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Molec Cell > Test 3A > Flashcards

Test 3A Flashcards

1
Q
  1. Which of the following is most true of mitochondria?
    a. They produce most of the ATP derived from the breakdown of carbohydrates and fatty acid
    b. They produce most of the ATP derived from the breakdown of carbohydrates
    c. They produce about half of the ATP derived from the breakdown of carbohydrates
    d. They produce about 10% of the ATP derived from the breakdown of carbohydrates
A

a. They produce most of the ATP derived from the breakdown of carbohydrates and fatty acid

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2
Q
  1. Actin exists in cells in two major forms called
    a. Monomers and dimers
    b. A-actin and B-actin
    c. G actin and D actin
    d. G actin and F actin
    e. Actin 1 and actin 2
A

d. G actin and F actin

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3
Q
  1. Each monomer of actin binds one molecule of the nucleotide triphosphate
    a. ATP
    b. GTP
    c. CTP
    d. UTP
A

a. ATP

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4
Q
  1. Which nucleotide triphosphate is hydrolyzed during a cycle of microtubule assembly and disassembly?
    a. ATP
    b. TTP
    c. CTP
    d. GTP
A

d. GTP

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5
Q
  1. Mitochondrial and chloroplast proteins are synthesized on
    a. ER ribosomes
    b. free cytosolic ribosomes
    c. organellar ribosomes
    d. Both b and c
A

b. free cytosolic ribosomes

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6
Q
  1. Which of the following contain their own genomes?
    a. Mitochondria, but not chloroplasts and peroxisomes
    b. Chloroplasts, but not mitochondria and peroxisomes
    c. Mitochondria and chloroplasts, but not peroxisomes
    d. Mitochondria, chloroplasts, and peroxisomes
A

c. Mitochondria and chloroplasts, but not peroxisomes

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7
Q
  1. The infoldings of the inner mitochondrial membrane are called
    a. Cisternae
    b. Cristae
    c. Laminae
    d. lacunae.
A

b. Cristae

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8
Q
  1. The inner compartment of mitochondria is called the
    a. Stroma
    b. intermembrane space
    c. inner membrane space
    d. matrix.
A

d. matrix.

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9
Q
  1. What product of glycolysis is transported into the mitochondria?
    a. Acetate as acetyl CoA
    b. Pyruvate
    c. Ethanol
    d. Lactic acid
A

b. Pyruvate

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10
Q
  1. The citric acid cycle consists of the incorporation of _______ and its oxidation to produce _______.
    a. pyruvate; CO2, NADH, and FADH2
    b. acetate from acetyl CoA; CO2, NADH, and FADH2
    c. pyruvate; CO2
    d. acetate; CO2
A

b. acetate from acetyl CoA; CO2, NADH, and FADH2

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11
Q
  1. Most small molecules are permeable across
    a. both mitochondrial membranes
    b. the inner, but not the outer, mitochondrial membrane
    c. the outer, but not the inner, mitochondrial membrane
    d. neither mitochondrial membrane.
A

c. the outer, but not the inner, mitochondrial membrane

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12
Q
  1. The outer mitochondrial membrane contains
    a. a lower concentration of proteins than the inner membrane
    b. an active transporter for pyruvate
    c. proton transporters
    d. an active transporter for ATP.
A

a. a lower concentration of proteins than the inner membrane

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13
Q
  1. Mitochondria contain
    a. no genes of their own
    b. genes for mitochondrial proteins
    c. genes for mitochondrial proteins and rRNAs
    d. genes for mitochondrial proteins, rRNAs, and tRNAs.
A

d. genes for mitochondrial proteins, rRNAs, and tRNAs.

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14
Q
  1. The mitochondrial outer membrane contains a channel composed of the protein
    a. Claudin
    b. Porin
    c. Channelin
    d. connexin.
A

b. Porin

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15
Q
  1. The inner mitochondrial membrane contains proteins that
    a. synthesize ATP
    b. pump protons
    c. transport pyruvate and fatty acids
    d. All of the above
A

d. All of the above

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16
Q
  1. The process by which mitochondria are thought to have arisen during evolution is called
    a. Symbiosis
    b. Phagocytosis
    c. Endosymbiosis
    d. autophagocytosis
A

c. Endosymbiosis

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17
Q
  1. The mitochondrial genomes usually consist of
    a. a single linear DNA molecule
    b. several linear DNA molecules
    c. circular DNA molecules
    d. None of the above—mitochondria do not have a genome.
A

c. circular DNA molecules

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18
Q
  1. The organisms most similar to mitochondria are
    a. Progenotes
    b. α-proteobacteria
    c. cyanobacteria
    d. purple sulfur bacteria.
A

b. α-proteobacteria

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19
Q
  1. Mitochondrial DNA is inherited by means of
    a. Mendelian genetics
    b. random assortment
    c. paternal transmission
    d. maternal transmission.
A

d. maternal transmission.

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20
Q
  1. In what way does the mitochondrial genetic code differ from the “universal” genetic code?
    a. Some codons code for different amino acids
    b. Some codons code for different stop codons
    c. The wobble rules are different
    d. All of the above
A

d. All of the above

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21
Q
  1. Which of the following is a mitochondrial disease?
    a. Lou Gehrig’s disease
    b. Leber’s hereditary optic neuropathy
    c. Crohn’s disease
    d. I-cell disease
A

b. Leber’s hereditary optic neuropathy

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22
Q
  1. Most mitochondrial proteins are synthesized on
    a. mitochondrial ribosomes from nuclear mRNAs
    b. cytoplasmic ribosomes; they are imported cotranslationally as they are being synthesized
    c. cytoplasmic ribosomes; they are imported after they are completely synthesized
    d. mitochondrial ribosomes from mitochondrial mRNAs.
A

c. cytoplasmic ribosomes; they are imported after they are completely synthesized

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23
Q
  1. Mitochondrial targeting presequences usually consist of a
    a. hydrophobic α helix
    b. hydrophobic random chain
    c. negatively charged α helix
    d. positively charged α helix.
A

d. positively charged α helix.

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24
Q
  1. Where are most mitochondrial phospholipids synthesized?
    a. Mitochondrial inner membrane
    b. Mitochondrial matrix
    c. ER
    d. Golgi apparatus
A

c. ER

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25
Q
  1. Import of mitochondrial proteins from the cytoplasm requires
    a. ATP
    b. a proton electrochemical gradient across the inner membrane
    c. a potassium electrochemical gradient across the inner membrane
    d. ATP and a proton gradient across the inner membrane.
A

b. a proton electrochemical gradient across the inner membrane

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26
Q
  1. The proteins encoded by the human mitochondrial genome function in
    a. mitochondrial ribosomes
    b. mitochondrial DNA polymerases
    c. respiratory complexes and oxidative phosphorylation
    d. Both a and c
A

a. mitochondrial ribosomes

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27
Q
  1. Tim and Tom are
    a. twin brothers with the same mitochondrial disease
    b. chaperones
    c. protein translocators in mitochondrial membranes
    d. pores in the outer mitochondrial membrane.
A

c. protein translocators in mitochondrial membranes

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28
Q
  1. The mitochondrial protein presequence is cleaved off by a protease called
    a. signal peptidase
    b. presequence protease
    c. ubiquitin-targeted protease
    d. matrix-processing protease.
A

d. matrix-processing protease.

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29
Q
  1. Mitochondrial inner membrane transmembrane proteins are inserted into the inner membrane
    a. directly from the matrix into the lipid bilayer
    b. through Tim
    c. through Tim and Tom
    d. through a transporter called Oxa1.
A

b. through Tim

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30
Q
  1. The free energy transferred by two electrons from NADH to O2 through the electron transport chain is _______ kcal/mol
    a. +52.5
    b. –52.5
    c. +7.5
    d. –7.5
A

b. –52.5

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31
Q
  1. When the electrons from reduced cofactors are transferred to oxygen in mitochondria, the process is coupled to the formation of _______ molecules of ATP
    a. 2
    b. 10–12
    c. 22–24
    d. 32–34
A

d. 32–34

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32
Q
  1. Electron transport and oxidative phosphorylation are performed by protein complexes in the mitochondrial
    a. outer membrane
    b. intermembrane space
    c. inner membrane
    d. matrix.
A

c. inner membrane

33
Q
    1. Coenzyme Q carries electrons from complex _______ to complex _______.
      a. I; II
      b. II; III
      c. I; III
      d. III; IV
A

a. I; II

34
Q
  1. Peter Mitchell received the Nobel Prize in 1978 for his revolutionary hypothesis of oxidative phosphorylation called the _______ hypothesis
    a. Chemiosmotic
    b. substrate-level phosphorylation
    c. ATP synthase
    d. endosymbiotic
A

a. Chemiosmotic

35
Q
  1. Chloroplasts differ from mitochondria in that chloroplasts
    a. do not generate ATP
    b. did not originate by endosymbiosis.
    c. do not replicate by division
    d. synthesize their own amino acids and fatty acids.
A

d. synthesize their own amino acids and fatty acids.

36
Q
  1. Chloroplasts are similar to mitochondria in that both
    a. have a porous outer membrane
    b. generate ATP by a chemiosmotic mechanism across the inner membrane
    c. require specific transporters across the inner membrane
    d. All of the above
    e. Both a and c
A

a. have a porous outer membrane

37
Q
  1. Carotenoids are stored in
    a. Chloroplasts
    b. Chromoplasts
    c. Amyloplasts
    d. carotoplasts.
A

b. Chromoplasts

38
Q
  1. Thylakoids are often arranged in stacks called
    a. Dictyosomes
    b. Quanta
    c. Grana
    d. plastids
A

c. Grana

39
Q
  1. The chloroplast genome contains
    a. about 20 genes
    b. about 150 genes
    c. about 1500 genes
    d. no genes; chloroplasts do not have genes.
A

b. about 150 genes

40
Q
  1. Chloroplast tRNAs translate
    a. all mRNA codons according to the universal code
    b. all the amino acids according to the universal code but have different stop codons
    c. some codons as amino acids that differ from the universal code but use the same stop codons
    d. some codons as amino acids that differ from the universal code and use some different stop codons.
A

a. all mRNA codons according to the universal code

41
Q
  1. Most chloroplast proteins are synthesized on
    a. free ribosomes in the cytosol
    b. RER membranes in the cytoplasm
    c. ribosomes bound to the outer chloroplast membrane
    d. ribosomes in the chloroplast stroma.
A

a. free ribosomes in the cytosol

42
Q
  1. Proteins incorporated into the thylakoid lumen are synthesized
    a. in the thylakoid lumen
    b. in the stroma and transported across the thylakoid membrane
    c. on the outer chloroplast membrane and incorporated across the thylakoid membrane because of its hydrophobic signal sequence
    d. in the cytosol, imported into the stroma, and transported across the thylakoid membrane because of its second (hydrophobic) signal sequence.
A

b. in the stroma and transported across the thylakoid membrane

43
Q
  1. Chloroplasts synthesize
    a. Sugars
    b. amino acids
    c. lipids
    d. All of the above
A

d. All of the above

44
Q
  1. All plastids, including chloroplasts, develop from
    a. Protoplastids
    b. Proplastids
    c. Etioplasts
    d. elaioplasts
A

b. Proplastids

45
Q
  1. The most abundant protein on Earth is
    a. cytochrome c
    b. rubisco
    c. ATP synthase
    d. tubulin.
A

b. rubisco

46
Q
  1. An etioplast is a plastid that
    a. stores starch
    b. stores lipid
    c. is arrested in chloroplast development by lack of light
    d. stores pigment.
A

c. is arrested in chloroplast development by lack of light

47
Q
  1. Collagens commonly contain the 3 repeating amino acids: ____, proline, and ____.
    a. Glutamine; hydroxyproline
    b. Glycine; hydroxyproline
    c. Glycine; hydroxylysine
    d. Gluatamate; hydroxylysine
    e. Glutamate; glycine
A

b. Glycine; hydroxyproline

48
Q
  1. The transport of proteins across the outer and inner chloroplast membranes occurs through complexes called
    a. Tim and Tom
    b. Tic and Toc
    c. Sec and Tat
    d. import complexes
A

b. Tic and Toc

49
Q
  1. The light-dependent generation of ATP in photosynthesis occurs in the
    a. stroma
    b. inner membrane
    c. thylakoid membrane
    d. thylakoid lumen.
A

c. thylakoid membrane

50
Q
  1. The dark reactions occur in the
    a. outer membrane
    b. inner membrane
    c. thylakoid membrane
    d. stroma
A

d. stroma

51
Q
  1. ATP is synthesized in photosynthesis by which of the following means?
    a. Light energy stored by chlorophyll of photosystem I is directly transferred to ATP synthase, which uses the energy to synthesize ATP
    b. Light energy absorbed by photosystems I and II generate energetic electrons that cause the cytochrome bf complex to pump protons across the thylakoid membrane; these protons drive ATP synthase to synthesize ATP
    c. Light energy absorbed by photosystems I and II generate energetic electrons that cause the cytochrome bf complex to pump protons across the inner chloroplast membrane; these protons drive ATP synthase to synthesize ATP
    d. Light energy is used to synthesize glucose, which is then metabolized to produce ATP.
A

c. Light energy absorbed by photosystems I and II generate energetic electrons that cause the cytochrome bf complex to pump protons across the inner chloroplast membrane; these protons drive ATP synthase to synthesize ATP

52
Q
  1. The function of peroxisomes is to
    a. oxidize certain organic molecules and degrade the H2O2 produced by these reactions
    b. reduce certain organic molecules using H2O2
    c. produce hydrogen peroxide for cells
    d. degrade old organelles
A

a. oxidize certain organic molecules and degrade the H2O2 produced by these reactions

53
Q
  1. Peroxisomes contain the enzyme _______, which breaks down H2O2 into H2O and oxygen
    a. Peroxidase
    b. Catalase
    c. Peroxigen
    d. plasmalogen
A

b. Catalase

54
Q
  1. Most peroxisomal proteins are synthesized on
    a. free ribosomes in the cytosol
    b. RER membranes in the cytoplasm
    c. ribosomes bound to the outer peroxisome membrane
    d. ribosomes inside the peroxisome.
A

a. free ribosomes in the cytosol

55
Q
  1. The human disease caused by mutations in the proteins required for import of functional proteins into peroxisomes is called
    a. Turner’s syndrome
    b. Zellweger syndrome
    c. I-cell disease
    d. Lou Gehrig’s disease.
A

b. Zellweger syndrome

56
Q
  1. Plant peroxisomes convert fatty acids to sugars and other carbohydrates via
    a. Plasmalogen
    b. the glyoxylate cycle
    c. the Calvin cycle
    d. the glycolate cycle
A

b. the glyoxylate cycle

57
Q
  1. New peroxisomes form by
    a. budding from the Golgi apparatus
    b. budding from preexisting peroxisomes
    c. assembly de novo from proteins synthesized in the cytosol
    d. fusion of vesicles from the ER and growth and division of preexisting peroxisomes
A

d. fusion of vesicles from the ER and growth and division of preexisting peroxisomes

58
Q
  1. Mitochondria differ from other organelles such as lysosomes and the Golgi apparatus in that they
    a. contain enzymes specific to their function
    b. contain their own genomes
    c. do not contain proteins that are imported from the cytosol
    d. are not membrane-bounded.
A

b. contain their own genomes

59
Q
  1. Human diseases caused by mutations in mitochondrial genomes
    a. are inherited from both parents
    b. are inherited from the father
    c. are inherited from the mother
    d. do not exist because the mutation is always complemented by the normal gene copy in the nucleus.
A

c. are inherited from the mother

60
Q
  1. The human mitochondrial genome encodes only 22 tRNAs. This limited array of tRNAs can read the 64 possible triplet codons through extreme wobble in base pairing at the third codon position and the use of a(n) _______ genetic cod
    a. a. chloroplast-mitochondrial-specific
    b. nonuniversal
    c. peroxisomal-mitochondrial-specific
    d. universal
A

b. nonuniversal

61
Q
  1. Assuming that human mitochondria contain 1000–2000 different polypeptides, approximately what percent of the mitochondrial proteome is encoded by mitochondrial DNA?
    a. 1%
    b. 5%
    c. 10%
    d. 50%
A

a. 1%

62
Q
  1. Which of the following is not involved in protein transport into mitochondria?
    a. A positively charged sequence of about 20–35 amino acids located at the N-terminus
    b. The Tom complex
    c. The proton gradient across the inner mitochondrial membrane
    d. Vesicular transport
A

d. Vesicular transport

63
Q
  1. Which of the following is not a protein translocon found in the mitochondrial inner or outer membrane?
    a. Oxa1
    b. Tim23
    c. Tom40
    d. Toc75
A

d. Toc75

64
Q
  1. Where do the phospholipids in mitochondrial membranes originate?
    a. In the ER
    b. The intermembrane space
    c. The cytosolic side of the outer membrane
    d. The lumenal side of the inner membrane
A

a. In the ER

65
Q
  1. What is the major site of energy production in the form of ATP in human cells?
    a. The mitochondrial matrix
    b. The cytoplasm
    c. The outer mitochondrial membrane
    d. The inner mitochondrial membrane
A

d. The inner mitochondrial membrane

66
Q
  1. The role of cytochrome c in the electron transport chain is to
    a. transfer electrons from complex III to complex IV
    b. transfer the electrons to molecular oxygen
    c. transfer electrons from complex I to complex III
    d. couple the passage of protons down the gradient to ATP production.
A

a. transfer electrons from complex III to complex IV

67
Q
  1. The electrochemical gradient across the mitochondrial inner membrane drives the import of all of the following except
    a. ADP
    b. Phosphate
    c. cytochrome c
    d. protons.
A

c. cytochrome c

68
Q
  1. The ATP synthases of mitochondria and chloroplasts are examples of _______ proteins in which polypeptide rotation provides a mechanical coupling to ATP synthesis
    a. motor
    b. Na+-K+ ATPase
    c. proton pump
    d. symport
A

a. motor

69
Q
  1. In terms of its role in the generation of metabolic energy, the inner membrane in mitochondria is equivalent to which of the following in chloroplasts?
    a. The inner membrane
    b. The thylakoid membrane
    c. The outer membrane
    d. The stroma
A

b. The thylakoid membrane

70
Q
  1. Chloroplast genomes contain approximately how many genes?
    a. 40
    b. 80,000–100,000
    c. None
    d. 150
A

d. 150

71
Q
  1. _______ different translocon systems are used for protein import from the chloroplast stroma into the thylakoid lumen or membrane
    a. Two
    b. Three
    c. Five
    d. Ten
A

b. Three

72
Q
  1. The carotenoids, which give many plants their yellow, orange, and red colors, are located in
    a. vacuoles
    b. chromoplasts
    c. leucoplasts
    d. etioplasts.
A

b. chromoplasts

73
Q
  1. Light is captured by _______ different photosystems associated with the thylakoid membranes of chloroplasts
    a. 2
    b. 3
    c. 5
    d. 10
A

a. 2

74
Q
  1. Each photocenter in a chloroplast consists of hundreds of antenna pigment molecules that absorb light and transfer energy to a reaction center
    a. carotenoid
    b. chlorophyll
    c. cytochrome bf
    d. plastoquinone.
A

b. chlorophyll

75
Q
  1. The difference between the proton gradient across the inner mitochondrial membrane and the proton gradient across the thylakoid membrane of chloroplasts is that
    a. the first creates an electrochemical gradient, while the second is largely just a chemical gradient
    b. there is no proton gradient across the thylakoid membrane. Magnesium ions create the gradient instead
    c. it is generated by an electron transport system in the first case, but not the second
    d. it drives the synthesis of ATP in the first case but not in the second
A

a. the first creates an electrochemical gradient, while the second is largely just a chemical gradient

76
Q
  1. Peroxisomes are involved all of the following reactions except
    a. biosynthesis of the amino acid lysine
    b. biosynthesis of the enzyme catalase, which breaks down hydrogen peroxide
    c. biosynthesis of lipids
    d. oxidative reactions leading to the production of hydrogen peroxide.
A

b. biosynthesis of the enzyme catalase, which breaks down hydrogen peroxide

77
Q
  1. Zellweger syndrome is caused by a defect in
    a. mitochondrial protein import
    b. the electron transport system in mitochondria
    c. protein import into peroxisomes
    d. the synthesis of peroxisomal proteins.
A

c. protein import into peroxisomes

78
Q
  1. The human mitochondrial genome encodes only 22 tRNAs. This limited array of tRNAs can read the 64 possible triplet codons through extreme wobble in base pairing at the third codon position and the use of a(n) _____ genetic code.
    a. Peroxisomal-mitochondrial-specific
    b. Universal
    c. Non-universal
    d. Chloroplast-mitochondrial-specific
A

c. Non-universal

Molec Cell (13 decks)

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