30) How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional mRNA?
A) the primary transcript is the same size as the mRNA
the primary transcript is larger than the mRNA
C) the primary transcript is smaller than the mRNA D) both the primary transcript and mRNA contain introns
31) How does the primary transcript in the nucleus of a prokaryotic cell compare to the functional mRNA?
the primary transcript is larger than the mRNA
) the primary transcript is smaller than the mRNA B
) the primary transcript and the mRNA both contain introns C
the primary transcript is the same size as the mRNA
32) A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
A) TTT
B) UUA UUU
D) AAA
33) Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on
specificity in the
A) binding of ribosomes to mRNA
B) binding of the anticodon to small subunit of the ribosome
C) attachment of amino acids to rRNAS
binding of the anticodon to the codon and the attachment of amino acids to tRNAs
34) What would be the consequence of a mutation in a bacterial cell that produces a defective aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNA with the anticodon AAA?
4) None of the proteins in the cell will contain phenylalanine.
The Correct Answer and Explanation is :
Here are the correct answers with explanations for each question:
30) How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional mRNA?
Answer: B) the primary transcript is larger than the mRNA
Explanation:
In eukaryotic cells, the primary transcript, also known as pre-mRNA, is synthesized in the nucleus and includes both exons (coding sequences) and introns (non-coding sequences). After transcription, the pre-mRNA undergoes several processing steps, such as splicing, where introns are removed, and the remaining exons are joined together. Additionally, a 5′ cap is added, and a poly-A tail is added to the 3′ end. The processed version of the mRNA, which is exported from the nucleus to the cytoplasm for translation, is shorter than the primary transcript because it no longer contains introns. Therefore, the primary transcript is larger than the functional mRNA.
31) How does the primary transcript in the nucleus of a prokaryotic cell compare to the functional mRNA?
Answer: C) the primary transcript is the same size as the mRNA
Explanation:
In prokaryotic cells, the primary transcript is essentially the same as the functional mRNA. Prokaryotes do not have introns in their genes, so the mRNA produced from transcription is directly used for translation without needing splicing. Therefore, there is no processing step that would alter the size of the transcript, making the primary transcript the same size as the mRNA.
32) A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is:
Answer: C) UUU
Explanation:
The codon in mRNA is transcribed from the DNA sequence. The codon in this case is AAA, which pairs with the anticodon UUU on the tRNA. This is because RNA uses uracil (U) instead of thymine (T), and tRNA anticodons are complementary to mRNA codons.
33) Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the:
Answer: D) binding of the anticodon to the codon and the attachment of amino acids to tRNAs
Explanation:
The accuracy of translation depends on two main factors: the correct pairing of tRNA anticodons with mRNA codons, and the accurate attachment of the correct amino acid to the tRNA. The anticodon-codon interaction ensures the proper amino acid is added based on the mRNA sequence, while the aminoacyl-tRNA synthetase enzyme ensures the correct amino acid is linked to the appropriate tRNA. Both are essential for ensuring the correct sequence of amino acids in the polypeptide chain.
34) What would be the consequence of a mutation in a bacterial cell that produces a defective aminoacyl-tRNA synthetase that attaches a lysine instead of the normal phenylalanine to tRNA with the anticodon AAA?
Answer: A) None of the proteins in the cell will contain phenylalanine
Explanation:
Aminoacyl-tRNA synthetases are responsible for attaching the correct amino acid to its corresponding tRNA. If a mutation causes a defective synthetase that attaches lysine instead of phenylalanine to the tRNA with the anticodon AAA, this will result in the incorporation of lysine in place of phenylalanine wherever that codon (AAA) is encountered in the mRNA. As a result, proteins that are supposed to contain phenylalanine at positions specified by the codon AAA will instead have lysine. This substitution could affect the structure and function of the protein, but none of the proteins will contain phenylalanine because it is being incorrectly replaced with lysine.