Biochemistry Questions and Answers
Question 33
I. Phosphoenolpyruvate
II. Carbamoyl phosphate
III. Glucose-6-phosphate
IV. 1,3-bisphosphoglycerate
Which of the following has a higher standard free hydrolysis energy than ATP?
a) I and III
B) I and IV
C) II and III
D) III and IV
E) I, II, IV
Question 34
Erythrocytes, the first carbon atom of which contains a radioactively labeled glucose molecule and obtained from venous blood, are incubated in an isotonic solution at physiological pH. At the end of the incubation period, these erythrocytes isolated by centrifugation are fragmented by hypotonic shock and hemolysate is obtained.
Which of the following is the metabolic product labeled with the radioactive carbon isotope in this hemolysate?
a) 6-phosphogluconate
B) Ribulose-5-phosphate
C) Ribose-5-phosphate
D) Xylulose-5-phosphate
E) Carbon dioxide
Question 35
In glycolysis, which of the following is obtained when 1 mole of pyruvate is formed from 1 mole of glyceraldehyde 3-phosphate as a substrate?
a) 1 mole of ATP and 2 moles of NADH
B) 2 moles of ATP and 2 moles of NADH
C) 2 moles of ATP and 1 mole of NADPH
D) 2 moles of ATP and 1 mole of NADH
E) 2 moles of ATP and 2 moles of NADPH
Question 36
Mycophenolic acid is added to two separate cell culture media media containing T and B lymphocytes in the S phase of the cell cycle. At the end of the incubation, the activities of the enzymes involved in de novo purine synthesis in the above experimental and related control groups are determined.
The activity of which of these enzymes is inhibited by mycophenolic acid?
a) Inositol monophosphate (IMP) dehydrogenase
B) Adenylosuccinate synthetase
C) Adenylosuccinate lyase
D) PRPP glutamyl amidotransferase
E) Glycinamide ribonucleotide (GAR) synthetase
Question 37
Which of the following statements about aminoacyl-tRNA synthetase involved in protein synthesis is false?
a) With the”Proofreadin” feature, the correct amino acid binds to the specific tRNA.
B) During the reaction, ATP decomposes into AMP and PPi.
C) Amino acids bind to the adenine nucleotide at the 3′ end of the specific tRNA.
D) An ester bond is formed between the ribose of the nucleotide in tRNA and the amino acid.
E) It performs aminoacyl-tRNA formation in a single step.
Question 38
Deficiency of which of the following causes primary hyperoxaluria type I?
a) Threonine aldolase
B) Glycine cleavage enzyme
C) D-amino acid oxidase
D) Serine hydroxymethyltransferase
E) Alanine:glyoxalate aminotransferase
Question 39
I. Carbamoyl phosphate synthetase I
II. Ornithine transcarbamoylase
III. Argininosuccinate synthetase
IV. Argininosuccinate lyase
V. Arginase
Which of the enzymes above catalyze the reactions of the urea cycle in the cytosol?
a) only I
B) I and III
C) I, II and IV
D) III, IV and V
E) II, III, IV and V
Question 40
Which of the following is not a protein folding disorder with aggregate deposition?
a) Alzheimer’s disease
B) Parkinson’s disease
C) Hirschsprung’s disease
D) Huntington’s disease
E) Creutzfeldt-Jakob disease
Question 41
Which of the following amino acids provides stabilization of the tertiary structure of proteins with the covalent bond formed by the side chain?
a) Glycine
B) Glutamate
C) Histidine
D) Asparagine
E) Cysteine
Question 42
Which of the following is the functional group shown in the figure?
[Figure not provided]
a) Ester
B) Ether
C) Enol
D) Mixed anhydride
E) Acid anhydride
Question 43
Which of the following statements about acetoacetic acid is correct?
a) It is synthesized in all cells with mitochondria.
B) It causes a decrease in pH by donating protons to the environment.
C) Its synthesis is stimulated by insulin.
D) It is used as a substrate in gluconeogenesis.
E) It is the main energy source for erythrocytes.
Question 44
A 46-year-old male patient, who applied to the dermatology outpatient clinic due to lesions on his hands, arms and fingers, had bullous lesions on the back of his hand, increased facial hair growth, and dark urine. It is learned that the complaints of the patient, who is a construction worker, increase with exposure to the sun and that similar complaints are also present in his uncle’s children.
Which of the following is the most likely cause of dark urine in this patient?
a) Uroporphyrin
B) Methemoglobin
C) Myoglobin
D) Hemosiderin
E) Bilirubin
Question 45
Which of the following fatty acids is an omega-3 fatty acid?
a) 16:1(Δ9)
B) 18:2(Δ9,12)
C) 18:3(Δ6,9,12)
D) 18:3(Δ9,12,15)
E) 20:4(Δ5,8,11,14)
Question 46
Which of the following is a messenger molecule that is formed in macrophages during heme degradation, can easily pass through the membrane and is responsible for signal transduction?
a) NADP+
B) Carbon monoxide
C) Fe+2
D) Heme
E) Bilirubin
Question 47
Which of the following is a coenzyme of the aromatic amino acid decarboxylase involved in catecholamine synthesis?
a) Pyridoxal phosphate
B) Tetrahydrobiopterin
C) Tetrahydrofolate
D) NAD+
E) Lipoic acid
Question 48
I. It is synthesized and released by the stomach.
II. Its synthesis increases in hunger.
III. Has a cholecystokinin-like effect
Which of the following statements about ghrelin are true?
a) Only I
B) Only III
C) I and II
D) II and III
E) I, II and III
Question 49
Which of the following glycosaminoglycans is not covalently bound to the core protein in the structure of the proteoglycan aggregate?
A. Heparan sulfate
B. Dermatan sulfate
C. Chondroitin sulfate
D. Hyaluronic acid
E. Keratan sulfate
Question 50
The patient with growth retardation, recurrent lung infection, hepatomegaly, elevated transaminases and cholestatic jaundice shows no alpha1 band in serum protein electrophoresis.
Which of the following serum proteins is most likely to be deficient in this case?
a) Alpha 1-acid glycoprotein
B) Alpha-lipoprotein
C) Alpha 1-antichymotrypsin
D) Gc-globulin
E) Alpha 1-antitrypsin
Question 51
Which of the following molecules produces a phosphaturic effect by inhibiting sodium-phosphate cotransporter and 25(OH)cholecalciferol 1α-hydroxylase in the proximal tubule, secreted from osteocytes and osteoblasts?
a) Fibroblast growth factor 23 (FGF-23)
B) Tumor necrosis factor alpha (TNF-α)
C) RANK-ligand
D) Osteopontin
E) Osteoprotegerin
Question 52
Serum prolactin level is measured as 1,250 ng/mL (reference <20 ng/mL in non-pregnant women) in the blood sample taken 2 hours after waking up from a 35-year-old female patient who applied to the obstetrics clinic with the complaint of infertility and has been married for 5 years. In computerized tomography of the brain, the sella turcica was normal in size and other anterior pituitary hormones were within the reference range. Which of the following is the most likely cause of prolactin elevation in this patient?
a) Acromegaly
B) Prolactinoma
C) Tertiary hypothyroidism
D) Dopamine use
E) Macroprolactinemia
Question 53
Which of the following is a class of enzyme that binds and transfers hydride ions?
a) Isomerases
B) Transferases
C) Oxidoreductases
D) Lyases
E) Hydrolases
Question 54
Which of the following does not use ascorbic acid as a coenzyme?
a) Tyrosine hydroxylase
B) Prolyl hydroxylase
C) Lysyl hydroxylase
D) Dopamine β-hydroxylase
E) 7α-hydroxylase