13. Translation of mRNA Flashcards
the process in which the sequence of codons within mRNA provides the information to synthesize the sequence of amino acids that constitute a polypeptide.
Translation
genes that produce mRNA and encode polypeptides
Protein-Coding (Structural) Genes
a type of RNA that is transcribed from a protein-encoding gene and contains the information for the synthesis of a polypeptide.
messenger RNA (mRNA)
a human genetic disorder involving the accumulation of homogentisic acid in the body due to a lack of the enzyme homogentisic acid oxidase.
Alkaptonuria
a genetic disease that involves a defect in a metabolic enzyme.
Inborn Error of Metabolism
the idea, which later needed to be expanded, that one gene encodes one enzyme.
One-Gene/One-Enzyme Hypothesis
a linear sequence of amino acids that is the product of mRNA translation. One or more polypeptides fold and associate with each other to form a functional protein.
Polypeptide
a functional unit composed of one or more polypeptides.
Protein
the correspondence between a codon (i.e., a sequence of three bases in an mRNA molecule) and the functional role that the codon plays during translation. Each codon specifies a particular amino acid or the end of translation.
Genetic Code
a codon that encodes a specific amino acid.
Sense Codon
a three-base sequence in mRNA that initiates translation. It is usually 5′-AUG-3′ and encodes methionine.
Start Codon
a three-base sequence in mRNA that signals the end of translation of a polypeptide. The three stop codons are 5′–UAA–3′, 5′–UAG–3′, and 5′–UGA–3′.
Stop (Termination, Nonsense) Codon
in an mRNA, the region at the 5′ end that precedes the codons that are translated into an amino acid sequence within a polypeptide.
5’-Untranslated Region
in an mRNA, the region at the 3′ end that follows the codons that are translated into an amino acid sequence within a polypeptide.
3’-Untranslated Region
a three-nucleotide sequence in tRNA that is complementary to a codon in mRNA.
Anticodon
in genetics, this term means that more that one codon specifies the same amino acid. For example, the codons GGU, GGC, GGA, and GGG all specify the amino acid glycine.
Degeneracy
two or more different codons that specify the same amino acid.
Synonymous Codons
a series of codons determined by reading bases in groups of three beginning with the start codon as a frame of reference.
Reading Frame
a nonstandard amino acid that may be incorporated into polypeptides during translation.
Selenocysteine (Sec)
a nonstandard amino acid that may be incorporated into polypeptides during translation.
Pyrrolysine (Pyl)
a covalent bond formed between the carboxyl group in one amino acid in a polypeptide and the amino group in the next amino acid.
Peptide Bond
the location of the first amino acid in a polypeptide. The amino acid at the amino-terminus retains a free amino group that is not covalently attached to the second amino acid.
Amino-Terminus (N-Terminus)
the location of the last amino acid in a polypeptide chain. The amino acid at the carboxyl-terminus retains a free carboxyl group that is not covalently attached to another amino acid.
Carboxyl-Terminus (C-Terminus)
in an amino acid, the chemical structure attached to the carbon atom (i.e., the α carbon) that is located between the amino and carboxyl groups.
Side Chain (R Group)
with regard to proteins, the linear sequence of amino acids that forms a polypeptide.
Primary Structure
a protein that aids in the folding of polypeptides.
Chaperone
a regular repeating pattern of molecular structure, such as the DNA double helix or the α helix and β sheet found in proteins.
Secondary Structure
a type of secondary structure found in proteins.
α Helix
a type of secondary structure found in proteins.
β sheet
the three-dimensional structure of a macromolecule, such as the tertiary structure of a polypeptide.
Tertiary Structure
the structure of a functional protein formed when two or more polypeptides associate with each other.
Quaternary Structure
a component of a larger complex. In a protein, each subunit is a single polypeptide.
Subunit
an experimental mixture that can synthesize polypeptides.
Cell-Free Translation System
a hypothesis that proposes a tRNA has two functions: recognizing a three-base codon sequence in mRNA and carrying an amino acid that is specific for that codon.
Adaptor Hypothesis
an enzyme that catalyzes the attachment of a specific amino acid to the correct tRNA.
Aminoacyl-tRNA Synthetase
a tRNA that has an amino acid attached to its 3′ end by a covalent bond.
Charged tRNA (Aminoacyl-tRNA)
rules that govern the binding specificity between the third base in a codon and the first base in an anticodon.
Wobble Rules
two or more tRNAs that differ at the wobble position but can recognize the same codon.
Isoacceptor tRNAs
a large macromolecular structure that acts as the catalytic site for polypeptide synthesis and allows the mRNA and tRNAs to be positioned correctly as the polypeptide is made.
Ribosome
an organelle within the nucleus of eukaryotic cells where the assembly of ribosomal subunits occurs.
Nucleolus
an mRNA transcript that has many bound ribosomes in the act of translation.
Polyribosom (Polysome)
a site on a ribosome that carries a tRNA along with a polypeptide.
Peptidyl Site (P Site)
a site on a ribosome where a charged tRNA initially binds.
Aminoacyl Site (A Site)
a site on a ribosome where an uncharged tRNA binds and then is released.
Exit Site (E Site)
(1) in transcription, the stage that involves the initial binding of RNA polymerase to the promoter in order to begin RNA synthesis; (2) in translation, the formation of a complex between mRNA, the initiator tRNA, and the ribosomal subunits.
Initiation
(1) in transcription, the synthesis of an RNA transcript using DNA as a template; (2) in translation, the synthesis of a polypeptide using the information within mRNA.
Elongation
(1) in transcription, the release of the newly made RNA transcript and RNA polymerase from the DNA; (2) in translation, the release of the polypeptide and the last tRNA and the disassembly of the ribosomal subunits and mRNA.
Termination
during translation, the tRNA that recognizes the start codon in the mRNA.
Initiator tRNA
a set of rules that identify the most favorable types of bases to flank a eukaryotic start codon in an mRNA molecule.
Kozak’s Rules
the ability of 16S rRNA to detect when an incorrect tRNA is bound at the A site and prevent elongation until the mispaired tRNA is released from the A site.
Decoding Function
the step during the elongation stage of translation in which the polypeptide is removed from the tRNA in the P site and transferred to the amino acid at the A site.
Peptidyl Transfer
a complex that functions during translation to catalyze the formation of a peptide bond between the amino acid in the A site of the ribosome and the growing polypeptide.
Peptidyl Transferase
a protein that recognizes a stop codon and promotes termination of translation and the release of the completed polypeptide.
Release Factor
any substance produced by a microorganism that inhibits the growth of other microorganisms, such as pathogenic bacteria.
Antibiotic
