Protein Synthesis Quiz
Questions: 16 · 10 minutes
1. A eukaryotic cell is making a protein that will be secreted outside the cell. Where is its translation typically directed after the signal sequence emerges?
To free ribosomes that remain beside the nucleus
To the interior of a lysosome for immediate processing
To the Golgi apparatus without passing through a membrane
To ribosomes associated with the rough endoplasmic reticulum
2. In a eukaryotic cell, where does transcription of a protein-coding nuclear gene normally occur?
In the nucleus
On ribosomes in the cytoplasm
Inside the Golgi apparatus
In transport vesicles leaving the endoplasmic reticulum
3. What is the usual role of the AUG codon in translation?
It ends translation and releases the completed polypeptide.
It commonly establishes the start of translation and codes for methionine.
It marks an intron for removal from pre-mRNA.
It directs RNA polymerase to a gene's promoter.
4. One nucleotide is inserted near the beginning of a protein-coding sequence. What is the most likely effect if the insertion is not in a multiple of three?
Only the amino acid at the insertion site must change.
The gene will be transcribed in the opposite direction.
The reading frame and many downstream codons may change.
The ribosome will ignore the added nucleotide and preserve every codon.
5. A mutation prevents RNA polymerase and its required factors from binding effectively to a gene's promoter. What is the most direct likely result?
The protein will gain additional amino acids during translation.
The mRNA will be translated from its 3′ end first.
Introns will remain in every other gene's transcript.
Transcription of that gene will decrease or fail to begin.
6. A DNA template segment reads 3′-TAC GGA-5′. Which mRNA segment would be transcribed from it?
3′-AUG CCU-5′
5′-UAC GGA-3′
5′-AUG CCU-3′
5′-ATG CCT-3′
7. A gene's coding DNA strand begins 5′-ATG TTT-3′. Ignoring later RNA processing, what is the corresponding mRNA sequence?
5′-UAC AAA-3′
5′-AUG UUU-3′
3′-AUG UUU-5′
5′-ATG TTT-3′
8. A ribosome reaches a stop codon in the correct reading frame. What normally happens next?
A tRNA carrying a special stop amino acid enters the ribosome.
A release factor promotes termination and release of the polypeptide.
RNA polymerase begins copying the mRNA back into DNA.
The ribosome shifts one nucleotide and continues translation.
9. What is the direct role of RNA polymerase during transcription?
It joins amino acids to form a polypeptide.
It carries a specific amino acid to a ribosome.
It removes introns from a newly made RNA transcript.
It links RNA nucleotides complementary to the DNA template strand.
10. Which statement best describes transcription in protein synthesis?
A ribosome links amino acids using information in mRNA.
DNA polymerase copies an entire chromosome before cell division.
RNA polymerase builds an RNA strand using DNA as a template.
A tRNA molecule converts an amino acid into a nucleotide sequence.
11. A base substitution changes an mRNA codon, but the new codon specifies the same amino acid. How is this mutation classified?
A nonsense mutation
A frameshift mutation
A missense mutation
A silent mutation
12. During translation, in which direction does a ribosome read an mRNA molecule?
From the 3′ end toward the 5′ end
From the amino end toward the carboxyl end
From the 5′ end toward the 3′ end
In either direction, depending on the first tRNA
13. What two functions does a tRNA molecule combine during translation?
It carries a particular amino acid and pairs its anticodon with an mRNA codon.
It copies DNA and transports the resulting gene out of the nucleus.
It removes introns and joins adjacent exons.
It forms the ribosome and catalyzes DNA replication.
14. A eukaryotic pre-mRNA contains introns between protein-coding exons. What normally occurs before the mature mRNA is translated?
The introns are removed and the exons are joined.
The exons are removed and the introns are translated.
Every uracil is replaced with thymine.
The RNA is converted into a second DNA chromosome.
15. A cell needs to make many copies of a protein quickly from one mRNA molecule. Which arrangement directly supports this?
Multiple promoters placed within the mature mRNA
Multiple ribosomes translating the same mRNA at the same time
Several DNA polymerases translating the same gene
A single tRNA carrying an entire chain of amino acids
16. An aminoacyl-tRNA synthetase attaches the wrong amino acid to a tRNA, but that tRNA's anticodon still pairs with its usual mRNA codon. What can happen during translation?
The wrong amino acid may be added even though codon-anticodon pairing is correct.
The mRNA codon will change to match the attached amino acid.
The tRNA anticodon will be rewritten by the ribosome.
The ribosome will necessarily detect the mismatch and stop before adding it.