Chapter 30 Flashcards
During translation, the mRNA is read in the _____ direction and protein synthesized in the _____ direction.
5′-to-3′; amino-to-carboxyl
During attachment of an amino acid to its tRNA, how is ATP required?
The ATP forms an amino acyl adenylate that transfers the activated amino acid to the tRNA.
The codon AUG specifies either initiation of protein synthesis or an internal methionine. What would be the sequence of the anticodon of a tRNA that binds to this codon?
5-CAU-3
During ribosomal protein synthesis, the growing peptide chain
is transferred from the tRNA in the P site to the amino acyl tRNA in the A site.
During protein synthesis, which of the following is NOT an energy-requiring step
formation of the peptide bond
Termination of protein synthesis occurs when a stop or termination codon is in the A site. This occurs because
these codons are recognized by specific proteins which also release the newly synthesized protein chain from the ribosome.
Puromycin is an antibiotic that functions by inhibiting protein synthesis. It does this by
causing premature release of protein chains being synthesized.
Where does wobble occur in the tRNA-mRNA recognition?
5´ base of the anticodon
Which of the following would be effective at blocking translation of a specific mRNA while allowing other mRNA molecules to undergo translation?
antisense mRNA
Which of the following provides the energy for the cotranslational movement of proteins across the endoplasmic reticulum?
peptide bond formation powered by hydrolysis of aminoacyl-tRNAs
What sequence allows bacterial ribosomes to identify the correct AUG start codon?
Shine-Dalgarno sequence
Which of the following details how SRP allows proteins to be transported into the ER?
SRP binds the peptide signal sequence and inhibits further translation until it interacts with its receptor.
Amino acids are attached to tRNA at the _____ end following the _____ sequence of the acceptor stem.
3’; CCA
If the anticodon of a tRNA molecule is 3’-AGU-5’, what is the matching codon?
UCA
Fidelity of protein synthesis is increased because:
They do not form double-helical regions.
Which of the following is NOT found in a eukaryotic ribosome?
DNA duplexes
Which of the following is a common characteristic of a protein enzyme and catalytic RNA
catalytic groups oriented in a specific manner within the molecule
defined secondary structure
defined tertiary structure
specific interactions between the monomers that comprise the macromolecule
When a bacterial ribosome has formed the final “initiation complex,” which of the following has occurred?
The 30S and 50S subunits have combined to form the 70S ribosome.
The mRNA from a prokaryote contains this purine-rich region that precedes the initiating codon and base-pairs with complementary nucleotides in the ribosomal RNA.
the Shine–Dalgarno sequence
What is a polyribosome?
a group of ribosomes bound to a single mRNA
How does the drug puromycin work to inhibit protein synthesis?
It resembles an aminoacyl-tRNA, enters the A site and becomes covalently attached to the growing peptide, thus terminating translation.
Which of the following antibiotics acts by inhibiting peptidyl transferase activity of the 50S ribosomal subunit
chloramphenicol
Which of the following is TRUE of puromycin
Proteins synthesized in the presence of puromycin would be covalently modified on their C-termini.
The antibiotic _____ inhibits prokaryotic ribosomes but not eukaryotic ribosomes by exploiting the fact that _____
streptomycin; prokaryotic initiation depends on formylmethionyl-tRNA binding
Which of the following binds the A site of the ribosome as part of its action?
puromycin
Diphtheria toxin blocks protein synthesis by
inhibiting translocation.
Proteins destined for excretion from the cell are ultimately synthesized on ribosomes located
on the rough endoplasmic reticulum
Signal sequences on nascent proteins are recognized and bound by the _____ in the cytoplasm, which directs the translating ribosome to the ER.
signal recognition particle
During the synthesis of a secretory protein, the _____ subunit of the ribosome interacts with the _____.
60S; translocon
mRNA encoding a lysosomal protease will contain codons for a stretch of _____ amino acids located _____ of the start codon.
hydrophobic; 3’
