Question

1. in the regulation of ferritin translation, to what element does the irp (iron regulatory protein) bind when iron levels are low? a. 3 utr (untranslated region) b. risc complex c. 5 utr d. promoter region e. intron 07. if the coding region of an mrna is 2,400 nucleotides long, how many codons does it have? a. 600 b. 800 c. 1,200 d. 2,400 e. 7,200 08. which components mimic trnas and recognize stop codons during translation termination? a. termination factors (etfs) b. ribosomal proteins c. release factors d. aminoacyl - trna synthetases e. micrornas (mirnas) 09. in the hershey - chase experiment, what molecule was found to be the carrier of genetic information? a. protein b. rna c. dna d. polysaccharide e. cdna 10. what component of nucleosomes has a positively charged \tail\ at its n - terminus? a. dna b. rna polymerase c. histones d. chromatin - remodeling complexes e. activator proteins 11. in transcription, which base in the newly synthesized rna strand replaces thymine (t) found in dna? a. guanine (g) b. cytosine (c) c. adenine (a) d. uracil (u) e. thymine (t) 12. which of the following types of rna chiefly functions in the processing and chemical modification of ribosomal rnas (rrnas)? a. small nuclear rnas (snrnas) b. small nucleolar rnas (snornas) pre - mrna c. messenger rnas (mrnas) d. transfer rnas (trnas) e. micrornas (mirnas)

Explanation:

• Question 06: When iron levels are low, IRP binds to the 3' UTR of ferritin - mRNA to inhibit translation.
• Question 07: Since each codon is 3 nucleotides long, for a 2400 - nucleotide coding region, the number of codons is $\frac{2400}{3}=800$.
• Question 08: Release factors mimic tRNAs and recognize stop codons during translation termination.
• Question 09: The Hershey - Chase experiment showed that DNA is the carrier of genetic information.
• Question 10: Histones in nucleosomes have positively - charged "tails" at their N - termini which help in DNA - histone interactions.
• Question 11: In transcription, uracil (U) replaces thymine (T) in the newly synthesized RNA strand.
• Question 12: Small nucleolar RNAs (snoRNAs) are mainly involved in the processing and chemical modification of ribosomal RNAs (rRNAs).

Answer:

• 06. a. 3' UTR (Untranslated Region)
• 07. b. 800
• 08. c. Release factors
• 09. c. DNA
• 10. c. Histones
• 11. d. Uracil (U)
• 12. b. Small nucleolar RNAs (snoRNAs)