Having a hard time with these two questions.

Processing of ribosomal RNA (rRNA) includes all of the following EXCEPT:
1. snoRNA-dependent trimming.

2. snoRNA-dependent nucleotide modification.

3. snoRNA-dependent splicing.

4. snoRNA-dependent cleavage.

tRNA molecules:
1. are comprised of the standard four nucleotides.

2. None of the above.

3. have their amino acid ATTACHED covalently at the 5’ end.

4. have a triplet codon that interacts with mRNA.

...don't bother replying if your response is 'idk.'

The answer to your first problem is 'splicing.' My book mentions snoRNA's role in rRNA modification, assembly and cleavage.

tRNA molecules have more than 4 standard nucleotides, the amino acid is attached at the 3' end, and they have anticodons to interact with mRNA. So the correct answer is 'none of the above.'

Hope that helps.

Thank you for the help and explanations, Sam! Very much appreciated.

To determine the correct answers to these questions, we can break down each option and eliminate the incorrect ones.

Question 1:

In the processing of ribosomal RNA (rRNA), we are looking for the exception, i.e., which process is not involved. Let's analyze each option:

1. snoRNA-dependent trimming: This is a known step in rRNA processing, where small nucleolar RNAs (snoRNAs) help remove excess nucleotides from the rRNA transcripts. This process occurs in the nucleolus of the cell.

2. snoRNA-dependent nucleotide modification: This is also a recognized step in rRNA processing. snoRNAs guide the site-specific modification of nucleotides in the rRNA, such as methylation or pseudouridylation.

3. snoRNA-dependent splicing: This is the removal of intervening sequences, called introns, from pre-ribosomal RNA molecules by the action of snoRNAs. Hence, this process is also involved in rRNA processing.

4. snoRNA-dependent cleavage: This option seems plausible but could potentially refer to different stages or types of cleavage involved in rRNA maturation. Without additional information, it is difficult to determine if this step is indeed part of the rRNA processing pathway.

By analyzing the information provided, option 4 (snoRNA-dependent cleavage) appears to be the least likely to be involved in rRNA processing. Therefore, the correct answer would be option 4.

Question 2:

For tRNA molecules, we need to identify the correct statement about their characteristics. Let's examine each option:

1. are comprised of the standard four nucleotides: This statement is true. tRNA molecules are made up of four nucleotides: adenine (A), cytosine (C), guanine (G), and uracil (U).

2. None of the above: This option is not a valid choice. We are looking for the correct statement, so we can eliminate this option.

3. have their amino acid ATTACHED covalently at the 5’ end: This statement is accurate. tRNA molecules have an amino acid attached to the 5' end through a covalent bond, forming an aminoacyl-tRNA.

4. have a triplet codon that interacts with mRNA: This statement is incorrect. The tRNA has an anticodon sequence that interacts specifically with the complementary codon on the mRNA during translation.

Based on the analysis, the correct answer would be option 3 (tRNA molecules have their amino acid attached covalently at the 5' end).