High School Biology : Understanding Transcription Processes

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #1 : Understanding Transcription Processes

Which of the following describes the process by which RNA polymerase II binds to the promoter of a target gene and recruits transcription machinery?

Possible Answers:

Splicing

Elongation

Termination

Initiation

Correct answer:

Initiation

Explanation:

The first stage of transcription is initiation, in which RNA polymerase II (PolII) engages the promoter and recruits the general transcription machinery. Following initiation, PolII travels down the length of the gene, producing a transcript (elongation). Finally, transcription is terminated, and PolII is removed from the gene. Following transcription, immature heterogeneous RNA (htRNA) can be processed during splicing to become mature messenger RNA (mRNA).

Summary of steps:

Initiation, elongation, termination, splicing

Example Question #1 : Understanding Transcription Processes

An mRNA strand is transcribed from the following template strand on DNA.

5'-CGAATGGCAT-3'

What is the mRNA strand created from this template strand?

Possible Answers:

5'-GCUUACCGUA-3'

5'-AUGCCAUUCG-3'

5'-GCTTACCGTA-3'

5'-ATGCCATTCG-3'

Correct answer:

5'-AUGCCAUUCG-3'

Explanation:

When transcribing from a template strand, the new strand is synthesized in the opposite direction, much like in DNA replication. This will result in antiparallel strands. Also, we need to replace thymine with uracil, because RNA uses uracil in place of thymine.

Template: 5'-CGAATGGCAT-3'

Answer:     5'-AUGCCAUUCG-3'

To see these pairs match up, the 3' end of the answer must align with the 5' end of the template.

Template:       5'-CGAATGGCAT-3'

Answer (3'-5'): 3'-GCUUACCGUA-5'

Example Question #3 : Transcription

What is the function of transfer RNA (tRNA)?

Possible Answers:

To convert the deoxyribose sugar on DNA to ribose to be incorporated into RNA

To bind with proteins and fold into a globular form to make up the ribosome structure

To transfer genetic information from the nucleus to the cytosol of a eukaryotic cell

To bind to specific amino acids and facilitate peptide bond formation

Correct answer:

To bind to specific amino acids and facilitate peptide bond formation

Explanation:

There are several types of RNA, but four main types: messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA), and heteronuclear RNA (htRNA).

Heteronuclear RNA is the direct product of transcription, prior to post-transcriptional modification. htRNA is unable to exit the nucleus until it has undergone RNA splicing to remove introns, addition of the poly-A tail, and addition of the 5' cap. At this point, the htRNA has matured to become functional mRNA.

Messenger RNA is the final transcription product from DNA and used as the template for protein translation. It carries genetic information in the form of codons from the nucleus to the cytosol to create protein chains.

Transfer RNA binds to specific amino acids and helps add them to protein chains during translation. tRNA molecules enter active sites in the ribosome and match an anticodon region to the mRNA template codon before transferring their amino acid cargo to the polypeptide chain.

Ribosomal RNA associates with proteins and is used to form the structure of the ribosomes.

Example Question #2 : Understanding Transcription Processes

Which of the following processes creates messenger RNA from a DNA?

Possible Answers:

Replication

Transcription

Respiration

Translation

Correct answer:

Transcription

Explanation:

The process of forming messenger RNA from a strand of DNA is called transcription. Replication is the creation of new DNA from the original DNA strands. Translation is the creation of a protein chain from the messenger RNA strand using transfer RNA.

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