Which of the following statements about post-transcriptional processing is true?
Possible Answers:A poly-A tail is added to the 5' end of the mature mRNA
Exons are spliced out of hnRNA and are not part of the mature mRNA
Post-transcriptional hnRNA processing prevents RNA from degrading as it leaves the nucleus
A methylguanine cap is added to the 3' end of the mature mRNA
Correct answer:Post-transcriptional hnRNA processing prevents RNA from degrading as it leaves the nucleus
Explanation :The hnRNA (heterogeneous nuclear RNA) produced from transcription must be processed by several enzymes to create an mRNA (messenger RNA) product that can pass from the nucleus to the cytoplasm without degrading. This involves cutting out introns, which remain in the nucleus, and splicing exons together. Furthermore, a methylguanine cap is added to the 5' end and a poly-A tail is added to the 3' end.
Which of the following is not an example of a post-transcriptional modification of mRNA molecules?
Possible Answers:Addition of a poly-A tail
Splicing of anticodons
Addition of a 5-methyl guanosine cap
Splicing of introns
Correct answer:Splicing of anticodons
Explanation :Addition of a 5-methyl guanosine cap, the splicing out and removal of introns, and the addition of a poly-A tail are all processes that are essential to making stable, mature mRNA.
Codons are contained on the exons of mature mRNA and are matched to appropriate anticodons during translation. Anticodons are found on tRNA molecules, and are not involved in mRNA transcription.
Which biotechnology method will allow you to distinguish between identical twins?
Possible Answers:Restriction fragment length polymorphism (RFLP) Analysis
Correct answer: Explanation :Fingerprints are different in all individuals, even identical twins. Due to RNA processing, or post-transcription modification, the grooves of a finger are different even in individuals with identical DNA.
The other techniques are used for DNA analysis between individuals with different DNA. Identical twins will be indistinguishable under these techniques, because their DNA is the same.
Which of the following statements is false concerning post-transcriptional modification?
Possible Answers:Spliceosomes remove exons from the transcript and splice together the introns
Methylation is not part of post-transcriptional modification
A poly A tail is attached to the 3' end of the transcript
A 5' cap is added in order to provide an attachment site for ribosomes during translation
Both the 5' cap and poly A tail protect the transcript from degradation
Correct answer:Spliceosomes remove exons from the transcript and splice together the introns
Explanation :During post-transcriptional modification, spliceosomes can remove introns from the transcript and splice together exons. Introns are the parts that are removed from the transcript, meaning they are not translated. Exons are the portions of mRNA that code for the correct amino acids sequence for the desired gene.
Other modifications involve the poly-A tail, which is added to the 3' end, and the 5' cap. Both structures protect the transcript from damage during transport and provide binding sites for various proteins, as well as the ribosome itself. Methylation is a part of epigenetic DNA modification, and is not involved with transcription processes.
snRNPs assist in what post-transcriptional modification?
Possible Answers:The removal of introns
Exporting the transcript to the ribosome
Addition of the poly-A tail
Addition of the 5' cap
Correct answer:The removal of introns
Explanation :snRNPs, or small nuclear ribonucleoproteins, are an essential part of the spliceosome complex. The spliceosome is responsible for the removal of introns from the primary transcript.
Which of the following is not an example of eukaryotic post-transcriptional modification?
Possible Answers:A methylguanosine cap is added to the 5' end
Exons, or non-coding regions, are removed via splicing
A poly-A tail is added to the 3' end
The 3' end of the growing strand is cleaved
After splicing, the exons are rejoined to form a final mRNA transcript
Correct answer:Exons, or non-coding regions, are removed via splicing
Explanation :Post-transcriptional modifications are changes that are made to the mRNA transcript before it is translated into a protein. The first of these changes is cleavage at the 3' end to separate the new strand, or "primary transcript," from the transcription machinery. Next, a protective 5' cap is added, as is a string of adenine nucleotides at the 3' end. Finally, noncoding regions, called introns, are spliced out and the exons, or coding regions, are reconnected.
The incorrect statement confuses exons and introns.
Which of the following choices is not one of the processes associated with post-transcriptional modification?
Possible Answers: Correct answer: Explanation :Post-transcriptional modification is the stage where the recently synthesized primary RNA transcript undergoes changes to become a mature RNA molecule. Post-transcriptional modifications ensure that the correct RNA transcripts are produced and that the correct proteins are translated. Post-transcriptional modification includes the processes of polyadenylation, 5’ capping, and splicing. Polyadenylation is the addition of adenine bases (the poly-A tail) to the 3’ end of the RNA primary transcript. The poly-A tail is important in export, stability, and translation of the transcript. 5’ capping is the addition of guanine bases to the 5’ end of the primary transcript. The 5’ cap aids in export and translation of the transcript and also protects it from degradation. Splicing is the removal of non-coding regions, or introns, from the primary transcript.
Which of the following choices is not a true characteristic of spliceosomes?
Possible Answers:Most spliceosomes are found in the nucleus
Both prokaryotes and eukaryotes have spliceosomes
They splice introns from primary RNA transcripts
They are composed of small nuclear RNA molecules (snRNAs)
Correct answer:Both prokaryotes and eukaryotes have spliceosomes
Explanation :The spliceosome is a complex structure composed of small nuclear RNA molecules (snRNAs) and other proteins. They are often located in the nucleus. The spliceosome splices introns from the primary RNA transcript. This process occurs through splicing at 5’ and 3’ sites that are identified by particular nucleotide sequences. Prokaryotic cells do not contain spliceosomes.
Which statement correctly describes the process of alternative splicing?
Possible Answers:Alternative splicing can create a variety of proteins from the same primary transcript
There are different methods of alternative splicing (spliceosomes, self-splicing, etc.)
There are different alternative splicing processes between prokaryotes and eukaryotes
In alternative splicing, some primary RNA transcripts are spliced and others are not
Correct answer:Alternative splicing can create a variety of proteins from the same primary transcript
Explanation :Alternative splicing is the process where many different proteins can be formed from a primary transcript. This can be done in a number of ways, including using different splice sites, maintaining introns, and splicing out exons. Alternative splicing is an important process because it increases cellular efficiency; if many proteins can result from the same primary transcript, then the genome doesn’t need to code for as many unique transcripts.
Benedictine College, Bachelor of Science, Biology Teacher Education. University of Illinois at Chicago, Master of Science, Bi.
University of Georgia, Bachelor in Arts, Agricultural Teacher Education. The Southern Baptist Theological Seminary, Master of.
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