Ch. 39 Genetic Code

What are the most important features of the genetic code?
A) It has no redundancy
B) It is non-overlapping
C) It only has stop codons
D) It is not universal
E) It is linear

B) It is non-overlapping.

What is degeneracy and what purpose might it serve?
A) Each amino acid has one codon
B) Multiple codons can specify the same amino acid
C) It only applies to mRNA
D) It is irrelevant to protein synthesis
E) It varies between species

B) Multiple codons can specify the same amino acid.

What general features do all tRNAs have in common?
A) They all have the same anticodon
B) They are all the same length
C) They contain a CCA terminus
D) They only carry one amino acid
E) They do not interact with ribosomes

C) They contain a CCA terminus.

What steps are necessary for the charging of a tRNA with an amino acid?
A) Binding to ribosome
B) Activation of the amino acid
C) Correctly pairing with mRNA
D) Forming peptide bonds
E) Catalyzing reactions

B) Activation of the amino acid.

What part of a tRNA interacts with mRNA?
A) Amino acid attachment site
B) Anticodon loop
C) Dihydrouridine
D) 3' terminus
E) Double sieve

B) Anticodon loop.

Is the genetic code universal?
A) Yes, it is universally the same
B) No, it differs in all organisms
C) Yes, but only in bacterial cells
D) No, only in eukaryotic cells
E) Yes, with minor variations

E) Yes, with minor variations.

What could happen if a mitochondrial protein were translated in the cytosol (or vice versa)?
A) No effect
B) The protein will fold correctly
C) The protein will be mislocalized
D) It will not be synthesized
E) It will be degraded

C) The protein will be mislocalized.

What are the conventions for writing the sequence of tRNA anticodons and mRNA codons?
A) Anticodons are written 5' to 3'
B) Codons are written 3' to 5'
C) Both are written from left to right
D) Only tRNA anticodons have directionality
E) There are no conventions

C) Both are written from left to right.

What is wobble? What bases (at what position in the anticodon) make it possible?
A) A stable pairing
B) Flexible pairing at the first position
C) Flexible pairing at the second position
D) Flexible pairing at the third position
E) Rigid pairing always

D) Flexible pairing at the third position.

What is the energetic cost of activating an amino acid?
A) 0 ATP
B) 1 ATP
C) 2 ATP
D) 3 ATP
E) It does not require energy

B) 1 ATP.

What is the role of pyrophosphate in the charging process?
A) To provide energy
B) To stabilize the tRNA
C) To inhibit the process
D) To bind amino acids
E) To elongate the peptide

A) To provide energy.

How do synthetases recognize the correct amino acid?
A) By size only
B) Using specific active sites
C) By random selection
D) With help from ribosomes
E) By nucleotide sequence

B) Using specific active sites.

How do synthetases recognize the correct tRNA?
A) By its size
B) By its shape and anticodon sequence
C) Randomly
D) Through its amino acid chain
E) By incubation time

B) By its shape and anticodon sequence.

What is the synthetase editing site and how does it work collaboratively with the active site?
A) It corrects errors
B) It only works independently
C) It is inactive
D) It only works with small amino acids
E) It is irrelevant to function

A) It corrects errors.

Why can co-transcriptional translation occur in bacteria?
A) Because of their nucleus
B) Due to simultaneous processes
C) It only occurs in eukaryotes
D) It happens during cell division
E) Bacterial genes are not transcribed

B) Due to simultaneous processes.