Chapter 30. Protein Synthesis

Question 1

the small subunit of the bacterial 70S ribosome. The 30S subunit is composed of 21 different proteins and a 16S RNA molecule.

Answer 1

30S subunit

Question 2

a member of the G-protein family that delivers aminoacyl-tRNAs to the A site of the ribosome with the concomitant hydrolysis of GTP to GDP.

Answer 2

Elongation factor Tu (EF-Tu)

Question 3

a protein that binds to the GDP-bound form of EF-Tu and induces the release of GDP, thereby enabling EF-Tu to participate in another elongation step.

Answer 3

Elongation factor Ts (EF-Ts)

Question 4

a large ribonucleoprotein assembly that catalyzes the formation of peptide bonds; a molecular machine that coordinates protein synthesis.

Answer 4

Ribosome

Question 5

Nucleotide triplet in mRNA that encodes for a particular amino acid.

Answer 5

Codon

Question 6

a member of the G-protein family that closely resembles the complex between EF-Tu and tRNA. Hydrolysis of GTP by EF-G causes the tRNAs and mRNA to move through the ribosome a distance corresponding to one codon.

Answer 6

Elongation factor G (EF-G) (translocase)

Question 7

the large subunit of the bacterial 70S ribosome. The 50S subunit, the site of peptide bond synthesis, contains 34 different proteins, a 5S RNA species and a 23S RNA species.

Answer 7

50S subunit

Question 8

three-nucleotide sequence of tRNA that base-pairs with the codon in mRNA.

Answer 8

Anticodon

Question 9

an enzyme that activates an amino acid and then links it to transfer RNA. Also known as activating enzymes, aminoacyl-tRNA synthetases are specific for a particular amino acid.

Answer 9

Aminoacyl-tRNA synthetase

Question 10

One of a set of proteins that assist in the association of the ribosome, mRNA, and initiator tRNA to initiate the process of protein synthesis.

Answer 10

Initiation factor

Question 11

one of a set of proteins that recognize stop codons on mRNA at the A site on the ribosome which leads to the release of the completed protein from the tRNA in the P site of the ribosome.

Answer 11

Release factor (RF)

Question 12

Proteins that facilitate the budding of transport vesicles from the endoplasmic reticulum.

Answer 12

Coat proteins

Question 13

A process which aligns the amino acids for peptide bond formation on the ribosome.

Answer 13

accommodation

Question 14

a group of ribosomes bound to an mRNA molecule and simultaneously carrying out translation.

Answer 14

Polysome

Question 15

A region of the large ribosomal subunit that catalyzes peptide-bond formation between the aminoacyl (or peptidyl) tRNA in the P site and the aminoacyl tRNA in the A site.

Answer 15

Peptidyl transferase center

Question 16

the notion that steric freedom in the pairing of the third base of an mRNA codon with the anticodon of a transfer RNA allows more than one codon to be recognized by a particular tRNA molecule.

Answer 16

Wobble hypothesis

Question 17

cellular protein synthesis, so-named because the four-letter alphabet of nucleic acids is translated into the different amino acid alphabet of proteins.

Answer 17

Translation

Question 18

the adapter molecule in protein synthesis. It contains an amino acid recognition site as well as a template-recognition site, or anticodon.

Answer 18

Transfer RNA (tRNA)

Question 19

In messenger RNA, a purine-rich region about 10 nucleotides on the 5’ side of an initiator codon that pairs with the 3’ end of 16S RNA in the 30S ribosomal subunit; helps to determine where translation is initiated on an mRNA molecule.

Answer 19

Shine-Dalgarno sequence

Question 20

A peptidase that resides in the lumen of the endoplasmic reticulum that cleaves signal sequences from nascent polypeptide chains synthesized by endoplasmic reticulum bound ribosomes.

Answer 20

Signal peptidase

Question 21

A ribonucleoprotein particle that recognizes and binds the signal sequence and the ribosome and then shepherds the ribosome and its nascent polypeptide chain to the ER membrane.

Answer 21

Signal-recognition particle (SRP)

Question 22

An integral endoplasmic membrane protein consisting of two subunits, SRa (a GTPase) and SRß that binds the SRP-ribosome complex.

Answer 22

SRP receptor (SR)

Question 23

A sequence of amino acid residues ranging in size from 13 to 36 residues, usually at the amino terminus of the nascent polypeptide chain, that marks the protein for translocation across the rough endoplasmic reticulum.

Answer 23

Signal sequence

Question 24

Membrane-bounded compartments that mediate the transfer of proteins between the endoplasmic reticulum and the Golgi complex, and between the Golgi complex and subsequent destinations.

Answer 24

Transport vesicle

Question 25

A multisubunit assembly of integral and peripheral endoplasmic reticulum membrane proteins that docks with the SRP-ribosome complex and allows insertion of the nascent protein through the endoplasmic membrane.

Answer 25

Translocon

Question 26

An intergral membrane protein that binds to v-SNARE to facilitate the delivery of cargo from transport vesicles.

Answer 26

t-SNARE

Question 27

Integral membrane proteins of transport vesicles that bind to a target membrane proteins called t-SNARE. The binding of the SNARE proteins results in the fusion of the transport vesicle to the target membrane, thereby delivering the cargo of the transport vesicle.

Answer 27

v-SNARE