Translation and Regulation Questions and Answers

Q: A system is in a ______ state if there exists a set of transactions such that every transaction in the set is waiting for another transaction in the set.

Correct answer: DeadlockA deadlock is a circle of waiting: each transaction in the set holds a lock another needs and waits for one that another holds, so none can proceed. Nothing resolves itself - the system must detect the cycle and roll one of them back.

Q: Which modified amino acid begins most prokaryotic proteins?

Correct answer: N-formylmethionineBacterial protein synthesis begins with N-formylmethionine: methionine whose amino group carries a formyl group, delivered by a special initiator tRNA. The formyl group is usually removed afterwards, and often the methionine with it. Our immune system recognises formylated peptides as a signature of bacteria, which is why they are potent chemoattractants for neutrophils.

Q: The three stop codons that terminate translation are also known as

Correct answer: nonsense codonsThey are called nonsense codons because they specify no amino acid - no tRNA recognises them. A missense mutation puts the wrong amino acid in; a nonsense mutation creates one of these codons prematurely and truncates the protein.

Q: Which codon acts as the universal initiation codon ?

Correct answer: AUGAUG is the start codon and also codes for methionine, which in bacteria is carried as N-formylmethionine. GUG can serve as an alternative start in some prokaryotic genes, but AUG is the universal one.

Q: The scheme that controls the interaction between executing transactions is called the _____

Correct answer: Concurrency control schemeThe concurrency control scheme governs how concurrent transactions interact - through locking, timestamps or multiversioning. Its purpose is to permit as much concurrency as possible while allowing only schedules that are serialisable.

Q: Catabolite repression of the lac operon is relieved by the binding of ________.

Correct answer: the CAP-cAMP complex to the promoter regionWhen glucose is scarce, cAMP rises and the catabolite activator protein binds it. The CAP-cAMP complex then binds near the promoter and helps recruit RNA polymerase, which is why the operon is fully expressed only when glucose is absent and lactose present.

Q: Translocation of the ribosome along the mRNA is catalysed by ________.

Correct answer: EF-GEF-G, also called translocase, uses GTP hydrolysis to advance the ribosome by exactly one codon, shifting the tRNAs from the A and P sites to the P and E sites. Without it the ribosome would stall after forming each peptide bond.

Q: The “all-or-none” property is commonly referred to as _________

Correct answer: AtomicityAtomicity is the all-or-nothing property: a transaction either completes in full or has no effect at all. If it fails part way through, everything it has done is rolled back - which is what stops money being debited from one account and never credited to the other.

A system is in a ______ state if there exists a set of transactions such that every transaction in the set is waiting for another transaction in the set.

A.Idle
B.Waiting
C.Deadlock
D.Ready

Answer: C

Correct answer: Deadlock

A deadlock is a circle of waiting: each transaction in the set holds a lock another needs and waits for one that another holds, so none can proceed. Nothing resolves itself - the system must detect the cycle and roll one of them back.

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Which modified amino acid begins most prokaryotic proteins?

A.N-formylserine
B.N-formylmethionine
C.N-formylleucine
D.N-formylalanine

Answer: B

Correct answer: N-formylmethionine

Bacterial protein synthesis begins with N-formylmethionine: methionine whose amino group carries a formyl group, delivered by a special initiator tRNA. The formyl group is usually removed afterwards, and often the methionine with it. Our immune system recognises formylated peptides as a signature of bacteria, which is why they are potent chemoattractants for neutrophils.

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The three stop codons that terminate translation are also known as

A.pause codons
B.nonsense codons
C.missense codons
D.antisense codons

Answer: B

Correct answer: nonsense codons

They are called nonsense codons because they specify no amino acid - no tRNA recognises them. A missense mutation puts the wrong amino acid in; a nonsense mutation creates one of these codons prematurely and truncates the protein.

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Which codon acts as the universal initiation codon ?

A.AUG
B.UAA
C.UGA
D.GUG

Answer: D

Correct answer: AUG

AUG is the start codon and also codes for methionine, which in bacteria is carried as N-formylmethionine. GUG can serve as an alternative start in some prokaryotic genes, but AUG is the universal one.

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The ribosome binding site

A.forms a stem-loop structure in the RNA
B.is located upstream of the promoter sequence
C.is located immediately upstream of the start codon
D.is more likely to be associated with an operon than with a gene encoding a single protein

Answer: C

Correct answer: is located immediately upstream of the start codon

The ribosome binding site sits a short distance upstream of the start codon - typically 5 to 10 bases - and that spacing is what positions the initiating AUG in the P site. The promoter is further upstream still, and is where transcription begins rather than translation.

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The scheme that controls the interaction between executing transactions is called the _____

A.Concurrency control scheme
B.Multiprogramming scheme
C.Serialization scheme
D.Schedule scheme

Answer: A

Correct answer: Concurrency control scheme

The concurrency control scheme governs how concurrent transactions interact - through locking, timestamps or multiversioning. Its purpose is to permit as much concurrency as possible while allowing only schedules that are serialisable.

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Catabolite repression of the lac operon is relieved by the binding of ________.

A.the repressor to the operator
B.the CAP-cAMP complex to the promoter region
C.glucose to the permease
D.tryptophan to the leader sequence

Answer: C

Correct answer: the CAP-cAMP complex to the promoter region

When glucose is scarce, cAMP rises and the catabolite activator protein binds it. The CAP-cAMP complex then binds near the promoter and helps recruit RNA polymerase, which is why the operon is fully expressed only when glucose is absent and lactose present.

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Translocation of the ribosome along the mRNA is catalysed by ________.

A.EF-Tu
B.EF-G
C.IF-3
D.RF-1

Answer: A

Correct answer: EF-G

EF-G, also called translocase, uses GTP hydrolysis to advance the ribosome by exactly one codon, shifting the tRNAs from the A and P sites to the P and E sites. Without it the ribosome would stall after forming each peptide bond.

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The “all-or-none” property is commonly referred to as _________

A.Isolation
B.Durability
C.Atomicity
D.None of the mentioned

Answer: C

Correct answer: Atomicity

Atomicity is the all-or-nothing property: a transaction either completes in full or has no effect at all. If it fails part way through, everything it has done is rolled back - which is what stops money being debited from one account and never credited to the other.

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10.

What are the ACID properties of transactions?

A.Atomicity, Consistency, Isolation, Database
B.Atomicity, Consistency, Isolation, Durability
C.Atomicity, Consistency, Inconsistent, Durability
D.Automatically, Concurrency, Isolation, Durability

Answer: B

Correct answer: Atomicity, Consistency, Isolation, Durability

ACID: Atomicity - all or nothing; Consistency - the database moves from one valid state to another; Isolation - concurrent transactions do not see each other’s partial work; Durability - a committed change survives a crash.

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