High School Biology : Understanding Transcription Processes
Study concepts, example questions & explanations for High School Biology
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Example Questions
Example Question #1 : Rna
Which of the following describes the process by which RNA polymerase II binds to the promoter of a target gene and recruits transcription machinery?
Elongation
Termination
Initiation
Splicing
Initiation
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?
5'-ATGCCATTCG-3'
5'-GCUUACCGUA-3'
5'-GCTTACCGTA-3'
5'-AUGCCAUUCG-3'
5'-AUGCCAUUCG-3'
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 : Understanding Transcription Processes
What is the function of transfer RNA (tRNA)?
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
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 bind to specific amino acids and facilitate peptide bond formation
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 #1 : Rna
Which of the following processes creates messenger RNA from a DNA?
Transcription
Respiration
Replication
Translation
Transcription
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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