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BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

CELL BIOLOGY & CELL

BIOCHEMISTRY FINAL EXAM Latest

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Choose the single best answer

1. Which of the following choices best describes the role of the lysosome?

(a) transport of material to the Golgi

(b) clean-up, recycling, and disposal of macromolecules

(c) sorting of transport vesicles

(d) the storage of excess macromolecules

2. are fairly small organelles that provide a safe place within the cell to carry out certain

biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals

are both generated and broken down in the same location.

(a) Nucleosomes

(b) Lysosomes

(c) Peroxisomes

(d) Endosomes

3. Which of the following monomer building blocks is necessary to assemble selectively

permeable boundaries around and inside cells?

(a) sugars

(b) fatty acids

(c) amino acids

(d) nucleotides

4. DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA

but not true of RNA?

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(a) It contains uracil.

(b) It contains thymine.

(c) It is single-stranded.

(d) It has 5′-to- 3 ′ directionality.

5. Because there are four different monomer building blocks that can be used to assemble RNA

polymers, the number of possible sequence combinations that can be created for an RNA

molecule made of 100 nucleotides is.

(a) 100

4

(b) 4

100

(c) 4 × 100

(d) 100/

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

6. Macromolecules in the cell can often interact transiently as a result of noncovalent interactions.

These weak interactions also produce stable, highly specific interactions between molecules.

Which of the factors below is the most significant in determining whether the interaction will

be transient or stable?

(a) the size of each molecule

(b) the concentration of each molecule

(c) the rate of synthesis

(d) surface complementarity between molecules

7. The first task you are assigned in your summer laboratory job is to prepare a concentrated

NaOH stock solution. The molecular weight of NaOH is 40. How many grams of solid NaOH will

you need to weigh out to obtain a 500 mL solution that has a concentration of 10 M?

(a) 800 g

(b) 200 g

(c) 400 g

(d) 160 g

8. Oxidation is the process by which oxygen atoms are added to a target molecule. Generally, the

atom that is oxidized will experience which of the following with respect to the electrons in its

outer shell?

(a) a net gain

(b) a net loss

(c) no change

(d) an equal sharing

9. The potential energy stored in high- energy bonds is commonly harnessed when the bonds are

split by the addition of in a process called.

(a) ATP, phosphorylation.

(b) water, hydrolysis.

(c) hydroxide, hydration.

(d) acetate, acetylation.

10)

The maximum velocity ( V max

) of an enzymatic reaction is an important piece of information

regarding how the enzyme works. What series of measurements can be taken in order to infer

the maximum velocity of an enzyme- catalyzed reaction?

(a) the rate of substrate consumption after the system reaches equilibrium, for several reactant

concentrations

(b) the rate of product consumption shortly after mixing the enzyme and substrate

(c) the rate of substrate consumption at high levels of enzyme concentration

(d) the rate of substrate consumption shortly after mixing the enzyme and substrate, for several

substrate concentrations

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

11. The synthesis of glutamine from glutamic acid requires the production of an activated

intermediate followed by a condensation step that completes the process. Both amino acids are

shown in the figure below.

In the condensation step, is displaced by.

(a) OH, NH 3

.

(b) ADP, NH 2

.

(c) ATP, NH 3

.

(d) phosphate, NH 3

.

12. Which of the following statements is true?

(a) Peptide bonds are the only covalent bonds that can link together two amino acids in proteins.

(b) The polypeptide backbone is free to rotate about each peptide bond.

(c) Nonpolar amino acids tend to be found in the interior of proteins.

(d) The sequence of the atoms in the polypeptide backbone varies between different proteins.

13. Which of the following is not true of molecular chaperones?

(a) They assist polypeptide folding by helping the folding process follow the most energetically

favorable pathway.

(b) They can isolate proteins from other components of the cells until folding is complete.

(c) They can interact with unfolded polypeptides in a way that changes the final fold of the

protein.

(d) They help streamline the protein-folding process by making it a more efficient and reliable

process inside the cell.

14. Coiled- coils are typically found in proteins that require an elongated structural framework.

Which of the following proteins do you expect to have a coiled- coil domain?

(a) insulin

(b) collagen

(c) myoglobin

(d) porin

15. Which DNA base pair is represented in the figure below?

(a) A-T

(b) T-A

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(c) G-C

(d) C-G

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

16. Energy required by the cell is generated in the form of ATP. ATP is hydrolyzed to power many

of the cellular processes, increasing the pool of ADP. As the relative amount of ADP molecules

increases, they can bind to glycolytic enzymes, which will lead to the production of more ATP.

The best way to describe this mechanism of regulation is.

(a) feedback inhibition.

(b) oxidative phosphorylation.

(c) allosteric activation.

(d) substrate-level phosphorylation.

17. Fred Griffith studied two strains of Streptococcus pneumonia, one that causes a lethal infection

when injected into mice, and a second that is harmless_._ He observed that pathogenic bacteria

that have been killed by heating can no longer cause an infection. But when these heat- killed

bacteria are mixed with live, harmless bacteria, this mixture is capable of infecting and killing a

mouse. What did Griffith conclude from this experiment?

(a) The infectious strain cannot killed by heating.

(b) The heat-killed pathogenic bacteria “transformed” the harmless strain into a lethal one.

(c) The harmless strain somehow revived the heat-killed pathogenic bacteria.

(d) The mice had lost their immunity to infection with S. pneumoniae.

18. The human genome is a diploid genome. However, when germ- line cells produce gametes, these

specialized cells are haploid. What is the total number of chromosomes found in each of the

gametes (egg or sperm) in your body?

(a) 22

(b) 23

(c) 44

(d) 46

19. Which of the following questions would not be answered by using karyotyping?

(a) Is the individual genetically female or male?

(b) Do any of the chromosomes contain pieces that belong to other chromosomes?

(c) Does the individual have an extra chromosome?

(d) Do any chromosomes contain point mutations?

20. Although the chromatin structure of interphase and mitotic chromosomes is very compact,

DNA- binding proteins and protein complexes must be able to gain access to the DNA molecule.

Chromatin- remodeling complexes provide this access by.

(a) recruiting other enzymes.

(b) modifying the N-terminal tails of core histones.

(c) using the energy of ATP hydrolysis to move nucleosomes.

(d) denaturing the DNA by interfering with hydrogen-bonding between base pairs.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

21. The N- terminal tail of histone H3 can be extensively modified, and depending on the number,

location, and combination of these modifications, these changes may promote the formation of

heterochromatin. What is the result of heterochromatin formation?

(a) increase in gene expression

(b) gene silencing

(c) recruitment of remodeling complexes

(d) displacement of histone H

22. You prepare bacterial cell extracts by lysing the cells and removing insoluble debris via

centrifugation. These extracts provide the proteins required for DNA replication. Your DNA

template is a small, double- stranded circular piece of DNA (a plasmid) with a single origin of

replication and a single replication termination site. The termination site is on the opposite side

of the plasmid from the origin.

Which of the following statements is true with respect to this in vitro replication system?

(a) There will be only one leading strand and one lagging strand produced using this template.

(b) The leading and lagging strands compose one half of each newly synthesized DNA strand.

(c) The DNA replication machinery can assemble at multiple places on this plasmid.

(d) One daughter DNA molecule will be slightly shorter than the other.

23. You have discovered an “Exo

–

” mutant form of DNA polymerase in which the 3′- to- 5 ′

exonuclease function has been destroyed but the ability to join nucleotides together is

unchanged. Which of the following properties do you expect the mutant polymerase to have?

(a) It will polymerize in both the 5 ′-to- 3 ′ direction and the 3 ′-to- 5 ′ direction.

(b) It will polymerize more slowly than the normal Exo

polymerase.

(c) It will fall off the template more frequently than the normal Exo

polymerase.

(d) It will be more likely to generate mismatched base pairs.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

24. Which diagram accurately represents the directionality of DNA strands at one side of a

replication fork? D

25. The events listed below are all necessary for homologous recombination to occur properly:

A. Holliday junction cut and ligated

B. strand invasion

C. DNA synthesis

D. DNA ligation

E. double-strand break

F. nucleases create uneven strands

Which of the following is the correct order of events during homologous recombination?

(a) E, B, F, D, C, A

(b) B, E, F, D, C, A

(c) C, E, F, B, D, A

(d) E, F, B, C, D, A

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

26. Consider two genes that are next to each other on a chromosome, as arranged in the figure below.

Which of the following statements is true?

(a) The two genes must be transcribed into RNA using the same strand of DNA.

(b) If gene A is transcribed in a cell, gene B cannot be transcribed.

(c) Gene A and gene B can be transcribed at different rates, producing different amounts of RNA

within the same cell.

(d) If gene A is transcribed in a cell, gene B must be transcribed.

27. The figure below shows a ribose sugar. The part of the ribose sugar where a new ribonucleotide will

attach in an RNA molecule is pointed to by arrow.

(a) 1.

(b) 3.

(c) 4.

(d) 5.

28. Which of the following might decrease the transcription of only one specific gene in a bacterial cell?

(a) a decrease in the amount of sigma factor

(b) a decrease in the amount of RNA polymerase

(c) a mutation that introduced a stop codon into the DNA that precedes the gene’s coding

sequence

(d) a mutation that introduced extensive sequence changes into the DNA that precedes the gene’s

transcription start site

29. You have discovered a gene (Figure A below) that is alternatively spliced to produce several forms of

mRNA in various cell types, three of which are shown in Figure B below. The lines connecting the

exons that are included in the mRNA indicate the splicing. From your experiments, you know that

protein translation begins in exon 1. For all forms of the mRNA, the encoded protein sequence is the

same in the regions of the mRNA that correspond to exons 1 and 10. Exons 2 and 3 are alternative

exons used in different mRNA, as are exons 7 and 8. Which of the following statements about exons

2 and 3 is the most accurate?

(a) Exons 2 and 3 must have the same number of

nucleotides.

(b) Exons 2 and 3 must contain an integral number of

codons (that is, the number of nucleotides divided

by 3 must be an integer).

(c) Exons 2 and 3 must contain a number of nucleotides

that when divided by 3, leaves the same remainder

(that is, 0, 1, or 2).

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(d) Exons 2 and 3 must have different numbers of

nucleotides.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

30. Which of the following molecules is thought to have arisen first during evolution?

(a) protein

(b) DNA

(c) RNA

(d) all came to be at the same time

31. Investigators performed nuclear transplant experiments to determine whether DNA is altered

irreversibly during development. Which of the following statements about these experiments is

true?

(a) Because the donor nucleus is taken from an adult animal, the chromosomes from the nucleus

must undergo recombination with the DNA in the egg for successful development to occur.

(b) The embryo that develops from the nuclear transplant experiment is genetically identical to

the donor of the nucleus.

(c) The meiotic spindle of the egg must interact with the chromosomes of the injected nuclei for

successful nuclear transplantation to occur.

(d) Although nuclear transplantation has been successful in producing embryos in some mammals

with the use of foster mothers, evidence of DNA alterations during differentiation has not

been obtained for plants.

32. Which of the following statements about transcriptional regulators is false?

(a) Transcriptional regulators usually interact with the sugar–phosphate backbone on the outside

of the double helix to determine where to bind on the DNA helix.

(b) Transcriptional regulators will form hydrogen bonds, ionic bonds, and hydrophobic

interactions with DNA.

(c) The DNA-binding motifs of transcriptional regulators usually bind in the major groove of the

DNA helix.

(d) The binding of transcriptional regulators generally does not disrupt the hydrogen bonds that

hold the double helix together.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

Note: Questions 33 to 34 use the following information and the data in the figure below.

You are interested in understanding the gene regulation of Lkp1, a protein that is normally

produced in liver and kidney cells in mice. Interestingly, you find that the LKP1 gene is not

expressed in heart cells. You isolate the DNA upstream of the LKP1 gene, place it upstream of

the gene for green fluorescent protein (GFP), and insert this entire piece of recombinant DNA

into mice. You find GFP expressed in liver and kidney cells but not in heart cells, an expression

pattern similar to the normal expression of the LKP1 gene. Further experiments demonstrate

that there are three regions in the promoter, labeled A, B, and C in the figure below, that

contribute to this expression pattern. Assume that a single and unique transcription factor

binds each site such that protein X binds site A, protein Y binds site B, and protein Z binds site C.

You want to determine which region is responsible for tissue- specific expression, and create

mutations in the promoter to determine the function of each of these regions. In the figure

below, if the site is missing, it is mutated such that it cannot bind its corresponding

transcription factor.

33. Which of the following proteins is likely to act as a gene repressor?

(a) factor X

(b) factor Y

(c) factor Z

(d) none of the above

34. Which of the following proteins are likely to act as gene activators?

(a) factors X and Y

(b) factors X and Z

(c) factors Y and Z

(d) factor X only

35. miRNAs, tRNAs, and rRNAs all.

(a) do not code for proteins.

(b) act in the nucleus.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(c) are packaged with other proteins to form RISC.

(d) form base pairs with mRNA molecules.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

36. Which of the following statements about pseudogenes is false?

(a) Pseudogenes code for microRNAs.

(b) Pseudogenes share significant nucleotide similarity with functional genes.

(c) Pseudogenes are no longer expressed in the cell.

(d) There are estimated to be approximately 20,000 pseudogenes in the human genome.

37. Which of the following statements about homologous genes is true?

(a) For protein-coding genes, homologous genes will show more similarity in their amino acid

sequences than in their nucleotide sequences.

(b) Fewer than 1% of human genes have homologs in the nematode and the fruit fly.

(c) Most homologous genes arose by gene duplication.

(d) A gene in humans that has homologs in plants and prokaryotes will show the same level of

similarity in nucleotide sequence when the human and prokaryotic sequences are compared as

when the human and chimpanzee sequences are compared.

38. Which of the following statements about the human genome is false?

(a) About 50% of the human genome is made up of mobile genetic elements.

(b) More of the human genome comprises intron sequences than exon sequences.

(c) About 1.5% of the human genome codes for exons.

(d) Only the exons are conserved between the genomes of humans and other mammals.

39. You have a piece of circular DNA that can be cut by the restriction nucleases XhoI and SmaI, as

indicated in the figure below.

If you were to cut this circular piece of DNA with both XhoI and SmaI, how many fragments of

DNA would you end up with?

(a) 1

(b) 2

(c) 3

(d) 4

40. A double- stranded DNA molecule can be separated into single strands by heating it to 90°C

because.

(a) heat disrupts the hydrogen bonds holding the sugar–phosphate backbone together.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(b) DNA is negatively charged.

(c) heat disrupts hydrogen-bonding between complementary nucleotides.

(d) DNA is positively charged.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

41. Your friend works at the Centers for Disease Control and Prevention and has discovered a

brand- new virus that has recently been introduced into the human population. She has just

developed a new assay that allows her to detect the virus by using PCR products made from the

blood of infected patients. The assay uses primers in the PCR assay that hybridize to sequences

in the viral genome.

Your friend is distraught because of the result she obtained (see Figure below) when she looked

at PCR products made using the blood of three patients suffering from the viral disease, using

her own blood, and using a leaf from her petunia plant.

You advise your friend not to panic, as you believe she is missing an important control. Which

one of the choices listed below is the best control for clarifying the results of her assay? Explain

your answer.

(a) a PCR assay using blood from a patient who is newly infected but does not yet show

symptoms

(b) a PCR assay using blood from a dog

(c) a PCR assay using blood from an uninfected person

(d) repeating the experiments she has already done with a new tube of polymerase

42. Why are dideoxyribonucleoside triphosphates used during DNA sequencing?

(a) They cannot be incorporated into DNA by DNA polymerase.

(b) They are incorporated into DNA particularly well by DNA polymerases from thermophilic

bacteria.

(c) Incorporation of a dideoxyribonucleoside triphosphate leads to the termination of replication

for that strand.

(d) Dideoxyribonucleoside triphosphates are more stable than deoxyribonucleoside triphosphates.

43. Which type of lipids are the most abundant in the plasma membrane?

(a) phospholipids

(b) glycolipids

(c) sterols

(d) triacylglycerides

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

44. Where does most new membrane synthesis take place in a eukaryotic cell?

(a) at the Golgi apparatus

(b) at the endoplasmic reticulum

(c) at the plasma membrane

(d) in the mitochondria

(e) on ribosomes

45. Consider the apical location of a particular protein expressed in gut epithelial cells, illustrated

in the figure below. Which type of defect described below is the most likely to cause the

redistribution of that protein around the entire cell, shown in the figure below?

(a) a nonfunctional protein glycosylase

(b) the deletion of a junctional protein

(c) the truncation of a protein found in the extracellular matrix

(d) a nonfunctional flippase

46. Which of the following statements about tumor suppressor genes is false?

(a) Gene amplification of a tumor suppressor gene is less dangerous than gene amplification of a

proto-oncogene.

(b) Cells with one functional copy of a tumor suppressor gene will usually proliferate faster than

normal cells.

(c) Inactivation of tumor suppressor genes leads to enhanced cell survival and proliferation.

(d) Individuals with only one functional copy of a tumor suppressor gene are more prone to

cancer than individuals with two functional copies of a tumor suppressor gene.

47. A metastasis is.

(a) a secondary tumor in a different part of the body that arises from a cell from the primary

tumor.

(b) a cell that is dividing in defiance of normal constraints.

(c) a part of the primary tumor that has invaded the surrounding tissue.

(d) the portion of the cancerous tumor that displays genetic instability.

48. The artificial introduction of three key into an adult cell can convert the adult cell

into a cell with the properties of ES cells.

(a) chromosomes

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(b) viruses

(c) hormones

(d) transcription factors

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

49. An individual that arises by reproductive cloning has a nuclear genome that is identical to

.

(a) the female who donated the egg.

(b) the adult who donated the cell for nuclear transplantation.

(c) both the female who donated the egg and the adult who donated the cell for nuclear

transplantation.

(d) the foster mother in which the embryo is placed.

50. How do reproductive cloning and therapeutic cloning differ?

(a) The DNA in the nucleus of cells produced for therapeutic cloning is genetically identical to

the donor genome, whereas in cells produced for reproductive cloning it is not.

(b) Reproductive cloning requires a supply of fertilized donor egg cells, whereas therapeutic

cloning requires unfertilized egg cells.

(c) Therapeutic cloning requires nuclear transplantation, whereas reproductive cloning does not.

(d) Embryos are placed into foster mothers during reproductive cloning but not during therapeutic

cloning.

51. A pluripotent cell.

(a) can only be produced in the laboratory.

(b) can give rise to all the tissues and cell types in the body.

(c) can only give rise to stem cells.

(d) is considered to be terminally differentiated.

52. When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by

a stock of.

(a) proliferating precursor cells.

(b) cells more apically located than the terminally differentiated cells.

(c) Wnt proteins.

(d) induced pluripotent cells.

53. Which type of junction contributes the most to the polarization of epithelial cells?

(a) adherens junctions

(b) desmosomes

(c) tight junctions

(d) gap junctions

54. Tight junctions.

(a) allow small, water-soluble molecules to pass from cell to cell.

(b) interact with the intermediate filaments inside the cell.

(c) are formed from claudins and occludins.

(d) are found in cells in connective tissues.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

55. In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two

three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which

enzyme catalyzes this reaction?

(a) aldolase

(b) phosphoglucose isomerase

(c) enolase

(d) triose phosphate isomerase

56. Pyruvate can be converted into many other molecules by various biosynthetic and metabolic

pathways, which makes it a central hub in the regulation of cellular metabolism. Which of the

following molecules is not made from pyruvate?

(a) oxaloacetate

(b) ethanol

(c) lactate

(d) NADH

57. Because bacteria do not have mitochondria, they cannot produce ATP in a membrane-dependent

fashion.

A. True

B. False

58. After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs

attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic

reticulum to encode?

(a) soluble secreted proteins

(b) ER membrane proteins

(c) plasma membrane proteins

(d) all of the above

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

59. Cells have oligosaccharides displayed on their cell surface that are important for cell–cell recognition.

Your friend discovered a transmembrane glycoprotein, GP1, on a pathogenic yeast cell that is

recognized by human immune cells. He decides to purify large amounts of GP1 by expressing it in

bacteria. To his purified protein he then adds a branched 14 - sugar oligosaccharide to the asparagine

of the only Asn-X-Ser sequence found on GP1 (Figure Q15-48). Unfortunately, immune cells do not

seem to recognize this synthesized glycoprotein. Which of the following statements is a likely

explanation for this problem?

Figure Q15- 48

(a) The oligosaccharide should have been added to the serine instead of the asparagine.

(b) The oligosaccharide should have been added one sugar at a time.

(c) The oligosaccharide needs to be further modified before it is mature.

(d) The oligosaccharide needs a disulfide bond.

60. Which of the following statements about secretion is true?

(a) The membrane of a secretory vesicle will fuse with the plasma membrane when it discharges

its contents to the cell’s exterior.

(b) Vesicles for regulated exocytosis will not bud off the trans Golgi network until the

appropriate signal has been received by the cell.

(c) The signal sequences of proteins destined for constitutive exocytosis ensure their packaging

into the correct vesicles.

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

(d) Proteins destined for constitutive exocytosis aggregate as a result of the acidic pH of the trans

Golgi network

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

61. Figure Q15-57 shows the orientation of the Krt1 protein on the membrane of a Golgi-derived vesicle

that will fuse with the plasma membrane.

Figure Q15- 57

Given this diagram, which of the following statements is true?

(a) When this vesicle fuses with the plasma membrane, the entire Krt1 protein will be secreted

into the extracellular space.

(b) When this vesicle fuses with the plasma membrane, the C-terminus of Krt1 will be inserted

into the plasma membrane.

(c) When this vesicle fuses with the plasma membrane, the N-terminus of Krt1 will be in the

extracellular space.

(d) When this vesicle fuses with the plasma membrane, the N-terminus of Krt1 will be

cytoplasmic.

62. Transporters, in contrast to channels, work by.

(a) specific binding to solutes.

(b) a gating mechanism.

(c) filtering solutes by charge.

(d) filtering solutes by size.

63. CO

2

and H 2

O are generated during the oxidation of food molecules.

A. True

B. False

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

64. Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the

following descriptions best matches the function of a mutase?

(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.

(b) An enzyme that catalyzes a change in the position of a specific chemical group within a single

molecule.

(c) An enzyme that catalyzes the oxidation of a molecule by removing a hydride ion.

(d) An enzyme that catalyzes the addition of phosphate groups to other molecules.

65. Several different classes of enzymes are needed for the catabolism of carbohydrates. Which of the

following descriptions best matches the function of a kinase?

(a) An enzyme that catalyzes the rearrangement of bonds within a single molecule.

(b) An enzyme that catalyzes a change in the position of a specific chemical group within a single

molecule.

(c) An enzyme that catalyzes the oxidation of a molecule by removing a hydride ion.

(d) An enzyme that catalyzes the addition of phosphate groups to other molecules.

66. The reaction cycle that uses acetyl CoA to generate electron carrier molecules needed in the electron-

transport chain is important for powering the cell. Which of the names below is not one of those

commonly used to describe this reaction cycle?

(a) tricarboxylic acid cycle

(b) Krebs cycle

(c) oxaloacetic acid cycle

(d) citric acid cycle

67. In step 4 of the citric acid cycle, the reduction of NAD

to NADH is coupled to the generation of CO 2

and the formation of a high-energy thioester bond. The energy of the thioester bond is harnessed in

step 5. What is the energy used for?

(a) to generate a molecule of GTP

(b) to generate a molecule of ATP

(c) to generate a proton gradient

(d) to generate a molecule of NADH

BIOL 4354 Cell Biology/Cell Exam/Biochemistry: Final Exam Latest Update

68. Which of the following statements about G-protein-coupled receptors (GPCRs) is false?

(a) GPCRs are the largest family of cell-surface receptors in humans.

(b) GPCRs are used in endocrine, paracrine, and neuronal signaling.

(c) GPCRs are found in yeast, mice, and humans.

(d) The different classes of GPCR ligands (proteins, amino acid derivatives, or fatty acids) bind to

receptors with different numbers of transmembrane domains.

69. At desmosomes, cadherin molecules are connected to.

(a) actin filaments.

(b) intermediate filaments.

(c) microtubules.

(d) gap junctions.

70. The growth factor RGF stimulates proliferation of cultured rat cells. The receptor that binds RGF is a

receptor tyrosine kinase called RGFR. Which of the following types of alteration would be most

likely to prevent receptor dimerization?

(a) a mutation that increases the affinity of RGFR for RGF

(b) a mutation that prevents RGFR from binding to RGF

(c) changing the tyrosines that are normally phosphorylated on RGFR dimerization to alanines

(d) changing the tyrosines that are normally phosphorylated on RGFR dimerization to glutamic

acid

71. Covalent bonds between protein monomers hold together cytoskeletal (all three) filaments.

A. True

B. False

72. Cadherins.

(a) are used to transfer proteins from one cell to another.

(b) mediate cell–cell attachments through homophilic interactions.

(c) are abundant in the plant cell wall.

(d) bind to collagen fibrils.