Which of the following statement(s) is/are false/incorrect? Select all that appl

Question

Which of the following statement(s) is/are false/incorrect? Select all that apply. You may select mutiple options. mRNA sequence downstream of the UGA stop codon is the 5' UTR mRNA cap and poly(A) tail make mRNAs unstable The AAUAAA signal is important for cleavage and polyadenylation of mRNAs in human cells The core enzyme contributes to the specificity of the holoenzyme in bacterial RNA polymerase U1 snRNA basepairs with 5' splice sites in mRNAs Suppressor tRNA can incorporate an amino at a premature mRNA stop codon Alternative splicing allows different genes to make one combined mRNA All amino acids are represented by the same number of codons

Explanation / Answer

mRNA sequence downstream of the UGA stop codon is the 3’ UTR region but not the 5’ UTR region. So, the statement is false. The 5’ mRNA cap and the 3’ poly(A) tail protect the mRNA from degradation and they make mRNAs stable. So, the statement mRNA cap and poly(A) tail make mRNAs unstable is false. Polyadenylation is the process of poly(A) tail addition to the mRNA. During post-transcriptional modifications of pre-mRNA, most part of the3’-end of the newly formed mRNA is cleaved and the resulting RNA is polyadenylated. Cleavage is catalyzed by the enzyme cleavage/polyadenylation specificity factor that recognizes the polyadenylation signal sequence site which in humans is mostly the AAUAAA sequence. So, the statement that the AAUAAA signal is important for cleavage and polyadenylation of mRNAs in human cells is true. The bacterial RNA polymerase has two components – the core enzyme and the sigma factor. Core enzyme together with the sigma factor constitutes the holoenzyme. The core enzyme has 5 subunits and it has catalytic activity. It can transcribe RNA from nonspecific initiation sites. Sigma factor addition to the core enzyme to form the holoenzyme will allow initiation from specific promoter sites. So, the statement that the core enzyme contributes to the specificity of the holoenzyme in bacterial RNA polymerase is false. Newly formed mRNA undergoes post transcriptional modifications and one of the post translational modifications is the splicing of mRNA to remove introns. RNA splicing is carried out by the spliceosome machinery that is made of small nuclear ribonucleoprotein (snRNP). Conserved sequence of U1 snRNA base-pairs with the 5’ splice site of introns in pre-mRNA during RNA splicing. So, the statement U1 snRNA basepairs with 5’ splice sites in mRNAs is true. Suppressor tRNAs are mutant tRNAs in which the anticodon is mutated so that it recognizes the stop codon but instead of terminating the mRNA translation it incorporates an amino acid into the growing polypeptide chain. So, the statement suppressor tRNA can incorporate an amino at a premature mRNA stop codon is true. Alternative splicing is the process of differential splicing of introns, exons, or portions of exons from a pre mRNA transcript resulting in a single gene encoding for multiple proteins. So, the statement that alternative splicing allows different genes to make one combined mRNA is false. Genetic codon is degenerate which means some amino acids are encoded by more than one codon. Some amino acids are encoded by more than one codon and some others are encoded by only one codon. So, the statement that all amino acids are represented by the same number of codons is false. In prokaryotes both transcription and translation are coupled while in eukaryotes transcription and translation are not coupled. In eukaryotes after transcription of RNA in the nucleus, the RNA undergoes post transcriptional modifications before it is translated in the cytoplasm. So, the statement that in eukaryotes, transcription and translation are coupled is false. 5’-UTR region is the mRNA region that is upstream of the initiation codon. So, the statement mRNA sequence upstream of the AUG start codon is the 5’ UTR is true.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.