BIOC 384 exam 3

Predict how oxygen saturation of hemoglobin would be affected in an individual with a defective hexokinase.

2,3-BPG levels would be reduced and oxygen binding increased.

The majority of sucralose ingested is not hydrolyzed in the human digestive tract, so it produces no glycemic response. A small percentage can be hydrolyzed to produce equimolar amounts of 1,6-dichloro-1,6-dideoxyfructose and 4-chloro-4-deoxygalactose. Would either of these hydrolysis products cause a false positive result with Benedict's test and the glucose oxidase-peroxidase system? Select all of the true statements below. A. 4-chloro-4-deoxygalactose would give a positive result with Benedict's test. B. 4-chloro-4-deoxygalactose would not cause a positive result with either test. C. 1,6-dichloro-1,6-dideoxyfructose would act as a substrate in the glucose oxidase-peroxidase reaction. D. 4-chloro-4-deoxygalactose would act as a substrate in the glucose oxidase-peroxidase reaction. E. 1,6-dichloro-1,6-dideoxyfructose would give a positive result with Benedict's test. F.1,6-dichloro-1,6-dideoxyfructose would not cause a positive result with either test.

4-chloro-4-deoxygalactose would give a positive result with Benedict's test. 1,6-dichloro-1,6-dideoxyfructose would not cause a positive result with either test.

If there were a technique that allowed one to isolate EGFR1 and EGFR2 at discrete steps along the activation pathway, which of the following would be isolated?

A dimer in which EGFR2 contains phosphotyrosines but EGFR1 does not.

Signal transduction is part of a cell's response to an external signal. Although signal transduction pathways can differ in their details, there are some common elements. Determine which of the statements below accurately describe signal transduction pathways. Select the three correct statements.

A receptor changes conformation upon binding, transmitting a signal across the cell membrane Signal transduction cascades, often involving protein kinases, amplify a signal intracellularly. A receptor may pass on a signal by interacting with another protein or by acting as an enzyme.

Identify the three signaling proteins shown in the box and list the amino acid sequence that is recognized by each signaling protein to specify distinct pY residues on binding partners.

A. IRS-1; N-P-A-pY B. Shc; N-P-E-pY C. GRB2; K-P-F-pY

The reaction catalyzed by phosphofructokinase-1 can be activated and inhibited by a number of allosteric factors. Sort the allosteric effectors listed below to indicate if they activate or inhibit this reaction.

Activate= AMP,ADP AND fructose-2,6-bisphospate Inhibit-ATP and citrate

If a mutation occurred in SODD that prohibited its interaction with the DD of TNF receptor, the TNF receptor would _____

Bind TRADD, even in the absence of TNF-a

For TNF receptors, which of the following inhibits receptor signaling?

Bound SODD proteins

Caspases (cysteine-aspartate proteases) function as "cutioners" in the cell death pathway. Choose three reasons why it makes sense that they function in this role rather than some other biomolecule.

Caspases must be activated by proteolytic cleavagge to convert the inactive zymogen to the active form-this provides a means to control caspase activity by initiating the cleavage reaciton. Caspases are enzymes that function catalytically and therefore can do a lot of damage in a very short amount of time Caspases have preferred substrate recognition sites for cleavage, and therefore can preferentially degrade other proteins

What effect do elevated levels of ATP have on glycolysis?

Decrease the affinity of PFK-1 for fructose-6-P and slow rate of the pathway.

If the standard free energy change for the reaction converting A to B is unfavorable, how can this reaction proceed in the forward direction under cellular conditions? Select TWO correct answers

Decrease the cellular concentration of B until the actual free energy change is now negative. Couple the reaction to an exergonic reaction such as ATP hydrolysis.

Which of the following best describes the location of the coordinating cysteines in the glucocorticoid receptor DNA binding element?

Each zinc ion is held in place by cysteines located in α helices and random coils, but not the β sheets.

Interaction of glucocorticoid receptors with which of the following prevents binding to glucocorticoid response elements (GREs)?

Hsp90

Which of the following is true of procaspase 8?

It is proteolytically inactive

How does phosphoglycerate kinase make glycolysis energy neutral at this step?

It produces 2 ATP along with 3-phosphoglycerate

What is the function of the lactate dehydrogenase reaction in muscle cells during intense exercise?

It regenerates NAD+ for the GAPDH reaction to maintain glycolytic flux and produce ATP for muscle contraction.

Which of the following correctly describes how phosphorylation of PIP2 to generate PIP3 propagates the insulin receptor signal?

PIP3 recruits Akt, a PH domain-containing protein, and PDK1 to the plasma membrane.

The catalytic acitivity and/or conformational stability of this protein is likely dependent upon ____ of peripheral amino acid side chains. These side chain's are expected to have a _____ value.

Protonation Low pKa

The figure below shows a membrane-associated multi-enzyme complex. Reaction intermediates in this enzyme complex are used effectively because they____

Quickly channel from one enzyme to the next in coupled reactions

Which one or more of the following statements is true about the complex structure above?

RGS2 does not participate in the active site chemistry needed to facilitate GTP hydrolysis. The GDP is held in place by the ends of three α helices.

An enzyme undergoes a mutation that causes it to lose the ability to be regulated via phosphorylation. Which of the following mutations may lead to this loss of regulation? Assume that the overall structure is not altered by the mutation and multiple kinases can phosphorylate the wild-type protein.

Ser to Phe

When ATCase is in the __________ state it indicates that ____________ is bound, and that ATCase is ______________ regulated.

T; CTP; down

What is the function of the GTPase activity in G proteins?

The GTPase cleaves GTP to generate GDP and inactivate signalin

What is the Warburg effect and why is it an advantage to cancer cells?

The Warburg effect refers high levels of glycolytic flux to compensate for tumor hypoxic conditions and to produce lactate, which provides a growth advantage.

When the regulatory subunit of PKA is bound to the catalytic subunit of PKA_____.

The catalytic subunit is inactive.

What is the target of β-adrenergic receptor kinase?

The cytoplasmic tail of the G protein-coupled receptor

Choose the statement below that best describes what the actual change in free energy (deltaG) tells you about an enzymatic reaction that cannot be determined by the standard free energy (deltaGº') change.

The direction of the reaction under steady state conditions.

What advantage is there to phosphoglycerate kinase having an open and closed configuration?

The induced-fit mechanism maximizes accessibility of active site without sacrificing hydrophobic environment.

What characteristic is true for both RTKs and GPCRs?

The receptor undergoes a conformational change on activation.

GRB2 protein is the common link between the insulin and EGF signaling pathways

True

Which statement explains why glucose phosphorylation could not occur without ATP investment?

Without ATP investment, one or both of the substrates would need to exceed the solvent capacity of the cell for glucose phosphorylation to occur.

Association of glucocorticoids with their DNA binding sites is essential for the regulation of inflammatory response genes. Which one or more of the following might disrupt normal association of glucocorticoids with their DNA binding sites and be cause for concern?

Zinc deficiency in a patient Genetic mutation in GRE

Find all of the conditions listed on the left side that either stimulate or inhibit liver PFK-1 activity as listed on the right. Note that every condition should lead to stimulated or inhibited PFK-1 activity ___Low energy charge in the cell. ____AMP is bound to the allosteric effector site and ATP is bound to the catalytic site. ____Increased citrate levels in the cell. ____ Increased levels of both ADP and AMP. ____The conformational equilibrium is shifted toward increased amounts of the R state structure. ____Increased fructose-2,6-bisphosphate levels. ____Decreased fructose-2,6-bisphosphate levels. ____The conformational equilibrium is shifted toward increased amounts of the T state structure. ____1 High energy charge in the cell. 1. Liver PFK-1 activity is stimulated. 2. Liver PFK-1 activity is inhibited.

_1__Low energy charge in the cell. __1__AMP is bound to the allosteric effector site and ATP is bound to the catalytic site. __2__Increased citrate levels in the cell. __1__ Increased levels of both ADP and AMP. __1__The conformational equilibrium is shifted toward increased amounts of the R state structure. __1__Increased fructose-2,6-bisphosphate levels. __2__Decreased fructose-2,6-bisphosphate levels. __2__The conformational equilibrium is shifted toward increased amounts of the T state structure. __2__1 High energy charge in the cell.

Put the following eight signaling events in the correct order describing how glucagon binding to glucagon receptors in liver cells increases blood glucose levels in between meals. ___The GDP-bound heterotrimeric G protein binds to the receptor. ____The G-alpha subunit binds to activates adenylate cyclase. ____Production of cyclic AMP leads to activation of PKA. ____GDP is exchanged for GTP in the G-alpha subunit. ____The G-alpha and G-beta/gamma subunits dissociate. ____The C-terminal domain undergoes a conformational change. ____Glucagon binds to the N-terminal domain of the receptor. ____PKA phosphorylates downstream proteins that control glucose export.

_3__The GDP-bound heterotrimeric G protein binds to the receptor. __6__The G-alpha subunit binds to activates adenylate cyclase. __7__Production of cyclic AMP leads to activation of PKA. __4__GDP is exchanged for GTP in the G-alpha subunit. __5__The G-alpha and G-beta/gamma subunits dissociate. __2__The C-terminal domain undergoes a conformational change. __1__Glucagon binds to the N-terminal domain of the receptor. __8__PKA phosphorylates downstream proteins that control glucose export.

Put the following biochemical processes in the correct order that specify the insulin signaling pathway from the point of insulin receptor activation to production of phosphatidylinositol-3,4,5-trisphosphat ___Tyrosine phosphorylation of insulin receptor substrate-1. ____Tyrosine phosphorylation of the cytosolic domains of the insulin receptor. ____Binding of insulin receptor substrate-1 to pY on the insulin receptor. ____Conformational change in the alpha subunit of the insulin receptor. ____Binding of phosphoinositide 3-kinase to pY residue on IRS-1. ____Phosphorylation of phosphatidylinositol-4,5-bisphosphate by phosphoinositide 3-kinase. ____Conformational change in the beta subunits of the insulin receptor.

_5__Tyrosine phosphorylation of insulin receptor substrate-1. __3__Tyrosine phosphorylation of the cytosolic domains of the insulin receptor. __4__Binding of insulin receptor substrate-1 to pY on the insulin receptor. __1__Conformational change in the alpha subunit of the insulin receptor. __6__Binding of phosphoinositide 3-kinase to pY residue on IRS-1. __7__Phosphorylation of phosphatidylinositol-4,5-bisphosphate by phosphoinositide 3-kinase. __2__Conformational change in the beta subunits of the insulin receptor.

Match the receptor type with the correct functional consequences of ligand binding and subsequent receptor activation. ____Nicotinic acetylcholine receptor ____G protein-coupled receptor ____Receptor tyrosine kinase ____Tumor necrosis factor receptor ____Nuclear receptor 1. opening of the inner chamber to facilitate passive ion transport. 2. binding to specific DNA sequences and activating topoisomerase activity to remove negative supercoils. 3. binding to specific DNA sequences and transcriptional regulation of downstream target genes. 4. GTP hydrolysis to form the active GDP-heterotrimeric G protein complex. 5. autophosphorylation of the cytoplasmic tail and binding of adaptor proteins to Tyr-P. 6. deprotonation of carboxyl groups in the inner chamber to form ionic bridges with Na+ and K+ ions. 7. assembly of adaptor complexes through TNF receptor associated death domain proteins. 8. GDP-GTP exchange and dissociation of the heterotrimeric G protein. 9. dephosphorylation of Tyr residues in the cytoplasmic tail by tyrosine kinases in the N-terminal domain. 10. activation of cysteine proteases as a result cleavage by the receptor C-terminal caspase domain.

__1__ Nicotinic acetylcholine receptor __8__ G protein-coupled receptor __5__ Receptor tyrosine kinase __7__ Tumor necrosis factor receptor __3__ Nuclear receptor

The second messenger cyclic AMP (cAMP) is synthesized from ATP by the activity of the enzyme adenylate cyclase. Cyclic AMP, in turn, activates proteins kinase A (PKA), which is responsible for most of the effects of cAMP within the cell. Determine the correct steps in the activation of PKA, and then number them in the correct order (1-5), starting after the adenylyl cyclase reaction. ____Cytosolic cAMP concentration increases. ____Each regulatory subunit is activated as the two cAMP molecules are released. ____The regulatory subunits move out of the active sites of the catalytic subunits, and the R2C2 complex dissociates._ ___The free catalytic subunits interact with proteins to phosphorylate Ser or Thr residues. ____Two cAMP molecules bind to each PKA regulatory subunit.

__1__Cytosolic cAMP concentration increases. __5__Each regulatory subunit is activated as the two cAMP molecules are released. __3__The regulatory subunits move out of the active sites of the catalytic subunits, and the R2C2 complex dissociates._ _4__The free catalytic subunits interact with proteins to phosphorylate Ser or Thr residues. __2__Two cAMP molecules bind to each PKA regulatory subunit.

Categorize each of the following as an aldose, a ketose, or neither ____Ribose ____Fructose ____Glyceraldehyde ____Mannose ____Dihydroxyacetone ____Glycerol ____Xylulose ____Glucose 1. Aldose 2. Ketose 3. Neither

__1__Ribose __2__Fructose __1__Glyceraldehyde __1__Mannose __2__Dihydroxyacetone __3__Glycerol __2__Xylulose __1__Glucose

For the cAMP-mediated pathway, identify the following components: ____Kinase ____Result ____Second messenger ____Second messenger produced by 1.cAMP 2. Adenylate cyclase 3. Protein kinase A (PKA) 4. Glucose mobilization 5. diacylglycerol (DAG) 6. phospholipase C (PLC) 7. protein kinase C (PKC) 8. Glucose storage (as glycogen)

__3__Kinase __4__Result __1__Second messenger __2__Second messenger produced by

Match the pY binding signaling protein with the downstream signaling protein it recruits. The match needs to include the correct adaptor interaction for the pY binding signaling protein and its cognate downstream signaling protein. ____GRB2 protein ___ Shc protein ____ IRS-1 protein 1. SOS protein through pY residue 2. GRB2 protein through pleckstrin homology domain 3. IRS-1 protein through GRB2 4. SOS protein through SH3 domain 5. PI3K protein through SH2 domain 6. SOS protein through PI3K 7. GRB2 protein through pY residue 8. PDK-1 protein through pY residue 9. PI3K through pY residue

__4__ GRB2 protein __7_ Shc protein __9__ IRS-1 protein

Auto-brewery syndrome in the human intestine mimics the process of home brew fermentation to produce beer. Put the following biochemical steps in order that are required to make a bottle of home brew beer. ____Incubate live yeast under optimal aerobic conditions for 5 days._ ___Germinate grain to activate enzymes that will be needed to convert starch to glucose. ____Allow carbonation to occur in the airtight container for 2 weeks. ____Disrupt the seed cell wall to release catabolic enzymes and incubate with water to produce glucose._ ___Boil the grain mixture in the presence of plant parts to release flavor molecules._ ___Decant mixture into air tight container and add a small amount of pure cane sugar. ____Incubate live yeast under optimal anaerobic conditions for 4 weeks. ____Remove liquid from airtight container and expose to gustatory GPCRs to activate neurons.

__4__Incubate live yeast under optimal aerobic conditions for 5 days._ _1__Germinate grain to activate enzymes that will be needed to convert starch to glucose. __7__Allow carbonation to occur in the airtight container for 2 weeks. __2__Disrupt the seed cell wall to release catabolic enzymes and incubate with water to produce glucose._ _3__Boil the grain mixture in the presence of plant parts to release flavor molecules._ _6__Decant mixture into air tight container and add a small amount of pure cane sugar. __5__Incubate live yeast under optimal anaerobic conditions for 4 weeks. __8__Remove liquid from airtight container and expose to gustatory GPCRs to activate neurons.

Put the following biochemical processes in the correct order that specify the insulin signaling pathway from the point of phosphatidylinositol-3,4,5- trisphosphate production to decreased serum glucose levels in liver cells. ____Phosphorylation of downstream target proteins by Akt._ ___Activation of kinase activity in Akt and dissociation from phosphatidylinositol-3,4,5- trisphosphate._ ___Activation of glycogen synthase and incorporation of imported glucose into glycogen._ ___Phosphoinositide-dependent kinase-1 phosphorylation of Akt on serine and threonine residues._ ___Increased glucose uptake by the GLUT4 glucose transporter. ____Phosphoinositide-dependent kinase-1 and Akt binding to phosphatidylinositol-3,4,5- trisphosphate.

__4__Phosphorylation of downstream target proteins by Akt._ _3__Activation of kinase activity in Akt and dissociation from phosphatidylinositol-3,4,5- trisphosphate._ _6__Activation of glycogen synthase and incorporation of imported glucose into glycogen._ _2__Phosphoinositide-dependent kinase-1 phosphorylation of Akt on serine and threonine residues._ _5__Increased glucose uptake by the GLUT4 glucose transporter. __1__Phosphoinositide-dependent kinase-1 and Akt binding to phosphatidylinositol-3,4,5- trisphosphate.

Put the following steps of the G protein cycle into the correct order. ____Reassociation of the heterotrimeric G complex with a GPCR_ __Ligand stimulation of the GEF function of a GPCR_ ___GAPs stimulate the GTPase activity of G-alpha_ ___Dissociation of G-alpha and G-beta/gamma from a GPCR

__4__Reassociation of the heterotrimeric G complex with a GPCR_ _1__Ligand stimulation of the GEF function of a GPCR_ _3__GAPs stimulate the GTPase activity of G-alpha_ _2__Dissociation of G-alpha and G-beta/gamma from a GPCR

A ligand binds to a transmembrane protein, which causes a conformational change in the protein that is detected by an intracellular protein. The intracellular protein is an enzyme that adds phosphate groups to target proteins. The phosphorylated proteins cause a physiological change within the cell. This process is an example of __________________.

a signal transduction pathway.

If Sydney's parents were both heterozygous for mutations in the lactate dehydrogenase gene, what is the probability that her little brother is a) homozygous for the disease, b) heterozygous for the disease, c) homozygous normal without mutations?

a) 25%; b) 50%; c) 25%

Answer the two questions regarding cancer diagnosis. a) Why does 18F-fluorodeoxyglucose accumulate in cells rather than being metabolized to pyruvate --> CO2 + H2O? b) Why is the brain and the bladder visualized by the 18F-fluorodeoxyglucose PET scan shown below of an adult male without any cancer?

a) Because after 18F-fluorodeoxyglucose is phosphorylated by hexokinase and is not metabolized or dephosphorylated. b) The brain uses glucose as an energy source and the bladder excretes the extra 18F-fluorodeoxyglucose.

Based on the Butowt, R. and von Bartheld, C.S. (2020) paper: a) what might explain why ~60% of COVID-19 patients do not experience anosmia even though they experience other symptoms of SARS-CoV-2 infection? b) what might explain why ~10% of COVID-19 patients with anosmia do not regain their sense of smell even after 3 months?

a) The olfactory support cells were not infected and/or killed by the virus. b) The stem cells needed to replenish olfactory support cells were killed.

The activity of protein kinase A (PKA) is regulated by cAMP. Which statement correctly describes the role of cAMP in this activation?

cAMP binds to the regulatory subunit of PKA, promoting its dissociation from the catalytic subunit and activating it.

Caffeine is a phosphodiesterase inhibitor. Based on your understanding of cAMP flux in the cell, which of the following might you see as a result of excessive caffeine intake by an undergraduate biochemistry student cramming for exams?

cAMP levels will increase.

On the basis of the molecular structure of the protease bound to inhibitor, which best describes the type of inhibition indinavir is most likely to demonstrate?

competative

Caspase 3 is responsible for_______________.

degrading key regulatory molecules

The best description of substrate-level phosphorylation is _______________.

direct transfer of a Pi to an ADP.

Acetylcholinesterase is an important enzyme in the nervous system. Acetylcholinesterase activity is blocked by the nerve agent sarin gas, which forms a covalent bond with a Ser in the active site of the enzyme. Sarin gas is a(n)

irreversible inhibitor

Enzyme inhibitors have incredible potential for improving human health. Researchers have become increasingly interested in therapeutic inhibition of main protease (Mpro), a critical enzyme for the assembly of the SARS-CoV-2 pandemic virus, as a means of reducing the severity and transmission of COVID-19. Which of the following describes the best-case scenario for inhibitor development?

low Kd, competitive inhibitor

Below is the molecular structure of a single bovine -arrestin subunit. Two locations are indicated. What is most likely to interact with the protein at these locations?

phosphorylated GPCR

If GRB2 were truncated so that the N-terminal domain was missing, the truncated protein would be unable to bind the_________________

proline-rich sequence of the SOS protein

A mutation causes a cell to divide uncontrollably. Analysis of the cell shows that both copies of the gene must have the mutation. From this information, it can be determined that the mutation is ____

recessive

List three ways in which flux is controlled through glycolysis.

regulation of glucokinase, regulation of PFK-1, and supply and demand of intermediates

If blood glucose levels are elevated, the net effect of activating glucokinase in pancreatic beta cells is _____________

stimulating the release of insulin from pancreatic cells

If blood glucose levels are elevated, the net effect of activating glucokinase in pancreatic beta cells is _____________.

stimulating the release of insulin from pancreatic cells.

For the following reaction A→ B, if at equilibrium delta Gº'> 0, what can be said about the directionality of the reaction?

strongly favored in the reverse direction

Which of the following correctly describes the biochemistry of the amino acids at the termini of pepsin?

two nonpolar amino acids at the N-terminus and one polar amino acid at the C-terminus

In the PDB molecule above, cysteines help position the four zinc ions. How many cysteines are holding each zinc ion in place?

4

What prevents hydrated Na+ and K+ ions from passing through the nicotinic acetylcholine receptor channel in the absence of acetylcholine?

A ring of nonpolar amino acids in the interior chamber prevents the hydrated ions from moving through the constricted channel.

Why are catabolic pathways always paired with anabolic pathways?

Catabolic pathways degrade molecules and anabolic pathways synthesize molecules.

The TNF signaling pathway stimulates both an apoptosis and a cell survival pathway in the same well. What molecular mechanism determines whether the cell survives or dies?

Cell death or survival in a TNF receptor stimulated cell is determined by the relative expression level of downstream signaling proteins in the propoptotic and anti-apoptotic pathways

Below is shown the structure of a homodimer of the GR DNA-binding domain. Four area are highlighted. Which is most likely to interact with DNA?

D

In the case study, the patient Peter experienced thirst, hunger, and fatigue owing to his undiagnosed Type 1 diabetes. What was the single biochemical cause of all three symptoms?

Dietary glucose was unable to be metabolized by cells because insulin-mediated signaling was insufficient.

Which of the following activates a zymogen?

Enterokinase

Phosphatase and tensin homolog is a phosphatase that converts phosphatidylinositol-4,5-bisphosphate to phosphatidylinositol-3,4,5-trisphosphate.

False

Glucose and fructose are both C6H12O6. What is the structural difference between them?

Fructose is a five-membered ring and glucose is a six-membered ring.

Which mutation would be most likely to drive cancer cell formation?

G12V

Signaling activity of G proteins is controlled by GTPase activating proteins (GAPs) and Guanine exchange factors (GEFs). What are the mechanisms by which GAPs and GEFs control G proteins?

GAPs inhibit G proteins by stimulating GTP hydrolysis; GEFs activate G proteins by stimulating GDP-GTP exchange.

The wild-type Ras gene normally has the codon GGT, coding for glycine at position 12. Which of the mutations shown in the above figure is least likely to affect Ras protein function?

GCT, Ala

Based on the structures of D-glucose and D-galactose, which one of the following statements is true?

Glucose and galactose are epimers of each other.

Which metabolic pathway is an example of a catabolic pathway in animals?

Glycogen degradation

If protein kinase A is activated in a liver cell in response to epinephrine binding to the 2-adrenergic receptor, which of the following will result?

Glycogen degradation will be turned on.

Long polypeptides, when folded into tertiary structures, can bring two amino acids within the polypeptide close together even though they are far apart in sequence. In the Gqα protein, the amino terminus and carboxyl terminus are found in close proximity. What would you say is an accurate description of this part of the protein?

Gqα has an α helix at one end and a β strand at the other that come in close proximity when folded.

Based on the activation state of the RGS2-Gqα protein complex shown in the virtual model, which of the following would you expect to happen next?

Gα will reassociate with Gβγ.

How will Taylor avoid auto-brewery syndrome given that he will likely still have yeast in his microbiome owing to the anti-inflammatory drugs?

He needs to avoid high carbohydrate snacks like potato chips and donuts on an empty stomach.

Which of the following statements best describes the effect of ADP on the activity of PFK-1?

High concentrations of ADP block the inhibitory effect of ATP by competing for the same allosteric site on PFK-1.

Which protein insulin receptor signlaling pathway is capable of autophosphorylation?

Insulin receptr (IR)

What kinds of chemical bonds do you identify as being critical for the formation of this quaternary complex?

Ionic Hydrogen

What is the function of growth factor receptor-bound 2 (GRB2) protein in RTK signaling?

It is an adaptor protein that binds to phosphotyrosine residues in RTKs and also binds to GEF proteins

Which of the following statements accurately describe receptor tyrosine kinases (RTKs)?

Ligand binding is required for autophosphorylation (cross-phosphorylation) A ligand binds to the extracellular domain RTKs are dimeric in the presence of ligand

If GRB2 were truncated so that the N-terminal domain was missing, the truncated protein would be unable to bind the _____

Proline-rich sequence of the SOS protein

Which of the following statements are true?

Pyruvate is a product of the catabolism of all major biomolecules. Acetyl CoA is a product of the catabolism of all major biomolecules.

Procathepsin B is a lysosomal protease that is first translated as a proenzyme. On autocleavage it is fully activated. Procathepsin B is ________________.

a zymogen.

Which of the following statements is true concerning the role of cGMP in vasodilation?

cGMP is a secondary messenger that acts on protein kinase G.

Which of the following choices below includes only first messenger signaling molecules?

cortisol, insulin, prostaglandins

What would be the effect in muscle cells of a deficiency in lactate dehydrogenase?

deficiency of ATP

Catabolic products of some pathways can be used as the substrates for anabolic pathways. During times of starvation or fasting, the liver uses many noncarbohydrate precursors to synthesize glucose. However, the catabolic products of _____ cannot be used to synthesize glucose.

fatty acids

Fructose-1,6-bisphosphate is cleaved by aldolase. What is required for the reaction to proceed?

formation of Schiff base intermediate

An infant who has galactosemia is unable to convert______________.

galactose-1-P to glucose-1-P.

Which of the following is the correct net reaction for glycolysis?

glucose + 2 ADP + 2 Pi + 2 NAD+ to 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2H2O

Which reaction in glycolysis is a redox reaction?

glyceraldehyde-3-P -> 1,3-bisphosphoglycerate

Which binding site most likely represents the area of greatest structural change in response to ligand binding?

heterotrimeric G protein binding

The β2-adrenergic receptor is best characterized as which of the following?

mostly α helices

Cyclic GMP is the __________ during vasodilation.

second messenger

In the following figure, what is the linkage between the two monosaccharide units, and is this a reducing or nonreducing sugar?

𝛼1->2, nonreducing