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One of the following statements describes ornithine:
- A. It is used only in mitochondria
- B. It is used only in the cytosol
- C. It participates in the urea cycle but is not used up in the process
- D. It requires vitamin B12 for synthesis
- E. It is an essential amino acid
One statement about fat metabolism is incorrect.
- A. The blood of patients with uncontrolled Type I diabetes usually contains low levels of free fatty acids.
- B. Insulin bind tos cell surface receptors on adipocytes.
- C. Glucagon binding to the glucagon receptor on adipocytes results in activation of adenylate cyclase.
- D. Glucagon binding to the glucagon receptor on adipocytes results in activation of hormone sensitive lipase.
- E. In the fed state adipocytes synthesize triglycerides (TG) from both fatty acids and glucose.
Which of the following statements is correct?
- A. Enzymes regulated in glycolysis are the same ones regulated in gluconeogenesis
- B. Fructose 2,6 bisphosphate concentration is increased by glucagon
- C. Glycolysis is the pathway by which the cells make most of their ATP
- D. Glucose 6-phosphatase is a liver enzyme that ensures an adequate supply of blood glucose even when we are not eating.
- E. Glycogen phosphorylase is the key enzyme for the synthesis of glycogen
TRUE or FALSE: Cholecystokinin is synthetized and released in the small intestine. It stimulates the secretion of pancreatic enzymes and gallbladder contraction.
Correct Answer: True
In comparing the fed and fasted state, one statement is incorrect.
- A. In the fed state the liver synthesizes fatty acids from two carbon acetyl CoA.
- B. Acetyl CoA carboxylase synthesizes malonyl CoA which is critical for the synthesis of saturated fatty acids.
- C. High levels of malonyl CoA in the liver inhibit the transfer of long chain fatty acid-CoA (acyl-CoA) into the mitochondria for -oxidation.
- D. Ketone bodies are synthesized in the brain during fasting or during unregulated diabetes so as to provide an energy source.
- E. Ketoacidosis, associated with sweet-smelling breath from expired acetone, can lead to coma and death.
The following statements describe the urea cycle, EXCEPT:
- A. The urea cycle generates ATP
- B. The urea cycle occurs in part in mitochondria and in part in cytosol
- C. The urea cycle is Is regulated, directly or indirectly, by the amount of protein consumed
- D. The urea cycle detoxifies NH4+
- E. the urea cycle can malfunction in some genetic and non-genetic diseases
Which of the following statements best described glucagon:
- A. It binds to the glucagon receptor
- B. It increases cyclic AMP, which activates protein kinase A
- C. It opposes the action of insulin
- D. It stimulates glycogen breakdown
- E. All of the above
TRUE or FALSE: The right half of this cartoon represents a hepatic lobule and the left side the acinus.
Correct Answer: False
Which of these statements is correct about the images of the liver illustrated in the figures? Please note that the cell with a large fat droplet, marked by the arrow in Fig. 3 is within the Disse space.
- A. Figs 1 and 2 illustrate lesions that develop in the same disease
- B. Figs 2 and 3 show lesions characteristically found in the same patient
- C. The cell pointed by the red arrow in Fig. 3 is involved in the pathogenesis of the lesion shown in fig. 1
- D. Fig. 1 shows an hepatocellular carcinoma
- E. The two spaces marked "S" in fig. 3 are bile canaliculi
The following statements describe type II diabetes, EXCEPT
- A. It is often associated with obesity
- B. It is caused by insulin resistance
- C. It causes exhaustion of beta cells and loss of insulin secretion
- D. It does not occur in children and adolescents
- E. Patients may have ketosis
Most lipids are insoluble in aqueous buffers. Consequently lipids are transported through the blood on lipoproteins. One statement is INCORRECT.
- A. Fatty acids are absorped from the intestinal lumen and activated to fatty acyl- CoA in the enterocyte.
- B. Fat soluble vitamins are carried out of the enterocyte in triglyceride-rich chylomicrons.
- C. Chylomicrons enter the lymphatic system before entering the blood.
- D. Lipoprotein lipase hydrolyzes both triglycerides and cholesterol esters in chylomicrons to release fatty acids, cholesterol and glycerol.
- E. HDL contains very little triglyceride.
Which of the following statements about folic acid is INCORRECT?
- A. Folic acid is involved in transamination
- B. Folic acid is synthesized by plants
- C. Folic acid is involved in the synthesis of purines and pyrimidines
- D. folic acid is involved in the formation of cysteine
- E. If taken in early pregnancy, folic acid can prevent birth defects
Political prisoners often go on hunger strikes for many weeks. Yet they can think clearly, because:
- A. Adipose tissue provides the brain with fatty acids and glycerol
- B. Muscle provides the brain with alanine
- C. The liver provides the brain with a mixture of glucose and ketone bodies
- D. The liver provides the brain with glucose
- E. The brain has adequate stores of glycogen
One of the following statements about homocysteine is INCORRECT:
- A. It is an essential amino acid
- B. It is an intermediate in the synthesis of cysteine
- C. It requires folic acid and Vitamin B12 for conversion to methionine
- D. High level of homocysteine in blood may have harmful effects on health
- E. It is derived from S-adenosylhomocysteine
Joan, a smart 17-year old, has phenylketonuria due to phenyl hydroxylase deficiency. She has been on a very strict low phenylalanine diet ever since she was 10 days old. The diet, a synthetic mixture of amino acids and other nutrients, is very unpalatable and she would like to get off it. She does not respond to tetrahydrobiopterin. She is strongly advised against getting off the diet because:
- A. If she were to get pregnant, elevated phenylalanine in her blood would cause birth defects in the fetus.
- B. Her dihydrobiopterin reductase is not functioning well
- C. Elevated phenylalanine may damage her brain and reduce her IQ
- D. B and C
- E. A and C
One of the following statements about protein nutrition is correct:
- A. Humans can synthesize most of the amino acids that they require
- B. Young children who have adequate calories but insufficient protein may have edema
- C. Protein malnutrition is rare in the United States
- D. Per kg body weight, athletes have the highest protein requirement of any population group
- E. All proteins found in vegetable have similar nutritive values
Regulation of metabolism can take place by all of the following mechanisms, EXCEPT:
- A. Allosteric effects on irreversible reactions
- B. Allosteric effects on reversible reactions
- C. Hormone-stimulated phosphorylation of key enzymes
- D. Hormone-stimulated dephosphorylation of key enzymes
- E. Km of transporters
The gross image on the left in Fig. 1 is of a normal liver. Which of the following statements is correct about the lesions shown in the other gross image on the right and in Fig. 2.
- A. The images show lesions seen in cirrhotic livers
- B. The images show irreversible liver injury
- C. The images illustrate the features of a cholangiocarcinoma
- D. The two images show lesions caused by anemia and coagulative necrosis of the liver
- E. The two images show a lesion seen in alcoholics as well as in obese and in diabetec patients
The following statements apply to MODY (Maturity Onset Diabetes of the Young) EXCEPT:
- A. It is transmitted in Mendelian (monogenic) fashion
- B. It may be caused by mutations in the gene encoding glucokinase
- C. It may be caused by mutations in transcription factors that control expression of the insulin gene
- D. It is clinically more similar to type 2 than to type I diabetes
- E. It may be caused by mutations of the gene encoding the insulin receptor
The citric acid cycle is described by all the following statements except one. Which is the INCORRECT statement?
- A. It allows complete oxidation to CO2
- B. It is inhibited when ATP supply is high
- C. It is anaerobic
- D. It provides electrons for oxidative phosphorylation
- E. It is the starting point for synthesis of many non-essential amino acids
Jaundice can result from from all of the following conditions except:
- A. Gallstones
- B. Iron deficiency anemia
- C. A hemolytic crisis
- D. Jaundice of the newborn
- E. Viral hepatitis
Patients with Metabolic Syndrome and/or Diabetes have a number of characteristics. One of the following is incorrect.
- A. A person with a body mass index (BMI) greater than 30 is at increased risk for developing Metabolic Syndrome and Diabetes.
- B. The livers of diabetic patients are likely to synthesize low levels of acetyl CoA as a result of low rates of oxidation of fatty acids.
- C. These patients are likely to have increased levels of plasma VLDL.
- D. These patients are likely to have low levels of lipoprotein lipase.
- E. These patients are likely to have increased activity of hormone sensitive lipase in adipocytes.
One statement about lipoprotein metabolism is incorrect.
- A. A patient with hyperchylomicronemia (also called chylomicronemia) may have a mutation in the gene encoding lipoprotein lipase.
- B. Patients with hyperchylomicronemia can present with eruptive lesions on the skin.
- C. Familial hypercholesterolemia (FH) is the name given to patients with mutations in the gene encoding the LDL receptor.
- D. Following endocytosis of LDL, cholesterol in the LDL is released from lysosomes and then represses the transcription of the genes encoding the LDL receptor and HMG-CoA reductase.
- E. Statins are a class of drugs that bind to the LDL receptor on the surface of cells leading to activation of LDL endocytosis.
TRUE or FALSE: Transmission of Hepatitis A is fecal-oral while hepatitis B is transmitted by parenteral or perinatal routes.
Correct Answer: True
Identify the protein that is not regulated by phosphorylation-dephosphorylation:
- A. Glucose 6-phosphate dehydrogenase
- B. Bifunctional enzyme
- C. Pyruvate kinase
- D. Glycogen phosphorylase
- E. Glycogen synthase
One statement is incorrect about LDL and HDL, two plasma lipoproteins.
- A. LDL is secreted by the liver and subsequently converted into VLDL in the blood.
- B. The lipid core of LDL is particularly enriched in cholesterol ester.
- C. HDL is secreted/formed by the liver.
- D. Niacin treatment raises HDL levels in the blood.
- E. Niacin treatment can cause “hot flashes” thus contributing to poor compliance.
The following statements describe type I diabetes, EXCEPT:
- A. It is an autoimmune disease.
- B. It occurs only among young people
- C. It is due to destruction of insulin-secreting beta cells
- D. It is frequently associated with ketosis
- E. The body acts as if it was fasting even though there are ample nutrients.