BIOL 286 Exam I

February 2018

01. Which of the following macromolecules would produce only one type of monomer after complete hydrolysis?

a. DNA

b. Glycogen

c. Polypeptide

d. RNA

e. Triacylglycerol

02. __________ bind(s) to the promoter DNA of a gene.

a. DNA-dependent RNA polymerase

b. The general transcription factor that adds the poly(A) tail

c. TATA binding protein

d. eIF2

e. snRNPs

03. Purines are characterized by _______, while pyrimidines are characterized by __________.

a. two rings; one ring

b. one ring; two rings

c. two rings; three rings

d. two rings; two rings

e. two rings; one chain

04. The phosphate group of a nucleotide is usually attached to the __________-carbon of the sugar.

a. 1'

b. 2'

c. 3'

d. 4'

e. 5’

05. The two strands of the DNA double helix are characterized as being

a. antiparallel.

b. complementary to each other.

c. identical to each other.

d. parallel.

e. Both a and b are correct answers.

06. What gives a DNA molecule its negative charge?

a. deoxyribose

b. ribose

c. phosphate groups

d. chlorine ions

e. adenine

07. What interactions are responsible for holding the nitrogenous bases together stacked one on top of another in the center of a DNA molecule and contribute to the stability of the whole DNA molecule

a. hydrophobic interactions

b. hydrophilic interactions

c. van der Waals interactions

d. H bonds

e. Both a and c are correct answers.

08. The information encoded in DNA resides in

a. phosphates in the backbone.

b. sugars in the backbone.

c. the DNA base sequence.

d. Answers a, b and c are correct.

e. Answers a and b are correct.

09. __________ recognize(s) the stop codons UAG, UAA, and UGA.

a. RNA polymerase

b. DNA polymerase

c. Initiation factors

d. Elongation factors

e. Release factors

10. What is chromatin that remains compacted during interphase called? This compacted, densely stained chromatin is found at the nuclear periphery.

a. granular chromatin

b. euchromatin

c. anabolic chromatin

d. heterochromatin

e. homochromatin

11. Of the following steps associated with translation, which does not involve hydrolysis of GTP

a. release of polypeptide

b. formation of the initiation complex

c. aminoacylation of tRNA

d. translocation of the ribosome

e. binding of the aminoacyl tRNA to codon at the A site

12. An unusual stretch of heterochromatic sequences at the tips of a DNA molecule forming a cap at each end of the chromosome is called a

a. telomere.

b. chromomere.

c. centromere.

d. telophase.

e. karyomere.

13. A site of indentation on the surface of a chromosome to which the mitotic spindle attaches?

a. centromere

b. centrosome

c. centriole

d. telomere

e. telosome

14. What two monosaccharides combine to form. lactose?

a. 2 glucose molecules

b. glucose and galactose

c. galactose and fructose

d. 2 galactose molecules

e. glucose and fructose

15. rRNAs

a. function in an informational storage capacity.

b. are adapted to recognize and bind other molecules.

c. provide structural support.

d. catalyze the chemical reaction that covalently links amino acids.

e. Answers b, c and d are correct.

16. __________ help RNA polymerase recognize promoters.

a. Transcription factors

b. Translation factors

c. Elongation factors

d. Proteases

e. Both a and c are correct answers.

17. Those portions of DNA succeeding (following) the initiation site toward the 5' end of the template are said to be __________that site.

a. to the left of

b. upstream from

c. to the right of

d. downstream from

e. exactly on

18. All three major types of RNA (mRNA, tRNA and rRNA) are processed before they are mature. They are derived from precursor RNA molecules that are considerably longer than the final RNA product. These precursor RNAs are called

a. pre-RNAs.

b. transcription factors.

c. prions.

d. nucleosides.

e. Both a and b are correct answers.

19. Ribosomal DNA (rDNA) clusters are gathered together to form. the

a. nucleus.

b. nucleoid.

c. nucleolus.

d. heterochromatic body.

e. telomere.

20. Modifications to the nucleotides of pre-rRNAs are made

a. post-translationally.

b. pre-transcriptionally.

c. post-transcriptionally.

d. during mitosis.

e. Pre–rRNAs are not modified.

21. Ribosomes are made of

a. proteins.

b. lipids.

c. tRNA.

d. rRNA.

e. Both a and d are correct answers.

22. What enzyme transcribes 5S rRNA?

a. RNA polymerase I

b. RNA polymerase II

c. RNA polymerase III

d. reverse transcriptase

e. RNA-dependent DNA polymerase

23. RNA Polymerase II promoters are located on the __________ side of each transcription unit.

a. 3'

b. 5'

c. N-terminal

d. C-terminal

e. internal

24. The RNA sequence __________ is called the polyadenylation sequence because the poly(A) tail invariably begins about 20 bases downstream from it.

a. AAUAAA

b. AAAAAU

c. AATAAA

d. GACUAU

e. AAAAAAA

25. What is the function of the poly(A) tail on most mRNAs?

a. to hasten degradation of the mRNA

b. to prevent premature degradation of the mRNA by exonucleases

c. to prevent premature degradation of the mRNA by endonucleases

d. to prevent viral infections

e. to decrease the stability of mRNA

26. What is the minimum number of tRNAs that a mammalian cell could have?

a. 20

b. 3

c. 64

d. 61

e. 23

27. The greatest variability (difference) among codons specifying the same amino acid occurs _________.

a. in the first two nucleotides of the triplet

b. in the last two nucleotides of the triplet

c. in the first and third nucleotides of the triplet

d. in the third nucleotide of the triplet

e. There is no variability among codons that specify the same amino acid.

28. What is probably responsible for driving the conformational shift that is required for the release of the eIF2 initiation factor from the initiation complex?

a. ATP hydrolysis

b. GTP hydrolysis

c. binding of eIF1-alpha

d. degradation of eIF2

e. Both b and d are correct answers.

29. What is the result of a nonsense mutation?

a. A change in a single amino acid in the whole polypeptide chain.

b. The addition of extra amino acids onto the end of the polypeptide chain.

c. A completely jumbled sequence of amino acids.

d. A premature termination of the polypeptide chain.

e. The addition of extra amino acids to the N-terminal end of the growing polypeptide chain.

30. Usually, mRNAs containing nonsense mutations are only translated once before being recognized and selectively destroyed. The process whereby the faulty mRNAs are destroyed is called

a. nonsense execution.

b. exon-junction complex.

c. nonsense-mediated decay (NMD).

d. splicing.

e. Answers c and d are correct.

31. A eukaryotic translation complex during the elongation stage is represented by the diagram below. Which of the following labels is NOT correct?

a. (A) is the location of the mRNA cap structure.

b. (B) is the direction of ribosome movement.

c. (C) is the anticodon of the tRNA molecule.

d. (D) is the 5’ end of the tRNA molecule.

e. (E) is the carboxyl–terminus of the growing polypeptide chain.

32. At which level of protein structure are interactions between R groups (amino acid side chains) MOST important?

a. primary

b. secondary

c. tertiary

d. Both a and b are correct answers.

e. Both b and c are correct answers.

33. Which interaction is most important in enhancing the solubility of macromolecules in water?

a. hydrophobic interactions

b. nonpolar covalent bonds

c. H bonds

d. van der Waals forces

e. Both a and b are equally important.

34. A triglyceride is formed when three fatty acids join a glycerol by a

a. hydrolysis reaction.

b. condensation reaction.

c. polymeric reaction.

d. digestive reaction.

e. catabolic reaction.

35. What does the primary structure of a protein refer to?

a. Its overall three-dimensional shape

b. The amino acid sequence of the protein.

c. The location of its α helices and β sheets

d. The peptide bonds that form. the protein’s backbone

e. The structure that forms first as the protein folds into its most compact, stable form.

36. The presence of a poly–(A) tail on a RNA molecule indicates that

a. there are exons present that must be removed.

b. this RNA molecule does not contain introns.

c. the transcript. should be immediately degraded.

d. this is a rRNA molecule.

e. None of the above answers is correct.

37. Which one of the following statements about nucleosomes is FALSE?

a. They are found in euchromatin.

b. They are composed of both proteins and DNA.

c. They are found in heterochromatin.

d. They are found only on mitotic chromosomes.

e. They contain histones.

38. Aminoacyl–tRNA–synthetase

a. catalyzes the formation of hydrogen–bonds between the correct amino acid and the correct tRNA.

b. catalyzes the formation of covalent bonds between the correct amino acid and the correct tRNA.

c. recognizes the tRNA sequences to be removed during tRNA maturation.

d. synthesizes tRNAs that recognize stop codons.

e. None of the above answers is correct.

39. Which parts of amino acids are involved in a peptide bond?

a. The amino group of one amino acid and the carboxyl group of the other.

b. The amino groups of both amino acids

c. The carboxyl group of one amino acid and the side chain of the other

d. The carboxyl groups of both amino acids

e. The side chains of both amino acids

40. The main function of tRNA in cell physiology is to

a. transport amino acids to be used in protein synthesis.

b. carry codons to the ribosomes.

c. synthesize proteins.

d. transcribe the DNA code.

e. form. peptide bonds.

41. The anticodon is part of

a. DNA.

b. tRNA.

c. mRNA

d. ribosomes.

e. rRNA.

42. Since the two strands of the DNA molecule are complementary, for any given gene

a. the RNA polymerase can bind to either strand.

b. only one strand actually carries the genetic code for a particular gene.

c. each gene possesses an exact replica that can be used should a mutation occur.

d. a gene transcribed in the 5’ to 3’ direction on one strand can be transcribed in the 3’ to 5’ direction on the other strand.

e. Both answers a and b are correct.

43. Which of the following is NOT a part of, or an activity carried out by, the ribosome?

a. A site

b. splicing

c. codon recognition

d. peptide bond formation

e. P site

44. Phospholipids are formed from

a. glycerol + carbohydrates + phosphate

b. carbohydrates + phosphate + 2 fatty acids

c. carbohydrates + phosphate + polar head group

d. glycerol + phosphate + polar head group + 2 fatty acids.

e. None of the answers are correct.

45. Adenine forms __________ H–bonds with thymine; guanine forms __________ H–bonds with cytosine.

a. two, two

b. three, three

c. two, three

d. three, two

e. three, no

46. snRNAs ___________________.

a. are translated into snRNPs.

b. are important for producing mature mRNA transcripts in bacteria.

c. are removed by the spliceosome during RNA splicing.

d. can bind to specific sequences at intron–exon boundaries through complementary base-pairing.

e. None of the above are correct answers.

Please refer to the figure below to choose the BEST answer to the following questions

47. In the figure, choose the letter pointing to a (boxed or encircled) gray highlighted area surrounding only a phosphodiester bond.

B

48. In the figure, choose the letter pointing to a (boxed or encircled) gray highlighted area surrounding only a nucleotide base.

C or D

49. In the figure, choose the letter pointing to the 3-prime end of the nucleic acid polymer.

E

50. In the figure, choose the letter pointing to the 5-prime end of the nucleic acid polymer.

A