biochem exam 3
what is the result of SGLT inhibition? A. inhibition of the Na+-K+ATPase B. increased intracellular glucose C. increased intracellular K+ D. activation of the Na+-K+ATPase
A
Match 3 specific examples of carbohydrate use to a general function: -A plant cell synthesizes starch from glucose: ___________ -A plant cell synthesizes cellulose from glucose: __________ -A brain cell uses the energy in glucose to synthesize ATP: ________
-energy storage -structural support -metabolism for energy
-Maltose hydrolyzes into ________ -lactose hydrolyzes into __________ -sucrose hydrolyzes into __________ -cellulose hydrolyzes into __________
-glucose -glucose + galactose -glucose + fructose -glucose
hydrolysis of each carbohydrate -maltose -> ________ -lactose -> ________ -sucrose -> _______ -glycogen -> _______-
-glucose -glucose + galactose -glucose + fructose -glucose
________ used for storage in animals ________ used for storage in plants _______ located in plant cell walls ________ simple sugar, can form a ring or chain
-glycogen -starch -cellulose -monosaccharide
-Hydrolysis of the ________ bonds yields _________ -Hydrolysis of the _____ bonds in triacylglycerols yields products including _________ -Hydrolysis of the _______ bonds of protein produces ___________
-glycosidic, monosaccharides -ester, fatty acids -peptide, amino acids
characteristics of interior of lipid bilayer vs. surface of lipid bilayer
-interior: hydrophobic, fatty acid chains, repels polar molecules -surface: hydrophilic, contains phosphate
Select the phrases that best describe the plasma membrane A. provides a rigid structure that allows the cell to hold its shape B. regulates transport of molecules into & out of cell C. separates the nucleus & the cytosol D. creates a barrier btwn the inside & the outside of the cell
B & D
What are the effects of trypsin inhibitor? A. trypsin inhibitor blocks zymogen activation at very low pH levels B. trypsin inhibitor blocks the proteolytic activity of trypsin C. trypsin inhibitor blocks trypsinogen's catalytic activity D. trypsin inhibitor prevents zymogen activation in the pancreatic ducts
B & D
Hormone-activated phospholipase C can convert phosphatidylinositol 4,5-bisphosphate to: A) diacylglycerol + inositol triphosphate. B) diacylglycerol + inositol + phosphate. C) glycerol + inositol + phosphate. D) phosphatidyl glycerol + inositol + phosphate.
A
Select the statements that accurately describe receptor tyrosine kinases (RTKs) A. a ligand binds to the extracellular domain B. RTKs are usually monomeric in the absence of a ligand C. ligand binding is required for autophosphorylation (cross-phosphorylation) D. the intracellular domain has phosphatase domains E. the alpha subunit contains seven alpha helices that span the membrane G. the structure includes a transmembrane helix
A, B, C, G
Identify the factors the directly favor the unloading of oxygen from hemoglobin in the blood near metabolically active tissues. A. an increase in blood temperature near the tissues B. the presence of a pressure gradient for oxygen C. an exchange of ions in the erythrocytes D. an increase in blood acidity near the tissues
A, B, D
Select the processes that make lipids accessible for the digestion A. Micelles carry fatty acids to the intestinal membrane B. Lipases degrade triacylglycerols into fatty acids C. the low pH of the stomach breaks down fatty acids D. lipid droplets & water mix into an emulsion into the stomach
A, B, D
Select all of the items that are a role or function of the cell membrane. A. regulating what enters the cell B. regulating what leaves the cell C. digesting proteins D. providing protection E. digesting carbohydrates F. providing support
A, B, D, F
Which structures are components of the plasma membrane? A. cholesterol B. nucleic acids C. phospholipids D. cristae
A, C
Which are functions of the eukaryotic plasma membrane & its components? A. cell adhesion B. generation of ATP ("energy") C. signal transduction D. digestion of small molecules E. regulation of flow of ions & molecules into cell
A, C, E
Which of the statements are true? A. unsaturated fats are more likely than saturated fats to be liquid at room temp B. unsaturated fats have higher melting points than saturated fats C. triacylglycerols (triglycerides) are composed of fatty acid residues & glycerol D. triacylglycerols (triglycerides) are carboxylic acids E. fats that contain more saturated fatty acid residues than unsaturated fatty acid residues are more likely to be solid at room temp
A, C, E
Which statements about reducing sugars are true? A) The oxidation of a reducing sugar forms a carboxylic acid sugar B) A reducing sugar will not react with the Cu2+ in Benedict's reagent C) Reducing sugars contain ketone groups instead of aldehyde groups D) A disaccharide with its anomeric carbons joined by the glycosidic linkage cannot be a reducing sugar E) D-glucose (an aldose) is a reducing sugar
A, D, E
amphipathic molecules
Amphipathic molecules have both hydrophobic regions and hydrophilic regions <phospholipids>.
A glycolipid is: A. a lipid molecule that is produced during glycolysis B. a lipid molecule that contains at least one carbohydrate unit C. a molecule produced during the breakdown of glycogen D. a lipid molecule that contains a glycerol backbone & 3 fatty acids
B
Choose the statement that correctly identifies a function of plasma membrane in both eukaryotic & prokaryotic cells A. produces food such as sugar molecules for the cell B. forms a protective barrier that keeps out harmful substances C. synthesizes proteins for the cell or to be released by the cell D. stores excess materials for the cells for long periods of time
B
How many asymmetric carbon atoms are there in the open-chain aldoheptose molecule? A. 4 B. 5 C. 6 D. 7 E. 8
B
How would you describe the linkages in the disaccharide at the right and the polysaccharide they are found in? A) beta 1 -> 4 in cellulose B) alpha 1 ->4 in amylose C) alpha 1 ->4 in cellulose D) beta 1-> 4 in amylose
B
Identify the pair of polysaccharides A. cellulose & sucrose B. glycogen & cellulose C. glucose & glycogen D. lactose & galactose
B
In normal digestion, trypsin activates several zymogotes or proenzymes in which organ? A. pancreas B. small intestine C. stomach D. mouth
B
Peripheral membrane proteins: A) can be released from membranes only by treatment with detergent. B) are generally noncovalently bound to membrane lipids. C) may have functional units on both sides of the membrane. D) penetrate deeply into the lipid bilayer.
B
Predict which fatty acid is most likely to be solid at room temperature A. CH3(CH2)3COOH B. CH3(CH2)10COOH C. CH3(CH=CHCH2)2(CH2)6COOH D. CH3(CH2)7CH=CH(CH2)7COOH
B
The compound shown here is not: A) a sphingolipid. B) a phosphoglyceride. C) amphipathic. D) a component of biological membranes.
B
The standard free-energy changes for the reactions below are given. Phosphocreatine-> creatine + Pi DG'° = -43.0 kJ/mol ATP ->ADP + Pi DG'° = -30.5 kJ/mol What is the overall DG'° for the following reaction? Phosphocreatine + ADP -> creatine + ATP A) -73.5 kJ/mol B) -12.5 kJ/mol C) +12.5 kJ/mol D) +73.5 kJ/mol
B
The type of membrane transport that uses ion gradients as the energy source is: A) facilitated diffusion B) secondary active transport. C) primary active transport. D) simple diffusion.
B
Unsaturated fatty acids found in most biological systems A) do not contain any double bonds B) typically contain cis- double bonds C) typically contain trans- double bonds D) typically contain triple bonds
B
What is a zymogen? A. a protein that emulsifies dietary lipids B. a protein that is the inactive form of an enzyme C. a protein that digests carbohydrates D. a protein that is a precursor to vitamin D
B
What is the digestive function of the liver? A. storage of bile B. production of bile C. absorption of nutrients D. production of amylase
B
What is the effect of cholesterol in the cell membrane? A. cholesterol reduces permeability to polar molecules over a wide temperature range B. cholesterol regulates membrane fluidity over a wide temperature range C. cholesterol increases membrane fluidity at all temperatures D. cholesterol facilitates an abrupt transition from a less fluid state to a more fluid state
B
What statement about oxygen transport by hemoglobin is true? A) Hemoglobin binds more oxygen at higher 2,3-BPG concentrations. B) Oxygen binds to the proximal histidine residue of the globin chain. C) Bonding of carbon dioxide to hemoglobin molecules increases the binding of oxygen. D) Hemoglobin binds more oxygen as the pH is raised.
B
Which of the following is an epimeric pair? A) D-lactose and D-sucrose B) D-glucose and D-galactose C) D-glucose and L-glucose D) D-glucose and D-glucosamine
B
Which property is not associated with lipid membranes? A) asymmetry B) solvent for carbohydrates C) self-assembled leaflets D) electric polarization
B
Which of the statements are true? A. a plant that produces more monounsaturated fatty acids than polyunsaturated fatty acids in its membranes in winter has an increased resistance to freeze damage B. yeast cells that produce more unsaturated fatty acids than saturated fatty acids in response to cold have greater cold tolerance C. cell membranes in cold tolerant winter wheat plants have a higher ratio of unsaturated fatty acids to saturated fatty acids than do cold intolerant wheat varieties D. cell membranes in reindeer legs (near the hooves) are kept flexible because they have a large number of saturated fatty acids
B & C
Choose 2 amino acids that would be reasonable candidates for the pocket-Val 6 interaction A. arginine B. leucine C. lysine D. phenylalanine E. glutamate
B & D
Select the biochemical roles of cholecystokinin, or CKK A. activates the pancreatic zymogens to form active enzymes B. stimulates the secretion of digestive enzymes by the pancreas C. stimulates the secretion of sodium bicarbonate by the pancreas D. stimulates the secretion of bile salts by the gall bladder
B & D
α-Amlase cleaves the ______ of a polysaccharide such as starch and does not digest a limit dextrin because of ________. a. α-1,4 bonds; α-1,6 bonds b. α-1,6 bonds; α-1,4 bonds c. α-1,2 bonds; α-1,4 bonds d. α-1,2 bonds; α-1,6 bonds e. α-1,6 bonds; α-1,2 bonds
a
An aldehyde and alcohol can react to form a(n): a. hemialkyl b. hemiketal c. hemiacetal d. amidyl e. carbonyl
c
What is the role of cholesterol in lipid digestion? a. cholesterol cleaves bonds of lipids b. cholesterol transports free fatty acids through the intestinal cell membrane c. bile salts necessary for lipid digestion are synthesized from cholesterol d. cholesterol emulsifies micelles e. cholesterol activates lipases
c
What statement about zymogens is FALSE? a. All digestive enzymes, except amylase, are synthesized in the inactive forms b. Before secretion, zymogens exist in granules near the cell membrane c. Zymogens are inactivated when a part of the precursor is proteolytically cleaved d. A pancreatic zymogen trypsinogen can be cleaved to form an enzyme such as trypsin e. Pepsinogen has a small amount of enzyme activity
c
how does HbS aggregation occur in sickle-cell anemia?
no aggregation -[O2] decreases due to vigorous exercise or high altitude -R state Hb shifts to T state Hb -Val interacts w/ the pocket of a beta chain on another HbS -Additional T state HbS interact w/ the growing aggregate to form an insoluble fiber sickled red blood cell
Where does absorption take place?
small intestine
How are biological membranes held together? A. covalent bonds B. peptide bonds C. gravity D. hydrophobic interactions
D
These 2 branched polysaccharides contain both alpha-1,4 and alpha-1,6 glycosidic bonds
amylopectin, glycogen
Diasteromers are
stereoisomers that are not enantiomers
Epimers are
stereoisomers that differ from each other in their configuration at a single carbon atom
Anomers are
subtype of epimers that differ at the anomeric carbon
epimers are
sugars that differ in configuration of a single stereocenter (unit of many)
classify the statements about the transport system as either true or false -pumps Na+ ions out of cell -pumps K+ ions into the cell -exchanges 3Na+ ions for 2K+ ions -creates a membrane potential that is negative on the inside -pumps Na+ ions into the cell -pumps K+ ions out of the cell -exchanges 3K+ ions for 2Na+ ions -the transport protein becomes adrenylated by ATP during the transport cycle
true -pumps Na+ ions out of cell -pumps K+ ions into the cell -exchanges 3Na+ ions for 2K+ ions -creates a membrane potential that is negative on the inside false -pumps Na+ ions into the cell -pumps K+ ions out of the cell -exchanges 3K+ ions for 2Na+ ions -the transport protein becomes adrenylated by ATP during the transport cycle
maltose vs. lactose vs. sucrose
-*maltose:* contains an alpha-1,4-glycosidic linkage, comprised of an alpha-D-glucose molecule & a D-glucose molecule, also known as malt sugar *lactose*: contains a beta-1,4-glycosidic linkage, comprised of a beta-D-galactose molecule & a D-glucose molecule, also known as milk sugar -*sucrose*: contains an alpha,beta-1,2-glycosidic linkage, comprised of an alpha-D-glucose molecule & a beta-D-fructose molecule, also known as table sugar, not a reducing sugar
Classify each structural feature as a characteristic of a sphingolipid or a phosphoglyceride -sphingosine backbone -one fatty acid chain attached to backbone by an amide bond -glycerol backbone -phosphorylated alcohol attached to backbone at C-3
-*sphingolipid*: sphingosine backbone, one fatty acid chain attached to backbone by an amide bond, more complicated structure -*phosphoglyceride*: glycerol backbone, phosphorylated alcohol attached to backbone at C-3, less complicated structure (HO-C-COH-C-OH)
difference btwn uniport, symport, & antiport
-Uniport: "uni" will have only one going in or out. -Symport: "sym" will have two moving together in the same direction. -Antiport: "anti" two moving in opposite directions.
how to distinguish sugars as aldoses vs ketoses
-aldose: has an aldehyde group (CHO) -ketose: has a keytone group (C=O)
Match each statement to the category of membrane-associated protein it describes (membrane-spanning alpha helix, membrane-spanning beta strands, lipid-anchored membrane protein, peripheral membrane protein) -composed of about 20 hydrophobic residues -amino acid sequence pattern: nonpolar R group, polar R group (repeats) -often contains residues w/ covalently attached fatty acyl groups -can usually be released from membrane by concentrated salt solutions -often tethered to membrane via a membrane-embedded protein
-membrane-spanning alpha helix: composed of about 20 hydrophobic residues -membrane-spanning beta strands: amino acid sequence pattern: nonpolar R group, polar R group (repeats) -lipid-anchored membrane protein: often contains residues w/ covalently attached fatty acyl groups -peripheral membrane protein: can usually be released from membrane by concentrated salt solutions, often tethered to membrane via a membrane-embedded protein
Determine which is a monosaccharide, disaccharide, or polysaccharide -fructose -glucose -lactose -cellulose -glycogen
-monosaccharide: fructose & glucose -disaccharide: lactose -polysaccharide: cellulose & glycogen
how to determine if a structure is a monosaccharide, disaccharide, or a polysaccharide
-monosaccharide: they are a white crystalline solid that contains a single aldehyde of ketone functional group -disaccharide: formed by condensing a pair of monosacchardies -polysaccharide: composed of long chains of monosaccharides
Characterize each term as pertaining to either simple or facilitated diffusion directly through membrane, via channel, O2, Na+, lipophilic molecules, polar molecules, steroid hormones, retinol, amino acids, Ca2+
-simple diffusion: directly through membrane, O2, lipophilic molecule, steroid hormones, -facilitated diffusion: via channel, Na+, polar molecule, retinol, amino acids, Ca2+
Determine from the set of phrases if they belong to starch, glycogen, or cellulose: 1) major storage form of glucose in plants 2) not digestible by humans 3) major storage form of carbohydrates in animals 4) made up of 2 glucose polysaccharides: amylose & amylopectin
-starch: 1, 4 -glycogen: 3 -cellulose: 2
How many fatty acids are required to form a : triacylglycerol? glycerophospholipid? sphingophospholipid?
-triacylglycerol : 3 -glycerophospholipid : 2 -sphingophospholipid : 1
classify the characteristics of triacylglycerols & phosphoglycerides -3 fatty acid chains -energy storage -membrane component -2 fatty acid chains -alcohol group -phosphate group
-triacylglycerols: 3 fatty acid chains, energy storage -phosphoglycerides: membrane component, 2 fatty acid chains, alcohol group, phosphate group
Lactose hydrolysis products are
1 mole of galactose and 1 mole of glucose
Select the 6 statements that accurately describe signal transduction pathways: 1. phosphatases remove phosphoryl groups from polypeptides, regulating a cell's response 2. signal transduction cascades, often involving protein kinases, amplify a signal intracellularly 3. a ligand, such as a hormone, binds to a specific cell surface receptor on a target cell 4. a 2nd messenger may carry a signal from the cell membrane to an organelle 5. a receptor changes conformation upon binding, transmitting a signal across the cell membrane 6. signal transduction cascades directly transmit a single stimulus to a single target 7. a ligand phosphorylates protein residues, ending the signaling cascade inside the cell 8. a 2nd messenger carries a signal from a tissue or organ to target a cell 9. a receptor may pass on a signal by interacting w/ another protein or by acting as an enzyme
1, 2, 3 ,4, 5, 9
All of the following contribute to the large, negative, free-energy change upon hydrolysis of "high-energy" compounds except: A) low activation energy of forward reaction. B) stabilization of products by extra resonance forms. C) stabilization of products by solvation. D) electrostatic repulsion in the reactant.
A
An allosteric interaction between a ligand and a protein is one in which: A) binding of a molecule to a binding site affects binding properties of another site on the protein. B) binding of a molecule to a binding site affects binding of additional molecules to the same site. C) binding of the ligand to the protein is covalent. multiple molecules of the same ligand can bind to the same binding site.
A
Identify the statement that describes how acarbose & miglitol decrease glucose absorption after a meal A. acarbose & miglitol bind to the alpha-glucosidase actives site & prevent the enzyme from binding to oligosaccharides in the small intestine & breaking them down to glucose B. acarbose & miglitol bind to the alpha-glucosidase actives site & prevent the enzyme from releasing the glucose formed from oligosaccharide breakdown in the small intestine C. acarbose & miglitol bind to a regulatory site on alpha-glucosidase & inhibit the digestion of oligosaccharides in the small intestine D. acarbose & miglitol bind to a regulatory site on alpha-glucosidase & change the conformation of the enzyme to the inactive T state
A
If a Lys residue is substituted with a Ser residue in the 2,3-bisphosphoglycerate (2,3-BPG) binding site of hemoglobin, 2,3-BPG would bind: A) tighter because of the loss of a positive charge. B) tighter because of the gain of a positive charge. C) less tightly because of the gain of a positive charge. D) less tightly because of the loss of a positive charge.
A
Reaction pathways that only transform fuels into cellular energy are: A) anabolic. B) catabolic. C) allosteric. D) amphibolic.
A
The biochemical property of lectins that is the basis for most of their biological effects is their ability to bind to: A) specific oligosaccharides. B) amphipathic molecules. C) specific lipids. D) specific peptides.
A
The transport of lipids in the lymph is carried out by: A) lipases. B) micelles. C) free fatty acids. D) chylomicrons.
A
What is the name of the disaccharide pictured at the right? A) Sucrose B) Lactose C) Maltose D) Galactose
A
Where does enzymatic degradation of dietary fat take place? A) mouth B) stomach C) gall bladder D) small intestine
A
Which carbohydrate is a polysaccharide? A. glycogen B. glucose C. sucrose D. carboxylase
A
Which carbon atom will always be outside of the ring in the cylclized form of the ketose? A. C-1 B. C-2 C. C-Beta D. C-5 E. C-6
A
Which of the statements is true regarding the digestion of starch & cellulose by humans? A. humans lack the enzymes required to hydrolyze the beta linkages in cellulose B. humans have the enzymes required to hydrolyze the beta linkages in starch C. cellulose contains alpha linkages, which humans lack the enzymes required to hydrolyze D. humans are able to digest both starch & cellulose
A
Which of these is a function of cholesterol in a cell's plasma membrane? A. regulating membrane fluidity B. replicating DNA C. helping in respiration D. helping in photosynthesis
A
what do triglycerides & disaccharides have in common? A. they both are macromolecules composed of the elements carbon, hydrogen & oxygen B. the basic structural unit of these 2 macromolecules is the glucose molecule C. they both are macromolecules composed of the elements carbon & nitrogen D. the basic structural unit of these 2 macromolecules is the fatty acid
A
Select all the statements that describe the beneficial roles of lipids in the body A. lipids provide a cushion for organs B. lipids support the function of myelin sheaths C. lipids supply the body w/ amino acids D. lipids maintain normal osmolarity
A & B
Select the structural features common to all membrane-bound receptors A. signal molecule binding site on the extracellular domain B. intracellular domain undergoes structural changes upon extracellular ligand binding C. kinase domain D. seven transmembrane helices
A & B
Which of these are components of biological membranes? A. proteins B. lipids C. nucleic acids
A & B
Select the statements about fatty acid melting points that are true A. a saturated fatty acid with a greater molar mass has a higher melting point than a saturated fatty acid with a lower molar mass B. a saturated fatty acid with a greater molar mass has a lower melting point than a saturated fatty acid with a lower molar mass C. a saturated fatty acid has a higher melting point than an unsaturated fatty acid D. a saturated fatty acid has a lower melting point than an unsaturated fatty acid
A & C
Identify true statements about cholesterol & its role in membrane fluidity A. cholesterol decreases membrane fluidity in areas called rafts, which contain large amounts of sphingolipids & cholesterol B. cholesterol inhibits the crystallization that would otherwise occur in membranes rich in unsaturated fatty acids C. cholesterol is generally buried in the bilayer, w/ its planar rings oriented toward the solvent & its hydroxyl group aligned w/ the fatty acid tails of the bilayer D. cholesterol increases membrane fluidity in a membrane that otherwise contains mostly long-chain saturated fatty acids
A & D
Why is cellulose not a source of nutrients for humans? A. Humans cannot absorb the hydrolyzed form of cellulose B. Vertebrate enzymes are unable to hydrolyze (beta 1-4) linked glucose monomers C. Human gut bacteria break down cellulose in the large intestine, after nutrient absorption occurs D. Animals use starch & glycogen as an energy source, whereas plants use cellulose for energy E. Humans, and most vertebrates, lack the enzyme cellulase
B & E
which amino acids would be expected to produce a sickling cell effect if substituted for Val at position 6? A. lysine B. leucine C. phenylalanine D. arginine E. alanine
B & E
Hemoglobin is a protein in RBC that binds to oxygen. Which physiological changes that naturally occur in the body reduce hemoglobin's affinity for oxygen? A. accumulation of nitrogen B. accumulation of carbon dioxide C. increase in pH D. increase in temperature
B, D
Select the fundamental properties of all ion channels A. use active transport B. rapid transport C. voltage-gated D. selectivity
B, D
Which of the outcomes could potentially result if a mutation in the gene encoding Galpha subunit eliminates its GTPase activity? (choose 3) A. The rate of GTP hydrolysis would increase B. Galpha would be activated for an extended period C. the cell would be unresponsive to molecules that act via cAMP D. the concentration of cAMP would be continuously elevated E. the signaling pathway could be activated for an extended period, possibly resulting in undesirable cell proliferation F. Galpha would be ineffective as a signal molecule
B, D, E
A biological membrane is a bilayer that contains lipids with A. hydrophilic head groups pointing inward & hydrophobic tail groups oriented toward the solvent (extracellular fluid & cytosol) B. hydrophobic head groups oriented toward the solvent (extracellular fluid & cytosol) & hydrophilic tail groups pointing inward C. hydrophilic head groups oriented toward the solvent (extracellular fluid & cytosol) & hydrophobic tail groups pointing inward
C
Identify the pair of disaccharides A. lactose & galactose B. cellulose & sucrose C. lactose & sucrose D. glucose & glycogen
C
Since lipids are not soluble in water, what is the problem with their digestion? a. lipids are not exposed to bile salt b. lipids are not digestible c. lipases cannot degrade large lipid droplets d. lipid droplets cannot be converted into an emulsion e. amylases cannot degrade large lipid droplets
C
The label on a container of margarine lists 'hydrogenated vegetable oil' as the major ingredient. What is the result of adding hydrogens to vegetable oil? A) The hydrogenated vegetable oil has a lower melting point. B) The hydrogenated vegetable oil has more "kinks" in the fatty acid chains. C) The hydrogenated vegetable oil stays solid at room temperature. D) The hydrogenated vegetable oil has fewer trans fatty acids.
C
What are the products of sucrose hydrolysis? A) glucose and galactose B) mannose and glucose C) glucose and fructose D) galactose and fructose
C
What is a property of phospholipids that explains why lipids self-assemble into a bilayer? A. opposite charges on the heads & tails of lipids cause them to be attracted to one another B. the hydrophobic tails of lipids form hydrogen bond w/ one another within the membrane C. the hydrophilic heads of lipids are exposed to water at the membrane's surface D. proteins help lipids form long chains E. lipids assemble the membrane around a protein scaffold, which then dissociates
C
What statement describes the structure of starch? A. starch is a polymer of cellulose B. starch is a monomer of glucose C. starch is a polymer of glucose D. starch is a polymer of mannose
C
Which carbohydrate is a monosaccharide? A. starch B. sucrose C. fructose D. carboxylase
C
Which of the phrases best describes the hydrophobic portion of a phospholipid? A. has an affinity for low salt concentrations B. forms hydrogen bonds with water C. has few interactions w/ water D. is repelled by lipids
C
Which of the statements correctly describes how the structure of plasma membrane allows it to function as a protective barrier for a cell? A. plasma membranes contain a single layer of phospholipid molecules which creates a barrier to permeability B. transmembrane proteins within the phospholipid molecules block all substances from entering the cell C. plasma membranes contain a phospholipid bilayer which creates a border between the cell and the outer environment D. proteins embedded within the fluid membrane structure allow the free passage of all substances
C
Which of these is a function of cholesterol in a cell's plasma membrane? A. helping in photosynthesis B. helping in respiration C. regulating membrane fluidity D. replicating DNA
C
Which of these is a general feature of the lipid bilayer in all biological membranes? A) Individual lipid molecules in one leaflet of the bilayer readily diffuse to the other leaflet. B) The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules. C) Individual lipid molecules are free to diffuse laterally in the surface of the bilayer. D) The polar head groups face inward toward the inside of the bilayer.
C
Why might this be biologically important? A. membrane phase transitions occur more rapidly in changing environments B. membranes are more effective barriers when fluidity increases C. membrane protein function depend on appropriate membrane fluidity D. lipid rafts do not form as quickly at moderate temperatures near Tm
C
Choose all the correct statements about protein digestion & hydrolysis A. enzymes present in saliva initiate the process of protein digestion B. gastric juices have a pH between 7.0 & 8.0 C. pepsin causes the hydrolysis of some of the peptide bonds in proteins D. in the small intestine, chymotrypsin attacks peptide bonds E. absorption of free amino acids occurs through the wall of the stomach
C & D
Which of the compounds can be considered 2nd messengers? A. Ser B. PLC C. Ca2+ D. DAG E. IP3 F. PIP2 G. PKC
C, D, E
Ms. Weber, a 17-year-old woman, has recently been diagnosed with cystic fibrosis, a disease caused by a genetic mutation. The mutated gene codes for a transmembrane protein, cystic fibrosis transmembrane conductance regulator. CFTR moves chloride ions (Cl-) across the membrane using ATP hydrolysis. What kind of transport is this? A. facilitated diffusion B. osmosis C. simple diffusion D. active transport
D
Protein kinase A (PKA) is: A) competitively inhibited by cyclic AMP. B) activated by covalent binding of cyclic AMP. C) affected by cyclic AMP only under unusual circumstances. D) allosterically activated by cyclic AMP.
D
What causes multidrug resistance in cancer cells? A. the smooth endoplasmic reticulum in some cancer cells neutralizes a variety of chemotherapy drugs B. the immune system identifies each chemotherapy drug as foreign & develops antibodies to each drug C. some cancer cells phagocytize chemotherapy drugs & use the lysosomes in the cell to destroy the drugs D. transmembrane proteins actively pump chemotherapy drugs & other toxins out of cancer cells
D
Which carbohydrate is a disaccharide? A. glucose B. glycogen C. amylase D. lactose
D
Which lipid or lipids must be obtained in the diet? A. endogenous cholesterols B. essential disaccharides C. endogenous glycogen D. essential fatty acids
D
Which of the following is not a reducing sugar? A) fructose B) ribose C) maltose D) sucrose
D
Which of the following is true of the structure to the right? A) It is an epimer of fructose. B) It is an aldose sugar. C) It is an L-sugar D) It is a nonreducing sugar
D
Which of the following statements about starch and glycogen is false? A) Amylose is unbranched; amylopectin and glycogen contain many (alpha 1 -> 6) branches. B) Both are homopolymers of glucose. C) Glycogen is more extensively branched than starch. D) Both serve primarily as structural elements in cell walls.
D
Which of the phrases best describes the hydrophilic region of a phospholipid? A. floats in nonpolar compounds B. has an high affinity for high salt concentrations C. repelled by water D. interacts w/ water
D
Digestion process of a complex carbohydrate
First -a person begins to take a bite & beings to chew the complex carbohydrate into smaller pieces -enzyme amylase breaks polysaccharide chains into disaccharides -amylase is deactivated by the low pH in the stomach -other enzymes in small intestine further break the polysaccharide into monosaccharides -monosaccharides are absorbed through the intestinal wall Last
Put the steps of the signal transduction pathway in order from the releasing of glucagon into the blood to the promotion of glycogenolysis
Glucagon is released into blood -Glucagon binds extracellulary to G protein-coupled receptor -G protein releases GDP and binds GTP -Activated G protein activates adenylate (adenylyl) cyclase -Cyclic AMP activates protein kinase A -Phosphorylase kinase phosphorylates glycogen phosphorylase Glycogenolysis is promoted
Steps regarding step digestion & absorption in order
Triacylglycerols enter stomach -undigested fats enter the small intestine -the gallbladder secretes bile into the small intestine -pancreatic lipase hydrolyzes TAGs in lipid droplets -insoluble lipids, in micelles, are absorbed through the lining of the small intestine -TAGs in chylomicrons enter the lymph system -TAGs in chylomicrons enter the blood stream Triacylglycerols absorbed into cells
Beta blockers are drugs that inhibit beta-adrenergic receptors and are used to control tachycardia (high heart rate) and anxiety disorders by countering the effects of epinephrine. Which of the following intracellular second messengers would be expected to decrease in a patient treated w/ a beta blocker? a. cAMP b. DAG c. IP3 d. Ca2+ e. cGMP
a
What is the structure of micelles? a. the polar head groups of fatty acids are outside the micelle and the carbon chains are inside b. the polar head gropus of proteins are inside the micelle and the carbon chains are outside c. bile salts are inside the micelle and the carbons are enclosed outside d. phospholipids are inside cholesterol is outside the micelle e. globular structure formed by small proteins in aqueous solution
a
What provides carbohydrates with an ability to form a vast array of spatial structures? a. They function in parallel with polysaccharides b. They are just as amino acids are for proteins c. The nature of covalent bonds of monosaccharides varies highly d. A large variety of monosaccharides can be linked together in many different ways e. Monosaccharides are basically hydrates of carbon
a
The glucose units in this polysaccharide are joined by alpha-1,4-glycosidic bonds
amylose
The G proteins found in RTK pathways differ from those in the 7TM receptor pathways in that they: a. are active only in the GTP bound state b. are monomeric c. are inactive when bound to GDP d. have GTPase activity e. activate downstream effector proteins
b
Which bonds link monosaccharides in oligosaccharides? a. N-glycosidic bonds b. O-glycosidic bonds c. ester bonds d. N-linkages e. noncovalent interactions
b
What would happen first if an enzyme mutation occured that would seriously inhibit the activity of pancreatic amylase? a. the carbohydrates could not be transported into intestinal cells b. the carbohydrates would be digested more quickly c. the carbohydrates would not be shortened to smaller simple sugars d. the polysaccharides would not be transported into the blood e. simple sugars would be resynthesized to di- or oligosaccharides
c
Which of the following is an accurate statement regarding carbohydrates? a. Dihydroxyacetone and glyceraldehyde are both hexoses b. Galactose and mannose are both ketoses c. Glycogen and starch are both homopolymers of glucose d. Lactose and sucrose are both monosaccharides e. Ribose and fructose are both pentoses
c
The glucose units in this polysaccharide are joined by beta-1,4-glycosidic bonds
cellulose
This polysaccharide is the structural component of plant cell walls & can't be digested by humans
cellulose
steps in the activation of PKA
cystolic cAMP concentration increases -> 2 cAMP molecules bind to each PKA regulatory subunit -> regulatory subunits move out of the active sites of the catalytic subunits, & the R2C2 complex dissociates -> free catalytic subunits interact w/ proteins to phosphorylate Ser or Thr residues
Which statement about protein digestion is CORRECT? a. The proteins are denatured by the alkaline environment of the stomach b. The proteins are not digested at the neutral environment of the intestine c. The denaturation is caused by the breakage of sulfate bonds due to the low pH d. The pancreatic proteases hydrolyze proteins into oligopeptides
d
A mutation of the SOS gene that results in a non-functional protein would have what effect on EGF signaling? a. EGF would not be able to bind to the EGF receptor b. The EGF receptor would not be able to dimerize after ligand binding c. The kinase activity of the EGF receptor would be inhibited d. Grb-2 would not be able to bind to the EGF receptor e. Ras could not be activated
e
Which carbon atoms are involved in the formation of alpha-D-fructofuranose? a. C-1 aldehyde group and C-5 hydroxyl group b. C-2 aldehyde group and C-6 hydroxyl group c. C-1 keto group and C-5 hydroxyl group d. C-2 keto group and C-6 hydroxyl group e. C-2 keto group and C-5 hydroxyl group
e
Which of the following is a direct product of a reaction catalyzed by phospholipase C? a. ATP b. cAMP c. Ras d. dihydroxyacetone phosphate e. inositol 1,4,5-triphosphate
e
classify into facilitated diffusion, active transport, or both -movement to area of lower concentration -glucose transport into muscle cell -requires energy -sodium ion transport out of cell -movement across a membrane -movement assisted by proteins
facilitated diffusion -movement to area of lower concentration -glucose transport into muscle cell active transport -requires energy -sodium ion transport out of cell both -movement across a membrane -movement assisted by proteins
This polysaccharide is the storage form of glucose in the human body
glycogen
Match the description to the type of G protein (heterotrimeric G protein, both, small G proteins) -activated by 7TM receptors -active form dissociates to Galpha & Gbeta -inactive form binds GDP -active form binds GTP -activated by dimerized growth factor receptors -monomeric in both active & inactive forms
heterotrimeric G protein -activated by 7TM receptors -active form dissociates to Galpha & Gbeta both -inactive form binds GDP -active form binds GTP small G proteins -activated by dimerized growth factor receptors -monomeric in both active & inactive forms
Arrange the substances in order of decreasing permeability through a lipid bilayer membrane indole, glycerol, Cl-, glucose
high permeability indole glycerol glucose Cl- low permeability
UDP -galactose + glucose galactosyltransferase --------------------->. __________ + UDP regulatory protein
lactose
____________ are the proteins involved in recognition of specific oligosaccharide structures
lectins
Why are lipids more complicated than carbohydrates & proteins?
lipids are not water soluble
anomers
same sugar differ at anomeric carbon only, the the stereocenter arises as the ring because -OH nucleophile can attack side of C=O
saturated phospholipids vs. unsaturated phospholipids
saturated: fatty acid tails are straight, -have no double bonds in the fatty acid carbon chains -fatty acid tails pack tightly together, -make the membrane somewhat rigid at low temperatures unsaturated: have bent fatty acid tails, -have at least one double bond in the fatty acid tails -maintain some space btwn adjacent phospholipids, -allow the membrane to remain fluid & flexible at low temperatures