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Eukaryotic mRNA:
usessnRNPs to cut out introns and seal together translatableexons.
uses a spliceosome mechanism made of DNA to recognizeconsensus sequences to cut and splice.
has a guanine cap on its 39 end and a poly(A) tail on its 59 end.
is composed of adenine, thymine, guanine, and cytosine.
codes the guanine cap and poly(A) tail from the DNAtemplate.
Introduction:
The messenger ribonucleic acid (mRNA) is that type of RNA that transcripts the DNA (deoxyribonucleic acid). RNA polymerase synthesizes a precursor of mRNA (pre-mRNA) in eukaryotes, which is then processed to form mRNA that is in a translatable form. The mRNA attaches to the ribosome where the amino acids bind to form polypeptide chains.
Answer to Problem 1TYK
Correct answer:
The eukaryotic mRNA uses snRNPs to cut out introns and seal together the translatable exons.
Explanation of Solution
Justification for the correct answer:
Option (a) states that the eukaryotic mRNA uses snRNPs to cut out introns and seal together translatable exons. The snRNPs (small nuclear ribonucleoprotein particles) bind to the pre-mRNA to form a complex spliceosome. The spliceosome breaks the pre-mRNA to remove nonprotein coding RNA sequences called introns and joins the coding RNA sequences named exons that can be translated. Hence, option (a) is correct.
Justification for the incorrect answers:
Option (b) states that eukaryotic mRNA uses a spliceosome mechanism made up of the DNA to recognize the consensus sequences to cut and splice. The spliceosome is a complex sequence formed by pre-mRNA and small nuclear ribonucleoprotein particles (snRNPs). The spliceosome breaks the pre-mRNA to remove the nonprotein coding sequences called introns. So, it is an incorrect option.
Option (c) states that the eukaryotic mRNA has a guanine cap on its 3′-end and the poly (A) tail on its 5′-end. The pre-mRNA process includes a capping enzyme that adds a cap at the 5′-end and at the 3′-end. The enzyme poly (A) polymerase adds a chain of adenine nucleotides at the 3′-end and 7-methylguanosine cap is added to the 5′-end of pre-mRNA. Thus, it is an incorrect option.
Option (d) states that the eukaryotic mRNA is composed of adenine, thymine, guanine, and cytosine. In the mRNA, there is uracil in the place of thymine. Both of these are pyrimidines that attach to adenine. So, it is an incorrect option.
Option (e) states that the eukaryotic mRNA codes the guanine cap and the poly (A) tail from the DNA template. This is incorrect because the guanine cap and the poly (A) tail in mRNA is not coded from the DNA template. A capping enzyme adds a cap at the 5′-end and at the 3′-end. The enzyme poly (A) polymerase adds a chain of adenine nucleotides, which makes the poly (A) tail of mRNA. So, it is an incorrect option.
Hence, options, (b), (c), (d), and (e) are incorrect.
Thus, it can be concluded that in the eukaryotes, small nuclear ribonucleoprotein particles (snRNPs) bind to the pre-mRNA to form a complex spliceosome. The spliceosome breaks the pre-mRNA to remove the nonprotein coding sequences called introns and joins the coding RNA sequences called exons, which can be translated.
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Chapter 15 Solutions
Biology: Dynamic Science - With MindTap
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- The fourth codon in an mRNA sequence is GGG, which specifies glycine. If we assume that no amino acids are removed from the polypeptide, which of the following statements is correct? a. The third amino acid from the N-terminus is glycine. b. The fourth amino acid from the N-terminus is glycine. c. The third amino acid from the C-terminus is glycine. d. The fourth amino acid from the C-terminus is glycine.arrow_forwardAll of the following are true about translation EXCEPT _____. as the ribosome moves from codon to codon, amino acids brought by successive tRNAs to the ribosome form a growing polypeptide when the ribosome reaches a stop codon, its subunits detach, and the mRNA and new polypeptide are released RNA polymerase assembles a strand of mRNA complementary to the coding strand of DNA Ribosomal subunits and a tRNA-carrying methionine converge on the start codon of an mRNAarrow_forwardNumber the following steps of protein synthesis in the order in which they occur, starting with 1 and ending with 9.a. _____ The stop codon is reached, and the polypeptide is released.b. _____ The small ribosomal subunit finds the start codon, and the large ribosomal subunit joins.c. _____ The end of the gene is reached, and the pre-mRNA is released and then edited.d. _____ The transcription factor binds the promoter.e. _____ The protein is folded and modified to become functional.f. _____ RNA polymerase builds the mRNA transcript.g. _____ mRNA and initiator tRNA bind the small ribosomal subunit.h. _____ New tRNA molecules are brought into the A site successively, and the peptide chain of the tRNA in the P site is joined to the amino acid of the tRNA in the A site.i. _____ mRNA exits the nucleus via a nuclear pore.arrow_forward
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