Exam 3 Flashcards by Whitney Haight

In the cotranslational translocation, as they emerge from the ribosome, signal sequences are recognized and bound by a(n) __________.

a. tRNA
b. signal peptidase
c. signal recognition particle
d. miRNA

c. signal recognition particle

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Some proteins have a targeting sequence (KDEL or KKXX) at the carboxy terminus that __________.

a. hold the proteins in the rough ER
b. hold the proteins in the smooth ER
c. hold the proteins in both the smooth ER and rough ER and prevent their transport to the Golgi apparatus
d. direct the proteins from the Golgi apparatus back to the ER

d. direct the proteins from the Golgi apparatus back to the ER

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Protein folding in the ER is assisted by a chaperone called _________.

a. BiP
b. PiP
c. Hsp60
d. Hsp90

a. BiP

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Formation of disulfide bonds is important in protein folding. In the ER, an ____________ environment promotes disulfide (S—S) bond formation, facilitates by protein disulfide isomerase.

a. reducing
b. oxidizing
c. both reducing and oxidizing
d. either reducing or oxidizing

b. oxidizing

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Which of the following classes of lipids is synthesized in the Golgi apparatus?

a. Phosphatidylcholine
b. Glycolipids
c. Cholesterol
d. Ceramide

b. Glycolipids

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Many proteins are inserted directly into the ER membrane by __________. These sequences are recognized by SRP, but not cleaved by signal peptidase.

a. glycosylation sites
b. internal signal sequences
c. phosphorylation sites
d. sulfation sites

b. internal signal sequences

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New phospholipids are added only to the cytosolic half of the ER membrane. Some must be transferred to the other half. This requires passage of polar head groups through the membrane, facilitated by membrane proteins called ___________.

a. flippases
b. signal peptidase
c. chaperone
d. MPP

a. flippases

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If an excess of unfolded proteins accumulates, a signaling pathway called the __________ is activated.

a. ER-associated degradation (ERAD)
b. unfolded protein response (UPR)
c. regulated secretory pathways
d. clathrin-coated vesicles transport

b. unfolded protein response (UPR)

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Vesicles that carry proteins from the rough ER to the Golgi apparatus bud off as _________ vesicles.

a. uncoated
b. clathrin-coated
c. COPI-coated
d. COPII-coated

d. COPII-coated

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The major model of vesicle fusion holds that actual fusion of a vesicle with its target membrane is driven by the interaction of pairs of proteins called vesicle and target _________.

a. SNAREs
b. SNEPs
c. COPs
d. tethers

d. tethers

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Lysosomes contain about 60 different degradative enzymes. Mutations in genes that encode these enzymes result in lysosomal storage diseases – undegraded material accumulates in the lysosomes of affected individuals. The enzyme deficiency in _________ prevents the hydrolysis of glucosylceramide to glucose and ceramide.

a. Multiple sclerosis
b. Leber’s disease
c. Crohn’s disease
d. Gaucher disease

d. Gaucher disease

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The inner compartment of mitochondria is called the ___________.

a. stroma
b. outer membrane space
c. inner membrane space
d. matrix

d. matrix

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Which of the following is a product of glycolysis that is transported into the mitochondria?

a. Pyruvate
b. Glucose
c. Lactic acid
d. Citric acid

a. Pyruvate

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The outer mitochondria membrane __________.

a. is NOT permeable to small molecules
b. contains porins which form channels to allow the free diffusion of small molecules
c. contains a high percentage of proteins involved in oxidative metabolism and transport
d. is the principle site of ATP generation

b. contains porins which form channels to allow the free diffusion of small molecules

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The process by which mitochondria are thought to have arisen during evolution is called ____________.

a. symbiosis
b. phagocytosis
c. endosymbiosis
d. pinocytosis

c. endosymbiosis

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Most mitochondrial genomes consist of ____________.

a. a single linear DNA molecule
b. several linear DNA molecules
c. several circular DNA molecules
d. a single circular DNA and a linear DNA molecules

c. several circular DNA molecules

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Mitochondria contain ___________.

a. no genes of their own
b. genes for only mitochondrial proteins
c. gene for only mitochondrial rRNAs
d. genes for mitochondrial proteins, rRNAs, and tRNAs

d. genes for mitochondrial proteins, rRNAs, and tRNAs

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The proteins encoded by the human mitochondrial genome function in ___________.

a. Cytosolic ribosomes synthesis
b. DNA duplication
c. respiratory complexes and oxidative phosphorylation
d. phospholipid synthesis in ER

c. respiratory complexes and oxidative phosphorylation

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Tim and Tom are _________.

a. twin brother with the same mitochondrial disease
b. chaperones
c. protein translocators in mitochondrial membranes
d. transporters of small molecules across the mitochondrial membranes

c. protein translocators in mitochondrial membranes

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The mitochondrial proteins presequence is cleaved off by a protease called _________.

a. collagenase
b. presequence protease
c. ubiquitin-targeting protease
d. matrix processing peptidase (MPP)

d. matrix processing peptidase (MPP)

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Electron transport occurs in the mitochondrial __________.

a. outer membrane
b. intermembrane space
c. inner membrane
d. matrix

c. inner membrane

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The transport of proteins across the outer and inner chloroplast membranes occurs through complexes called __________.

a. Time and Tome
b. Tic and Toc
c. Sec and Tat
d. import complexes

b. Tic and Toc

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The _________ is equivalent in function to the mitochondrial matrix. It contains the genetic system and metabolic enzymes, including those needed to convert CO2 to carbohydrates during photosynthesis.

a. intermembrane space
b. stroma
c. thylakoid lumen
d. thylakoid membrane

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b. stroma

All plastids, including chloroplasts, develop from ________.

a. Chromoplasts
b. Etioplasts
c. Elaioplasts
d. Proplastids

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d. Proplastids

In terms of its role in the generations 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

b. The thylakoid membrane

Many proteins are synthesized on free ribosomes and imported into chloroplasts as completed polypeptides. The N-terminal __________ direct translocation across the two membranes of the envelope and are then removed by proteolytic cleavage. a. Phospholipid transfer proteins b. Poly AAA c. Telomere d. Transit peptides

d. Transit peptides

What triggers lipid-containing etioplasts to undergo complete development into chloroplasts? a. Light b. Glucose c. Darkness d. Pigment

a. Light

The cytoskeleton is composed of three main types of protein filaments. Which one is not cytoskeleton? a. Actin filaments b. Microtubules c. Intermediate filaments d. Laminin

d. Laminin

Actin exists in cells in two major forms called _____________. a. alpha-tubules and beta-tubules b. alpha-actin and beta-actin c. G actin and D actin d. G actin and F actin

d. G actin and F actin

___________ contain carotenoids, resulting in the yellow, orange, and red colors of flowers and fruits. a. Chromoplasts b. Chloroplasts c. Amyloplasts d. Elaioplasts

a. Chromoplasts

Branching of actin filaments can be initiated by _________. a. Arp 2/3 b. Formin c. ADF/cofilin d. Fimbrin

a. Arp 2/3

__________ bind at ATP-actin and nucleate initial polymerization of long unbranched actin filaments. a. Spectrin b. Formin c. ADF/cofilin d. Fimbrin

b. Formin

Actin filaments are bound into bundles of parallel filament by the protein’s _________. a. filamin and cofilin b. troponin and tropomyosis c. profilmin an thymyosin d. alpha-actinin and fimbrin

d. alpha-actinin and fimbrin

In actin filament assembly, the process in which ATP-actin monomers are added to the barbed end of the filament while at the same time ADP-actin monomers are dissociating from the points end of the filament is referred to as _________. a. equilibrium b. dynamic instability c. treadmilling d. balancing

c. treadmilling

During muscle contraction, the A band _________. a. stays the same width, and the I band and H zone shorten b. and H zone stay the same width, and the I bands shorten c. shortens, and the I bands and H zone stay the same d. and H zone shorten, and the I band stay the same

a. stays the same width, and the I band and H zone shorten

In nonmuscle cells and smooth muscle, contraction is regulated primarily by phosphorylation of a myosin light chain, which is catalyzed by myosin light chain kinase (MLCK), which is regulated by the Ca2+-binding protein _________. a. Akt b. calmodulin c. integrin d. collagen

b. calmodulin

Myosin _______ is present in muscle sarcomeres. a. I b. II c. III d. IV

b. II

Microtubules are assembled from __________. a. alpha-tubulin dimers b. beta-tubulin dimers c. altering alpha-tubulin dimers and beta-tubulin dimers d. dimers of alpha- and beta-tubulin

d. dimers of alpha- and beta-tubulin

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

d. GTP

The microtubule behavior in which some microtubules are rapidly depolymerizing and some are growing is called __________. a. an equilibrium state b. dynamic instability c. treadmilling d. balancing

b. dynamic instability

The major microtubules-organizing center in most animal cells is the __________. a. kinetochore b. polar microtubules c. centrosome d. centromere

c. centrosome

The basis for muscle contraction is the _____________. a. rotation of myosin fibers around actin fibers b. expansion of the sarcomere c. sliding of myosin and actin fibers past each other d. movement of the Z discs away from each other

c. sliding of myosin and actin fibers past each other

Like myosins, kinesin and dyneins are both proteins. Which of the following statements is true of all kinesins and dyneins? a. They are microtubules-dependent motors b. They are both minus-end-directed motors c. They are neither minus-end-directed nor plus-end-directed motors d. They are both plus-end-directed motors

a. They are microtubules-dependent motors

Cell division follow mitosis. A contractile ring of _________ and myosin II is assembled by membrane-bound myosin just beneath the plasma membrane. a. collagen b. actin c. intermediate filament d. fibronectin

b. actin

Collagen commonly contain the three repeating amino acids: _______, proline, and ________. a. glutamine; proline b. glycine; hydroxyproline c. glycine; arginine d. glutamine; lysine

b. glycine; hydroxyproline

Adherens junctions are linked to cytoplasmic _________. a. actin filaments b. intermediate filaments c. microtubules d. myosin filaments

a. actin filaments

Desmosomes are linked to cytoplasmic _________. a. collagen b. intermediate filaments c. microtubules d. myosin filaments

b. intermediate filaments

_________ transport does not involve karyopherins and its independents of Ran. A distinct transporter complex moves the ________ through the nuclear pore. a. tRNAs b. rRNAs c. mRNAs d. miRNAs

c. mRNAs

Which of the following does not take place in the nucleus? a. DNA replication b. Translation c. RNA processing d. Transcription

d. Transcription

The outer nuclear membrane is contiguous with the _________. a. Endoplasmic reticulum b. Nuclear lamina c. Chromosomes d. Plasma membrane

a. Endoplasmic reticulum

Which of the following contain their own genomes? a. Mitochondria, but no chloroplasts and peroxisomes b. Chloroplasts, but not mitochondria and peroxisomes c. Mitochondria and chloroplasts, but not peroxisomes d. Mitochondria, chloroplasts, and peroxisomes

c. Mitochondria and chloroplasts, but not peroxisomes

The mitochondrial outer membrane contains channels composed of proteins called _______. a. porins b. aquaporins c. connexins d. claudins

a. porins

The inner mitochondrial membrane contains proteins that __________. a. synthesize ATP b. pump protons c. transport pyruvate d. all of the above

d. all of the above

Most mitochondrial genomes consist of ___________. a. a single linear DNA molecule b. several linear DNA molecules c. several circular DNA molecules d. a single circular DNA molecules

c. several circular DNA molecules

Tim and Tom are ___________. a. twin brothers with the same mitochondrial disease b. chaperones c. protein translocators in mitochondrial membranes d. transporters of small molecules across the mitochondrial membranes

c. protein translocators in mitochondrial membranes

Exam 3 Flashcards

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