High School Biology : Understanding Translation Processes

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Proteins

Which of the following statements about the genetic code is true?

Possible Answers:

An amino acid can only have one codon that codes for it

The genetic code has different rules between different species

The codon found on mRNA is an exact match for the anticodon found on the tRNA

A codon will only code for one amino acid

Correct answer:

A codon will only code for one amino acid

Explanation:

The genetic code is considered both degenerative and unambiguous. A codon will only code for one amino acid, making the code unambiguous. In contrast, multiple codons can code for the same amino acid, making it degenerative. For example, UGU will always code for cysteine, but UGC also codes for cysteine.

Nearly every living organism uses the same genetic code. tRNA anticodons are complementary to mRNA codons; they are not the same code.

Example Question #2 : Proteins

During protein elongation, what site in the ribosome do tRNA molecules enter?

Possible Answers:

The P site

The A site

The R site

The E site

Correct answer:

The A site

Explanation:

As amino acids are added to a polypeptide during translation, tRNA molecules will enter the A site of the ribosome. The tRNA is then transferred to the P site, where a peptide bond is formed between the amino acid residue and the amino acid chain. Finally, the tRNA moves to the E site to release its tRNA and exit the ribosome.

Example Question #3 : Proteins

How many sites are there on the ribosome to house tRNA?

Possible Answers:

One

Four

Five

Two

Three

Correct answer:

Three

Explanation:

The ribosome contains three sites: the A, P, and E sites.

The A site is where activation occurs, starting translation. This is where a tRNA molecule enters the ribosome and matches its anticodon to the mRNA codon.

The tRNA then shifts over to the P site to attach the amino acid. The ribosome facilitates the formation of a peptide bond, adding the amino acid to the chain.

At the E site, the empty tRNA exits the ribosome and dissociates from mRNA.

Example Question #4 : Proteins

Which of the following accurately illustrates the central dogma of biochemistry?

Possible Answers:

DNA is transcribed into RNA, which is translated into protein 

RNA is translated into DNA, which is transcribed into protein

Protein is transcribed into RNA, which is translated into DNA

DNA is translated into RNA, which is transcribed into protein

Protein is translated into RNA, which is transcribed into DNA

Correct answer:

DNA is transcribed into RNA, which is translated into protein 

Explanation:

DNA contains genetic information that is transcribed into mRNA. This process is known as transcription, and occurs in the nucleus. After modification in the nucleus, mRNA exits the nucleus and enters the cell cytoplasm. In a process called translation, mRNA (in conjuction with tRNA and a ribosome) is used as a template to join amino acids to form specific polypeptides.

In summary, DNA is transcribed into RNA, which is translated into protein.

Example Question #5 : Proteins

What ribosomal site does the first amino acid occupy during the initiation of translation?

Possible Answers:

A site

P site

E site

B site

Correct answer:

P site

Explanation:

During initiation, the first tRNA molecule will bring the first amino acid to the ribosome. Although the following amino acids will enter at the A site, the first amino acid is positioned in the middle P site. The large ribosomal subunit will then attach, and translation can begin.

During the subsequent elongation phase of translation, tRNA/amino acid complexes will enter the ribosome at the A site, transfer to the P site, and then exit through the E site. Only the first complex will begin in the P site, during initiation.

Example Question #6 : Proteins

If a mature mRNA strand consists of 90 nucleotides, how many amino acids does the newly-translated the protein contain?

Possible Answers:

None of these answers

Correct answer:

Explanation:

While one might quickly calculate that 90 nucleotides/3 would yield a 30 amino acid sequence, it is important to remember that while the first 3 nucleotides will encode for an amino acid to start translation (methionine), the last 3 nucleotides do not. They simply stop translation and signal for the growing polypeptide chain to be released from the ribosome-tRNA translation complex without actually adding another amino acid to the end of the chain.

Example Question #7 : Proteins

The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome.  

Which of the following represents the start codon.  

Possible Answers:

5' AUG 3' 

5' UAA 3'

5' UAG 3'

5' UGA 3'

5' CAU 3'

Correct answer:

5' AUG 3' 

Explanation:

The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes, and a modified methionine (f-Met) in prokaryotes. The most common start codon is 5' AUG 3'. The start codon is preceded by a untranslated region which includes the ribosome binding site in prokaryotes. 

5' UAA 3', 5' UGA 3', 5' UAG 3' are all stop codons.  

Example Question #8 : Proteins

The process of creating a protein from mRNA is known as __________.

Possible Answers:

extraction

translation

modification

transcription

Correct answer:

translation

Explanation:

Translation refers to the processing of an mRNA script into a protein. This process utilizes ribosomes and tRNA. In translation, messenger RNA (which is produced by transcription from DNA) is decoded by a ribosome to produce a specific amino acid chain, or polypeptide. The polypeptide is later folded into an active protein.

Example Question #9 : Proteins

Which of the following is not a phase of translation?

Possible Answers:

Elongation

Termination

Initiation

Modification

Correct answer:

Modification

Explanation:

Translation is the process of creating protein from an mRNA template, and consists of initiation, elongation, and termination. Modification of protein strands may occur after translation, but the three defined steps of translation are initiation, elongation, and termination. Many types of transcribed RNA, such as tRNA, rRNA (ribosomal), and small nuclear RNA, do not undergo translation in order to become functional proteins.

Example Question #10 : Proteins

Which of the following best describes the process of translation?

Possible Answers:

DNA to mRNA

mRNA to protein 

DNA to rRNA

DNA to protein

Correct answer:

mRNA to protein 

Explanation:

Protein synthesis starts in the nucleus with transcription. Transcription is the process where DNA is transcribed into mRNA. Translation occurs in the cytoplasm within ribosomes where mRNA is translated and becomes a protein with the help of rRNA and tRNA.

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