Question

1. during translation initiation in eukaryotes, the 43s complex binds to the mrna. what specific structural sequence helps the ribosome distinguish the correct aug start codon from internal aug sequences?

a. the tata box.
b. the aauaaa sequence.
c. the 3 poly(a) tail.
d. the kozak sequence.
e. the exon - junction complex (ejc).

1. if an investigator is trying to determine if a specific gene is active in liver cells but not in muscle cells, the most appropriate method would be to identify all the unique rnas in each cell type. which technique is designed for this specific purpose?

a. dna sequencing
b. gene cloning
c. microarrays (dna chip)
d. proteasome inhibition
e. karyotyping

1. when considering the energetic cost of translation, what is the primary energy requirement used directly to form the peptide bond during elongation?

a. 1 atp used during aminoacyl - trna activation (charging the trna).
b. 1 gtp used during initiation.
c. 1 gtp used during elongation step 1 (eef1a delivery).
d. 1 gtp used during elongation step 3 (eef2 translocation).
e. 1 atp used during the combination of the carboxyl group of one amino acid to the amino group of another.

1. the half - life of mrna varies from minutes to days, while rrnas and trnas have half - lives of days or weeks. what inference can be made about the cellular regulation or function of these rna types based on their stability?

a. mrnas are constantly needed and thus very stable.
b. rrnas and trnas are structural or universal components that gradually accumulate, whereas mrna levels must be rapidly adjustable for changing protein needs.
c. only mrna synthesis requires rnap - ii.
d. rrna processing prevents degradation.
e. the coding segment determines half - life.

1. which of the following rna types is most vital for enabling the overall process of translation by directly carrying amino acids to the ribosome?

a. mrna
b. rrna
c. trna
d. mirna
e. snrna

1. which of the following is a component of ribosomes?

a. dna
b. rna
c. phospholipids
d. protein
e. answers b and d are correct.

Explanation:

1. The Kozak sequence helps the ribosome identify the correct AUG start codon in eukaryotes.
2. Microarrays (DNA chips) are used to identify unique RNAs in different cell - types to study gene activity.
3. 1 ATP is used during aminoacyl - tRNA activation for the energy cost of translation related to peptide bond formation.
4. rRNAs and tRNAs are structural or universal components that accumulate gradually and are stable, while mRNA levels must adjust rapidly for changing protein needs.
5. tRNA directly carries amino acids to the ribosome for translation.
6. Ribosomes are composed of RNA and protein.

Answer:

1. d. The Kozak sequence.
2. c. Microarrays (DNA chip)
3. a. 1 ATP used during aminoacyl - tRNA activation (charging the tRNA).
4. b. rRNAs and tRNAs are structural or universal components that gradually accumulate, whereas mRNA levels must be rapidly adjustable for changing protein needs.
5. c. tRNA
6. e. Answers b and d are correct.