MCM Flashcards
Which of the following is formed exclusively in the liver?
25-Hydroxycholecalciferol
Which of the following minerals is the major intracellular cation?
Potassium
Associated with calcium absorption from the intestinal tract?
Calcitriol
Best describes iron absorption?
The low pH of the stomach favors production of Fe2+ and thus enhances absorption
If you sequenced COL11A2 gene, which contains type XI collagen, what type of mutation are you likely to find?
A glycine –> arginine missense mutation in the triple-helical region
Hemorrhagic disease of the newborn, rare but preventable because a deficiency of following?
Vitamin K
Which element can increase the strength of bones and teeth?
Flourine
If the pH were lowered below the pKa of the His-57 side chain, what would happen to the enzymatic activity?
The enzyme would be inactivated because His-57 needs to be deprotonated to be active
Some collection tubes for blood contain trisodium citrate. Why?
Citrate binds calcium and hence unhibits blood clotting
The following diagram shows an ezyme-catalyzed reaction. Which class does the ezyme belong to?
NAD+ –> NADH+ H+
Oxidoreductase
Pepsin, Ala-aminopeptidase, trypsin pH
2, 6.8, 8
Omeprazole inhibits the gastic proton pump, it will indirectly reduce the activity of which of the following digestive proteases?
Pepsin
Which line represents competitive inhibition?
A (starts at -1)
Which of the following compounds will act the fastest?
Lidocaine
Group with only essential amino acids
Lys, tryp, pheny, threo
Correct statement about BMR
It is higher in people with hyperthyroidism
In hyperventilation syndrome, pts feel that they can’t get enough air. As a result, they breathe faster. Regarding blood pH, pts will have
Respiratory alkalosis without metabolic compensation
Which of the following effects is produced when the first molecule of O2 binds to sickle cell hemoglobin?
A decrease in probability of sickling
Which AA would you expect to find in the core of a protein?
Leucine
Patients in a refugee camp after a famine would be expected to be in neg nitrogen balance because
Nitrogen loss exceeds dietary nitrogen intake
Which of following would need Mg2+ as a cofactor?
All ATPases
Which of the following will be absent from ganliosides extracted from ganglion cells?
Phosphate
Major site of carb digestion is
Small intestine
Coenzyme involved in biochemical transfer of methyl, formyl or hydroxymethyl form one molecule to another is derivative of
Folic acid
Which of following is not function or role of phosphate?
A part of structure of adenosine
Pt in CHF, complains of muscle weakness, which drug do you add?
Amiloride (K+ sparing diuretic)
A person with a gallstone blocking bile duct is at some risk of developing
Night blindness
Which of the following is a ketose?
D-Fructose
The apparent Km of an enzyme for its substrate is increased by which?
Competitive inhibitor
Deficiency of which of the following produces pellagra with dermatitis, diarrhea, dementia and death?
Niacin
Which statement about dietary fiber is incorrect?
Fiber promotes absorption of certain nutrients, such as iron
Excessive intake of which of the following may trigger HTN in sensitive people?
Sodium
Obstruction jaundice due to gallstones. The uptake of which of following vitamins will be reduced in this patient?
Retinal
6 yo with 10th percentile height, rough skin, nails are spoon shaped. Eats soil, upper resp infections. Supplement which mineral?
Zinc
The skin and joint problems in these pts are caused by their inability to produce a protein with
A triple helix
Slit lamp exam shows Kayser-Fleischer rings in both eyes and pt is diagnosed with Wilson dz. Treated with
Penicillamine (Cu chelation therapy)
He will suffer from vitamin A
Deficiency with a probability of ~2%
Under the influence of allopurinol, the conc of which compound would decrease in a pt
Uric acid
Pt has azotemia (high blood levels of N containing compounds) Has mutations of cystic fibrosis. The pt is in
Metabolic alkalosis with respiratory compensation
Low O2, high serum pyruvate. Treat with
Thiamine
The most likely cause of anatomical defects observed in fetus are from?
Use of oral isotretinoin
10 month old infant, lots of shit wrong. Treat with
Biotin
Pancreas stained with Congo red and observed shows birefringence caused by Congo red staining of
Amylin
If count dracula were your pt treat with
Niacin
Suspected of abuse, bleeding gums, petechiae, ecchymoses. Low levels of water-soluble vitamin. Why does a def in this vitamin cause mentioned sxs?
The deficient vitamin is needed for the function of prolyl hydroxylase
V. ambiguus contains thiaminase, which destroys B1 (thiamine) in dies. This is related to which hypovitaminosis?
Beriberi
Which proteins have barrel shaped compartments that admit unfolded proteins and catalyze their folding in an ATP-dependent manner?
Chaperonins
Which proteins are auxillary proteins that protect proteins and help them fold into proper tertiary structure?
Chaperones
Example of chaperone?
Hsp 70; Uses ATP-hydrolysis
Example of Chaperonins?
Hsp 60; ATP-dependent
What process converts inactive forms of enzymes to active forms?
Proteolytic Cleavage
examples of proteins that must undergo proteolytic cleavage?
Trysinogen and Chymotrypsinogen to trypsin and chymotrypsin, respectively
3 covalent modifications?
glycosylation, phosphorylation, disulfide bond formation
2 major types of glycolsylation forms?
O-linked and N-linked
Difference between O-linked and N-linked?
O-linked: Serine or Threonine
N-linked: Amide group attached to Aspartic Acid reside; two types: mannose or complex type
Is O-linked or N-linked more common?
N-linked
What inhibits the initial step in the formation of core oligo attached to the surface of the protein?
Tunicamycin
Where are proteins that use the cytoplasmic pathway destined for?
cytosol, mito, nucleus, peroxisomes; free ribosomes in cytoplasm
Where are proteins that use the secretory pathway destined for?
ER, lysosomes,secretion, membranes; all have ER targeting signal
Proteins in cytoplasmic pathway are synthesized where?
in cytoplasm
Proteins destined for mitochondria have what kind of signal?
N-terminal hydrophobic alpha-helix; helps them interact with chaperone proteins
Abdomen pain after drinking milk and eating ice cream. What enzyme is patient deficient in?
Lactase
young, single mother presents with complaints of physical and emotional stress. working multiple low paid jobs, raising two kids, and attending comity college. Skips meals due to hectic life. Very low calorie meals and poor quality protein. lab results show that serum cortisone level is high. You think this pt developed a neg. nitrogen balance through the consumption of which dietary factor?
lacking just one essential amino acid
two transporters on mitochondrial membrane?
TOM and TIM
Method in which glucose is transported into cell?
requires specialized transporters
steatorrhea is presence of excess fat in stool and may be associated w/fecal incontinence. This situation may occur due to malabsorption or maldigestion of fat. A problem with the digestion of fat could be due to which of the following?
decreased lipase activity
you join Doctors without Borders and travel to remote village in Sudan. Children malnourished. Diet insufficient and low in protein. Which test is used to measure as an indicator of protein malnutrition?
Serum albumin level
phosphatidylcholine is a major component of RBC membranes, myelin, surfactant, and cholesterol. Phosphatidylcholine is synthesized through phosphorylation of choline obtained from the diet or with reused choline derived from phospholipid turnover. De novo synthesis requires an addition of 3 methyl groups, transferred from an amino acid. With the turnover component, deficiency in which essential amino acid would make dietary choline essential for phosphatidylcholine synthesis?
Methionine
Increases in intracellular calcium can be especially detrimental to the cell. Therefore, calcium homeostasis is very tightly regulated not only across the cell membrane but also through the additional work of sequestration in ER and mitochondria. In which of the following does increased intracellular calcium concentration cause the most damage?
Enzyme activation
8-mo lost ability to hold toys and crawl on exam pt is tachypneic and breathing with considerable effort; the liver is palpable 5 finger widths below the right costal margin X-ray of the chest reveals cardiomegaly. He has difficulty sitting upright and cannot squeeze the physician’s fingers or the ring of his pacifier with any noticeable force. Despite a number of interventions, the child dies 2 weeks later. On autopsy, pt’s cells will likely contain an accumulation of which substance?
Glycogen
protein folding is the process by which a protein will attain its characteristic and functional 3d conformation. proteins emerge as a random coil following translation. which of the following determines all levels of protein structure?
primary structure
essential amino acids
phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, arginine, lysine, leucine
activated by enteropeptidase
trypsin
pyruvate dehydrogenase deficiency? what is the enzyme cofactor?
thymine phosphate cofactor needed for PDH complex E subunit
after consumption of a carb-rich meal, the liver continues to convert glucose to glucose-6-phosphate. The liver’s ability to continue this processing of high levels of glucose is important in minimizing increases in blood glucose after eating. What is the best explanation for the liver’s ability to continue this conversion after eating a carb-rich meal?
the high max rxn rate of glucokinase
hemoglobin consists of 2 alpha and 2 beta subunits. each alpha is bound to a beta by strong hydrophobic bonds. The beta and alpha units are bound to one another by weaker polar bonds that are somewhat mobile. This change in quaternary structure changes the affinity for oxygen that hemoglobin exhibits as it shifts between its taut and relaxed form. At a given pressure of oxygen, which of the following will increase the amount of T hemoglobin?
binding of carbon dioxide to hemoglobin
A group of scientists have recently discovered a new drug for treating hypercholesterolemia. In vitro studies with a hepatocyte cell line have revealed that the drug increases the number of LDL cholesterol receptors by acting in a manner similar to steroids. What is the mechanism by which this drug is acting on hepatocytes?
hormone-receptor complex formation
A woman gives birth to a full term baby. Upon delivery, the baby is small and has a musty odor. Upon questioning the woman says she did not smoke or drink alcohol during pregnancy; only water and diet soda. Which of the following amino acids is most likely to be deficient in the newborn?
serine
3yo born at home in rural area is brought to local clinic with seizures. Pale skinned, mental retardation, musty body odor. Dr. diagnoses defect in tetrhydrobiopterin metabolism. Which is the correct therapeutic measure for this child?
Low-phenylalanine diet
A mass is felt in the groin of an infant girl during a physical exam. Surgical resection shows it is a testicle. The baby is diagnosed with testicular feminization syndrome. In this syndrome, androgens are produced but cells fail to respond to the steroid hormones because they lack appropriate intracellular receptors. After binding intracellular receptors, steroids regulate the rate of which of the following?
transcription of genes
A 69yo woman diagnosed with RA being given antimetabolite therapy with methotrexate. Her physician explains to her that she can expect the greatest toxicity of the drug to the cells with the shortest G1 phase. Which cell has the shortest G1 phase?
intestinal mucosal cell
A group of mountain climbers went on a high altitude climbing expedition in Everest. One group member, 32yo male, low in supplemental oxygen in metal cylinder. Good breakfast in base camp before climbing. body needs energy. Which of the following pathways will be the critical source of ATP for this mountaineer?
Anaerobic glycolysis in RBCs
Which intracellular protein degradation control mechanism requires tagging?
proteasomal degradation
which disaccharide is responsible for giving fruits their sweet flavor?
sucrose
Which of the following best describes glycosaminoglycans?
acidic sugars
9 grams of proteins yields how much energy when metabolized?
36kcal
pH at which the charge of an amino acid is zero is referred to as?
isoelectric point
Beta pleated sheets are characteristic of which protein structure?
secondary
which process marks proteins for eventual degradation by proteasome?
ubiquination
which of the following best describes trypsinogen?
inactive form of trypsin
damaged or defective cells are labeled with a specific marker for apoptosis by phagocytes. Upon damage to the cell, the molecule is relocated from the inner leaflet of the binaryer to the extracellular surface where it can be recognized for destruction
phosphatidylserine
Which is essential AA: tyrosine, threonine, serene, or asparagine?
threonine
A 1yo pt w/failure to thrive and “weird eye movement” per mother. She is unable to coordinate muscle movements and appears to be sensitive to light. You suspect Hartnup Disease. Caused by a defect in what?
Transporter of neutral amino acids
which is not a function of mitochondria?
anareobic glycolysis
patient X has breakfast but skips lunch. What physiological process is occurring to maintain energy levels and various cellular functions in her body?
gluconeogenesis
protein that has 10 transmembrane domains and embedded in the neuronal membrane. what kind of protein?
integral protein
A 2yo brought to clinic with severe abdominal pain. Pale skinned, metal retardation, enlarged abdomen. diagnosed with Neimann-Pick’s disease. Symptoms of disease are due to accumulation of which lipid?
phosphatidylcholine
Which lipid found on inner leaflet of control cells?
phosphatidylserine
45yo woman with BMI 34 reports difficulty breathing. Suffered from chronic alcoholism for 10 years. Pale, swelling of ankles. BP 150/90 pulse 90 resp 21. Triglycerides=270 LDL= 200 HDL=30 glucose= 220 Hb=9. Diagnosed with spur cell anemia associated with liver dysfunction. Abnormal accumulation of which of following lipids in RBCs of pt?
cholesterol
A 59yo male on zoloft (serotonin reuptake inhibitors). Med counteracts mood swings, occasional suicidal thoughts, and depression. Serotonin works by facilitating which transport mechanism?
open of ligand gated ion channel
jo and jill ate at a famous seafood restaurant while on vacation. The same night they fell ill with vomiting, diarrhea abdominal cramps. Result of blood and stool test showed presence of PTX, toxin produced by algae. PTX binds to the extracellular domain of the Na/K-ATPase turning it into a permanently opened ion channel. After poisoning with PTX how would the cytosoolic ion conc. change?
Na elevated, K reduced, Ca elevated
9mo brought in by mother due to seizures, swollen abdomen, declining mental function. Physician notes cherry red spot near macula of eye. What pathology does infant display?
Niemann-Pick Disease
Male brought to ER by ambulance after car accident. Blood loss, must administer blood. Blood type O. What type of blood can he be given?
Type O
Researcher wants to make membrane as fluid as possible. Which intervention would help researcher achieve goal?
increase temp surrounding membrane
which of the following enzymes would need Mg2+ as a cofactor?
All ATPases
Monosaccharides can exist in linear or cyclic form. Cyclization occurs when carbonyl carbon of aldoes and ketoses reversibly react with an internal hydroxyl group, forming a hemiacetal or hemiketal, respectively. which of following is ketoses?
D-fructose
you prescribe omeprazole to pt w ulcus verticuli. Because omeprazole inhibits gastric proton pump H/K-ATPase, leads to reduced activity of which digestive protease?
Pepsin
Which of the following compounds could readily diffuse across a pure lipid bilayer with no transport proteins?
N2
You have created phospholipid vesicles with Na+ and K+ pumps oriented in the lipid bilayer so that the side of the pump that normally faces the cytosol is on the outside of the vesicle. There are equal conc of NaCl- on both sides of the vesicle, ATP on the outside, but no K+ on either side of the vesicle. What will happen?
Each pump would transport one Na+ ion from the outside to the inside of the vesicle and then stall
In a typical lipid bilayer, the hydrophilic head groups of the molecules
Face outwards toward the water
Covalent bonds in some cases can involve
All of the above
- equal sharing of e’ by the bonded atoms
- unequal sharing
- sharing of one e’ pr
- sharing of more than one e’ pr
Most biological polymers are synthesized from monomers in;
Condensation reactions, in which a molecule of water is produced for each covalent bond formed between monomers
Which of the following types of bonds between atoms would not be involved in forming and stabilizing a protein’s tertiary structure?
Ionic bonds between two negatively charged AA side chains
Consider an enzyme catalyzed rxn. If conc of substrate is much greater than Km, so that rxn rate is at maximal rate (Vmax), the largest increase in reaction rate (moles of product per second) would be produced by which of the following?
Doubling the enzyme conc
The term quaternary structure refers to
The structure formed by interactions of more than one polypeptide chain (or subunit)
The main fxn of the citric acid cycle (TCA) is:
The formation of NADH and FADH2 which are then used in the ETC
What is function of mitochondria shown in picture?
Energy production
Hydrophilic substances made of polysaccharide and proteins that provide mechanical support and lubrication to connective tissue called which of the following?
Glycosaminoglycans
A sequence of dna is found to have a frameshift mutation in the adenine and thymine-rich region upstream of a gene. Which of the following processes will be impaired by this mutation?
Binding of negative regulators
During a workup for anemia, a pt is found to have deficiency in the enzyme Glucose 6-phosphate Dehydrogenase (G6PD). Which of the following correctly describes the action of C6PD?
Metabolizes glucose 6-phosphate to form NADPH, an important antioxidant in rbcs
Which statement best describes the direction new strands are synthesized in transcription and replication?
In transcription the transcript is synthesized from 5’ to 3’; in replication both strands are synthesized from 5’ to 3’
The following is the sum of 3 steps of TCA(citric acid cycle)
A + B + GDP + Pi + FAD+ —> C + D + FADH2 + NADH + CO2
A, B, C, D identity
A - alpha-Ketoglutarate
B - NAD+
C - Fumarate
D - GTP
Investigators are studying the regulation of glycolytic pathway enzymes in a culture of hepatocytes. After citrate is added to the culture, a substrate of which of the following enzyme catalyzed rxns will accumulate in the hepatocytes?
Fructose-6-phosphate –> Fructose-1,6-biphosphate
Which pair of AA serves as precursors of neurotransmitters?
Serine and valine
All of the following components make up the cytoskeleton of most eukaryotic cells EXCEPT
Chromatin
During fasting, the mitochondria is active in
Oxidation of fatty acids
The most imp factor in phase transitions with regions of membrane undergoing reversible transitions between a ‘solid’ crystalline state and a ‘fluid’ liquid-crystalline state
Cholesterol concentration
A typical bilayer-forming glycerphospholipid consists of a diacyl region and a ______ region
Phosphorylalcohol
When a voltage gated ion channel opens it allows ions to flow down their conc gradient past cell membrane. Which of these ions move extracellularly when this happens?
K+
The Na+/K+ ATPase utilizes the E gained from hydrolysis of ATP in order to normalize intracellular and extracellular conc of sodium and potassium. What type of transporter is it?
Antiporter
Under normal conditions pyruvate is decarboxylated by pyruvate dehydrogenase complex to make Acetyl CoA and from there enters the TCA cycle. Pts with a phosphate deficiency, as well as pts in shock, have a decreased efficiency of the pyruvate dehydrogenase complex. This decreased efficiency results in less acetyl-CoA being produced and an increase of what compound in the blood?
Lactic Acid
Reduced NADH+ cannot cross the mito membrane and so must be shuttled across by transporter. The glycerophosphate shuttle, in particular, is found in which specific tissue types? A. Brain B. Heart C. Liver D. Skeletal muscle E. Smooth muscle
A and D
Brain and skeletal
Barrett’s esophagus is a medical condition in which stratified squamous epithelium cells change over time into simple columnar epithelium due to chronic exposure to gastric acid. This is an example of
Metaplasia
What is the normal serum glucose level in a healthy ind?
70-100
Glucose transporters (GLUTs) are essential for regulating the amount of glucose in the blood and different tissues. Some transporters work constantly, while some only work after blood glucose levels become relatively high. Another type, that transports glucose into muscle and fat cells, is regulated by insulin. What is this last type?
GLUT4
