Question

1. why are polar molecules often involved in hydrogen bond formation?

a. to fill there outer shell with electrons.
b. they possess partial charges that attract each other, forming hydrogen bonds.
c. they primarily contain c and h atoms.
d. they store chemical energy in their bonds.
e. they are not involved in hydrogen bonds, but hydrophobic forces only.

1. why is the coordination of multiple genes in the same pathway more complex in eukaryotes than in bacteria?

a. bacteria utilize specific transcription factors while eukaryotes only use general ones.
b. in eukaryotes, genes involved in the same pathway are often located on different chromosomes.
c. eukaryotic genes are always repressed (turned off) by default.
d. bacterial genes are typically repressed by default.
e. eukaryotic gene expression is primarily controlled after transcription.

1. the phosphorylation of the c - terminal domain (ctd) of an rnap - ii subunit by tfiih serves what primary function in transcription initiation?

a. it terminates transcription immediately.
b. it promotes the binding of tfiid to the tata box.
c. it releases the polymerase from the promoter site, allowing elongation to begin.
d. it stabilizes the preinitiation complex.
e. it ensures the binding of the 5 cap.

1. how does the addition of a poly(a) tail to the 3 end of an mrna molecule protect it?

a. it ensures proper splicing.
b. it helps initiate translation in the nucleus.
c. it protects the mrna from premature degradation.
d. it forms the lariat intron structure.
e. it attracts the spliceosome complex.

1. how does the non - overlapping nature of the genetic code protect the resulting protein from the effects of small mutations?

a. a mutation in one codon affects many amino acids in the final protein.
b. it allows for frameshift mutations to occur more easily.
c. the mutation is corrected immediately by the aminoacyl - trna synthetase.
d. only mutations in the 5 utr are effective.
e. a mutation in one codon affects only one amino acid in the final protein

1. what is the primary role of the rrna of the large ribosomal subunit during the elongation cycle of translation?

a. it catalyzes the transfer of the amino acid (peptidyl transferase).
b. it selects the aminoacyl - trna for the a site.
c. it provides the energy through gtp hydrolysis.
d. it translocates the ribosome along the mrna.
e. it ensures the fidelity of the reading frame.

1. which of the following is not a normal property of mature eukaryotic mrnas?

a. they contain a continuous nucleotide sequence encoding a specific polypeptide.
b. they contain intron sequences which will be spliced out.
c. they are attached to ribosomes when they are translated.
d. most have a significant noncoding segment that does not direct assembly of amino acids.
e. eukaryotic mrnas have special modifications at their 5 and 3 termini.

Explanation:

• Question 20: Polar molecules have partial charges due to electronegativity differences, which attract each other to form hydrogen bonds.
• Question 21: In eukaryotes, genes in the same pathway are often on different chromosomes, making coordination more complex compared to bacteria.
• Question 22: Phosphorylation of the C - terminal domain of RNAP - II by TFIIH releases the polymerase from the promoter site to start elongation.
• Question 23: The poly(A) tail protects mRNA from premature degradation.
• Question 24: The non - overlapping nature of the genetic code means a mutation in one codon affects only one amino acid in the final protein.
• Question 25: The rRNA of the large ribosomal subunit catalyzes the transfer of the amino acid (peptidyl transferase) during translation elongation.
• Question 26: Mature eukaryotic mRNAs do not contain intron sequences as they are spliced out.

Answer:

• 20. b. They possess partial charges that attract each other, forming hydrogen bonds.
• 21. b. In eukaryotes, genes involved in the same pathway are often located on different chromosomes.
• 22. c. It releases the polymerase from the promoter site, allowing elongation to begin.
• 23. c. It protects the mRNA from premature degradation.
• 24. e. A mutation in one codon affects only one amino acid in the final protein
• 25. a. It catalyzes the transfer of the amino acid (peptidyl transferase).
• 26. b. They contain intron sequences which will be spliced out.