13. Translation of mRNA

Question 1

the process in which the sequence of codons within mRNA provides the information to synthesize the sequence of amino acids that constitute a polypeptide.

Answer 1

Translation

Question 2

genes that produce mRNA and encode polypeptides

Answer 2

Protein-Coding (Structural) Genes

Question 3

a type of RNA that is transcribed from a protein-encoding gene and contains the information for the synthesis of a polypeptide.

Answer 3

messenger RNA (mRNA)

Question 4

a human genetic disorder involving the accumulation of homogentisic acid in the body due to a lack of the enzyme homogentisic acid oxidase.

Answer 4

Alkaptonuria

Question 5

a genetic disease that involves a defect in a metabolic enzyme.

Answer 5

Inborn Error of Metabolism

Question 6

the idea, which later needed to be expanded, that one gene encodes one enzyme.

Answer 6

One-Gene/One-Enzyme Hypothesis

Question 7

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.

Answer 7

Polypeptide

Question 8

a functional unit composed of one or more polypeptides.

Answer 8

Protein

Question 9

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.

Answer 9

Genetic Code

Question 10

a codon that encodes a specific amino acid.

Answer 10

Sense Codon

Question 11

a three-base sequence in mRNA that initiates translation. It is usually 5′-AUG-3′ and encodes methionine.

Answer 11

Start Codon

Question 12

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′.

Answer 12

Stop (Termination, Nonsense) Codon

Question 13

in an mRNA, the region at the 5′ end that precedes the codons that are translated into an amino acid sequence within a polypeptide.

Answer 13

5’-Untranslated Region

Question 14

in an mRNA, the region at the 3′ end that follows the codons that are translated into an amino acid sequence within a polypeptide.

Answer 14

3’-Untranslated Region

Question 15

a three-nucleotide sequence in tRNA that is complementary to a codon in mRNA.

Answer 15

Anticodon

Question 16

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.

Answer 16

Degeneracy

Question 17

two or more different codons that specify the same amino acid.

Answer 17

Synonymous Codons

Question 18

a series of codons determined by reading bases in groups of three beginning with the start codon as a frame of reference.

Answer 18

Reading Frame

Question 19

a nonstandard amino acid that may be incorporated into polypeptides during translation.

Answer 19

Selenocysteine (Sec)

Question 20

a nonstandard amino acid that may be incorporated into polypeptides during translation.

Answer 20

Pyrrolysine (Pyl)

Question 21

a covalent bond formed between the carboxyl group in one amino acid in a polypeptide and the amino group in the next amino acid.

Answer 21

Peptide Bond

Question 22

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.

Answer 22

Amino-Terminus (N-Terminus)

Question 23

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.

Answer 23

Carboxyl-Terminus (C-Terminus)

Question 24

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.

Answer 24

Side Chain (R Group)

Question 25

with regard to proteins, the linear sequence of amino acids that forms a polypeptide.

Answer 25

Primary Structure

Question 26

a protein that aids in the folding of polypeptides.

Answer 26

Chaperone

Question 27

a regular repeating pattern of molecular structure, such as the DNA double helix or the α helix and β sheet found in proteins.

Answer 27

Secondary Structure

Question 28

a type of secondary structure found in proteins.

Answer 28

α Helix

Question 29

a type of secondary structure found in proteins.

Answer 29

β sheet

Question 30

the three-dimensional structure of a macromolecule, such as the tertiary structure of a polypeptide.

Answer 30

Tertiary Structure

Question 31

the structure of a functional protein formed when two or more polypeptides associate with each other.

Answer 31

Quaternary Structure

Question 32

a component of a larger complex. In a protein, each subunit is a single polypeptide.

Answer 32

Subunit

Question 33

an experimental mixture that can synthesize polypeptides.

Answer 33

Cell-Free Translation System

Question 34

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.

Answer 34

Adaptor Hypothesis

Question 35

an enzyme that catalyzes the attachment of a specific amino acid to the correct tRNA.

Answer 35

Aminoacyl-tRNA Synthetase

Question 36

a tRNA that has an amino acid attached to its 3′ end by a covalent bond.

Answer 36

Charged tRNA (Aminoacyl-tRNA)

Question 37

rules that govern the binding specificity between the third base in a codon and the first base in an anticodon.

Answer 37

Wobble Rules

Question 38

two or more tRNAs that differ at the wobble position but can recognize the same codon.

Answer 38

Isoacceptor tRNAs

Question 39

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.

Answer 39

Ribosome

Question 40

an organelle within the nucleus of eukaryotic cells where the assembly of ribosomal subunits occurs.

Answer 40

Nucleolus

Question 41

an mRNA transcript that has many bound ribosomes in the act of translation.

Answer 41

Polyribosom (Polysome)

Question 42

a site on a ribosome that carries a tRNA along with a polypeptide.

Answer 42

Peptidyl Site (P Site)

Question 43

a site on a ribosome where a charged tRNA initially binds.

Answer 43

Aminoacyl Site (A Site)

Question 44

a site on a ribosome where an uncharged tRNA binds and then is released.

Answer 44

Exit Site (E Site)

Question 45

(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.

Answer 45

Initiation

Question 46

(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.

Answer 46

Elongation

Question 47

(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.

Answer 47

Termination

Question 48

during translation, the tRNA that recognizes the start codon in the mRNA.

Answer 48

Initiator tRNA

Question 49

a set of rules that identify the most favorable types of bases to flank a eukaryotic start codon in an mRNA molecule.

Answer 49

Kozak's Rules

Question 50

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.

Answer 50

Decoding Function

Question 51

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.

Answer 51

Peptidyl Transfer

Question 52

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.

Answer 52

Peptidyl Transferase

Question 53

a protein that recognizes a stop codon and promotes termination of translation and the release of the completed polypeptide.

Answer 53

Release Factor

Question 54

any substance produced by a microorganism that inhibits the growth of other microorganisms, such as pathogenic bacteria.

Answer 54

Antibiotic