Biochem/Physiology Pt 2 Flashcards
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+
\_\_\_ 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
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
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
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
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)
carbonic anhydrase cofactor
Zn
PLP is cofactor for
aminotransferases
arginase fx
urea formation in cell, cofactor = Mn
Mn is cofactor for what
arginase which makes urea in cell
- 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
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
channels in cardiac mm
fast Na (also in skel) and slow Ca (make plateau)
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
An electrocardiogram is a graphic illustration of the: • cardiac cycle • cardiac conduction system • cardiac output • systemic and pulmonary circuits heart
cardiac conduction system
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
equation for BP
CO x TPR
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
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
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 valvesmitral 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
S2
semilunars close, aortic before pulmonary –> S2 splitting
S1
AV close
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
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)
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
CO
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
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
L
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
- Which of the following is the pace-setting enzyme of glycolysis?
- Which of the following is the first step to use energy rather than produce it?
- 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
HT
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
