uiuc mcb 150 practice exam 02 fall 2009

5/22/2018 UIUC MCB 150 Practice Exam 02 Fall 2009

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MCB 150 Practice Exam II, Fall 2009

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1. Which one of the following represents a pair of molecules involved in the full aerobic

respiration of a hexose sugar, from which no more usable energy is likely to be obtained?

A. Glucose and oxygen

B. Pyruvate and ATP

C. NADH and FADH2D. Acetyl CoA and GTP

E. Carbon dioxide and water

2.

An organism's DNA is analyzed and found to contain 28% guanine. What percentage ofthat organism's DNA would be thymine?

A. 72%

B. 56%C. 44%

D. 28%E. 22%

3. True or False: Under identical conditions, the DNA in the organism described in the

previous question would be expected to have a higher Tmthan an organism with 32%

guanine.

A. True

B. False

4. Relative to the DNA it is bound to, approximately how many base pairs doesE. coli RNA

polymerase move during the transition from closed promoter complex to open promoter

complex?

A. 3

B. 10

C. 35

D. 60E. RNA polymerase does not move relative to the DNA during the transition from

closed promoter complex to open promoter complex.


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5. Which one of the following steps in translation initiation requires an input of energy?

A. Hybridization of initiator charged tRNA to mRNA

B. Joining of the large ribosomal subunit to the rest of the initiation complex

C. Binding of translation initiation factors

D. Identification of the correct start signalE. None of the above steps in translation initiation require an input of energy.

6.

The reaction (A)(B) is a normal cellular reaction, coupled to the hydrolysis of two

molecules of ATP in vivo. ATP hydrolysis has a G of 7 kcal/mol. Which one of the

following statements about the reaction (A)(B) is incorrect?

A. The reaction is endergonic.

B. The reaction has a G of greater than 7 kcal/mol.

C. The reaction would most likely proceed if coupled to the hydrolysis of only one ATP.

D. The reaction is biosynthetic.E. All of the above statements about the reaction (A)(B) are correct.

7.

How many replicons are found in theE. colichromosome?

A. 0B. 1

C. 2

D. 3

E. 4

8. Which one of the followingE. coli enzymes is an RNA-dependent, DNA-synthesizing

enzyme?

A. DNA polymerase III

B. RNA polymerase holoenzyme

C. Primase

D. DNA polymerase IE. None of the above enzymes are RNA-dependent, DNA-synthesizing enzymes.


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Use the following figure to answer the next two (2) questions.

9. If the sequence at the region labeled (B) was 5'-GCA-3', then the amino acid labeled on the

right would be:

A. cysteine.B. alanine.

C. threonine.

D. arginine.

E. methionine.

10.

The energy required to add the amino acid to the tRNA molecule comes from ,and the reaction is catalyzed by an enzyme called a(n) .

A. removal of the nucleotide at the 3' end of the tRNA; ribonuclease

B. GTP hydrolysis; aminoacyl tRNA synthetase

C. GTP hydrolysis; elongation factorD. ATP hydrolysis; aminoacyl tRNA synthetase

E. ATP hydrolysis; peptidyl transferase


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11. "Phase 2" of aerobic respiration involves both the conversion of pyruvate into Acetyl CoA

and the Krebs cycle. For every molecule of pyruvate that enters Phase 2, how manymolecules of the two major biological coenzymes are oxidized? [Note: for this question,

ignore what may have preceded Phase 2 or what might occur as a result of Phase 2.]

A. 0B. 4

C. 5

D. 8

E. 10

12.

Which one of the following statements about chromatin organization is incorrect?

A. Although the amino acids in a histone tail do not adopt appreciable secondarystructure, those amino acids play an important role in regulation of chromatin

accessibility.B. Histones are evolutionarily ancient molecules, as evidenced by their conserved

sequences in all three domains.C. Linker DNA between core nucleosomes can be degraded without disrupting the

structure of the core nucleosome itself.

D. The similarity in primary structure of a given histone, when compared among many

species, suggests a strongly negative consequence of significant variation from theestablished sequence.

E. All of the above statements about chromatin organization are correct.

13. Which one of the following molecules would least likely be involved in the production of a

mature human messenger RNA?

A. RNA polymerase IIB. TFIID

C. Poly-A polymerase

D. snRNPs

E. 40S ribosomal subunit


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14. One strand of a section of DNA reads:

5 CTCGATCGGTCAACGTGCCAT 3

What would be the sequence of the polypeptide expressed from this region of DNA if this

strand was used as a template during transcription?

A. Glu-Leu-Ala-Ser-Cys-Thr-ValB. Leu-Asp-Arg-Ser-Thr-Cys-His

C. Met-Ala-Arg

D. Tyr-Arg-Ala-Thr-Gly

E. None of the above polypeptide sequences would be expressed from this templateDNA.

15. When FADH2donates electrons to the electron transport chain, the eventual yield of ATP

is lower than when NADH donates electrons to the electron transport chain. Which one ofthe following statements most accurately explains this observation?

A. The energy released during the transfer of electrons from FADH2is used to move

fewer protons into the mitochondrial intermembrane space, contributing less to theelectrochemical gradient.

B. There is less energy in the electrons donated by FADH2than there is in the electrons

donated by NADH, resulting in fewer protons moved in an equal number ofopportunities.

C. The FADH2is generated in the cytoplasm but releases its electrons in the

mitochondrial matrix, therefore a transport cost is involved that reduces the overall

yield of ATP for each molecule of FADH2involved.D. FADH2is a significantly lower energy molecule than NADH, resulting in a lower

overall G for the electron transport chain and contributing less to the

electrochemical gradient.

E. None of the above statements accurately explain the observation described in the

question.


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The following figure shows anE. coli replication bubble. Arrows with pointed arrowheads

indicate newly synthesized molecules of DNA; arrows with circular arrowheads serve aspointers. Use the figure to answer the next five (5) questions.

16. The region of the strand labeled (A) is the end of that strand.

A. 5'B. 3'

C. N-terminal

D. C-terminal

E. coding

17.

How many primers would have been synthesized in this replication bubble up to this point?

A. 2B. 3

C. 4

D. 6

E. 8

18. Which one of the following molecules is least likely to be found in the region labeled (B) at

this moment? [Note: the letter (B) is not pointing at a specific structure, it is identifying an

area at the edge of the replication bubble.]

A. Helicase

B. DNA polymerase IIIC. DNA ligase

D. Primase

E. Single strand DNA binding proteins


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19. The region labeled (C) would be most accurately referred to as a(n):

A. promoter.

B. Shine-Dalgarno sequence.

C. ribosome binding site.

D. ori.E. splice site.

20.

The fragment of DNA initiated the earliest during this process would be , and

the fragment of DNA initiated most recently would be .

A. (E); (G)

B. (G); (H)

C. (D); (G)D. (E); (F)

E. (D); (E)

21. True or False: Catalytic activity within a snRNP can be found in a ribonucleic acidmolecule.

A. True

B. False

22. It's the year 2012, and the Kepler planet-hunting spacecraft returns with a good candidate

for an Earth-like planet. You lead a subsequent mission to study that planet, and discover asingle-celled life form. Upon closer biochemical inspection, you determine that this

organism has a genome of nucleic acid composed of five different nucleotides.

Furthermore, this organism appears to have intermediate nucleic acid molecules read in

groups of three bases by structures resembling ribosomes. Through additional experiments,you determine that five of these codons specify the termination of protein synthesis. How

many of this organism's codons specify amino acids?

A. 59B. 120

C. 125

D. 130

E. 238


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23. The covalent addition of a phosphate group to adenosine diphosphate, powered by the

kinetic movement of hydrogen ions in an attempt to balance out a concentration gradient, ismost accurately referred to as:

A. polymerization.

B. substrate level phosphorylation.C. oxidative phosphorylation.

D. charging.

E. replication.

24. Which one of the following statements about the initiation of DNA replication inE. coli is

correct?

A. DNA polymerase III requires a primer of a specifically defined length, and will notextend a shorter primer even if the primer is stably attached to a ss-DNA template.

B. DNA polymerase III requires a primer whose bases have ribose, and will not extend aprimer whose bases have deoxyribose even if one were provided in vitro.

C. DNA polymerase III requires an unoccupied hydroxyl group at the 3' end of anexisting nucleic acid molecule from which to extend, and will not initiate a new

strand without that hydroxyl group.

D. (A) and (C)

E. (A), (B) and (C)

25. Consider the following two statements about an allosteric regulator molecule named BM1:

1) BM1 can decrease the activity of one enzyme and increase the activity of anotherenzyme.

2) BM1 can either decrease or increase the activity of a given enzyme depending on

the regulatory needs of the cell.

Determine which one of the statements below is correct.

A. Statement 1) and statement 2) are both true.

B. Statement 1) and statement 2) are both false.

C. Statement 1) is true; statement 2) is false.D. Statement 1) is false; statement 2) is true.


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26. The sequences shown below represent possible sequences to lie upstream of the +1 base of

anE. coli mRNA gene. In each sequence, the underlined base represents the +1 base.From which one of the sequences would you predict the most efficient levels of expression

of that mRNA?

A. GAATATAATGCTCAACGTACGCAGACGTTGACACGTACCGAB. TGCGATCAGACGTACTATTGACAGCGTATAATACGCTAGAA

C. ATTGACACGATATAATGGCTAGCTAGTCAGTTGCATCGAGA

D. CGCTTGTCATCCTGAAGCCGACTCCCTATAATGCGCCTCCA

E. GCCGATCAGTCTTGACATGACACGTTAGCGAGCGTATAATA

27.

The molecule needed to examine the sequences in the previous question looking for an

appropriate signal would most accurately be referred to as:

A. RNA polymerase core enzyme.

B. RNA polymerase holoenzyme.C. RNA polymerase I.

D. RNA polymerase II.E. RNA polymerase III.

28. What is the most likely identity of the molecule labeled (X) in the figure below?

A. E. coliPrimase

B. Human RNA polymerase IIC. E. coli DNA polymerase III

D. E. coli DNA polymerase IE. Human telomerase


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29. You are studying the effects of oxygen deprivation on human muscle tissue. As oxygen is

depleted from your tissue sample, which one of the following observations would you mostlikely make?

A. The amount of ATP produced during glycolysis alone per unit of time will not change

during the course of the experiment.B. As the oxygen level decreases, FADH2levels will rise.

C. As oxygen levels fall, the rate limiting step in glycolysis will become increasingly

regulated by ADP as opposed to ATP.

D. Ethanol will accumulate as a by-product, but will quickly be metabolized andconverted into a product usable by the tissue.

E. Each of the above observations is equally unlikely to be made during this experiment.

30. Order the events of translation from earliest to latest. Assume one round of elongationonly, followed by a stop codon.

a. movement of the ribosome 3 bases closer to 3' end of mRNA

b. successful binding of accessory protein to codon; subunits dissociatec. hybridization of codon and anticodon in the A site

d. appropriate selection of initiator codon

e. peptide bond formation

f. release of amino acid from tRNA in the P site

A. d : f : c : a : e : b

B. d : b : a : c : f : eC. d : c : f : e : a : b

D. b : d : e : f : c : aE. c : d : e : f : a : b

31.

Non-coding DNA that lies within a protein coding gene is most accurately referred to as

a(n) , while non-coding DNA that lies between genes is most accurately

referred to as a(n) .

A. exon; intron

B. intron; spacer

C. promoter; terminator

D. intron; exonE. mRNA; tRNA


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The following figure shows DNA being compacted in a eukaryotic nucleus. Use the figure to

answer the next four (4) questions.

32.

The amount of DNA between the region labeled (A) and the region labeled (B) is most

likely to be approximately:

A. 10 base pairs.

B. 30 base pairs.

C. 146 base pairs.

D. 166 base pairs.E. 200 base pairs.

33.

The diameter of the structure labeled (C) is most likely to be approximately:

A. 10 nm.

B. 30 nm.

C. 146 nm.D. 166 nm.

E. 200 nm.

34. If a region of chromosomal DNA was found in the "zig-zag" form shown in the figure, itwould be referred to as and would most likely be .

A. euchromatin; transcriptionally silent

B. euchromatin; transcriptionally activeC. heterochromatin; transcriptionally silent

D. heterochromatin; transcriptionally active


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35. Which one of the following codons (each given 5'-3' below) would you expect to find with

the highest frequency within the mature mRNA of one of the polypeptide chains within thestructure labeled (C)? Consult the table of amino acid side chains and/or codon table

attached to this exam packet if necessary.

A. UUUB. AAA

C. AUG

D. GAG

E. UGA

36.

As electrons are passed from NADH to the terminal electron acceptor through the electron

transport chain, energy is released. How is this energy directly utilized?

A. The energy release is secondary to the movement of electrons and inconsequential,

and is therefore lost as heat.B. The energy is used to directly phosphorylate a molecule of ADP.

C. The energy is used to ferment two molecules of pyruvate for every molecule ofglucose that entered glycolysis.

D. The energy is used to reduce NAD+into NADH.

E. None of the above describe how the energy released during the electron transport

chain is directly utilized.

37. Which one of the following statements about gene expression is incorrect?

A. A messenger RNA molecule can be translated by multiple ribosomes at a time.

B. Translation of bacterial messenger RNAs does not occur until the 5' cap and poly-A

tail have been added.

C. Simultaneous transcription and translation can occur in bacteria because thoseprocesses occur in the same cellular compartment.

D. Bacteria can produce multiple different proteins from a single messenger RNA.

E. Higher eukaryotes can synthesize different proteins from a single gene by using

different combinations of exons.

38. Which one of the following processes occurs in the nucleus of eukaryotic cells?

A. Poly-A tail additionB. DNA replication

C. Transcription

D. (B) and (C)

E. (A), (B) and (C)


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39. In which one of the following organisms would you expect to find circular molecules of

double-stranded DNA?

A. Eukaryotes

B. Archaea

C. BacteriaD. (B) and (C)

E. (A), (B) and (C)

Use the following figure to answer the next two (2) questions.

40.

Using only the information provided in the figure, you could reasonably deduce that

reaction is endergonic, and reaction is exergonic.

A. 5; 1B. 3; 4

C. 3; 1

D. 1; 3E. 1; 2

41. If product (Y) is a feedback inhibitor of its own production, which step is product (Y) most

likely to inhibit?

A. (1)

B. (2)

C. (3)

D. (4)E. (5)


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42. The energy to power peptide bond formation comes directly from:

A. hydrolysis of a covalent bond between an amino acid and a nucleotide.

B. hydrolysis of ATP into ADP and inorganic phosphate.

C. hydrolysis of GTP into GDP and inorganic phosphate.

D. hydrolysis of ATP into AMP and pyrophosphate.E. Peptide bond formation is exergonic and therefore requires no input of energy.

43.

A messenger RNA is 963 nucleotides long, including the sequences for the initiator and

termination codons, and ignoring the untranslated regions at the 5' and 3' ends. Thenumber of amino acids in the protein made from this mRNA would be:

A. 2889.

B. 963.C. 321.

D. 320.E. 319.

44.

In a typical mitotic chromosome, the number of chromosome arms equals the number of:

A. centromeres.

B. origins of replication.C. telomeres.

D. identical double helices.

E. sister chromatids.

45. One of the enzymes in glycolysis is named phosphohexose isomerase. Which one of the

following would most accurately describe the function of this enzyme?

A. Covalent addition of a phosphate group onto a six carbon sugar

B. Covalent addition of a second phosphate group onto a phosphorylated six carbon

sugar

C. Conversion of a five carbon sugar to a six carbon sugarD. Conversion of one phosphorylated six carbon sugar to a different phosphorylated six

carbon sugar

E. Conversion of one phosphorylated six carbon sugar into two phosphorylated three

carbon sugars


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46. True or False: The reaction catalyzed by the enzyme in the previous question would most

likely occur in the payoff phase of glycolysis.

A. True

B. False

47.

Which one of the following statements about a 50S ribosomal subunit is correct?

A. It consists of multiple proteins and three different pieces of rRNA.

B. It would be found in the cytoplasm of all living cells.C. It recognizes an mRNA molecule via a ribosome binding site (RBS).

D. The site of its assembly would be the nucleolus.

E. These subunits have catalytic activity in the form of RNA molecules.

48. Which one of the following types of molecules would least likely be found in a

spliceosome?

A. Messenger RNAB. Small nuclear RNA

C. Protein

D. Ribosomal RNA

E. All of the above types of molecules are equally likely to be found in a spliceosome.

49. The X-ray diffraction data generated by Franklin and Wilkins directly demonstrated that

DNA:

A. is a double helical molecule.

B. has a uniform width.

C. has the bases stacked on the outside and alternating sugars and phosphates on theinside.

D. (A) and (B)

E. (A), (B) and (C)

50. The protein complexes of the electron transport chain in bacteria are found in the:

A. plasma membrane.B. inner mitochondrial membrane.C. cytoplasm.

D. outer mitochondrial membrane.

E. nucleus.

uiuc mcb 150 practice exam 02 fall 2009

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