical attractants and away from repellents.
Corepressor
an allosteric effector that is required to be bound by the repressor (technically called an aporepressor in this situation) before it can bind its target site.
CRISPR-Cas system
an array of DNA sequences and a set of enzymes that recognize invading DNA and targeting it for destruction (found in many bacteria and most archaea).
Enhancer
a site in DNA to which a subclass of eukaryotic activator proteins bind.
Helix-turn-helix
the most common protein structure for DNA binding proteins. The name describes how one domain is a helix folded structure that binds to its partner subunit, followed by a turn in the protein structure, then a second helix fold that is the DNA binding domain.
Inducer
a small molecule that stimulates the synthesis of an inducible enzyme.
Inhibitor
a small molecule that allosterically binds to an activator protein to prevent its binding to DNA, thus inhibiting transcription initiation.
Intron/exon spliceosome
a system by which introns – noncoding intervening sequence in a gene that codes for pre-mRNA – are removed (spliced) from the final RNA product. The regions in a gene that are retained in are called exons. It is common in many eukaryotes, and rare but present in some prokaryotic genes.
Negative control
where the binding of the regulatory protein to DNA inhibits transcriptional initiation. This class of regulatory proteins are called repressor proteins (repressors).
Nucleic acids
the main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Operator
the repressor binding site in bacteria; the segment of DNA in an operon to which the repressor protein binds; it controls the expression of the genes adjacent to it.
Operon
in bacteria and archaea, the sequence of bases in DNA that contains a promoter and one or more structural genes and often an operator or activator-binding site that controls their expression.
Origin of replication
a site on a chromosome, plasmid, or virus where DNA replication is initiated.
