Biochem/Physiology Pt 2 Flashcards by Ch Mora

The kidneys regulate acid-base balance by the:
• secretion of bicarbonate ions (HC03-) into the renal tubules and the reabsorption of
hydrogen ions (H’)
• secretion of hydrogen ions (W) into the renal tubules and the reabsorption of
bicarbonate ions (HC03-)
• secretion of both hydrogen (W) and bicarbonate ions (HC03-) into the renal tubules
• reabsorption of both hydrogen (W) and bicarbonate ions (HC03-)

• secretion of hydrogen ions (H’) into the renal tubules and the
reabsorption of bicarbonate ions (HCo3·)

hydrogen ions secreted; derived from carbonic acid

HCO3- into blood

net reabsorption of HCO3 but not a net secretion of H+

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\_\_\_ is the best overall index of kidney function.
• CPR
• TFR
•APR
• GFR

GFR

inulin and creatinine: neither absorb nor secrete; clearance = GFR

excessive constriction of afferent arteriole –> decrease RBF and GFR

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The countercurrent mechanism is a system in the renal _ _ that facilitates
the __ of the urine. The system is responsible for the secretion of __
urine in response to __ plasma osmolarity.
• cortex/concentration/
hyperosmotic/elevated
• medulla/dilution/hypo-osmotic/depressed
• cortex/dilution/hypo-osmotic/
depressed
• medulla/concentration/
hyperosmotic/elevated

medulla, concentration, hyperosmotic, elevated

countercurrent - concentration of urine in medulla
Henle penetrates into medulla to create gradient
hyperosmotic interstitium –> water reabsorbed from urine

BUT asc loop is impermeable to water!

NaCl reabsorbed from asc loop of Henle and water is retained –> increases in medullary interstitium

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Reabsorption of glomerular filtrate would be most affected if modifications
were made to the permeability of which section of the nephron?
• descending loop of Henle
• distal convoluted tubule
• proximal convoluted tubule
• ascending loop of Henle

proximal tubule

2/3 is reabsorbed (almost all of glucose)

also some in Henle, distal and collecting

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Your afternoon patient complains that she has consumed “tons of liquids”
today. The patient asks ifthis will have an effect on her urine concentration.
What would you say in response to this question?
• Your plasma osmolarity is lower than normal, and you will likely excrete a large amount
of concentrated urine
• Your plasma osmolarity is lower than normal, and you will likely excrete a large amount
of dilute urine
• Your plasma osmolarity is higher than normal, and you will likely excrete a large amount
of concentrated urine
• Your plasma osmolarity is higher than normal, and you will likely excrete a large amount
of dilute urine
What are the normal values for daily glomerular filtrate amount and
excretion amount, respectively?
• 1 SO - 2SO L; 1 - 2 L
• 1 SO - 2SO L; 12 L
• 4S - 7S L; 1 - 2 L
• 4S - 7S L; 12 L

plasma lower, dilute urine

150-250 GFR, 1-2 urine/day

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Ammonia is produced from the metabolism of a variety of compounds.
1. Which compound listed below is quantitatively the most important source
of ammonia?
2. Which compound is not a source of ammonia?
3. Which compound is converted to ammonia mainly in the kidney?
• glutamine
• amino acids
• a mines
• purines and pyrimidines
• triglycerides

AA
TGs
glutamine

sources of ammonia: AA in liver by aminotransferases (PLP cofactor)

glutamine in kidney

urea forms in liver
uric acid crystals –> gout

arginase catalyzes urea formation (cofactor Mn)

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carbonic anhydrase cofactor

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PLP is cofactor for

aminotransferases

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arginase fx

urea formation in cell, cofactor = Mn

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Mn is cofactor for what

arginase which makes urea in cell

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Which of the following processes is not involved in the formation of urine?
Which two of the following processes in the formation of urine involve the
most similar amounts of fluid transport?
Which two processes supplement each other, working in the same
“direction”?
Which process is most affected by levels of ADH?
Which process occurs in Bowman’s capsule?
• filtration
• reabsorption
• excretion
• secretion

excretion - not a part of formation
filtration and reabsorption - about 99% of filtrate is reabsorbed
filtration and secretion - both from blood to tubules
reabsorption
filtration

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Cardiac muscle has a shortened action potential compared to skeletal
muscle.
In cardiac muscle, the action potential is caused by opening oftwo types of
channels.
• both statements are t rue
• both statements are fa lse
• the first statement is true, the second is fa lse
• the first statement is false, the second is true

first false, second true

cardiac mm has a plateau –> 15x longer potential

skel mm: fast Na channels
cardiac mm: fast Na + slow Ca (which actually make plateau)

strength of Ca directly proportional to intracellular Ca

refractory of atria much shorter than ventricles, can depol again faster

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channels in cardiac mm

fast Na (also in skel) and slow Ca (make plateau)

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The bicuspid or mitral valve is located between which two chambers of the
heart?
• the right and left ventricl es
• the right atrium and the left ventricle
• the right and left atri a
• the left atrium and the left ventri cle
Which valve is unique in having a different number of cusps than the others?
• mitral valve
• tri cuspid valve
• pulmonary semilunar valve
• aortic semilunar valve

LA and LV

mitral - 2

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An electrocardiogram is a graphic illustration of the:
• cardiac cycle
• cardiac conduction system
• cardiac output
• systemic and pulmonary circuits
heart

cardiac conduction system

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Cardiac function is the volume of blood pumped each minute, and is
expressed by which equation?
• CO = SV- HR
• CO = SV + HR
• CO = SVx HR
• CO = SV I HR

CO = SV x HR
5-6 L

SV = end diastolic - end systolic (70-80 ml)

BP = CO x TPR

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equation for BP

CO x TPR

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The Bainbridge Reflex is a positive feedback mechanism in which there is a
compensatory increase in heart rate, due to a rise in right atrial pressure.
It is commonly referred to as an Atrial Reflex.
• both statements are true
• both statements are false
• the f irst statement is t rue, the second is false
• the f irst statement is fa lse, the second is true
164

both true

Bainbridge reflex = atrial reflex

HR increases when RA pressure increases

stretch receptors through vagus to medulla

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Use the same answer options for the following questions.
1. Your patient has a defective mitral valve, allowing backflow. Which of the
following cardiac phases will be least affected by this defect?
2. Normally, which phase would have the highest ventricular pressure?
• isovolumetric contraction
• fill ing phase
• isovolumetric relaxation
• ejection phase

filling (bc valve is open anyway)
ejection

each cardiac cycle ~0.8 seconds

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The first heart sound ("Lub") is associated with the closure of the:
• aortic and mit ral valves
• mit ral and t ri cuspid valves
• aortic and pulmonary valves
• t ri cuspid and pulmonary valves

mitral and tricuspid (AV valves)

ventricular systole begins at S1, ventricular diastole ends with S1

second sound - closure of semilunars
ventricular diastole begins at S2

aortic valve closes before pulmonary valve –> splitting of S2

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semilunars close, aortic before pulmonary –> S2 splitting

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AV close

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You have four patients with the following heart defects. For each patient,
choose which portion of the cardiac conduction system that is most likely
malfunctioning.
1. Craig has a higher than normal heart rate (tachycardia).
2. Gary’s ventricles contract nearly simultaneously with the atria.
3. Ashley’s right ventricle does not contract on the lateral side.
4. Jimmy’s entire left ventricle does not contract.
• sinoatrial node
• atrioventricular node
• internodal pathways
• atrioventricular bundle
• purkinje fibers

SA node
AV node (responsible for delaying)
purkinje
AV bundle

AV node located in lower interatrial septum; impulse is delayed to allow filling

purkinje fibers -> to lateral walls

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Use the same answer options for the following questions.
1. The ventricles are completely depolarized during which isoelectric
portion of the ECG?
2. This portion of the ECG represents atrial depolarization.
3. This portion of the ECG represents the segment between depolarization of
the atria and depolarization of the ventricle.
• QRS complex
• Q-T interval
• S-T segment
• P wave
• P-R interval

QRS
P
PR

ST segment: period when ventricles depolarized (from full depol to beginning of repol; isoelectric)

QT - between depol and repol

also isoelectric bw T and P (resting)

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Venous return (VR) is the flow of blood back to the heart. Under steady-state conditions, venous return must equal _____ when averaged over time because the cardiovascular system is essentially a closed loop . • sv ·CO • HR • BP

what is frank-starling relationship

SV increases in response to increased filling

Which of the following equations correctly defines blood flow through the vasculature? · flow = (initia l pressure - fina l pressure) x resistance • flow = (init ial pressu re - final pressure ) I resistance • flow = resistance I (initial pressure - fina l pressure)

flow = CO = BP/TPR BP = CO x TPR flow inversely proportional to resistance and directly proportional to pressure gradient resistance inversely proportional to radius^4

Changes in vessel __ are most important quantitatively for regulating blood flow within an organ, as well as for regulating arterial pressure. · thickness •length • diameter • viscosity

diameter

Fill in the blanks so that each statement correctly describes a situation that will increase venous return to the heart. • the contraction of _____(skeletal I cardiac I smooth) muscle • a(n) _____ (increase I decrease) in intrathoracic pressure • the presence of venous _____ (valves I peristalsis) • a(n) ______ (increase I decrease) in venous compliance

contraction of skeletal decrease in intrathoracic pressure presence of valves decrease in compliance (increases central venous pressure)

``` Which ofthe following parameters is decreased during exercise? • heart rate • cardiac output • total peripheral resistance • stroke volume • arteria l pressure ```

TPR vasodilator metabolites (lactate, K, adenosine), bc increased metabolism, to increase blood flow to mm -- and constriction elsewhere, in veins too in exercise, CO increases more than TPR decreases; mean pressure is higher

Parasympathetic fibers innervate the heart by way of the vagus nerves. The right vagus nerve goes to the AV node while the left vagus nerve goes to the SA node. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true

first true, second false symp also increases ICF Ca --> stronger contractions right vagus --> SA node, left vagus --> AV node velocity of conduction: fastest in Purkinje, slowest in AV (Av responsible for delay) automaticity: SA > AV > Purkinje

If a patient's SA and AV nodes fail, what is the most likely situation the patient will be in? • dead; the patient's heart will fail immediately • both the atria and ventricl es will continue to contract on the pace of the bundle of His (30-40 impulses per minute) • the ventricles will contract and passively fil l, keeping the patient alive for a short period • the atri a will take over and contract; the ventricles will allow the blood to flow through and out to the periphery of t he body [

His will take over (proximal interventricular septum). 30-40

The isoelectric point (pi): • is the pH at which the number of positive and negative charges on a molecule equal each other • is the pH at which the number of posit ive and negative charges in a solution equal each other • can be determined using the Henderson-Hasselbalch equation • is the pKa of a solution at which it is neither basic nor acidic • two of the above

+ and - on molecule equal each other pK - dissociation constant

``` Which of the following represents the pH of a solution that has a 10-4 M concentration of OH- ion? • 5 ·8 ·7 ·10 ```

Carbonic acid/bicarbonate is the most important physiological buffer system in the body. Proteins also participate in pH buffering, mainly through their histidine side chains. • both statements are t rue • both statements are false • the fi rst statement is true, the second is false • the fi rst statement is fa lse, the second is t rue 178

both true histidine side chain not far from from blood pH Hb - major intracellular buffer buffers commonly consist of weak acid and salt (or conjugate base) reduce effect of abrupt change in H+ ion concentration - release ions when pH rises and accept ions when pH drops

The famous relationship stated in the Henderson-Hasselbalch equation can be used to: • predict the pH that acid buffers work best at • predict the pKa that acid buffers work best at • predict the dissociation constant of a weak acid only • predict the dissociation constant of a strong acid only • predict the dissociation constant of any acid 179

predict optimal pH of buffer CANNOT predict dissociation constants pH = pK when acid half-neutralized HH equation: pH = pKa + log A-/HA

All of the following are mechanisms the body uses to control the blood's acid-base balance EXCEPT one. Which one is the EXCEPTION? • excess acid is excreted by the kidneys • pH buffers are found in the blood • excretion of carbon dioxide • filtering blood by the spleen

filtering blood by spleen kidneys excrete H+ in acidosis and HCO3- in alkalosis

Respiratory acidosis results from hyperventilation. Metabolic acidosis results from excessive vomiting. • both statements are t rue • both statements are fa lse • the first statement is t rue, the second is fa lse • the first statement is fa lse, the second is true pH

both wrong respiratory acidosis - when don't dispose of CO2; respiratory alkalosis in hyperventilation metabolic acidosis: when kidney can't excrete excess; metabolic alkalosis - excessive vomiting (bc loss of acids) in respiratory acidosis: total CO2 in blood is elevated bc retained and is the cause of this acidosis in metabolic acidosis, pt hyperventilates in attempt to compensate for kidney --> CO2 decreased

``` The cell (plasma) membrane is a fluid mosaic of: • lipids and carbohydrates • proteins and carbohydrates • lipids and proteins • carbohydrates membranes ```

lipids and proteins

Proteins account for about one quarter of the total mass in most membranes. Membrane proteins are globular proteins. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true 183

first wrong, second true proteins ~1/2, globular also carbs on exterior of membrane held together by non-covalent interactions lipid distribution is asymmetrical

``` Molecules that can easily penetrate a biologic membrane are usually: • large and nonpolar • small and polar • large and polar • small and nonpolar ```

small and nonpolar water and gases

The organic matrix of enamel is made from noncollagenous proteins only and contains several enamel proteins and enzymes. Of the enamel proteins, 90% are a heterogenous group of low-molecularweight proteins known as amelogenins. • both statements are true • both statements are false • the fi rst statement is true, the second is false • the fi rst statement is fa lse, the second is true

both true

All of the following statements concerning enamel hypoplasia are true EXCEPT one. Which one is the EXCEPTION? • it is a defect in the mineralization of the formed enamel matrix • the enamel of primary and permanent teeth appear pitted • radiographically, the enamel is either absent or very thin over tips of cusps and interproximal areas • it can be caused by nutritional deficiencies

• it is a defect in the mineralization of the formed enamel matrix this is false hypoplasia is defect in formation of enamel matrix enamel hypoplasia refers to defects of thickness (quantitative defect) hypocalcification - qualitative defect enamel is hard but thin

Caries activity is directly proportional to all of the following EXCEPT one. Which one is the EXCEPTION? • the consistency of fermentable carbohydrates ingested • the quantity of fermentable carbohydrates ingested • the frequency of ingesting fermentable carbohydrates • the oral retention of fermentable carbohydrates ingested

• the quantity of fe rmentable carbohydrates ingeste d ``` Strep mutans dextran sucrose (glucosyltransferase) ``` S. sanguis most common in oral cavity others are s salivarius and lactobacillus glucans --> dental plaque, holds lactic acid which dissolves HA crystals

most common oral bact

s sanguis

what makes dental plaque

glucans, holds lactic acid --> dissolves HA crystals

The primary physiologic control of the salivary glands is by the sympathetic nervous system. Control of salivary secretion is exclusively neural. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is t rue

first false, second true ``` exclusively neural (not hormonal) primary control is parasymps (VIP + ACh), symps also present ``` atropine blocks ACh --> decreased salivation

All of the following characterize saliva EXCEPT one. Which one is the EXCEPTION? • low K+ concentration • low osmolarity • the inorganic composition is entirely dependent on the stimulus and the rate of salivary flow • it is always hypotonic

• low K• concentration low osmolarity, high K+, always hypotonic bc NaCl reabsorbed in ducts inorganics depend on rate of flow and stimulation

The nonessential amino acids are synthesized either from common metabolic intermediates or from other amino acids. Only three amino acids: leucine, lysine and histidine, are exclusively ketogenic. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true 191

first true, second false only leucine and lysine are purely ketogenic

purely ketogenic acids

lysine and leucine

In eukaryotes, DNA does not exist free; it is complexed with an approximately equal mass of basic proteins called histones. These histones contain a large portion of: • cysteine and lysine • arginine and lysine •lysine and glutamine • glutamine and arginine

arg and lys (also histidine) all +

Which one of the following statements about protein structure is correct? • proteins consisting of one polypeptide can have quaternary structure • the formation of a disulfide bond in a protein requires that the two participating cysteine residues be adjacent to each other in the primary sequence of the protein • the stability of quaternary structure in proteins is mainly due to covalent bonds among the subunits • the information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain

• the information required for the correct folding of a protein i s contained in the specific sequence of amino acids along the polypeptide chain quaternary is non-covalent S-S - cysteins

``` Most plasma proteins are derived from the: • kidney •liver • plasma cells • T cells ```

liver only Igs are not produced by liver - by plasma cells most plasma proteins are glycoproteins (except albumin) albumin - 60% of total, 80% of colloid pressure

``` A peptide bond forms between the __ group of one amino acid and the __ group of the adjacent amino acid. • amino; amino • carboxyl; carboxyl • carboxyl; amino ```

carboxyl and amino

Both hemoglobin in RBCs and myoglobin in the muscles employ heme as a prosthetic group. Myoglobin consists of a single polypeptide with a noncovalently bound heme group while hemoglobin has four polypeptides, each with its own heme. • both statements are true • both statements are false • the first statement is t rue, the second is false • the first statement is false, the second is t rue

both true myoglobin much better at binding oxygen; monomeric heme protein

``` All amino acids found in proteins are of the: • D-configuration •L-configuration • F-configuration • C-configuration ```

In contrast to hemoglobin and myoglobin where the iron is always in the ferrous state (Fe2• ), the heme iron of the cytochromes: • is always in the Fe3• state • is always in the Fe

switches | prostethic group of cytochromes is porphyrin

All amino acids have a carboxyl group and an amino group, both bound to the same carbon. This carbon is called the: • a-carbon • f3 -carbon •y-ca rbon • lambda-carbon

alpha

Glutamate can be synthesized by the addition of ammonia to a -ketoglutarate. All of the following amino acids can be derived from glutamate EXCEPT one. Which one is the EXCEPTION? • asparagine • glutamine • proline • arginine

asparagine alphaKG --> glutamate (--> glutamine, proline, arginine)

``` Elastin has an aberrant amino acid composition, with high proportions of: • valine, phenylalanine and lysine • tryptophan, histidine and methionine • glycine, alanine and proline • threonine, cysteine and glutamate ```

gly ala pro

``` Which of the following amino acids carry a positive charge on the side chain which makes them basic? Select all that apply . • lysine • glutamate • arginine • histidine • aspartate • tyrosine ```

lys arg his

The primary st ructure of a protein refers to the spatial a rrangement of a portion of a polypeptide chain determined by the amino acids present. The secondary structure of a protein refers to the irregular folding of a polypeptide chain (the overall three-dimensional conformation of the polypeptide). • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true 203

both false secondary is regular and determined by primary tertiary is irregular quaternary is subunits when more than one polypeptide

``` Patients with vitamin C deficiency (scurvy) form a collagen with insufficient: • isoleucine • hydroxylysine • valine • hydroxyproline ```

hydroxyproline hydroxylation of prolyl and lysyl side chains in procollagen requires vi C

``` Which of the following serves as a principal source of carbon for nonessential amino acids? • fats • water • carbohydrates • urea ```

carbs essential AAs = val thre leu met ile lys phe his and try

A patient of yours suffers from phenylketonuria (PKU). Your dental assistant offers her a bottle of soda. The patient, a relatively intelligent dental student, responds by saying: •I cannot have this because it contains tyrosine, which I am unable to metabolize • I cannot have this because it contains phenylalanine, which I am unable to metaboli ze • Thank you, I need to drink this to supplement my phenylalanine levels • Thank you, I need to drink this to supplement my tyrosine levels Which supplement would you expect this patient to be taking? • tyrosine • phenylalanine • both tyrosine and phenylalanine • neither, no supplement needed

phenylalanine unable to metabolize | tyrosine supplement

All G proteins exist in two forms: • an inactive GTP-bound form that acts on the effector and an active GOP-bound form that does not • an active GTP-bound form that acts on the effector and an inactive GOP-bound form that does not • an active ATP-bound form that acts on the effector and an inactive AOP-bound form that does not • an inactive ATP-bound form that acts on the effector and an active AOP-bound form that does not

active GTP, inactive GDP activates adenylate cyclase --> cAMP --> protein kinase A

In saturated fatty acids, the carbons are linked exclusively by single bonds. Monounsaturated fatty acids have one carbon-carbon double bond and polyunsaturated fatty acids have more than one. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is t rue 208

both true

Dietary triglycerides are digested and broken down to free fatty acids and 2- monoacylglycerol by pancreatic lipase which are absorbed with the help of: • elastase • pepsinogen • t rypsinogen • bile salts 209

bile salts

``` A membrane phospholipid that does NOT contain glycerol is: •lecithin • sphingomyelin • cerebroside • cardiolipin 210 ```

sphingomyelin - based on sphingosine

``` Which one of the following sequences places the lipoproteins in the order of most dense to least dense? • HDL- VLDL- chylomicrons- LDL • LDL-chylomicrons-HDL-VLDL • HDL-LDL-VLDL-chylomicrons • VLDL-chylomicrons-LDL-HDL • chylomicrons-HDL-LDL-VLDL ```

• HDL-LDL-VLDL-chylomicrons protein component = apolipoprotein

Which of the following statements about plasma lipoproteins are correct? Select all that apply. • chylomicrons are synthesized in the intestinal mucosal cells and transport triacylglycerol to the peripheral tissues • HDL particles are produced from LDL particles in the circulation by the action of lipoprotein lipase • HDL competes with LDL for binding to receptors on the surface of cells in extrahepatic tissues • very low density lipoprotein (VLDL) particles are the precursors of LDL in the circulation

chylomicrons synth in intestinal mucosa; transport triacylglycerol to peripheral tissues VLDLs are precursors of LDLs chylomicrons: plasma lipoproteins = large droplet of triacylglycerols that are stabilized by a coat of protein and phospholipid carry FAs from intestine to peripheral tissues to store or fuel remnants of chylomicrons with cholesterol degraded in liver chylomicrons least dense: most TGs and least protein LDLs - major cholesterol carrier

``` Ketone bodies are formed only in the: • stomach • kidney • pancreas · liver ```

liver ketone bodies = acetoacetate, beta hydroxybutyrate and acetone ketone body production regulates by acetyl CoA low glucose - mobilization of FAs by beta oxidation rate limiting step is HMG-CoA synthase (acetoacetyl coA --> HMG-CoA --> acetoacetate + AcCoA

ketone bodies

acetoacetate, beta hydroxybutyrate and acetone

``` All of the following are sources of acetyi-CoA for fatty acid synthesis EXCEPT one. Which one is the EXCEPTION? • creatinine • pyruvate • glucose • citrate ```

creatinine major source = glucose ``` FA synthesis: glucose --> pyruvate (c/pl) pyruvate to m/ch --> AcCoA AcCoA --> citrate citrate to c/pl --> citrate/malate/pyruvate shuttle --> cytoplasmic AcCoA for FA synthesis ``` malonyl CoA - participates in synthesis but not breakdown of FAs

FA synthesis

glucose --> pyruvate --> m/ch: --> AcCoA --> citrate --> c/pl: --> AcCoA (+ bicarb and ATP= malonyl CoA --> FAs)

``` Which of the following is involved in both fatty acid catabolism and synthesis? • carnitine • coenzyme A • malonyi-CoA • alcohol dehydrogenase 215 ```

CoA FA catabolism: carnitine carries FA to m/ch --> oxidation to AcCoA --> Krebs, CO2 and NADH/FADH2

A patient of yours has uncontrolled diabetes mellitus. This causes ketosis, or high levels of ketone bodies, in the body tissues and fluid. Which of the following is NOT a symptom of this condition? • fruity breath • lowered pH of the blood • decreased potassium in the urine • ketone bodies in the urine

decreased K in urine

All of the following statements concerning fatty acid synthesis are true EXCEPT one. Which one is the EXCEPTION? • fatty acid synthesis involves two carbon additions primaril y from acetyi-CoA • the important step in fatty acid synthesis is the fi rst one in which acetyi-CoA, ATP and bicarbonate form malonyi-CoA • fatty acid synthesis is not a simple reversal of beta-oxidation used for the catabolism of fatty acids • fatty acid synthesis takes place in the mitochondria while fatty acid breakdown (catabolism) occurs in the cytosol (cytoplasm)

``` fatty acid synthesis takes place in the mitochondria while fatty acid breakdown (catabolism) occurs in the cytosol (cytoplasm) ``` this is false synthesis is in cytosol and breakdown in m/ch

fx of triglyceride

``` energy source (liver, heart, skel mm) 9.3 kcal/g ``` not membrane constituents as phospholipids and steroids!

Choline is required for synthesis and release of acetylcholine. Choline is also a precursor for synthesis of the phospholipids phosphatidylcholine (lecithin) and sphingomyelin. • both statements are true • both statements are false • the first statement is t rue, the second is fa lse • the f irst statement is fa lse, the second is t rue

both true

The binding of glucagon to its receptor: • deactivates adenylate cyclase • activates adenyl ate cyclase • causes the breakdown of cyclic AMP to ATP • causes the production of ATP f rom cAMP • deactivates protein kinase lipids

activates adenylate cyclase after cascade TG lipase is activated

The electron transport or respiratory chain gets its name from the fact that electrons are transported to meet up with oxygen from respiration at the end of the chain. The overall electron chain transport reaction is: 1H + 1e + 2O2 --> H20 + energy 2H + 2e + 1/2O2 --> H20 + energy 3H + 3e + 1O2 --> H2O + energy 4H + 4e + 2O2 --> H2O + energy

2H + 2e + 1/2 O2 --> H2O + energy 3ATPs per use of transport chain localized in m/ch ATP forms by oxidative phosphorylation oxidative phosphorylation in m/ch membrane glycolysis in c/pl TCA in m/ch matrix proton gradient used to produce ATP

``` Which complex contains cytochromes b and c1 and an Fe-S center? • complex I • complex II • complex Ill • complex IV ```

III I is FMN II is ubiQ III is cytochromes b and c IV is cytochrome c oxidase + cytochromes a 2.5 ATPs per NADH, 1.5 per FADH2 (bs skips first and enters and II complex)

All of the following statements concerning the citric acid cycle (Krebs cycle) are true EXCEPT one. Which one is the EXCEPTION? • the cycle starts with the 4-carbon compound oxaloacetate, adds 2 carbons f rom acetyi-CoA, loses 2 carbons as C02 and regenerates the 4-carbon compound oxaloacetate • the pyruvate that enters this cycl e is generated by the glycolysis of glucose or protein catabolism • this cycle is controlled by regulation of several enzyme activities. The most important of these regulated enzymes are cit rate synthase, isocitrate dehydrogenase and a-ketoglutarate dehydrogenase complex • the enzymes involved in the citric acid cycle are found in the cytosol • aspartic acid and oxaloacetic acid are interconvertible

• the enzymes involved in the citric acid cycle are found in the cytosol in m/ch

1. Which of the following is the pace-setting enzyme of glycolysis? 2. Which of the following is the first step to use energy rather than produce it? 3. Which of the following is the enzyme that produces two distinct carbon-based molecules? • hexokinase • phosphoglucose isomerase • phosphofructokinase • aldolase • triose phosphate isomerase • glyceraldehyde-3-phosphate dehydrogenase • phosphoglycerate kinase • phosphog lyceromutase • enolase • pyruvate kinase

1 - PFK 2 - hexokinase 3 - aldolase

Which of the following is the metabolic pathway in which there is a shuttling of glucose and lactate between muscle and liver during physical exercise? • hydrologic cycle • cori cycle • carbon cycle • glucose cycle

cori glucose converted in exercising cells via pyruvate and ATP release to lactate lactate brought to liver and converted via pyruvate to glucose

``` Lactic acid fermentation is a reaction which occurs in cells without or in cells when is limited. • nucleoli; C02 • mitochondri a; 0 2 • cytoplasmic granules; H+ • mitochondri a; C02 ```

• mitochondria; 0 2 pyruvate reduced to lactate and NADH oxidized to NAD in citric acid pyruvate oxidized to AcCoA and NAD reduced to NADH

``` The most common pathway of glycolysis is: • the Entner-Doudoroff pathway • the Embden-Meyerhof pathway • the Pentose Phosphate pathway • the Urea pathway metabolism ```

Embden-Meyerhof

All of the following are characteristic of the pentose phosphate pathway EXCEPT one. Which one is the EXCEPTION? • it produces C02 • it is controlled by inhibition of glucose 6-phosphate dehydrogenase by NADPH • it requires ATP fo r phosphorylation • it produces ribose 5-phosphate • it involves the breakage and formation of C-C bonds

requires ATP for phosphorylation this is FALSE occurs in cytosol makes 2NADPH per each glucose 6 P(oxidative branch, irreversible) and ribose 5 P (nonoxidative branch, reversible; one carbon from glucose6P is released as CO2) important in liver and mammary glands

Oxidative phosphorylation is the major source of ATP in aerobic organisms. The generation of GTP from succinyl CoA is an example of substrate levelphosphorylation in which the production of high-energy phosphate is coupled to the conversion of substrate to product, rather than resulting from oxidative phosphorylation. • both statements are true • both statements are false • the first statement is true, the second is fa lse • the first statement is fa lse, the second is t rue

both true types of phosphorylation: substrate-level (like glycolysis) electron transport/oxidative phosphorylation (major source of ATP in aerobic) photophosphorylation (also involves electron transport)

``` Theoretically, in most human cells, one glucose molecule produces enough usable chemical energy to synthesize: • 30-32 ATP molecules • 32-34 ATP molecules • 36-38 ATP molecules • 44-48 ATP molecules ```

36-38 4 from substrate level - 2 from glycolysis and 2 from Krebs + 32-34 from ETC oxidative phosphorylation

ATPs per NADH

2.5

ATPs per FADH2

1.5

Gluconeogenesis is the reverse of glycolysis. Gluconeogenesis produces glucose from amino acids, lactate and glycerol. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true

first false, second true

``` Which of the following cells in the body metabolize glucose only through anaerobic pathways? • muscle cells • red blood cells • hepatocytes • neural cells ```

RBCs bc no m/ch

``` The common precursor of all three aromatic amino acids is: • chorismate • phosphoenolpyruvate • shikimate • ribose 5-phosphate ```

chorismate tyrosine can be synth from phenylalanine serotonin synth from tryptophan

A patient of yours fails to tell you about his or her allergy to latex. You walk into the room and begin treatment. The allergic reaction presenting causes histamine release. All of the following are responses to this EXCEPT one. Which one is the EXCEPTION? • vasodilation (part icularly the arterioles) • secretion of HC L • bronchoconstriction • increased blood pressure • increased vascular permeability (particularly in capillaries and venules)

increased blood pressure HCl via histamine in stomach

All of the following statements concerning heparin are true EXCEPT one. Which one is the EXCEPTION? • unlike other glycosaminoglycans that are extracellular compounds, heparin is an intracellular component of mast cells that line arteri es, especiall y in the liver, lungs and skin • it serves as a powerful anticoagulant • it is used in the t reatment of certain types of lung, blood vessel and heart disorders, and during or after certain types of surgery (open heart or bypass surgeries) • small quantities are produced by basophil cells of the blood • it is usually found in large quantities in the blood

• it is usually found in large quantities in the blood prevents activation of coagulation factors

An apprehensive dental patient comes in and states that he already took ibuprofen for the pain he anticipates from the appointment today. As you know, this inhibits the synthesis of prostaglandins. All of the following statements are true about prostaglandins EXCEPT one. Which one is the EXCEPTION? • they have a very short half-life • they generally act locally on or near the tissue that produced them • they are synthesized only in the liver and the adrenal cortex • the common precursor of prostaglandins is arachidonic acid (an unsaturated fatty acid) • their synthesis can be inhibited by a number of unrelated compounds, including aspirin and cortisol

• they are synthesized only in the liver and the adrenal cortex this is false

``` All of the following are formed via the cyclooxygenase pathway EXCEPT one. Which one is the EXCEPTION? • prostaglandins • prostacyclin • leukotrienes • thromboxanes ```

LTs -- via lipoxygenase PGs, TXAs and prostacyclin via COX prostacyclin inhibits plt aggregation LTs are bronchoconstrictors phospholipase A2 cleaves arachidonic, common precursor of all these things

what cleaves arachidonic

phospholipase A2

LT effect

bronchoconstriction

The liver synthesizes all of the so-called nonessential amino acids. The liver plays an important role in glucose metabolism by engaging in gluconeogenesis. • both statements are true • both statements are fa lse • the first statement is t rue, the second is fa lse • the first statement is fa lse, the second is true

both true

In a cotton-candy-eating competition, you consume 14 moderately sized and overpriced bags of threaded sugar. This causes your portal vein to drop tremendous loads of glucose to your hepatocytes soon after. Which of the following enzymes functions only when this happens? • pyruvate kinase • glucokinase • phosphofructokinase • hexokinase

glucokinase (Mg cofactor, also hexokinase) specific to liver

``` The liver releases glucose back into the circulating blood during exercise. Which organs take up this extra glucose? Select all that apply. • kidneys • muscle • heart • brain •lungs ```

mm, brain

``` One of the two nitrogen atoms in urea comes from ammonia via carbamoyl phosphate; and the other from: • valine • glycine • aspartate • isoleucine ```

aspartate one from glu, one from asp, CO part from CO2

``` The major regulatory enzyme of cholesterol synthesis is: • thiolase • HMG-CoA reductase • HMG-CoA synthase • HMG-CoA kinase ```

HMG-CoA reductase thiolase and synthase are reversible

``` Which of the following is a cofactor required for the hydroxylation of lysine and proline? • riboflavin • vitamin E • vitamin C • folacin ```

vit C

``` Which of the following is a part of active cytochrome oxidase? • zinc • vitamin C • copper • vitamin K • magnesium ```

Cu like lysyl oxidase

A patient of yours with a PhD in nutrition tries to trip you up by saying that he supplements every morning with tocopherol. What is he talking about? • riboflavin • vitamin E • vitamin C • fo lacin

vit E - antioxidant vit D is most toxic of all vitamins

Cu is cofactor for

cytochrome oxidase and pyruvate phosphokinase

Which of the following is a severe thiamine-deficiency syndrome found in areas where polished rice is the major component of the diet? • pellagra • megaloblastic anemia • pernicious anemia • beri-beri

beri-beri thiamine is vit B coenzyme in oxidative decarboxylation, particularly nervous system deficiency common in alcoholics --> Wernicke-Korsakoff (encephalopathy and psychosis)

Which of the following statements concerning niacin are correct? Select all that apply. • a deficiency causes pellagra • it is the precursor of FAD • pork, whole grains, and legumes are the richest sources of niacin ·limited quantities of niacin can be obtained f rom the metabolism of t ryptophan

deficiency causes pellagra can be obtained from tryptophan --> NAD and NADP yeast, meat, legumes, cereal pellagra -= 3Ds diarrhea, dermatitis and dementia

``` Pernicious anemia is caused by the malabsorption of: • vitamin A • vitamin B12 • vitamin C • vitamin E ```

B12 (cobalamin) meat, eggs, dairy, fish may be present in vegans

``` Which vitamin plays a key role in amino acid metabolism? • vitamin A • vitamin B6 • vitamin K • vitamin B12 ```

B6 (PLP) - transamination

Which of the following plays a key role in one-carbon metabolism, and is essential for the biosynthesis of the purines and the pyrimidine, thymine? • biotin • riboflavin • pantothenic acid • folic acid

folic acid DNA replication; necessary for purines and thymine megaloblastic, diarrhea, glossitis

The determination of the prothrombin time is the most important laboratory test for the evaluation of the vitamin K status. Vitamin K deficiency is most common in the elderly. • both statements are true • both statements are fa lse • the first statement is t rue, the second is fa lse • the first statement is fa lse, the second is true

first is true, second is false deficiency most common on newborns in adults usually caused by fat malabsorption decreases coagulation time

``` Pantothenic acid is a component of which of the following? Select all that apply. • pyridoxal phosphate • coenzyme A • retinoic acid • fatty acid synthase ```

CoA and FA synthase

``` Biotin is a prosthetic group of: • pyruvate carboxylase • acetyi-CoA carboxylase • propionyi-CoA carboxylase • all of the above minerals/vitamins ```

all of the above | all ATP-dependent carboxylases

The biologically active forms of vitamin A are the flavoproteins. In vitamin A deficiency, columnar epithelia are transformed into heavily keratinized squamous epithelia, a process known as squamous metaplasia. • both statements are true • both statements are false • the first statement is true, the second is false • the first statement is false, the second is true

first is false, second is true retinoids are active required for maintenance of epithelia forms of A deficiency --> xerophthalmia

``` All of the following vitamins have little to no risk of overdose EXCEPT one. Which one is the EXCEPTION? • niacin • biotin • vitamin C • vitamin K ```

K Bs and C are not stored and must be replaced every day B12 excreted in feces ADEK (fat solubles) can be stored and overdosed

Vitamin Dis required in the diet of individuals exposed to sunlight. Cholecalciferol is not the active form of vitamin D and needs to be converted to active 1,25-dihydroxycholecalciferol (calcitriol) by successive hydroxylations in the liver and kidney. • both statements are true • both statements are fa lse • the first statement is t rue, the second is fa lse • the first statement is fa lse, the second is true

forst is false, second is true Vit D necessary if NO sun otherwise made by skin under UV cholecalciferol - initial product calcitriol (1, 25) is active by successive hydroxylations in liver and kidney deficiency - rickets in children osteomalacia in adults

``` Riboflavin is a precursor of: • NAD• and NADP• • ATP and ADP • pyridoxal phosphate (PLP) • FMN and FAD minerals/vitamins ```

FMN and FAD | B2 = riboflavin

All of the following statements concerning fluoride are true EXCEPT one. Which one is the EXCEPTION? • it may have some protective effect in osteoporosis • it can be incorporated in the inorganic substance of bones and teeth • it hardens tooth enamel • although not absolutely essential, it strengthens teeth and bones

• it hardens tooth enamel does NOT make harder but decreases solubility also inhibits bacterial enolase excreted by kidney deposited in calcified tissues

Your dental assistant comes in one day all smiles. At lunch, she announces that she is pregnant. You recommend that she makes sure to keep her intake of this mineral high because it helps her immune system, as well as the growth and development of her and her unborn child. She often comes in with loads of perfume on and you are hoping that this change in diet might also improve her sense of smell, so she tones it down a notch. Which mineral are we talking about? • phosphorus • cobalt • copper • zinc

Zn cofactor of carbonic anhydrase, polymerases and others

``` Ovulation occurs as a result of: • the progesterone-induced LH surge • the estrogen-induced FSH surge • the progesterone-induced FSH surge • the estrogen-induced LH surge reproductive system ```

estrogen, LH

``` GnRH is produced by the: • pituitary gland • adrenal gland • hypothalamus • thyroid gland ```

Initiation of the onset of puberty has long been a mystery. But now it has been determined that during childhood the hypothalamus simply does not secrete significant amounts of GnRH. For reasons still not understood, at the time of puberty, the secretion of hypothalamic GnRH breaks through the childhood inhibition and adult sexual life begins. • both statements are true • both statements are false • the first statement is true, the second is false • the first statement is false, the second is true

both true menarche - first bleeding

The first half of the monthly menstrual cycle is referred to as the luteal phase. The second half of the monthly menstrual cycle is referred to as the follicular phase. • both statements are true • both statements are false • the f irst statement is t rue, the second is false • the f irst statement is fa lse, the second is true

both false events: follicular phase (menstrual + proliferative in endometrium) ovulation, luteal phase w/ progesterone, mucus is thick and doesn't let sperm in