Monday, October 22, 2012

Multiple Choice Questions- Haem synthesis and Degradation


Q.1- Which out of the followings is not a haemo protein?

a) Tryptophan pyrrolase

b) Tyrosinase

c) Myoglobin

d) Cytochrome P450

Q.2- Which out of the following enzymes catalyses a rate limiting step in the pathway of haem biosynthesis?

a) ALA synthase

b) ALA dehydratase

c) PBG deaminase

d) Coproporphrinogen oxidase

Q.3- High levels of lead can affect heme metabolism by combining with SH groups of which out the following enzymes?

a) ALA synthase

b) ALA dehydratase

c) PBG deaminase

d) Coproporphrinogen oxidase

Q.4- Pyridoxal phosphate is necessary in the pathway of Haem biosynthesis, which out of the following enzymes requires Pyridoxal –P as a coenzyme?

a) ALA synthase

b) ALA dehydratase

c) PBG deaminase

d) Ferrochelatase

Q.5- In general, the porphyrias are inherited in an autosomal dominant manner, with the exception of

a) Acute intermittent porphyria

b) Porphyria Cutanea Tarda

c) Variegate Porphyria

d) Congenital Erythropoietic porphyria

Q.6- Choose the incorrect statement out of the followings-

a) Synthesis of ALA occurs in the mitochondria

b) Uroporphyrinogen formed is almost exclusively the III isomer

c) A porphyrin with symmetric substitution of side chains is classified as a type III porphyrin

d) Coproporphyrinogen oxidase is able to act only on type III isomers

Q.7- In which of the following porphyrias, cutaneous hypersensitivity is not observed?

a) Variegate porphyria

b) Acute intermittent porphyria

c) Congenital Erythropoietic porphyria

d) Hereditary Coproporphyria

Q.8-Which of the following statements describes the basis of giving I/V Hemin infusion?

a) Haem/ Hemin acts as a negative regulator of the synthesis of ALA synthase

b) Heme affects translation of the enzyme

c) Heme affects transfer of enzyme from the cytosol to the mitochondrion

d) All of the above

Q.9- Porphyrins are deposited in teeth and in bones, as a result, the teeth are reddish-brown and fluoresce on exposure to long-wave ultraviolet light, so called ‘Erythtrodontia ‘, is a sign of which porphyria ?

a) Variegate porphyria

b) Acute intermittent porphyria

c) Congenital Erythropoietic porphyria

d) Hereditary Coproporphyria

Q.10-A 24- year- old patient was brought to medical OPD with acute abdominal pain, depression and extreme weakness.  Urine analysis revealed the presence of ALA and PBG (Delta amino Levulinic acid and Porphobilinogen).   The patient was diagnosed with acute intermittent porphyria, which of the following enzyme deficiencies is expected in this patient?

a) Uroporphyrinogen III cosynthase

b) Uroporphyrinogen decarboxylase

c) Porphobilinogen decarboxylase

d) None of the above.

Q.11-An 8 year old boy was brought to a dermatologist as he had developed vesicles and bullae on his face and arms that appeared after a week long  football practice in sun. His father had a similar condition. A diagnosis of Porphyria cutanea tarda was confirmed by finding elevated levels of porphyrins in his serum. His disease is due to a deficiency of which of the following enzymes?

a) ALA dehydratase

b) Ferrochelatase

c) PBG deaminase

d) Uroporphyrinogen decarboxylase.

Q.12- A 23 –year-old young woman, who recently began taking birth control pills, presents to emergency room with cramping abdominal pain, anxiety, hallucinations and paranoid behavior. A surgical evaluation, including Ultrasound and computed tomography (CT) scan have failed to demonstrate any abdominal process. Examination reveals vesicles and bullae on the skin of arms and face. Urine analysis reveals the presence of porphyrins (ALA, PBG, Uro and Coproporphyrins). What is the possible diagnosis for this patient?

a)  Variegate porphyria

b) Acute intermittent porphyria

c) Congenital Erythropoietic porphyria

d) Hereditary Coproporphyria

Q.13- A patient presents with dull right sided abdominal pain, fever from the 7 days, loss of appetite, pale stool and jaundice. Blood biochemistry reveals, mixed hyperbilirubinemia, high SGPT but near normal alkaline phosphatase levels. What is the cause of jaundice?

a) Viral hepatitis

b) Post hepatic jaundice

c) Hemolytic jaundice

d) None of the above

Q.14- Impaired Glucuronyl transferase activity is observed in all of the followings except-

a) Breast milk jaundice

b) Physiological jaundice of the new born

c) Crigler Najjar syndrome

d) Dubin Johnson syndrome

Q.15- Which out of the following conditions is not associated with excessive bilirubin formation from hemolysis –

a) Sickle cell anemia

b) Thalassemia

c) Malaria

d) Rotor syndrome

Q.16-What is expected out of Van den Bergh reaction in hepatic jaundice?

a) Direct positive

b) Indirect positive

c) Biphasic

d) None of the above.

Q.17- Which serum enzyme elevation is most diagnostic in obstructive jaundice?

a) ALT(Alanine amino transferase)

b) AST (Aspartate amino transferase)

c) LDH (Lactate dehydrogenase)

d) ALP (Alkaline phosphatase).

Q.18- Acholuric jaundice is –

a) Hemolytic jaundice

b) Hepatic jaundice

c) Post hepatic jaundice

d) None of the above

Q.19- Urine analysis of a patient reveals the presence of Bilirubin and urobilinogen, which serum enzyme is expected to be elevated  much higher than normal?

a) ALT (Alanine amino transferase)

b) AST (Aspartate amino transferase)

c) 5’ Nucleotidase

d) ALP (Alkaline phosphatase).

Q.20-A 65- year –old patient presents with weight loss, loss of appetite, dull dragging pain in the right hypochondrium and jaundice from the last 1 month.  Stool is reported to be clay colored from the same duration.   Blood biochemistry reveals Conjugated hyperbilirubinemia. Urine shows the presence of bilirubin. The patient has been diagnosed with carcinoma of head of the pancreas. Which serum enzyme is expected to be much higher than normal for this patient?

a) ALT (Alanine amino transferase)

b) AST (Aspartate amino transferase)

c) LDH (Lactate dehydrogenase)

d) ALP (Alkaline phosphatase).

Answers-

Q-1-b

Q.2- a

Q-3-b

Q-4-a

Q-5-d

Q-6-c

Q-7-c

Q-8-d

Q-9-c,

Q-10-c

Q11-d

Q12-a

Q-13-a

Q14-d

Q-15-d

Q.16-c

Q-17-d

Q-18-a

Q-19-a

Q-20-d


------------------------------------------ Best Wishes: Dr.Ehab Aboueladab, Tel:01007834123 Email:ehab10f@gmail.com,ehababoueladab@yahoo.com ------------------------------------------
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