BIOL 215 Exam 4
The motor proteins interacting with the MTs in axonemal structures are the... a. dyneins b. myosins c. kinesins d. all of the above e. A and B
Dyneins
True or false? The ligand-binding domain of a GPCR was initially extending into the cytoplasm as it was transported to the PM in a transport vesicle.
False
True or false? The minus end of microtubules and microfilaments is so named because subunits are lost and never added there.
False
True or false? The production of ATP during aerobic respiration is called photophosphorylation.
False
True or false? Viruses are considered living organisms.
False
True or false? Regarding a biological process that requires active transport, the free energy change is positive.
True
True or false? The fight or flight response involves endocrine signaling.
True
True or false? Treadmilling is not observed as frequently in vivo as it is in vitro because the minus ends of most MTs are anchored in the y-tubulin ring complexes of the MTOCs inside the cell.
True
What causes catastrophe of the microtubule in vitro? a. the lack of tubulin heterodimers b. non-motor microtubule associated proteins (MAPs) c. mutation of the β-tubulin d. GTP hydrolysis
GTP hydrolysis
What is the role of GTP in microtubule polymerization? a. GTP is a second messenger that signals the need for polymerization/de-polymerization. b. GTP stabilizes the tip of the microtubule, allowing more monomers to be added. c. GTP hydrolysis provides the energy for the polymerization of the microtubule. d. GTP binds the alpha and beta tubulin subunits together to form the tubulin monomer.
GTP stabilizes the tip of the microtubule, allowing more monomers to be added.
NAD+ is NOT a product of the TCA cycle. a. True b. False c. Depends on the availability of oxygen
True
True or false? A GPCR is involved in the vasodilation pathway.
True
True or false? AMP cannot propagate a signal transduction cascade mediated by cAMP.
True
True or false? Cells within a tissue need to communicate with each other in order for the tissue to function properly.
True
Histamine is a chemical substance released in inflammatory and allergic responses. The histamine H1 receptor is a G protein-coupled receptor that activates phospholipase C in response to the binding of histamine. Put the following labels in order to show the process of histamine signal transduction from the H1 receptor. Not all labels will be used. a. Calcium ions flow through the ligand-gated ion channel. b. Phosphorylation cascade leads to the activation of a cellular response. c. Calcium ion concentration increases in the cytosol. d. Enzyme cleaves PIP2, forming DAG and IP3. e. IP3 binds to a ligand-gated ion channel in the ER membrane. f. Calcium ions activate a protein, leading to a cellular response.
1. Enzyme cleaves PIP2, forming DAG and IP3. 2. IP3 binds to a ligand-gated ion channel in the ER membrane. 3. Calcium ions flow through the ligand-gated ion channel. 4. Calcium ion concentration increases in the cytosol. 5. Calcium ions activate a protein, leading to a cellular response.
The critical concentration of GTP-tubulin heterodimers in vitro has been measured and found to be 200 nM and 1000 nM for the plus and minus ends, respectively. Which of the following GTP-tubulin heterodimer concentrations would favor treadmilling? a. 1 pM b. 1 nM c. 650 uM d. 650 nM e. 1200 nM
650 nM
How many membrane-spanning segments do all GPCRs contain? a. 1 b. 3 c. 7 d. 12 e. It's variable
7
True or false? DAG is hydrophobic, while IP3 is hydrophilic.
True
What is a hepatocyte? a. A cell from a horse b. A stem cell that gives rise to blood cells c. A cell infected with the hepatitis A virus d. a type of helper T cell e. a liver cell
A liver cell
Comparing the interface between CoV and ACE2 to that between ACE2 and the novel CoV-2 has revealed several variations that appear to strengthen the binding between CoV-2 and ACE2. For example, a valine in CoV was replaced with a lysine in CoV-2. What sort of change has taken place in CoV-2 with this substitution? a. a nonpolar amino acid in CoV was replaced with a basic amino acid in CoV-2 b. a polar amino acid in CoV was replaced with a nonpolar amino acid in CoV-2 c. a basic amino acid in CoV was replaced with a nonpolar amino acid in CoV-2 d. a nonpolar amino acid in CoV was replaced with an acidic amino acid in CoV-2 e. an acidic amino acid in CoV was replaced with a basic amino acid in CoV-2
A nonpolar amino acid in CoV was replaced with a basic amino acid in CoV-2
Which is an example of endocrine signaling? a. A peptide made in the liver promotes uptake of amino acids from the blood throughout the body b. A steroid causes adjacent cells to become pigmented c. A derivative of tryptophan diffuses to neighboring cells to trigger signs of inflammation d. both A and B e. both A and C
A peptide made in the liver promotes uptake of amino acids from the blood throughout the body
True or false? GPCRs directly interact with primary messengers.
True
PKA targets phosphorylase kinase. The action of PKA on phosphorylase kinase then leads to the [ ] of the [ ] pathway. a. activation; glycogenolysis b. deactivation; glycogenolysis c. activation; glycogenesis d. deactivation; glycogenesis e. Both A and D
Activation; glycogenolysis
Which of the following experimental strategies could be used to block the IP3 branch but not the DAG branch of the signaling pathway that involves phosphatidylinositol-4,5-bisphosphate (PIP2)? a. addition of a cAMP phosphodiesterase inhibitor b. blocking the GPCR involved c. inhibition of protein kinase A d. inhibition of phospholipase C e. adding an antagonist of the IP3 receptor
Adding an antagonist of the IP3 receptor
Cell signaling involves converting extracellular signals to specific responses inside the target cell. Different molecules are involved at each stage of the process. In this activity, you will sort items based on which stage they are involved in: reception, transduction, or response. Choose the items that are involved in transduction. a. adenylyl cyclase b. G-protein coupled receptor c. protein synthesis d. second messenger e. signaling molecule f. IP3 g. Ca2+ h. cAMP i. phosphorylation cascade j. receptor tyrosine kinase
Adenylyl cyclase; second messenger; IP3; Ca2+; cAMP; phosphorylation cascade
Where is epinephrine synthesized in our bodies? a. pituitary gland b. hypothalamus c. red blood cells d. adrenal gland e. kidney tubules
Adrenal gland
In order for tissues to form, cells must... a. Recognize each other b. Communicate with each other c. Adhere to each other d. All of the above
All of the above
When nitric oxide is used in the dilation of smooth muscle cells, which of the following would interfere with the relaxation of the smooth muscle cells? Inhibitors of... a. calmodulin b. guanylyl cyclase c. calcium release by the ER d. nitric oxide e. all of the above
All of the above
All of the following are activated in an insulin-stimulated cell except... a. AKT kinase b. GLUT c. PI3-kinase d. glycogenesis e. All of the above are activated in response to insulin stimulation
All of the above are activated in response to insulin stimulation
Which of the following functions is NOT associated with the cytoskeleton in eukaryotic cells? a. cell locomotion b. organizing contents of the cytoplasm c. the beating of cilia or flagella d. determining the shape of animal cells e. all of the above are functions of the cytoskeleton
All of the above are functions of the cytoskeleton
Yogurt production involves all of the following except... a. decreasing pH of the milk b. lactate fermentation c. lactose catabolism d. glycolysis e. all of the above are involved in yogurt production
All of the above are involved in yogurt production
Which of the following is NOT a role of the cytoskeleton in the cell? a. Provides cells with mechanical strength b. Organize internal contents c. Cell division d. Cell motility e. All of the above are roles of the cytoskeleton
All of the above are roles of the cytoskeleton
CAMS, selectins, and integrins are all types of cell adhesion proteins. Such proteins share all of the following characteristics EXCEPT... a. they have a cytoplasmic domain that directly or indirectly interacts with cytoskeletal elements b. they have an extracellular domain involved in adhesion to neighboring cells through other adhesion molecules and/or ECM components c. they are involved in cell adhesion d. they are integral membrane proteins e. all of the above are true
All of the above are true
CAMS, selectins, and integrins are all types of cell adhesion proteins. Such proteins share all of the following characteristics except... a. they are integral membrane proteins b. they have an extracellular domain involved in adhesion to neighboring cells through other adhesion molecules and/or ECM components c. they have a cytoplasmic domain that directly or indirectly interacts with cytoskeletal elements d. they went through the endomembrane system e. all of the above are true
All of the above are true
Which of the following is NOT a function of the cytoskeleton? a. cell shape b. vesicle transport c. cell division d. cell locomotion e. all of the above involves the cytoskeleton
All of the above involves the cytoskeleton
Which of the following regarding channel proteins is false? a. can not be used to actively transport an ion into a cell b. do not directly interact with the solute being transported c. are regulated by IP3 d. are allosterically regulated e. all of the above statements are true
All of the above statements are true
Select all of the following that apply to cAMP. a. is part of the signal transduction cascade resulting in vasodilation b. allosterically activates protein kinase A c. acts as a non-competitive inhibitor of protein kinase A d. is a type of secondary messenger e. inhibits protein kinase A f. is part of the fight or flight signal transduction cascade g. is produced by protein kinase A
Allosterically activates protein kinase A Is a type of secondary messenger Is part of the fight or flight signal transduction cascade
Hyperphosphorylation of tau is associated with... a. hypercholesterolemia b. hyperglycemia c. Alzheimer's disease d. leukemia e. Creutzfeld-Jakob disease
Alzheimer's disease
Microfilaments... a. are composed of two helical strands of actin monomers oriented in the same direction b. are composed of two helical antiparallel strands of actin monomers c. polymerize at the same rate from both ends of the filament d. are composed of eight protofilaments joined end to end with staggered overlaps e. are composed of α- and β-actin dimers f. more than one of the above
Are composed of two helical strands of actin monomers oriented in the same direction
Phalloidin is a peptide that can be conjugated to fluorescent dyes, such as fluorescein, and used to label actin in cells. Phalloidin-fluorescein was added to dividing, ciliated cells in culture. Where will the fluorescence be localized in the cells when looking at the treated cultures using fluorescence microscopy? a. cilia b. at the inner surface of the inner nuclear membrane c. at the inner surface of the plasma membrane d. microtubule-organizing centers (MTOC) e. more than one of the above
At the inner surface of the plasma membrane
Hyperglycemia induces the pancreatic [ ] cells to produce and secrete [ ]. a. beta; insulin b. beta; glucagon c. alpha; insulin d. alpha; glucagon e. Both A and D occur during hyperglycemia
Beta; insulin
Where do we find endothelial tissue? Lining the... a. Small intestine b. Kidneys c. Pancreas d. Blood vessels e. Mouth
Blood vessels
By replacing a valine (non-polar) with a lysine (basic) in CoV-2, this, among other substitutions, appears to have strengthened the interaction between CoV-2 and ACE2, thus making the virus more stably attached to host cells. The lysine on CoV-2 is shown to interact with an aspartate on ACE2. What type of interaction(s) would take place between these two amino acids? a. ionic b. hydrogen bond c. disulfide bridge d. nonpolar repulsions e. both A and B
Both A and B
Where do we find the cytoskeleton in our cells? a. In the cytoplasm b. In the nucleus c. Outside of the plasma membrane, forming the extracellular matrix d. All of the above e. Both A and B
Both A and B
GPCRs directly interact with which type of signaling molecules? a. G proteins b. adenylyl cyclase c. phospholipase C d. primary messengers e. Both A and D
Both A and D
The SARS-CoV/CoV-2 spike protein is a type of [ ] that interacts with ACE2 host receptors. a. glycoprotein b. enzyme c. receptor d. ligand e. Both A and D f. Both A and C g. A, C, and D
Both A and D
Which amino acid(s) would you expect to predominate the membrane-spanning segments? a. alanine b. aspartate c. glutamine d. leucine e. both A and D
Both A and D
The SARS-CoV/CoV-2 spike protein is a type of glycoprotein, which is a polypeptide with a [ ] attached to it. a. lipid b. phosphate c. nucleic acid d. carbohydrate e. none of the above
Carbohydrate
What explains increased concentrations of Ca2+ in the ER? a. Calcium levels in the blood or other body fluids are extremely low b. Calcium ions are actively imported from the cytoplasm into the ER c. The calcium ions are recycled from other molecules in the ER d. Calcium cannot enter the plasma membrane through ion channels e. Calcium concentration is kept low in the cytoplasm because of its high usage levels
Calcium ions are actively imported from the cytoplasm into the ER
What is the role of a kinase? a. catalyze the hydrolytic remove of phosphate groups from target molecules b. catalyze the addition of phosphate groups to target molecules, involving ATP c. catalyze the addition of phosphate groups to target molecules, involving inorganic phosphate (Pi) d. catalyze the breakdown of nucleic acids e. catalyze the hydrolysis of target molecules
Catalyze the addition of phosphate groups to target molecules, involving ATP
Which of the following cytoskeletal components are involved in propelling substances across cell surfaces? a. flagella b. microfilaments c. myosins d. cilia e. both A and C
Cilia
Which of the following is involved in propelling mucus across the epithelial layer of the trachea? a. flagella b. cilia c. microfilaments d. all of the above e. both B and C
Cilia
Which of the following structures is (are) involved in the movement of mucus across an epithelial layer? a. cilia b. flagella c. microfilaments d. all of the above e. both A and C
Cilia
ACE2 contains a PEPTIDASE domain (PD), which normally acts on angiotensin and other related endogenous substrates. What does the PD domain do to its substrates? a. converts substrates into SARS-CoV/CoV-2 b. covalently attaches substrates to the cell membrane c. cleaves substrates into smaller molecules d. glycosylates substrates e. polymerizes substrates into larger molecules
Cleaves substrates into smaller molecules
The ligand-binding domain of the ACE2 receptor binds to the SARS-CoV/CoV-2 spike protein, specifically to the receptor-binding domain (RBD) of the spike protein. The ACE2 ligand-binding domain emerges from the plasma membrane of host cells. Which translational pathway synthesized the ACE2 receptor? a. co-translational b. poly-translational c. cytoplasmic (default) d. post-translational e. none of the above
Co-translational
Which translational pathway would be used by the cell to synthesize a cell adhesion molecule? a. co-translational b. co-transcriptional c. post-transcriptional d. post-translational e. any of the above
Co-translational
Which of the following is a product of the TCA cycle? Select all that apply. a. CoA b. O2 c. FADH2 d. NADH e. CO2
CoA; FADH2; NADH; CO2
What category of tissue is blood? a. Nervous b. Connective c. Muscle d. Epithelia e. None of the above, blood is not a tissue
Connective
Which of the following properties are shared by myosins, kinesins, and dyneins? Select all that apply. a. considered accessory proteins b. found in axoneme structures c. involved in cell crawling d. bind to microtubules e. ATPase activity f. an individual protein can move back and forth along a cytoskeletal element
Considered accessory proteins ATPase activity
What effect does angiotensin have on blood vessels? a. increased intermediate filament production in blood vessels b. dilation of blood vessels c. branching of blood vessels d. replication of blood vessels e. constriction of blood vessels
Constriction of blood vessels
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures? a. ribosomes b. cellulose fibers in the cell wall c. membrane proteins d. sites of energy production in cellular respiration e. cytoskeletal structures
Cytoskeletal structures
True or false? Intermediate filaments do not use motor proteins.
True
After PIP2 is cleaved, where will you find DAG and IP3? a. Both remain in the plasma membrane b. Both diffuse through the cytoplasm c. IP3 remains in the plasma membrane, DAG diffuses through the cytoplasm d. DAG remains in the plasma membrane, IP3 diffuses through the cytoplasm
DAG remains in the plasma membrane, IP3 diffuses through the cytoplasm
Protein kinase A will [ ] glycogen synthase. a. deactivate b. activate
Deactivate
If the [free tubulin]cyt = 3 uM, what will happen to that concentration as MT growth occurs? The [free tubulin]cyt will... a. Increase b. Decrease c. Stay the same
Decrease
What is the correct order of assembly of intermediate filaments? a. dimer, protofilament, intermediate filament b. tetramer, dimer, protofilament, intermediate filament c. protofilament, dimer, tetramer, intermediate filament d. dimer, tetramer, protofilament, intermediate filament
Dimer, tetramer, protofilament, intermediate filament
Using nanoengineering techniques, it is possible to attach magnetic beads to the surface of cells to measure their resistance to applied forces. It is also known that the toxin acrylamide can depolymerize intermediate filaments, such as keratin. Treating cells with acrylamide would have what effect on the mechanical rigidity of a skin cell, i.e. keratinocytes? a. Disrupting intermediate filaments will result in cells that are less susceptible to mechanical forces. In the case of the keratinocytes, disrupting keratin, a key IF in these cells, would result in the production of microfilaments and thus very tough cells. More force would need to be applied using the magnetic beads to damage them or change their shape. b. Disrupting intermediate filaments will result in cells that are more susceptible to mechanical forces. In the case of the keratinocytes, disrupting keratin, a key IF in these cells, would result in very fragile cells. Less force would need to be applied using the magnetic beads to damage them or change their shape. c. Disrupting intermediate filaments will have no effect on their susceptibility to mechanical forces. In the case of the keratinocytes, disrupting keratin, a key IF in these cells, would not change the amount of force needed to be applied using the magnetic beads to damage them or change their shape.
Disrupting intermediate filaments will result in cells that are more susceptible to mechanical forces. In the case of the keratinocytes, disrupting keratin, a key IF in these cells, would result in very fragile cells. Less force would need to be applied using the magnetic beads to damage them or change their shape.
Which motor protein would carry a vesicle towards the centrosome? a. kinesin b. myosin c. dynein d. kinase e. not enough information given
Dynein
The synthesis of ATP by oxidative phosphorylation is based on several lines of experimental evidence. Which of the following statements regarding experimental observations does not support the oxidative phosphorylation model? a. Artificial proton gradient established by the addition of an acid can drive ATP synthesis in the absence of electron transport b. Uncoupling agents that abolish the proton gradient also abolish ATP synthesis c. Oxidative phosphorylation requires a membrane enclosed compartment d. The proton gradient established by electron transport has enough energy to drive ATP synthesis e. Electron transport increases the pH of the intermembrane space.
Electron transport increases the pH of the intermembrane space.
All of the following are examples of local-signaling pathways except... a. paracine b. cell-cell contact c. gap junctions d. endocrine e. synpase
Endocrine
Angiotensin is a peptide hormone produced by the liver. It circulates in the cardiovascular system and binds to ACE2 receptors on various cell types, such as pulmonary, endothelial and cardiac cells. Angiotensin is involved in which type of signaling? a. synaptic b. paracrine c. endocrine d. gap junctions e. cell-cell
Endocrine
Epinephrine is considered what type of signaling molecule? a. GPCR b. paracrine hormone c. G-protein ligand d. endocrine hormone e. neurotransmitter
Endocrine hormone
Virus particles are too small to be seen by the naked eye or a typical light microscope. The SARS-CoV-2 (the virus responsible for the current pandemic) has been shown to range in size from 70 - 90 nm. Entry of SARS-CoV-2 into host cells has been shown to involve virus particles enclosed in plasma membrane-derived vesicles inside the infected host cells. These vesicles are known to interact with endosomes inside the infected cells. What does this suggest about the method of entry by the virus particles? a. Particles passed through the membrane by facilitated diffusion b. Entry involves receptor-mediated endocytosis c. Entry occured by phagocytosis d. Particles passed through the membrane by simple diffusion e. Virus particles are not entering the cell. The infection occurs in the extracellular space
Entry involves receptor-mediated endocytosis
All of the following are considered secondary messengers except... a. DAG b. epinephrine c. Ca2+ d. cAMP e. IP3 f. All of the above are secondary messengers
Epinephrine
At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects? a. Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding b. Estrogen is produced in very large concentration and therefore diffuses widely c. Estrogen is kept away from the surface of any cells not able to bind it at the surface d. The subcomponents of estrogen, when metabolized, can influence cell response e. Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding
Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding
If a protein contains only an internal start-transfer sequence, where would the C terminus be found? a. RER lumen b. cytoplasm c. extracellular space d. Golgi membrane e. Not enough information given
Extracellular space
True or false? After being transported into the mitochondrion, the pyruvate molecule will enter the TCA cycle.
False
True or false? Antibiotics can be used to eliminate a viral infection.
False
True or false? Chemicals that block the assembly of microtubules or microfilaments would cause little effect on the cell.
False
True or false? During photophosphorylation, ADP and Pi are combined in the thylakoid lumen.
False
True or false? During the Cori cycle, glucose is converted into lactate in the liver.
False
True or false? E is DIRECTLY needed for Ca2+ to enter the cell during odorant response. (hint: Ca2+ enters the ciliary lumen WITH Na+)
False
True or false? GPCRs contain 12 membrane-spanning domains.
False
True or false? If the concentration of ATP inside a cell increases, the TCA cycle will be activated.
False
True or false? In animal cells, microfilaments are organized by the centrosome.
False
True or false? Lactose is considered a polysaccharide.
False
True or false? Plants do not utilize long-distance signaling.
False
True or false? Tau is a protein associated with microfilaments.
False
Cell signaling involves converting extracellular signals to specific responses inside the target cell. Different molecules are involved at each stage of the process. In this activity, you will sort items based on which stage they are involved in: reception, transduction, or response. Choose the items that are involved in reception. a. adenylyl cyclase b. G-protein coupled receptor c. protein synthesis d. second messenger e. signaling molecule f. IP3 g. Ca2+ h. cAMP i. phosphorylation cascade j. receptor tyrosine kinase
G-protein coupled receptor; signaling molecule; receptor tyrosine kinase
A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to [ ] receptors. a. intracellular b. G-protein linked c. ion-channel d. steroid e. receptor tyrosine kinase
G-protein linked
Epinephrine acts as a signal molecule that attaches to [ ] proteins. a. ion-channel receptor b. nuclear receptor c. receptor tyrosine kinase d. intracellular receptor e. G-protein linked receptor
G-protein linked receptor
What type of receptor is involved in detecting this particular odorant? (hint: G-alpha, adenylyl cyclase, and cAMP are involved) a. cytoplasmic steroid receptor b. GPCR c. adenylyl cyclase d. tyrosine kinase receptor e. not enough information given
GPCR
Which of the following is a correct association? a. phosphodiesterase activity and the removal of phosphate groups b. phosphorylase activity and the catabolism of glucose c. kinase activity and the addition of a tyrosine d. GTPase activity and the hydrolysis of GTP to GDP e. adenylyl cyclase activity and the conversion of cAMP to AMP
GTPase activity and the hydrolysis of GTP to GDP
The cleavage of glycogen by glycogen phosphorylase releases... a. cellulose b. galactose-1-phosphate c. glucose-1-phosphate d. fructose-1-phosphate e. nothing; glycogen phosphorylase cannot glycogen
Glucose-1-phosphate
What happens during glycogenolysis? a. CO2 is reduced to form carbohydrates b. glycogen is phosphorolyzed to release glucose-1-phosphate c. glycogen is hydrolyzed to release glucose-1-phosphate d. glucose is oxidized, producing ATP by oxidative phosphorylation e. glucose is synthesized from non-carbohydrate sources
Glycogen is phosphorolyzed to release glucose-1-phosphate
Which enzyme catalyzes glycogenolysis? a. glycogen phosphorylase b. phosphorylase phosphatase c. protein kinase A d. phosphorylase kinase e. glycogen synthase
Glycogen phosphorylase
Glycogenesis is catalyzed by which enzyme? a. glycogen phosphorylase b. phosphorylase phosphatase c. glycogen synthase d. protein kinase A e. phosphorylase kinase
Glycogen synthase
Glycogen synthase catalyzes which reaction? a. Glycolysis b. Gluconeogenesis c. Glycogenolysis d. Glycogenesis e. Glyconeolysis
Glycogenesis
What reaction does glycogen synthase catalyze? a. glycogenesis b. gluconeogenesis c. glycolysis d. glycogenolysis e. glycogen decarboxylation
Glycogenesis
One treatment of type II diabetes involves reducing the activity of the liver. Reduction in which of the following pathways would help alleviate type II diabetes? a. glycolysis b. glycogenolysis c. glycogenesis
Glycogenolysis
Microfilaments and microtubules are similar in that both [ ]. Select all choices that apply. a. form hollow tubes found in the cytosol b. are involved in determining the shape of cells c. use kinesins and dyneins to mobilize transport vesicles d. are composed of subunits bound to GTP e. have intrinsic directionality because one end of each structure is distinct from the other end
Have intrinsic directionality because one end of each structure is distinct from the other end
Diabetes is a result of chronically [ ] blood glucose levels. a. High b. Low
High
True or false? Intermediate filaments lack structural polarity.
True
Is the [Ca2+]EC higher or lower than the cytoplasm? a. higher b. lower
Higher
Is the [Ca2+]ER higher or lower than the cytoplasm? a. higher b. lower
Higher
During the day, the pH of the stroma is [ ] the thylakoid lumen. a. the same as b. higher than c. lower than
Higher than
When blood glucose levels are high, this is called... a. hypotonic b. hyperglycemic c. isoglycemic d. hyperglycan e. hypoglycemic
Hyperglycemic
PKA also phosphorylates glycogen synthase. The phosphorylation will [ ] glycogen synthase. a. activate b. inactivate c. not enough information given
Inactivate
Yogurt production involves all of the following EXCEPT... a. lactate fermentation b. increasing pH of the milk c. glycolysis d. lactose catabolism e. all of the above are involved in yogurt production
Increasing pH of the milk
What does IP3 stand for? a. inositol phosphate b. phosphatidylinositol c. inositol triphosphate d. inositol diphosphate e. inositol acylglycerol
Inositol triphosphate
A virus genome is engineered so that mature viral particles will express Green Fluorescent Protein (GFP) on the surface of the particles. This will enable researchers to visualize green fluorescence wherever the virus particles are found inside of living cells. A particular virus, ZZY, is thought to enter cells by receptor-mediated endocytosis. There is some dispute that this virus is also able to fuse to the plasma membrane of host cells in order to gain direct access across the plasma membrane into the cell. If both entry mechanisms are occuring, where would you expect to find green fluorescence? a. inside both endocytic vesicle and the cytoplasm b. inside the cytoplasm only c. inside of endocytic vesicles only
Inside both endocytic vesicle and the cytoplasm
The interaction between which types of adhesion molecules are required to STOP a leukocyte prior to extravastion? a. integrins on leukocytes, I-CAMS on endothelial cells b. GPLRs on leukocytes, G-proteins on endothelial cells c. L-selectins on leukocytes, I-CAMS on endothelial cells d. L-selectins on leukocytes, E- and P-selectins on endothelial cells
Integrins on leukocytes, I-CAMS on endothelial cells
Mutations of keratins in the [ ] that resist tensile forces in the skin cause the blistering disease known as epidermolysis bullosa simplex. a. intermediate filaments b. crescentin filaments c. microtubules d. microfilaments e. actin filaments
Intermediate filaments
Which cytoskeletal element can be used to identify a specific cell type? a. microfilaments b. microtubules c. intermediate filaments d. all of the above e. both B and C
Intermediate filaments
The cilia and flagella of eukaryotic cells are composed of... a. intermediate filaments b. microfilaments c. tonofilaments d. microtubules e. pili
Microtubules
[ ] are the most heterogeneous type of cytoskeletal element. a. microtubules b. intermediate filaments c. microfilaments d. all of the elements are heterogeneous e. none of the elements are heterogeneous
Intermediate filaments
What exactly is the role of phosphodiesterase in signal transduction? a. it acts as a non-competitive inhibitor, binding to adenylyl cyclase to inhibit its action b. it hydrolyzes phospholipids found in cellular membranes c. it hydrolyzes the GTP on the Ga-GTP, inactivating the G protein d. it is released upon cleavage of PIP2 in the plasma membrane, where it will diffuse and activate cellular targets e. it degrades cAMP by cleaving the phosphodiester bond, resulting in the formation of AMP
It degrades cAMP by cleaving the phosphodiester bond, resulting in the formation of AMP
What can be said about the ACE2 protein if it is a homodimer? a. it has 12 identical subunits b. it has 3 different subunits c. it has 2 identical subunits d. it has 2 different subunits e. not enough information given
It has 2 identical subunits
The target of glycogen phosphorylase is the glycogen. What reaction will glycogen phosphorylase catalyze involving glycogen? a. It will remove phosphate from glycogen. b. It will transfer phosphate to glycogen, using ATP as a phosphate source. c. It will transfer phosphate to glycogen using Pi as a phosphate source. d. It will hydrolyze glycogen e. It will hydrogenate glycogen
It will transfer phosphate to glycogen using Pi as a phosphate source.
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system? a. It could only activate the epinephrine system b. It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane c. It would employ a transduction pathway directly from an external messenger d. It would be able to carry out reception and transduction but would not be able to respond to a signal e. It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane
Dephosphorylation of tau results in its interactions with MTs, which helps to stabilize MTs. Which type of protein would have opposite effect, i.e. destabilizing the MTs? a. GTPase b. kinase c. ATP synthase d. phosphatase e. none of the above
Kinase
True or false? Kinesin is a motor protein that moves toward the plus end of microtubules.
True
Glycogen phosphorylase will be activated by a [ ] and deactivated by a [ ]. a. Kinase; phosphatase b. Phosphatase; phosphorylase c. Phosphorylase; kinase d. Phosphorylase; phosphatase e. Kinase; phosphorylase
Kinase; phosphatase
To deliver a vesicle to the end of an axon in a neuron, the motor protein [ ] would be required. a. axonemal dynein b. kinesin c. myosin d. dynein e. more than one of the above
Kinesin
Flow of transport vesicles from the ER to the Golgi involves all of the following except... a. kinesin b. microtubules c. ATP d. dynein e. All of the above are required
Kinesin (MTOC is located on trans face of Golgi)
Which of these statements accurately describes an MTOC in the cytoplasm of an undifferentiated cell? a. MTOCs bind and stabilize the minus ends of most of the microtubules. b. MTOCs bind and stabilize the minus ends of most of the microfilaments. c. MTOCs bind and stabilize the plus ends of most of the microfilaments. d. MTOCs bind and stabilize the plus ends of most of the microtubules.
MTOCs bind and stabilize the minus ends of most of the microtubules.
Comparing the mitochondrion and the chloroplast, which compartment in the mitochondria is most like the stroma in the chloroplast, in terms of function? a. thylakoid lumen b. matrix c. mitochondrial stroma d. intermembrane space e. thylakoid membrane
Matrix
During oxidative phosphorylation, ADP and Pi are combined in the... a. stroma b. matrix c. intermembrane space d. thylakoid lumen e. cytoplasm
Matrix
Which type of cytoskeletal element is primarily involved in the formation of lamellapodia during cell crawling? a. intermediate filaments b. microvilli c. microfilaments d. microtubules e. more than one of the above
Microfilaments
Microfilaments and intermediate filaments are different in that only... a. microfilaments are composed of proteins bound to a nucleotide b. microfilaments are made of protein c. intermediate filaments undergo depolymerization d. intermediate filaments are found in the extracellular matrix e. more than one of the above
Microfilaments are composed of proteins bound to a nucleotide
True or false? Polymerization of MTs occurs at a concentration above the critical concentration.
True
Microtubules (tubulin polymers): Hollow tubes; wall consists of 13 columns of tubulin molecules; 25 nm with 15 nm lumen; cell motility Microfilaments (actin filaments): Two intertwined strands of actin, each a polymer of actin subunits; 7 nm; cell locomotion Intermediate filaments: Fibrous proteins supercoiled into thicker cables; 8-12 nm; mechanical strength The differences among the three categories of cytoskeletal elements outlined in the table above would suggest that each of the following has specialized roles. Which of the following is a correct match? a. microtubules and cleavage furrow formation b. microfilaments and ciliary motion c. microfilaments and the nuclear lamina d. intermediate filaments and vesicle movement e. microtubules and chromosome movement
Microtubules and chromosome movement
Movement of vesicles within the cell depends on which cellular structures? a. centrioles and motor proteins b. actin filaments and microtubules c. actin filaments and ribosomes d. microtubules and motor proteins e. actin filaments and motor proteins
Microtubules and motor proteins
As growth occurs and the [free tubulin]cyt decreases, growth will stop first at which end of the MT? a. Minus end b. Plus end c. Could be either
Minus end
Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to... a. extend pseudopodia b. move vesicles around the cell c. perform amoeboid (crawling) movement d. form cleavage furrows e. none of the above
Move vesicles around the cell
GPCRs are considered... a. multi-subunit integral membrane proteins b. multi-pass integral membrane proteins c. peripheral membrane proteins d. lipid-anchored membrane proteins e. single-pass integral membrane proteins f. integral monotopic proteins g. more than one of the above
Multi-pass integral membrane proteins
A GPCR is a type of [ ] membrane protein. a. single-pass integral b. monotopic integral c. multi-subunit integral d. peripheral e. multipass integral
Multipass integral
Which of the following tissues is NOT classified as connective tissue? a. blood b. adipose c. bone d. cartilage e. nervous
Nervous
COX4 is a nuclear-encoded protein that resides in the mitochondrial matrix. Which of the following statements regarding targeting of the COX4 protein is true? a. COX4 is transcribed and translated in mitochondria b. COX4 is co-translationally imported c. COX4 would contain a signaling sequence that first targeted it to the RER before it eventually makes its way to the mitochondria d. None of the above are true e. both A and B are true
None of the above are true
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound... a. that mimics epinephrine and can bind to the epinephrine receptor b. that increases phosphodiesterase activity c. to stimulate G protein activity in liver cells d. that stimulates cAMP production in liver cells e. that does any of the above
That increases phosphodiesterase activity
In what sense do intermediate filaments lack polarity? a. One end of an intermediate filament dimer is not distinct from the other. b. They have a constant distribution of electrons over their whole length. c. One end of a protofilament is not chemically distinct from the other. d. Unlike most polypeptides, IF subunits do not have a positively charged N-terminus and a negatively charged C-terminus. e. None of the above
One end of a protofilament is not chemically distinct from the other.
Active transport differs from facilitated diffusion because... a. transporter proteins are required only during active transport b. only in active transport is [solute] low --> [solute] high c. the electrochemical gradient of the solute being transported provides the necessary energy for movement only during active transport d. energy is not required during active transport e. both B and C
Only in active transport is [solute] low --> [solute] high
To ensure regulation, certain Calvin cycle enzymes are deactivated when they are [ ]. Others are deactivated by an increase in [ ]. a. oxidized; pH b. reduced; pH c. reduced; [H+] d. oxidized; [H+]
Oxidized; [H+]
IP3 is released from... a. smooth ER b. PIP2 in the plasma membrane c. adenylyl cyclase d. GPCR e. G-alpha
PIP2 in the plasma membrane
Glycogen phosphorylase will be deactivated by a [ ] and activated by a [ ]. a. kinase; phosphatase b. phosphorylase; kinase c. phosphorylase; phosphatase d. phosphatase; kinase e. kinase; phosphorylase
Phosphatase; kinase
Which cellular molecule will have an antagonistic action to the effects of adenylyl cyclase? a. glycogen phosphorylase b. cAMP c. phosphodiesterase d. Galpha-GTP e. none of the above
Phosphodiesterase
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? a. phosphodiesterase b. serine/threonine kinase c. adenylyl cyclase d. tyrosine kinases e. phospholipase C
Phospholipase C
Glycogenolysis involves... a. glucose synthesis from non-carbohydrate sources b. oxidation of glucose c. hydrolysis of glycogen to release glucose-1-phosphate d. phosphorolysis of glycoegn to release glucose-1-phosphate e. reduction of CO2 to form carbohydrates
Phosphorolysis of glycoegn to release glucose-1-phosphate
Glycogenesis will be [ ] regulated by the insulin signal transduction pathway. a. positively b. negatively
Positively
Cell signaling involves converting extracellular signals to specific responses inside the target cell. Different molecules are involved at each stage of the process. In this activity, you will sort items based on which stage they are involved in: reception, transduction, or response. Choose the items that are involved in response. a. adenylyl cyclase b. G-protein coupled receptor c. protein synthesis d. second messenger e. signaling molecule f. IP3 g. Ca2+ h. cAMP i. phosphorylation cascade j. receptor tyrosine kinase
Protein synthesis
The study reveals that ACE2 functions as a homodimer. What is the highest level of protein structure found in ACE2? a. primary b. secondary c. tertiary d. quaternary e. none of the above
Quaternary
During its synthesis, the ligand-binding domain of the ACE2 receptor would have extended into the... a. cytoplasm b. RER lumen
RER lumen
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this? a. G-protein coupled receptors b. ligand-gated ion channels c. receptor tyrosine kinases d. steroid receptors
Receptor tyrosine kinases
During the Calvin cycle, the intermediate molecules are [ ] to form triose phosphates. a. reduced by ATP b. oxidized by ATP c. reduced and phosphorylated by NADPH d. oxidized by NADPH e. reduced by NADPH
Reduced by NADPH
How do leukocytes travel in our blood stream? a. transported in lipoproteins b. carried by the velocity of the blood flow, along with red blood cells c. transported in vesicles through the co-translational import pathway d. rolling along endothelial cells
Rolling along endothelial cells
How do leukocytes travel in our bloodstream? a. rolling along endothelial cells b. transported in vesicles through the co-translational import pathway c. carried by the velocity of the blood flow, along with red blood cells and platelets d. transported in lipoproteins e. by the movement of cilia along epithelial cells
Rolling along endothelial cells
Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to... a. extend pseudopods b. maintain the shape of the nucleus c. form cleavage furrows during cell division d. separate chromosomes during cell division e. migrate by amoeboid movement
Separate chromosomes during cell division
Where is most of the Ca2+ stored in cells? a. cytoplasm b. Golgi c. mitochondria d. nucleus e. smooth ER
Smooth ER
Shown below is the structure of a SARS-CoV virus particle. SARS-CoV and the related SARS-CoV-2 (responsible for the current pandemic) have very similar structures. Both are a type of single-stranded RNA (ssRNA) virus, with the ssRNA genome enclosed inside a membrane. Like cell membranes, the SARS-CoV/CoV-2 membrane is lipid-based and embedded with various proteins. Washing hands with soap and water FOR AT LEAST 20 SECONDS is proven to be an effect method to remove SARS-CoV-2 from hands. How is this possible? a. Soap molecules are hydrophilic and will bind to the hydrophilic proteins on the surface of the virus. This will allow the virus particles to be washed away. b. Soap is not effective in removing SARS-CoV from hands. Water alone is fine. c. Soap molecules are hydrophobic and can therefore disrupt the virus membrane. But the disrupted particles remain on the skin. d. Soap molecules are amphipathic, and can therefore interact with both the lipid layer of the virus and the water molecules to break apart and solubilize the virus, allowing it to be washed away.
Soap molecules are amphipathic, and can therefore interact with both the lipid layer of the virus and the water molecules to break apart and solubilize the virus, allowing it to be washed away.
If an individual has abnormal microtubules, due to a hereditary condition, in which cell type(s), tissues or organs would you expect dysfunction? a. skeletal muscles, heart, or any areas with a good deal of muscle contraction b. all cells with nuclei, as the nuclei will be misshapen c. sperm and trachea: cells and tissues that contain flagella or cilia d. microvilli, alveoli, and glomeruli, or other such cellular projections that increase surface area e. phagocytic cells and white blood cells that exhibit cell locomotion
Sperm and trachea: cells and tissues that contain flagella or cilia
The main role of intermediate filaments is... a. cell locomotion b. structural or tension-bearing c. cell division d. vesicle transport e. more than one of the above
Structural or tension-bearing
How would the drug taxol affect the in vitro dynamic instability and treadmilling experiments? a. Taxol would stabilize the microtubules in both experiments, leading to polymerization without catastrophe. b. Taxol would block catastrophe at the plus end in the dynamic instability experiment but not depolymerization at the minus end in the treadmilling experiment. c. Taxol would block depolymerization at the minus end in the treadmilling experiment but not catastrophe at the plus end in the dynamic instability experiment. d. Taxol would block the addition of tubulin in both experiments, leading to a destruction of the microtubules.
Taxol would stabilize the microtubules in both experiments, leading to polymerization without catastrophe.
What type of signal could enter the cell by simple diffusion to activate a cytoplasmic receptor? a. glucose b. testosterone c. insulin d. ATP e. All of the above
Testosterone
Not all signaling molecules act through PM receptors. Some bind to receptors found in the cytoplasm. Others bind to nuclear receptors. What type of signal could enter the cell by simple diffusion to activate a cytoplasmic receptor? a. glucose b. testosterone (steroid) c. insulin (hydrophilic protein) d. ATP e. all of the above
Testosterone (steroid)
Colchicine is a cellular toxin known to bind to beta-tubulin, preventing its ability to interact with alpha-tubulin. Cytochalasin is a toxin that binds to G-actin, preventing its ability to polymerize. If a cell process is disrupted by colchicine, but not by cytochalasin, one can conclude that the cell process requires... a. F-actin b. the assembly of intermediate filaments c. the assembly of microtubules d. depolymerization of microtubules e. Both A and D
The assembly of microtubules
True or false? Lactose intolerance is characterized by an inability to CATABOLIZE lactose due to the lack of an active lactase enzyme.
True
True or false? Lactose is made up of the two monosaccharides glucose and galactose.
True
Choose the best description of the cell cytoskeleton. a. The cell cytoskeleton is similar to an animal skeleton in providing rigid internal support and structure to the cell. b. The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components. c. The cell cytoskeleton serves as permanent scaffolding to anchor cell components into position within the cell cytoplasm.
The cell cytoskeleton is a dynamic network of fibers that can be quickly dismantled and reassembled to change cell shape and the position of cell components.
A defective hepatocyte was isolated from a liver cancer patient. This hepatocyte contains approximated 75+ active protein kinase A (PKA) molecules, even in the absence of epinephrine. What is a plausible explanation? a. The cell's phosphorylase kinase gene has a mutation that makes the kinase active all of the time. b. The cell's adenylate cyclase gene has a mutation that makes the cyclase active all of the time. c. The cell's glycogen phosphorylase gene has a mutation that makes the phosphorylase active all of the time. d. The cell's adenylate cyclase gene has a mutation that makes the cyclase inactive all of the time. e. None of the above
The cell's adenylate cyclase gene has a mutation that makes the cyclase active all of the time.
Why is the consequence of epinephrine signaling so different for cardiac cells and hepatocytes? a. The epinephrine receptors are more abundant on the surface of cardiac cells. b. Different amounts of epinephrine reach each different type of target cell. c. The downstream signaling components stimulated by the activated epinephrine receptor are different in cardiac cells and hepatocytes. d. The epinephrine receptors on the surface of their target cells are different. e. There is no difference in the responses of these cell types to epinephrine.
The downstream signaling components stimulated by the activated epinephrine receptor are different in cardiac cells and hepatocytes.
True or false? Motor proteins that bind to cytoskeletal elements have ATPase activity.
True
The histamine H1 receptor is one of several existing histamine G protein-coupled receptors. Depending on many factors, including the type of receptor, histamine can trigger a variety of responses, including vasodilation, smooth muscle contraction, stimulation of gastric secretion, cardiac stimulation, and increased vascular permeability (causing runny nose and watery eyes). Which of the following could account for the different cellular responses to histamine? Select all that apply. a. the enzyme that is activated by the G protein associated with the receptor b. the type of signaling molecule c. the cell type in which the histamine receptor is located d. the types of relay molecules within the cell e. the type of second messengers involved in the signal transduction pathway
The enzyme that is activated by the G protein associated with the receptor The cell type in which the histamine receptor is located The types of relay molecules within the cell The type of second messengers involved in the signal transduction pathway
Microtubules are involved in all of the following except... a. transport of vesicles between organelles of the endomembrane system b. the formation of the spindle apparatus during cell division c. the extension of the lamellopodium of a white blood cell during cell locomotion d. the formation of flagella used by sperm cells to swim e. microtubules are involved in all of the above
The extension of the lamellopodium of a white blood cell during cell locomotion
Which of the following is TRUE about GPCRs? Select all statements that apply. a. The first membrane-spanning segment is an internal stop-transfer sequence b. The last membrane spanning segment is a start-transfer sequence c. The segment interacting with the G protein is extracellular. d. The N-terminus is extracellular and the C-terminus is intracellular. e. The C-terminus interacts with the G-protein f. They contain 5 membrane-spanning segments
The first membrane-spanning segment is an internal stop-transfer sequence The N-terminus is extracellular and the C-terminus is intracellular
What would happen in the treadmilling experiment if a non-hydrolyzable analogue of GTP were used? a. The monomers would be unable to add to the plus end, and the microtubules would shrink until they disappeared. b. The microtubule would treadmill until the new tubulin, with non-hydrolyzable GTP, reached the minus end, and then it would only extend at the plus end. c. The non-hydrolyzable GTP would stabilize both ends, causing treadmilling to stop. d. The microtubule would add monomers at both the plus and minus ends, growing in both directions.
The microtubule would treadmill until the new tubulin, with non-hydrolyzable GTP, reached the minus end, and then it would only extend at the plus end.
What is the difference between the plus and minus ends of the microtubule in in vitro experiments? a. Polymerization occurs at the plus end. b. The beta subunit of the tubulin is exposed on the minus end. c. The plus end has a lower critical concentration for tubulin heterodimers. d. Catastrophe occurs at the minus end.
The plus end has a lower critical concentration for tubulin heterodimers.
A plasma membrane protein begins with a large hydrophilic regulatory domain. This is followed by six hydrophobic regions of 20+ amino acids, with short hydrophilic regions in between. Finally, a large hydrophilic domain, called domain A, is at the end of the polypeptide. The first signaling sequence of this protein is an N-terminal signal sequence. If all six hydrophobic domains cross the membrane one time each, then it is possible that... a. the regulatory domain and domain A will be on the same side of the membrane b. the regulatory domain and domain A will both be intracellular c. the regulatory domain is intracellular and domain A is extracellular d. the regulatory domain and domain A are transmembrane domains e. Choices A and B are both possible
The regulatory domain and domain A will be on the same side of the membrane
As common targets of kinases, what do serine, threonine, and tyrosine all have in common? a. They are all basic b. They are all acidic c. They are all proteins d. They all have hydroxyl groups e. More than one of the above
They all have hydroxyl groups
You are studying microtubules (MTs) in vitro and have isolated MTs and their subunits in a test tube. If the critical concentration of tubulin dimers in the last tube is above the critical concentration for the plus end but below the critical concentration for the minus end, what will you observe in this in vitro system? a. the MTs will not change in size b. the cell would not be able to crawl c. the MTs would get shorter d. treadmilling will occur (i.e. simultaneous assembly and disassembly) e. the MTs will continue to grow at both ends
Treadmilling will occur (i.e. simultaneous assembly and disassembly)
Microtubules have a larger diameter than both microfilaments and intermediate filaments. a. True b. False c. Not always. It depends on the type of protein comprising the intermediate filaments
True
True or false? Tubulin dimers will add to either end of a growing microtubule although they add more rapidly to the plus end than the minus end. a. True b. False, the minus end of a microtubule grows more rapidly than the plus end. c. False, because microtubules do not have a plus and minus end.
True
Cells require which of the following to form cilia or flagella? a. tubulin b. intermediate filaments c. secretory vesicles d. laminin e. actin
Tubulin
What could you add to an in vitro system to stop MTs from treadmilling? a. tubulin-GTP dimers b. tubulin-GDP dimers c. GDP d. could add either A or B
Tubulin-GTP dimers
Which of the following apply to cilia but NOT flagella? Select all that apply. a. constructed of microtubules b. typically only a few per cell c. typically one to many per cell d. involved in cell motility e. 10-200 um lng f. play a sensory role on certain cell types g. 2-10 um long
Typically one to many per cell Play a sensory role on certain cell types 2-10 um long
The CRD of a selectin protein was initially extending into the [ ] as it was transported in a vesicle on its way to its final destination. a. extracellular space b. vesicle lumen c. nucleus d. cytoplasm
Vesicle lumen
The ligand-binding domain of a GPCR was initially extending into the [ ] as it was transported to the PM in a transport vesicle. a. cytoplasm b. vesicle lumen c. extracellular space d. nucleus e. not enough information given
Vesicle lumen
The ligand-binding domain of a GPCR was initially extending into the [ ] as it was transported to the PM in a transport vesicle. a. nucleus b. vesicle lumen c. extracellular space d. cytoplasm e. not enough information given
Vesicle lumen
Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of... a. adenylyl cyclase b. phosphorylated proteins c. cAMP d. activated G proteins e. GTP
cAMP
