Lecture 22-30 Flashcards
Metabolic pathways that lead to the synthesis of more complex compounds from simpler starting materials are known as ________.
a. anabolism b. catabolism c. manabolism d. a and b e. allosterism
a
Glycolysis occurs in the ________; the Krebs (TCA) cycle occurs in the ______ of eukaryotes and the ______ of prokaryotes.
a. cytoplasm, cytoplasm, cytoplasm b. mitochondria, cytoplasm, mitochondria c. cytoplasm, mitochondria, cytoplasm d. cytoplasm, photosynthesis, cytoplasm e. cytoplasm, mitochondria, mitochondria
c
How are new mitochondria produced?
a. They arise by fission from preexisting mitochondria. b. They bud off of the Golgi apparatus. c. They bud off of the rough endoplasmic reticulum. d. They self-assemble spontaneously. e. They arise through fusion.
a
How do mitochondria generate and store the energy used to produce most of the ATP made during aerobic respiration?
a. by producing heat b. by generating a heat gradient c. by generating an ionic (electrochemical) gradient d. by generating a Cl- ion gradient e. c and d
c
Peroxisomal enzymes __________.
a. produce hydrogen peroxide b. break down hydrogen peroxide c. include catalase d. a and b e. a, b and c
e
Organisms that can survive on carbon dioxide as their principal carbon source are called ________.
a. autotrophs b. heterotrophs c. chemotrophs d. phototrophs e. externotrophs
a
Organisms that use the energy stored in inorganic molecules, like ammonia, hydrogen sulfide and nitrites, to convert carbon dioxide to organic molecules like carbohydrates and proteins are called _____.
a. chemoautotrophs b. chemoheterotrophs c. photoautotrophs d. photoheterotrophs e. didliotrophs
a
What is the plant cell’s primary source of chemical energy?
a. CO2 b. ADP c. ATP d. NAD e. NADPH
c
What is the plant cell’s primary source of reducing power?
a. CO2 b. ADP c. ATP d. NAD e. NADPH
e
What color of light does chlorophyll absorb?
a. red b. blue c. green d. a and b e. a, b and c
d
Which of the following is a function of carotenoids?
a. They act as primary light collectors during photosynthesis. b. They act as secondary light collectors during photosynthesis. c. They draw excess energy away from excited chlorophylls and dissipate it as heat. d. b and c e. a and c
d
The PSII reaction center, also known as P680, _____________.
a. absorbs light most strongly at 680 nm b. reflects light most strongly at 680 nm c. absorbs light most weakly at 680 nm d. b and c e. absorbs light most strongly at 700 nm
a
For what purpose(s) does photosystem II (PSII) use absorbed light energy?
a. removing electrons from alcohol b. removing electrons from sugars c. generating a proton gradient d. removing electrons from water e. c and d
e
Which of the following activities contribute to the establishment of a H+ ion (proton) gradient across the thylakoid membrane?
a. splitting of water in the thylakoid lumen b. translocation of protons from the stroma to the thylakoid lumen by cytochromes c. reduction of NADP+ in the stroma d. reduction of NADP+ in the thylakoid lumen e. a, b and c
e
You inject an antibody against the protein actin into a living animal cell. After the injection, the cell begins mitosis and the process proceeds normally until cytokinesis would normally occur. Instead, the contractile ring does not form and cytokinesis does not occur. What do these results mean?
a. Cytokinesis is dependent upon microtubules. b. Cytokinesis is dependent upon microfilaments. c. The separation of chromosomes by the spindle is dependent upon microtubules. d. A major component of the contractile ring is microfilaments. e. b and d
e
You inject an antibody against the protein tubulin into a living animal cell. After the injection, the cell begins mitosis but the chromosomes do not become attached to the spindle; in fact, there is no spindle. The contractile ring does form however. What do these results mean?
a. The contractile ring is composed of microtubules. b. Cytokinesis is dependent upon microtubules. c. The separation of chromosomes by the spindle is dependent upon microtubules. d. The spindle is composed, at least in part, by microtubules. e. c and d
e
Which end of a microtubule is the fast growing end?
a. the plus end b. the end with beta-tubulin at the tip c. the end with alpha-tubulin at the tip d. the minus end e. a and b
e
The core of a cilium is called the ________.
a. troponeme b. dynomeme c. cilioneme d. axoneme e. flagelloneme
d
Which of the following is a family of molecular motors?
a. myosins b. kinesins c. dyneins d. motorins e. a, b and c
e
Which of the following molecular motors is associated with microfilaments?
a. kinesins b. dyneins c. myosins d. a and b e. a, b and c
c
What part of the molecular motor kinesin is responsible for binding to the cargo to be hauled?
a. the motor domain b. the neck c. the rodlike stalk d. the fan-shaped tail e. all of the above
d
A _____ moves the cell in a direction ________ to itself.
a. cilium, perpendicular b. cilium, parallel c. flagellum, perpendicular d. cilium, diagonal e. a and d
a
Each step that kinesin makes along a microtubule is about 8 nm. How many tubulin subunits correspond to this distance?
a. 1 b. 3 c. 4 d. 2 e. 5
d
When microtubules grow out of a centrosome, which end is associated with the centrosome?
a. the plus end b. the minus end c. the N-terminal end d. the C-terminal end e. the 5'- end
b
Which of the following cell processes involve microfilaments?
a. movement of chromosomes during mitosis b. phagocytosis c. cytokinesis d. b and c e. a, b and c
d
Which of the following words best describes the structure of an actin filament?
a. single actin strand b. triple helix c. hyperpolar filament d. double helix e. supercoil
d
What motor is associated with microfilaments?
a. myoglobin b. kinesin c. myosin d. dynein e. myometrium
c
Where does the energy to run myosin motors come from?
a. GTP b. ATP c. proton gradient d. CTP e. creatine phosphate
b
What causes rigor mortis?
a. In the absence of ATP, cross-bridges do not detach from the actin thin filament. b. In the absence of ATP, cross-bridges will not attach to the actin thin filament. c. In the absence of ADP, cross-bridges do not detach from the actin thin filament. d. In the absence of ADP, cross-bridges will not attach to the actin thin filament. e. When organism dies the cross-bridges denature rapidly.
a
What is a major influence in determining the organization and behavior of actin filaments inside cells?
a. actinin-binding proteins b. tubulin c. actin-binding proteins d. dynein e. a and c
c
As a fibroblast moves, its leading edge extends from the cell as a broad, flattened, veil-like protrusion called a ________.
a. pseudopodium b. lamella c. lamellipodium d. podium e. extensor
c
During embryonic development, the generation of new tissues is often triggered by ________.
a. the disappearance of cadherins from the cell surface
b. the appearance of cadherins on the cell surface
c. the breakage of cadherins at the cell surface
d. the disintegration of cadherins inside the cell
e. a and b
e
What type of cell adhesion molecule is associated with cells being held together by adherens junctions at the site of the junction? a. adherins b. selectins c. IgSFs d. integrins e. cadherins
e
Each connexon is constructed of ___ protein subunits.
a. 2
b. 4
c. 6
d. 8
e. 10
c
What kind of molecule does not pass through a gap junction?
a. ions
b. cAMP
c. inositol phosphate
d. peptide hormones
e. cGMP
d
What lines the plasmodesmata?
a. integral membrane proteins
b. peripheral proteins
c. carbohydrates
d. the plasma membrane
e. DNA
d
What is the arrangement of collagen fibers in tendons that allows them to resist large pulling
forces during muscle contraction?
a. perpendicular to the long axis of the tendon
b. parallel to the long axis of the tendon
c. parallel to the direction of the pulling force
d. perpendicular to the direction of pulling force
e. b and c
e
Which of the following is a characteristic of glycosaminoglycans (GAGs)?
a. repeating trisaccharides
b. repeating disaccharides
c. very acidic
d. very basic
e. b and c
e
Why are proteoglycans able to occupy so much space?
a. They are highly sulfated and thus negatively charged.
b. They attract and bind large numbers of cations.
c. They attract and bind large numbers of anions.
d. They attract lots of water.
e. a, b and d
e
What forms the barrier of the tight junctions that seals off the space between adjacent cells?
a. paired rows of aligned integral membrane proteins
b. paired rows of aligned phospholipids
c. paired rows of carbohydrates
d. paired rows of polynucleotides
e. a and d
a
What kind of cell adhesion molecule mediates transient interactions between circulating
leukocytes and vessel walls at inflammation and clotting sites?
a. IgSFs
b. integrins
c. selectins
d. cadherins
e. calmodulins
c
Which of the following exposures can transform cells into cancer cells?
a. radiation
b. carcinogenic chemicals
c. certain viruses
d. a and b
e. a, b and c
e
Estrogen ___________.
a. may promote breast cancer development
b. is a steroid hormone
c. is not mutagenic
d. may raise the risk of tumorigenesis by causing target cell growth and division
e. all of the above
e
What is the most important property of a cancer cell, whether it is in the body or the culture dish?
a. its chromosome complement
b. its loss of growth control
c. its size
d. its secretions
e. its inability to divide
b
How do cancer cells differ from normal cells in their capacity for cell division?
a. Normal cells have a limited capacity for cell division; cancer cells are seemingly immortal.
b. Normal cells age so that they eventually become unfit to grow and divide; cancer cells
continue to divide indefinitely.
c. Cancer cells tend to have greater affinity for their host tissue than do normal cells.
d. a and b
e. b and c
d
What enzyme possessed by cancer cells but lacking in normal cells is thought to contribute to the seeming immortality of cancer cells? a. telomerase b. RNA polymerase c. DNA-directed DNA polymerase d. reverse transcriptase e. RNA-directed DNA polymerase
a
The long life of stem cells and indefinite number of cell divisions that they undergo allows them
to ________.
a. accumulate more mutations than less mitotically active somatic cells
b. have a better chance at developing a malignant transformation
c. be protected against malignant transformation
d. be protected from viral infection
e. a and b
e
The \_\_\_\_\_\_\_\_\_ pathway of apoptosis is one in which external stimuli activate apoptosis via a signaling pathway. a. extrinsic b. external c. intrinsic d. peripheral e. integral
a
What is the name of an extracellular messenger protein that is named for its ability to kill
tumor cells and also serves as an apoptotic stimulus.
a. tumor angiogenesis factor
b. tumor death factor
c. tumor necrosis factor
d. necromancer factor
e. tumorigenic factor
c
After activation by stressful stimuli, certain pro-apoptotic proteins like Bax translocate from
the _____ to the _____.
a. cytosol, outer mitochondrial membrane
b. cytosol, inner mitochondrial membrane
c. outer mitochondrial membrane, cytosol
d. inner mitochondrial membrane, cytosol
e. cytosol, inner chloroplast membrane
a
What molecule, when incorporated into the outer surface of apoptotic bodies, serves to identify them as such? a. phosphatidylserine b. phosphatidylinositol c. phosphatidic acid d. phospholipase C e. proteoglycan
a
Why is it important that apoptotic cell death occurs without spilling cellular content into the
extracellular environment?
a. The release of cellular debris would trigger inflammation, which could cause
significant tissue damage.
b. Release of cellular debris would cause enhanced cell growth.
c. Cellular debris would invariably be toxic.
d. Cellular debris would raise the pH of the extracellular fluids immediately.
e. Cellular debris would lower the pH of the extracellular fluids immediately.
a
What are the processes, sequentially, that decode DNA into an RNA sequence and then decode the RNA into a polypeptide?
a. translation followed by transcription
b. transcription followed by translation
c. transduction followed by protein synthesis
d. transcription followed by transduction
e. transliteration followed by transformation
b
What advantage do the cristae confer on the mitochondria?
a. They allow the mitochondria to shrink.
b. They greatly increase the surface area for aerobic respiration machinery.
c. They confer resiliency on the cells.
d. They allow swelling of mitochondria.
e. They activate the matrix.
b
What is the immediate (proximal) source of energy that powers molecular motors?
a. hydrolysis of GTP
b. hydrolysis of ATP
c. proton gradient
d. H+ gradient
e. condensation of ATP
b
Why do tumor cells die after exposure to drugs that either disrupt or stabilize the structure of microtubules?
a. Mitosis is stopped in the presence of the drugs.
b. Tumor cells attempt cell division, even in the absence of a functional spindle, killing the cells.
c. There is a checkpoint that prevents the entry into mitosis.
d. The drugs cause the disintegration of the tumor cell membranes.
e. none of the above
b
Name two structures within a cell that can destroy proteins and give one reason why some proteins need to be destroyed. [2 marks]
proteosome and lysosome
because they become worn out, mutated, oxidized, misfolded
Name two microtubule-based cell motility structures and provide one difference that distinguishes them from each other. [2 marks]
cilia and flagella
usually there are multiple short cilia, but only one or two long flagella
Name one signaling chemical, identify its type of receptor, and name one downstream effect that would follow from this signal-receptor interaction. [3 marks]
ON EXAM*
- **ON EXAM:
- signaling chemical: insulin
- receptor: RTK
- downstream effect: decrease blood glucose levels by producing glycogen and fat, as well as inhibiting gluconeogenesis
A patient’s liver cells are having difficulty responding to an extracellular signal that induces glucose uptake. Suggest one possible cause for this problem, and indicate how you could use gene therapy to correct the problem. [2 marks]
- cause: Type 2 diabetes where the receptors are no longer sensitive to insulin
- gene therapy: PTP gene knockout to make receptors insulin sensitive again by removing a phosphate from the insulin receptor
What do all cancer-causing agents have in common?
a. They can all alter the genome.
b. They are all soluble in water.
c. They can all alter lipid membranes.
d. They all resemble nucleotides.
e. They all can alter proteins present in the cell cytoplasm that are responsible for the onset of
cancer.
a
Which of the following statements does not reflect differences between cancer cells and
normal cells?
a. failure of cancer cells to carry out apoptosis, while normal cells can
b. aneuploidy in cancer cells, while normal cells have a normal chromosome complement
c. apparent immortality of cancer cells, while normal cells undergo a finite number of divisions
d. the absence of telomerase in cancer cells and its presence in normal cells
e. slowing of normal cell growth rates in response to environmental stimuli, while cancer cells
divide in an uncontrolled fashion
d
Which of the following statements does not help explain why cancer is relatively rare?
a. Cancer development requires more than one genetic alteration. b. Cancer development is a multi-step process characterized by a progression of permanent alterations in a single cell line. c. Cancer development is a multi-step process characterized by a progression of permanent alterations in multiple cell lines. d. Multiple changes are required to make the cell non-responsive to the body's regulatory machinery. e. Numerous mutation-detection and corrective mechanisms exist in cells.
c
The glycocalyx consists of:
a. integral membrane proteins
b. extracellular fibrous proteins such as the basement membrane
c. oligopolysaccharides on the exterior face of the membrane, attached to integral membrane proteins
d. cytosolic glycoprotein scaffold
e. the protein layer surrounding the nucleus.
d
Collagen fibrils show _________ cross-linking with age, which results in ___________ elasticity of the skin in the elderly.
a. increased; increased
b. increased; decreased
c. decreased; increased
d. decreased; decreased
e. decreased; no change in the
b
If antibodies specific to fibronectin are exposed to an embryo through which neural crest cells
are migrating, what happens?
a. Neural crest cell movements are inhibited.
b. Neural crest cell movements are excited.
c. Neural crest cells die.
d. Neural crest cells divide.
e. Neural crest cells are unaffected and migrate normally
a
From what structure do cilia and flagella emerge?
basal bodies
What is responsible for degrading misfolded proteins in the cytoplasm?
proteasomes
The core of a cilium is called the _______________
axoneme
Which of the following is normally associated with the cilia of organisms from protists to mammals?
a 9+2 pattern
The outer and inner chloroplast membranes contain distinct translocation complexes named __________, respectively that work together during protein import.
Toc and Tic complexes
Treatment of lysosomal storage disorders with substrate reduction therapy involves ____________.
administration of small molecular weight drugs to inhibit the synthesis of the substances that accumulate in the disease
The following ARE functions of cilium
- moving the cell from place to place
- a role in sensory function in monitoring the properties of extracellular fluids
- moving fluid and particulate materials past the cell
The following IS NOT a function of the cilium
moving vesicles down the nerve cell axon
All collagen family members consist of __________ chains arranged in a ____________. (hint: col-la-gen)
- 3
- triple helix
The loss of cadherin function may be instrumental in what disease state?
the spread of malignant tumors
Evidence strongly suggests that the bent conformation of an integrin is ____________ and unable to bind its ligand.
inactive
Which procedure below would lead to the visualization of the dynamic movements of specific proteins as they move through a single living cell? The proteins can be seen through the microscope eyepiece and the cells do not have to be killed for the protein to be detected.
fusion of the green fluorescent protein gene to the gene encoding the protein to be tracked through the cell
In cell biology and with respect to microtubules and microfilaments, the word “dynamic” means
ever-changing
What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? These complexes can occupy very large volumes.
hyaluronic acid
What is the function of most IgSFs?
mediating specific interactions of lymphocytes with cells needed for the immune response
What explains the fact that plants lack the specialized junctions seen in animal cells?
the presence of the cell wall
What tubulin protein is involved in the nucleation of the microtubule?
gamma
The following are functions of the cell wall
- it allows plant cells to develop osmotic turgor pressure that pushes against their surrounding walls.
- it provides mechanical support for individual cells and serves as a type of skeleton for the whole plant
- it protects cells against damage from mechanical abrasion, osmotic influx of water and pathogens
- it can be a source of signals that alter activities of cells that it contacts
- allows cell-cell interactions
What integral membrane protein family made of two membrane-spanning chains (alpha and beta) is involved in attaching cell their extracellular micro-environment?
integrins
Along which structure do membranous vesicles and organelles typically move long distances in an animal cell?
microtubules
Which of the following molecular motors is associated with microfilaments?
myosin
The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is called ___________.
inside-out signaling
Why is RNAi now used as a strategy for investigating the effect of a missing protein more often than generating an organism that possesses a mutant gene?
its easier to synthesize a small RNA than to generate an organism that possess a mutant gene
Which protein below is often a component of intermediate filaments?
keratin
What appears to be the purpose of molecular chaperones like BiP?
they recognize and bind to unfolded or misfolded proteins and help them attain their native structure
What is the minimum number of kinesin heads in contact with a microtubule at all times?
one
Why are yeast cells often used to study eukaryotic gene mutations affecting secretion and other cytomembrane processes?
- they have only a few genes
- they are small and single celled and can be cultured easily
- they can be grown as haploid organisms so mutants are easily seen
- deficiencies in yeast cells caused by mutants are easily detected
What are the two sites within a cell at which protein synthesis is generally thought to occur?
cytosolic surface of RER and free ribosomes
The tightest attachment between a cell and its extracellular matrix is seen at the site where an epithelial cell is attached to the underlying basement membrane. This specialized adhesive structure is called a
a. gap junction
b. desmosome
c. plasmodesma
d. hemidesmosome
e. cadherin
d
Filaments connected to the dense plaque underlying the membrane in a hemidesmosome extend outward into the cytoplasm. These filaments are composed of the protein _____ and are best known as ______.
a. actin, microfilaments b. keratin, microfilaments c. actin, intermediate filaments d. keratin, intermediate filaments e. tubulin, intermediate filaments
d
________ are members of an integral membrane glycoprotein family that bind to specific sugar arrangements in oligosaccharides that project from the surfaces of other cells.
a. Selectins b. Integrins c. Immunoglobulin super family proteins d. Cadherins e. Calmodulins
a
- Which of the following is not a function of the plant cell wall?
(1) It allows plant cells to develop osmotic turgor pressure that pushes against their surrounding walls.
(2) It provides mechanical support for individual cells and serves as a type of “skeleton” for the whole plant.
(3) It protects cells against damage from mechanical abrasion, osmotic influx of water & pathogens.
(4) It prevents cell-cell interactions.
(5) It can be a source of signals that alter activities of cells that it contacts.
4
- What kind of molecule does not pass through a gap junction?
(1) ions
(2) cAMP
(3) inositol phosphate
(4) protein
(5) cGMP
4
- The cytoplasmic domain of cadherins is often associated with ________.
(1) the same type of cadherin
(2) catenins
(3) the cytoskeleton
(4) Ca2+ ion
(5) none of above
2
The “upright” conformation of an integrin is _______.
(1) loose
(2) active
(3) tight
(4) stretched
(5) inactive
2
In an integrin, what structure crosses the lipid bilayer?
(1) a transmembrane pleated sheet
(2) a transmembrane spear
(3) a transmembrane plate
(4) a transmembrane helix
(5) a bent leg
4
- Where are the enzymes that synthesize carbohydrates located?
(1) grana
(2) thylakoids
(3) the lumen
(4) stroma
(5) chloroplast envelope
4
You are growing algae in culture and expose them to CO2 that contains radiolabeled oxygen. Where does the radiolabeled oxygen end up after photosynthesis?
(1) water
(2) oxygen
(3) carbon dioxide
(4) carbohydrates
(5) carbon monoxide
4
The PSII reaction center, also known as P680, _____________.
(1) absorbs light most strongly at 680 nm
(2) reflects light most strongly at 680 nm
(3) absorbs light most weakly at 680 nm
(4) reflects light most strongly at 700 nm
(5) absorbs light most strongly at 700 nm
1
The excited PSII reaction-center pigment (P680*) transfers a single photoexcited electron to a closely associated, chlorophyll-like molecule called _________.
(1) theophyllin
(2) carotene
(3) pheophytin
(4) xanthophylls
(5) succinate dehydrogenase
3
The light-driven splitting of a water molecule is known as _______.
(1) hydrolysis
(2) photonization
(3) photolysis
(4) condensation
(5) dehydration
3
Mercaptoethanol is a reagent that breaks disulfide linkages. If you were to treat Calvin cycle enzymes with this reagent, what effect might it have on them?
(1) It might competitively inhibit them.
(2) It might noncompetitively inhibit them.
(3) It might split them in two pieces.
(4) It might activate them.
(5) It might deactivate them.
4
In mitochondrion, what is the terminal electron acceptor of the electron transport chain?
(1) water
(2) O2
(3) CO2
(4) cytochrome a
(5) NADP+
2
It has been shown that one part of ATP synthase rotates relative to another part of the enzyme. This phenomenon is referred to as ________.
(1) turning catalysis
(2) revolutionary catalysis
(3) rotational catalysis
(4) rotatalysis
(5) revolalysis
3
Peroxisomal enzymes __________.
a. produce hydrogen peroxide
b. break down hydrogen peroxide
c. include catalase
(1) a and c
(2) b
(3) b and c
(4) a and b
(5) a, b and c
5
In mitochondrion, which electron carrier transfers electrons from complex II to complex III?
(1) Flavoprotein
(2) Cytochrome c
(3) Ubiquinone
(4) Copper atom
(5) Iron-sulfur protein
3
What effect does cholesterol have on membrane fluidity?
a. Cholesterol disrupts close packing of fatty acid chains.
b. Cholesterol enhances sharp transition temperature and creates a condition of intermediate fluidity.
c. Cholesterol interferes with the mobility of fatty acid chains.
d. Cholesterol abolishes sharp transition temperature and creates a condition of intermediate fluidity.
(1) a and d
(2) c and d
(3) a and b
(4) b and c
(5) a, c and d
5
The movement of a substance from an area of high concentration to an area of lower concentration is called_________.
(1) Denaturation
(2) Osmosis
(3) Diffusion
(4) Transport
(5) Defusion
3
Diffusion during which the substance to be transported binds selectively to a membrane-spanning protein, which helps the process along, is called ________.
(1) osmosis
(2) facilitated osmosis
(3) simple diffusion
(4) facilitated diffusion
(5) active transport
4
Which integral proteins are involved in both cell-extracellular matrix (ECM) and cell-cell interactions?
(1) integrins
(2) cadherins
(3) selectins
(4) immunoglobulin superfamily
(5) connexins
1
When protons move through the membrane via the channel in the F0 base, in F1 head ______ subunit(s) rotate(s).
(1) α and β
(2) γ
(3) β
(4) ε
(5) δ
2
How is a nerve impulse transmitted across a synapse from a presynaptic cell to a postsynaptic cell?
(1) via a direct connection
(2) via a spark
(3) via a neurotransmitter
(4) via Na+ ions
(5) via Ca2+ions
3
For N-glycosidic linkages, to which amino acid(s) are oligosaccharides attached?
(1) asparagine
(2) threonine and serine
(3) aspartic acid
(4) arginine
(5) tyrosine and serine
1
_________ are characterized as hollow, rigid cylindrical tubes with walls composed of
tubulin subunits; ________ are solid fiber structures composed of actin subunits; and ______
are tough, ropelike fibers composed of a variety of related proteins like keratin
a. microfilaments, microtubules, intermediate filaments
b. microtubules, microfilaments, intermediate filaments
c. intermediate filaments, microtubules, microfilaments
d. microtubules, intermediate filaments, microfilaments
e. microfilaments, intermediate filaments, microtubules
b
Which of the following sites within a cell are places where microtubules are found? a. mitotic spindle b. ciliary core c. cytoplasm d a, b, and c e. none of the above
d
What word or phrase below characterizes the three cytoskeletal filaments?
a. polymer of protein subunits
b. protein subunits connected to one another by covalent bonds
c. protein subunits connected to one another by weak, noncovalent bonds
d. a and c
e. a and b
d
The advantage of the type of structure displayed by cytoskeletal filaments is that _________.
a. it lends itself to rapid assembly and disassembly
b. it is dependent upon and responsive to complex cellular regulation
c. it is tremendously stable
d. a and c
e. a and b
e
Which type of cytoskeletal element is characterized as a hollow, rigid cylindrical tube with walls composed of tubulin subunits?
a. microfilaments
b. microtubules (because microfilaments are helical)
c. intermediate filaments
d. all of the above
e. minitubules
b
Which type of cytoskeletal element is described as a solid structure composed of actin subunits?
a. microfilaments
b. microtubules
c. intermediate filaments
d. all of the above
e. macrofilaments
a
Which type of cytoskeletal element is described as a tough, ropelike fibers composed of a variety of related proteins like keratin?
a. microfilaments
b. microtubules
c. intermediate filaments
d. a and c
e. macrofilaments
c
Which of the following activities are identified as functions of the cytoskeleton?
a. a dynamic scaffold that provides structural support that helps to determine cell shape
b. internal framework that positions organelles in cell interior
c. a network of tracks that direct the movement of materials and organelles within the cell
d. a force-generating apparatus
e. all of the above
e
What kinds of materials appear to be moved around the cell by the tracks of the cytoskeleton?
a. mRNA molecules
b. membranous carriers between the ER and Golgi complex
c. transport vesicles containing DNA
d. a and b
e. all of the above
e
The microtubule wall is composed of globular proteins arranged in longitudinal rows called _________. in the book
a. microfilaments
b. protofilaments
c. prototubules
d. prototubulins
e. microtubular units
b
In a normal microtubule, how many protofilaments make up its cylindrical wall?
a. 13
b. 15
c. 11
d. 9
e. 17
a
What kind of forces are thought to hold microtubular structure together?
a. strong interactions
b. noncovalent interactions
c. covalent interactions
d. a and c
e. all of the above
b
The dimers that assemble to form a microtubule are ________.
a. homodimers
b. heterodimers-Beta and alpha
c. alpha-tubulins
d. beta-tunulins
e. b and c
b
Which end of a microtubule is the fast growing end?
a. the plus end
b. tubulin at the tip probably sposed to be alpha and beta tubulin, which the plus end i think involves beta on the plus end
c. tubulin at the tip
d. the minus end
e. a and b
a
MAPs are microtubule-associated proteins. What role are they thought to play with respect to microtubules?
a. They increase microtubule stability.
b. They decrease microtubule stability.
c. They promote microtubule assembly.
d. They promote microtubule disassembly.
e. a and c
e
The activity of various MAPs is controlled mostly by the \_\_\_\_\_\_ of phosphate groups from particular amino acid residues by \_\_\_\_\_\_\_\_. pg 1080 and pg 1001 a. addition, protein kinases b. addition, phosphatases c. removal, protein kinases d. removal, phosphatases e. a and d a
a
An abnormally high level of ______ of the MAP protein tau is implicated in the development of strange, tangled filaments called _________ that have been seen in the brains of patients suffering from several fatal neurodegenerative diseases like Alzheimer’s disease.
a. phosphorylation, neurofibrillary tangles
b. phosphorylation, neurofibrillary anastomoses
c. dephosphorylation, neurofibrillary tangles
d. dephosphorylation, neurofibrillary anastomoses
e. amination, neurofibrillary tangles
a
Which of the following is a function of microtubules?
a. They provide mechanical support for cells.
b. They help to maintain cell shape.
c. They are skeletal elements in certain highly elongated cellular processes like axons.
d. They form most of the structure of centrioles.
e. all of the above
e
Cells that have a _________ shape have microtubules that __________.
a. columnar; are oriented with their long axis parallel to the long axis of the cell
b. columnar; are oriented with their long axis perpendicular to the long axis of the cell
c. rounded, flattened shape; extend in a radial array outward from the area around the nucleus
d. rounded, flattened shape; extend in a radial array inward from the area around the nucleus
e. a and c
e
What happens to axons growing out from a neuron when they are exposed to colchicine or nocodazole and why does this happen?
a. Axons grow more rapidly. The drugs disrupt microtubule growth.
b. Axonal outgrowth stops. The drugs disrupt microtubule growth.
c. Axons grow more rapidly. The drugs enhance microtubule growth.
d. Axonal outgrowth stops. The drugs enhance microtubule growth.
e. There is no change in axonal outgrowth. The drugs disrupt microtubule growth.
b
How are microtubules thought to affect cell shape in plants?
a. Microtubules of the plant cell cortex are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane, which, in turn, affect cell wall growth and shape.
b. Microtubules of the plant cell vacuole are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane, which, in turn, affect cell wall growth and shape.
c. Microtubules of the plant cell cortex are thought to affect the movement of lipid-synthesizing enzymes in the cell membrane, which, in turn, affect cell wall growth and shape.
d. Microtubules of the plant cell wall are thought to affect the movement of cellulose-synthesizing enzymes in the cell membrane, which, in turn, affect cell wall growth and shape.
e. none of the above
e
You are performing an experiment on a cultured animal cell and observing the Golgi complex as part of your study. You add a drug to the cultured cells and when you do, the elements of the Golgi complex disperse into the cell periphery. When the drug is removed, the Golgi membranes return to their normal position in the cell interior. What drug was likely to have been used?
a. actinomycin D
b. colchicine
c. nocodazole
d. aspirin
e. b and c
e
You are performing an experiment on a cultured animal cell and observing the Golgi complex as part of your study. You add colchicine to the cultured cells and when you do, the elements of the Golgi complex disperse into the cell periphery. When colchicine is removed, the Golgi membranes return to their normal position in the cell interior. What conclusion would you draw from this result?
a. The correct positioning of the Golgi complex is dependent upon microfilaments.
b. The correct positioning of the Golgi complex is dependent upon microtubules.
c. The correct positioning of the Golgi complex is dependent upon intermediate filaments.
d. Colchicine kills the cell.
e. Colchicine binds to the Golgi complex and disperses it.
b
In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell?
a. individually by diffusion
b. in groups of ten
c. inside transport vesicles
d. inside the Golgi complex
c
Structures that move from the cell body of a neuron down the axon toward the neuron terminals are said to move in a(n) \_\_\_\_\_\_\_\_\_ direction. a. retrograde b. anterograde c. astronomical d. radial b
b
The movement of endocytic vesicles formed in the neuron terminals from the synapse to the cell body is said to be in a(n) ________ direction.
a. retrograde
b. anterograde
c. astronomical
d. radial
e. intergrade
a
Which of the following is known to be transported at one time or another by molecular motors?
a. synaptic vesicles
b. mitochondria
c. chromosomes
d. lysosomes
e. all of the above
e
Which of the following is a family of molecular motors?
a. myosins
b. kinesins
c. dyneins
d. motorins
e. a, b and c
e
Which of the following serve as tracks for molecular motors?
a. intermediate filaments
b. microtubules
c. microfilaments
d. a, b and c
e. b and c
e
Which of the following molecular motors is associated with microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c
d
Which of the following molecular motors is associated with microfilaments?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c
c
Which of the following molecular motors is associated with intermediate filaments?
a. kinesins
b. dyneins
c. myosins
d. none of the other answers
e. a, b and c
d
Which of the following molecular motors is known to travel in a retrograde direction along microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c
b
Which of the following molecular motors is known to travel in an anterograde direction along microtubules?
a. kinesins
b. dyneins
c. myosins
d. a and b
e. a, b and c
a
The heads of kinesin-like proteins have fairly closely related amino acid sequences but diverse tail sequences. What is the explanation for this seeming contradiction?
a. The similarity of kinesin-like protein heads and the variation in their tails are purely random.
b. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
c. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
d. The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
e. The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
b
What is the direct source of energy that powers molecular motors?
a. hydrolysis of GTP
b. hydrolysis of ATP
c. proton gradient
d. H+ gradient
e. condensation of ATP
b
What part of the molecular motor kinesin is responsible for binding to the cargo to be hauled?
a. the motor domain
b. the neck
c. the rodlike stalk
d. the fan-shaped tail
e. all of the above
d
Microscopic beads are coated with kinesin and subjected to an in vitro mobility assay. In which direction and along what cytoskeletal element are they seen to move?
a. toward the plus end of the microtubule
b. toward the plus end of the microfilament
c. toward the minus end of the microtubule
d. toward the minus end of the microfilament
e. toward the plus end of the intermediate filament
a
Kinesin movement along a microtubule is said to be ________ meaning that it can move long distances along an individual microtubule without falling off.
a. excessive
b. processive
c. depressive
d. progressive
e. egressive
b
Each step that kinesin makes along a microtubule is about 8 nm. How many tubulin subunits correspond to this distance?
a. 1
b. 3
c. 4
d. 2
e. 5
d
A small subfamily of kinesins moves toward the minus end of a microtubule, while the rest move toward the plus end. When the neck and stalk of a plus-directed kinesin is joined to the head of a minus-directed kinesin, in what direction will the hybrid motor protein travel along a microtubule?
a. toward the minus-end of the microtubule
b. in a retrograde direction
c. toward the plus-end of the microtubule
d. in an anterograde direction
e. c and d
e
Cytoplasmic dynein moves __________ in a __________ direction.
a. regressively, retrograde
b. processively, anterograde
c. processively, retrograde
d. retrogradely, processive
e. hurriedly, anterograde
c
Cytoplasmic dynein moves ________.
a. organelles down the axon toward the cell body
b. organelles down the axon toward the synapse
c. lysosomes from the cell periphery to the cell center
d. endosomes from the cell center toward the cell periphery
e. a and c
e
Cytoplasmic dynein requires a multisubunit adaptor called _______ to bind its cargo. It cannot bind its cargo directly. This adaptor may also regulate dynein activity and help bind the motor protein to the microtubule.
a. dynactin
b. dynamin
c. stratin
d. dyneinactin
e. didactin
a
The slower phase of microtubule assembly in which a small portion of the microtubule is initially formed is called \_\_\_\_\_\_\_\_\_\_\_. a. elongation b. nucleation c. centrosome d. translation e. insulation
b
There is a variety of specialized cellular structures that direct the polymerization of microtubules, the best studied one of which is the centrosome. The general name of these structures is _________.
a. microtubule-organizing centers
b. MTOCs
c. a and b
d. nucleus
e. mitochondrion
c
The structure that contains two barrel-shaped centrioles surrounded by amorphous, electron-dense pericentriolar material is called a(n) _________.
a. centrosome
b. nucleus
c. pericentriosome
d. spindle
e. aster
a
What word below describes the arrangement of microtubules in a centriole?
a. doublet
b. triplet
c. pinwheel
d. perpendicular
e. b and c (both)
e
Which of the following statements is not true about a cilium?
a. A cilium helps move the cell from place to place b. A cilium helps move fluid and particulate material past the cell c. Microtubules within a cilium are arranged in a structure called an axoneme. d. Microtubules slide past each other within a cilium with the aid of the motor protein kinesin. e. A microtubule organizing center is located at the base of a cilium.
d
The cross-bridges that hold intermediate filaments together are composed of _______.
a. filamentin b. plectin c. ascriptin d. dynein e. myosin
b
What causes myosin heads to bend toward the sarcomere center after cross-bridges between actin filaments and myosin heads form?
a. a conformational change in myosin b. a conformational change in actin filaments c. a conformational change in titin d. addition of amino acids to the myosin head e. chemical alteration of the actin filament
a
What adaptation did organisms on Earth make to the presence of O2 in the atmosphere?
a. They got smaller.
b. They evolved mechanisms that blocked O2 entry into many oxygen-sensitive organelles.
c. They evolved metabolic pathways that used O2 to extract more energy from foodstuffs.
d. They evolved metabolic pathways that used O2 to extract more H2 from foodstuffs.
e. They evolved mechanisms to convert O2 into free radicals that are less harmful to cell’s
membranes and proteins.
c
What is the final electron acceptor in the electron transport chain of mitochondria?
a. water b. carbon dioxide c. carbon monoxide d. hydrogen e. oxygen
e
What properties do mitochondria share with peroxisomes?
a. Both form by splitting from preexisting organelles. b. Both import preformed proteins from the cytosol. c. Both are involved in oxidative metabolism. d. a and b. e. a,b, and c
e
As glucose is catabolized, the energy is captured by:
a. forming ADP and by oxidizing adenine dinucleotides
b. forming ATP and by oxidizing adenine dinucleotides
c. forming ADP and by reducing adenine dinucleotides
d. forming ATP and by reducing adenine dinucleotides
e. forming ATP and by transforming adenine dinucleotides
d
Green plants _____ most of the green light to which they are exposed. In the presence of pure
green light, plants can still drive photosynthesis, with the aid of the ______ pigments.
a. absorb, chlorophyll
b. reflect, chlorophyll
c. absorb, carotenoid
d. reflect, carotenoid
e. absorb, xanthophyll
d
Organisms that depend on an external source of organic compounds are called _________.
a. autotrophs b. heterotrophs c. chemotrophs d. phototrophs e. externotrophs
b
Based on cell activities readily visible in the light microscope, there are two major cell cycle phases, ________ and __________.
a. M phase, cytokinesis b. interphase, cytokinesis c. M phase, C phase d. M phase, interphase e. C phase, interphase
d
Which type of gene regulatory element is typically most distant from the actual start
of the coding region of the gene?
a. the proximal promoter
b. the TATA box
c. the GC box
d. the enhancer element
e. the distal promoterd
What are the processes, sequentially, that decode DNA into an RNA sequence and then decode the RNA into a polypeptide?
a. translation followed by transcription b. transcription followed by translation c. transduction followed by protein synthesis d. transcription followed by transduction e. transliteration followed by transformation
b
Which of the following is NOT an example of a reaction known to be catalyzed by a ribozyme?
a. cleavage and ligation of phosphodiester bonds needed for RNA splicing b. attachment of glycerol to fatty acids c. formation of peptide bonds during protein synthesis d. none of the above are examples of ribozyme function e. a ,b, and c are all examples of ribozyme function
b
Proteins synthesized in association with the endoplasmic reticulum are synthesized
by:
a. ribosomes within the endoplasmic reticulum, with the messenger RNA passed through a translocon in the membrane.
b. ribosomes initially free in the cytosol, but guided to the endoplasmic reticulum when the nascent protein contains a signal sequence at the amino-terminus.
c. ribosomes permanently attached to the endoplasmic reticulum membrane.
d. ribosomes that first attach to the endoplasmic reticulum and then to mRNA which they translate.
e. free ribosomes within the cisterna of the endoplasmic reticulum.
b
In what part of the cell are new membranes synthesized?
a. the rough endoplasmic reticulum
b. the smooth endoplasmic reticulum
c. the cytoplasm
d. the ribosomes
e. the plasma membrane
b
. The following mechanisms have been implicated in maintaining proteins in a particular membrane-bound compartment, with the exception of:
a. retention of resident molecules by limiting their inclusion in transport vesicles b. degradation of proteins that drift out of the compartment in which they normally reside c. retention of some proteins that become part of complexes too large to get into a budding transport vesicle. d. retrieval of escaped molecules, bringing them back to their normal compartment of residence e. none of the above mechanisms explain how certain proteins are maintained in organelles
c
What is the source of energy for the process of co-transport?
a. ATP
b. light
c. electron transport
d. the concentration gradient of the substance being transported
e. the concentration gradient of a second substance
e
What kind of response is not often initiated when signals traveling down signaling pathways reach their target proteins, which are usually involved in basic cellular processes?
a. a change in gene expression b. a change in ion movements across membranes c. cessation of DNA synthesis and degradation of DNA d. a change in gene expression e. an alteration of the activity of metabolic enzymes through changes in phosphorylations
c
Which hormone receptor is a receptor tyrosine kinase?
a. epinephrine receptor
b. adrenalin receptor
c. glucocorticoid receptor
d. insulin receptor
e. none of the above
d
What advantage do the cristae confer on the mitochondria?
a. They allow the mitochondria to shrink. b. They greatly increase the surface area for aerobic respiration machinery. c. They confer resiliency on the cells. d. They allow swelling of mitochondria. e. They activate the matrix.
b
What metabolic process below do all eukaryotic green algae and higher plants have in common?
a. glycolysis b. photosynthesis c. transcription d. translation e. all of the above
e
What is the direct source of energy that powers molecular motors?
a. hydrolysis of GTP b. hydrolysis of ATP c. proton gradient d. H+ gradient e. condensation of ATP
b
Why do tumor cells die after exposure to drugs that either disrupt or stabilize the structure of microtubules?
a. Mitosis is stopped in the presence of the drugs. b. Tumor cells attempt cell division, even in the absence of a functional spindle, killing the cells. c. There is a checkpoint that prevents the entry into mitosis. d. The drugs cause the disintegration of the tumor cell membranes. e. none of the above
b
What explains the fact that plants lack the specialized junctions seen in animal cells?
a. the presence of the large central vacuole b. the presence of chloroplasts c. the presence of the cell wall d. the presence of mitochondria e. the absence of centrioles, basal bodies, cilia and flagellae
c
Which protein below is the single most abundant protein in the human body?
a. hemoglobin
b. collagen
c. osteogenin
d. actin
e. cartilage
b
- Which of the following is not, strictly speaking, a cell adhesion molecule?
a. keratin
b. connexin
c. cadherin
d. integrin
e. selectin
a
Match the cell components in column A with the single best descriptions from column B (note excess items in column B – please choose carefully). Please write your answer on the blank lines – do not draw lines between columns. [0.5 marks per component]
____ rough ER A. anterograde vesicle movement
____ chloroplast matrix B. site of protein translation
____ endosome C. site of protein destruction
____ COP-II coated vesicle D. site of dark reaction
____ Kinesin E. site of receptor intake into cell
____ actin F. rRNA synthesis
____ selectin G. most abundant protein in the
human body
____ collagen H. component of microfilaments
I. a cell adhesion molecule J. a microtubule-binding motor protein
rough ER: B chloroplast matrix: D endosome: E COP II coated vesicle: A kinesin: J actin: H selectin: I collagen: G
Provide one function of the following items: [6 marks in total] (each is worth 1 mark)
a. Caspase:
b. Fibronectin
c. Gap Junction:
d. Peroxisome:
e. cAMP:
f. Microtubule associated protein (MAP):
Caspase: proteases that induce apoptosis or cell death
Fibronectin: helps guide cells as they move through the body
Gap Junction: allows passage of small water-soluble molecules from cell to cell
Peroxisome: converts hydrogen peroxide to a less toxic form
cAMP: a secondary messenger that induces cell movement of the soil living amoeba wherever there are high concentrations of cAMP
MAP: help support and stabilize microtubules, even in the absence of GTP
Name two structures within a cell that can destroy proteins and give one reason why some proteins need to be destroyed. [3 marks]
- proteosome and lysosome
- because they become worn out, mutated, oxidized, misfolded
Name two microtubule-based cell motility structures and provide one difference that distinguishes them from each other. [2 marks]
cilia: short but many
flagella: long but only one or two
Name one signaling chemical, identify its type of receptor, and name one downstream effect that would follow from this signal-receptor interaction.
- signaling chemical: insulin
- receptor: RTK
- downstream effect: decrease blood glucose levels by producing glycogen and fat, as well as inhibiting gluconeogenesis
Ribozymes
a) ribozymes are catalytic RNA molecules;
b) they are found in the spliceosome, where they mediate RNA cutting and ligating, to cut out the introns and to glue the exons together;
c) there is a ribozyme in the ribosome that mediates peptide bond formation during translation
