1. Biochemie all questions - final PDF

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Which kinds of hemoglobin are formed in cases of Į -thalassemia?A. metHb (Fe3+) and HbH (4ȕ) B. HbH (4ȕ) and Hb Bart (4Ȗ) C. HbF (2Į 2 Ȗ) and HbH (4ȕ) D. HbA2 (2Į 2 į) and Hb Bart (4Ȗ)Which of the following is not related to Sickle cell disease:A. Molecular reason is a single point mutation in ȕ cha...

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Which kinds of hemoglobin are formed in cases of Į-thalassemia? A. metHb (Fe3+) and HbH (4ȕ) B. HbH (4ȕ) and Hb Bart (4Ȗ) C. HbF (2Į2Ȗ) and HbH (4ȕ) D. HbA2 (2Į2į) and Hb Bart (4Ȗ)

Which of the following is not related to Sickle cell disease: A. Molecular reason is a single point mutation in ȕ chains where a charged amino acid is replaced by nonpolar amino acid B. Hemoglobin shows a reduced ability of to bind oxygen C. A tendency of the deoxy hemoglobin to polymerize D. Oxidation of hemoglobin to met-hemoglobin

In the metabolically active muscle tissue, the local increase in proton concentration leads to: A. Increased affinity of hemoglobin for oxygen B. Decreased affinity of myoglobin for oxygen C. Increased affinity of myoglobin for oxygen D. Decreased affinity of hemoglobin for oxygen

Which of the following statements concerning the enzyme cofactors are correct: A. Ascorbic acid is a coenzyme in hydroxylation reactions B. Thiamin pyrophosphate is involved in reactions of transamination C. The biologically active forms of niacin are involved in oxidation/reduction reactions D. Pantothenic acid is a structural component of Coenzyme A group

Which of the following statements concerning elastin are correct

A. Į1-antitripsin is an elastase inhibitor B. Deficiency of Į1-antitripsin results in lung emphysema C. Į1-antitripsin is an elastase activator D. Į1-antitripsin is the major enzyme for elastin degradation

Similarities between hemoglobin and myoglobin include A. The effect of pH on oxygen binding B. The shape of the oxygen dissociation curve C. The effect of 2,3-bis-phosphoglycerate D. Heme as a prosthetic group

Which of the statements concerning the collagen is CORRECT: A. It is built up from two Į and two ȕ chains with left motion B. Every third amino acid is alanine C. It is built up from three Į chains with left motion, combined into one triple helix with right motion D. Ascorbic acid is a coenzyme of the enzyme lysyl oxidase, needed for tropocollagen cross-linking

Approximately one third of the amino acids in the collagen molecules are represented by: A. Glutamate B. Lysine C. Glycine D. Aspartate

Which of the following statements concerning collagen are correct: Tropocollagen is a right-handed triple helix

The enzyme lysyl oxidase requires vitamin C as a cofactor The enzyme lysyl oxidase contributes to tropocollagen cross-linking in fibrils Lysyl oxidase is an extracellular enzyme

Protein secondary structures such as Į-helices and ȕ-sheets are stabilized mainly by A. Van der Waals forces B. Hydrophobic interactions C. Hydrogen bond formation D. Disulfide bond formation

Which of the following statement concerning hemoglobin A is false: A. Its polypeptide chains are folded mostly into Į-helices B. It has higher affinity to oxygen than myoglobin C. Its affinity to oxygen could be allosterically regulated D. It is a heterotetramer containing 2 Į and 2 ȕ chains E. Each chain contains a heme prosthetic group

The Bohr effect could be described with: A. The activity of carbonic anhydrase in changing the concentration of protons and CO 2 B. The influence of concentration of protons and CO2 for hemoglobin affinity to oxygen C. The structural differences between HbA and HbF D. The role of heme-heme interactions for hemoglobin saturation with oxygen

It is known that the pH of gastric juices is between 1.2 and 2.0 and pepsin has pI~ 1.0. Answer, which amino acids should be present in greater quantity in the structure of this enzyme? A. Glutamate and aspartate

B. Methionine and cysteine C. Serine and threonine D. Lysine and arginine

Which of the following enzymes has as a cofactor ascorbate (vitamin C): A. Lysyl oxidase B. Prolyl hydroxylase C. Collagen synthase D. Elastase

Which of the following statements concerning the oxygen binding of hemoglobin and myoglobin are correct: A. Heme-heme interaction is a phenomenon concerning only hemoglobin B. Myoglobin reversibly binds a single molecule of oxygen C. Myoglobin starts to release oxygen when the partial pressure of oxygen in the cells falls below 5mm Hg D. Myoglobin has lower affinity to oxygen compared to hemoglobin

Which of the following effectors increases the affinity of hemoglobin to oxygen: A. Decreased pH B. Increased 2,3-bisphosphoglycerate levels C. One or more hemes saturated with oxygen D. Increased CO2 levels

In myoglobin and hemoglobin, oxygen binds directly to A. The proximal histidine B. The distal histidine C. Fe3+ in the heme

D. Fe2+ in the heme

Which of the statements concerning the prion diseases is INCORRECT: A. The pathological prion protein (PrPSc) contains mainly ȕ-sheets B. The structure of the normal prion protein (PrPc) contains mainly Į-helixes C. The pathological prion protein (PrPSc) causes spongiform encephalopathy D. The pathological prion protein (PrPc) contains mainly Į-helixes

Which of the statements below describes nonfunctional plasma enzymes: A. They are not active under physiological conditions B. Under normal conditions, they are not found in plasma, or can be found in very small quantities C. They are not used as diagnostic markers D. They are synthesized in plasma and do not enter the cells

Which organizational level of a protein molecule is stabilized by hydrogen bonds formed between peptide groups within a polypeptide chain? A. Tertiary B. Primary C. Quaternary D. Secondary

In which of the following amino acids takes place the reversible covalent modification by phosphorylation, dephosphorylation: A. Glutamate and aspartate in their carboxyl groups B. Serine and threonine in their hydroxyl groups C. Cysteine and methionine in their SH groups D. Any amino acid may be modified in this way

Which of the following would favor oxygen release from hemoglobin? Low pH High partial pressure of carbon dioxide 2,3-bisphosphoglycerate High partial pressure of oxygen

At what values of pH have the amino acids maximal buffer capacity? A. pH values equal to the pK of the COOH group B. at pI C. pH values equal to the pK of the Nɇ2 group D. pH values equal to the pK of the ɋɈɈɇ and Nɇ2 groups

Which of the following statements concerning the hemoglobins are correct: A. HbA1c differs from HbA by a single, genetically determined amino acid substitution B. Fetal blood has a higher affinity for oxygen than does adult blood because HbF has a decreased affinity for 2,3-BPG C. The chain composition of hemoglobin F is 2 Į2į D. 7KHFKDLQFRPSRVLWLRQRI%DUW¶VKHPRJORELQLVȖ

Fetal hemoglobin (HbF): A. The oxygen saturation curve is shifted to the left compared to the saturation curve of HbA B. Has a higher affinity to 2,3-bisphosphoglycerate than the normal hemoglobin (HbA) C. Has a lower affinity to the oxygen than the HbA D. Contains 2 Į and 2 į chains

All statements are correct as for hemoglobin as well as for myoglobin EXCEPT:

A. Each heme group can bind one molecule Ɉ2 B. Their function can be described with the Bohr effect C. Their heme groups contain ferrous ion (Fe2+) D. They are globular proteins

Sickle cell anemia is caused by a mutation expressed as: A. A failure to reduce Fe3+ to Fe2+ B. Replacement of a charged amino acid to a hydrophobic amino acid C. Replacement of a non-charged amino acid to a charged amino acid D. Loss of a post-translational modification of an amino acid

Amino acids

Which one of the following cofactors is required for the synthesis of gamma-amino butyric acid (GABA), serotonin, epinephrine, dopamine and histamine from their respective amino acid precursors? A. tetrahydrofolate B. tetrahydrobiopterin C. thiamine pyrophosphate D. biotine

Amino acids that give rise to acetyl CoA are not glucogenic because: A. For every acetyl CoA that enters the tricarbixylic acid cycle, an equivalent amount of CO2 is evolved before the formation of oxaloacetate, which is the link to the gluconeogenetic pathway B. There is no net synthesis of any glycolytic intermediate from acetyl CoA C. Feeding the amino acids to a fasted animal does not cause a rise in blood glucose or in liver glycogen D. There is no metabolic pathway that permits the carbon atoms of the acetyl group to enter the gluconeogenetic pathway

Which one of the following metabolites is inhibitory neurotransmitter in brain? A. gamma-aminobutyric acid (GABA) B. serotonin C. histamine D. melanin

/Question with MORE than ONE correct answers!/ Among the principal roles of albumin is transport of: A. Fe3+ B. free fatty acids C. bilirubin D. HCO3-

A metabolic disease, the underlying defect of which lies in an enzyme that hydroxylates an aromatic ring, is: A. Albinism B. +DUWQXS¶VGLVHDVH C. Maple syrup urine disease D. Phenylketonuria

A patient has low levels of urea, blood glucose and cholesterol, high total bilirubin, and creatinine, total protein and albumin were within the reference range. Serum ALT (alanine aminotransferase) and AST (aspartate aminotransferase) were elevated. From the following list select the most likely diagnosis: A. myocardial infarction B. diabetic ketoacidosis C. liver insufficiency D. kidney failure

The toxicity of ammonia is thought to be due to: A. depletion of cellular NADH B. depletion of cellular ATP C. metabolic alkalosis D. depletion of cellular alpha-ketoglutarate

Whish one of the following statements concerning pepsin is CORRECT? A. is synthesized by intestinal cells B. is produced by the action of trypsin on its precursor C. digests dietary proteins in the stomach D. cleaves bounds at the carboxyl end of the arginine and lysine residues within a polypeptide chain

A physiological methylating agent is: A. S-adenosyl methionine B. Choline 5 C. N -methyl-tetrahydrofolate

D. Methylxantine

In the transamination reaction shown below, which of the following are the products X and Y? ɨxaloacetate + glutamate ĺX + Y A. pyruvate, aspartate

B. aspartate, alfa-ketoglutarate C. alanine, alfa-ketoglutarate D. pyruvate, alanine

Which one of the following statements is correct ? A. ornitine and citrulline are found in tissue proteins B. cysteine is an essential amino acid in individuals consuming a diet devoid of methionine C. all essential amino acids are glycogenic D. an increase of gluconeogenesis from amino acids results in a decrease in urea formation

A person consuming a diet deficient in methionine is likely to have decreased synthesis of: A. donor of methyl groups - SAM B. dTMP from dUMP C. methylmalonyl-CoA from propionyl-CoA D. alanine from glucose

Which one of the following statements concerning urea cycle is correct? A. the alfa-amino group of arginine forms one of the nitrogens of urea B. ornitine directly reacts with carbamoyl phosphate to form citrulline C. ornitine reacts with aspartate to generate argininosuccinate D. carbamoyl phosphate is derived directly from glutamine and CO 2

After completion of intestinal proteolysis: eins von den schwarzen ist auch noch richtig A. all protein has been converted ONLY to amino acids B. some amino acids are absorbed by the intestine through a Na + symport system C. some peptides are absorbed by the intestine through a ubiquitin-dependent mechanism D. some dipeptides are absorbed by the intestine

Which one of the following statements about the Ȗ-glutamyl cycle is CORRECT? A. the tripeptide glutathione is involved in it B. WKHPHPEUDQHHQ]\PHȖ-glutamylcysteine synthetase is involved in it C. is a chain of four consecutive reactions D. is supported by the hydrolyses of 2 macroergic bounds of ATP

Which one of the following statements concerning glutamate is true? A. it undergoes a series of reactions in which it cycles to produce histidine B. it produced by the action of glutamate dehydrogenase an enzyme that requires NH4+ and FAD C. it is produced in a transamination reaction in which aspartate reacts with oxalacetate D. it can be converted to alpha-ketoglutarate and ammonium ion by an enzyme which requires as a cofactor NAD+

Choose WKH&255(&7FRPELQDWLRQ7KHQLWURJHQIURPĮ-amino groups of amino acids circulates in the blood mainly under the form of: A. aspartate, glutamate and urea B. urea, alanine and glutamine C. pyruvate, lactate and alanine D. lactate, alanine and urea

Mark the correct answer. In a person with phenylketonuria (a deficiency of phenylalanine hydroxylase): A. tyrosine is an essential amino acid, but phenylalanine is not B. phenylalanine can be replaced by tyrosine in the diet C. phenylalanine and tyrosine are both essential amino acids D. phenylalanine is an essential amino acid, but tyrosine is not

Which of the following statements concerning a one-week-old male infant with undetected classic phenylketonuria (PKU) is CORRECT? A. tyrosine is a nonessential amino acid for the infant B. a diet devoid of phenylalanine should be initiated within the first year of life C. high levels of phenylpyruvate appears in his urine D. therapy must began within the first year of life

A deficiency of each of the following substances could cause increase blood levels of homocystine EXCEPT: A. vitamin B12 B. folate C. cystationine synthetase D. S-adenosylhomocysteine (SAH) FOHDYLQJHQ]\PH6$+ĺDGHQRVLQH homocysteine)

Which one is the CORRECT statement about tyrosinemia type I: A. the treatment includes diet rich in phenylalanine and tyros B. is a result of fumarylacetoacetate hydrolase deficiency C. homogentisate accumulation D. there are no serious consequences for the organism

Each of the following statements about nitrogen metabolism is correct EXCEPT: A. in the degradation of histidine, the intermediate formiminoglutamate (FIGLU) is cleaved to form glutamate B. alanine may be produced from serine by the action of dehydratase followed by the action of transaminase C. vitamin B12 can transfer a methyl group to propionyl CoA to form methylmalonyl CoA D. glutamate is produced from alpha-ketoglutarate by fixation of ammonia or by transamination

Which one of the following digestive enzymes is a pancreatic one involved in proteins digestion? A. pepsin B. trypsin C. SDQFUHDWLFĮ-amylase D. pancreatic lipase

Which one is the CORRECT statement about de novo creatine synthesis: A. requires AMP B. requires NAD+ C. requires alanine D. requires arginine

Which one of the following statements about reactions of the urea cycle is TRUE? A. N-acetylglutamate is a positive allosetic activator of carbamoylphosphate synthethase I B. aspartate reacts with ornithine to form citrulline C. the enzyme arginase releases fumarate from argininosuccinate D. the urea cycle is exergonic process

During intestinal proteolysis: A. unless pepsin is first acted on it, pancreatic proteases cannot produce free amino acids from dietary protein B. enteropeptidase converts trypsinogen to trypsin C. activation of trypsinogen involves a conformational change, but no change in covalent structure D. trypsin activates pro-carboxypeptidase and pro-elastase

Each of the following statements about serine is correct EXCEPT: A. it is glucogenic amino acid B. it is converted to glycine by a reaction requiring tetrahydrofolate C. it is the only amino acid that contains a hydroxyl group D. it is converted to pyruvate and ammonia by a dehydratase

Each of the following about the kidney is correct EXCEPT: A. it converts glutamine to glutamate B. it converts glutamate to alfa-ketoglutarate C. it uses ammonia released from glutamine to buffer acids in the urine D. it synthesized most of the urea that is excreted into the urine

Which one of the following amino acids is essential and a substrate for the biosynthesis of N-formiminoglutamate (FIGLU)? A. serine B. cysteine C. glutamine D. histidine

Which one of the following statements is INCORRECT? A. JOXWDPDWHDQGĮ-ketoglutarate pair is always involved in reactions of transamination B. transamination is the first step of amino acids catabolism C. oxaloacetate is one of the alanine aminotransferase reaction products D. the active form of vitamin B6 is a cofactor of transaminases

A newborn with a defect in ornitine transcarbamoylase is being fed with a synthetic low protein diet, with essential amino acids, as well as drugs to promote ammonium excretion were administered. To reduce ammonium ions (NH4+) concentration you should: A. measure plasma glucose B. administer sodium benzoate C. measure plasma homocysteine D. administer cysteine

During fasting, nitrogen is transported from muscle to liver and kidney as: A. alanine B. asparagine C. glutamine D. serine

The plasma and urine of patients with maple syrup disease contain elevated levels of each of the following amino acids EXCEPT: A. leucine B. lysine C. valine D. isoleucine

Phenylketonuria, alcaptonuria and albinism are caused by deficiencies in enzymes involved in the metabolism of: A. tyrosine B. tryptophan C. histidine D. valine

Which one of the following statements about the urea cycle is correct? A. the nitrogen atoms that are incorporated into urea enter the cycle as ammonia and alanine B. ATP is required for the reaction in which argininosuccinate is cleaved to form arginine C. urinary urea is increased by a diet rich in protein D. urea is produced directly by the hydrolysis of ornitine

The major amino acid that is released from muscle and converted to glucose in the liver is: A. aspartate B. valine C. alanine D. glutamate

The symptoms of dietary deficiency of niacin (which results in pellagra) will be less severe if the diet has a high content of: A. tryptophan B. thiamine C. tyrosine D. thymine

Which metabolic product below is derivative of tryptophan? A. serotonin B. histamine C. gamma-aminobutyric acid (GABA) D. epinephrine

Which one of the following statements concerning a one-week-old male infant with undetected classic phanylketonuria is correct? A. high levels of phenylpyruvate appear in his urine B. therapy must begin with the first year of life C. a diet devoid of phenylalanine should be initiated immediately D. tyrosine is a nonessential amino acid for the infant

Decreased activity of which one of the following enzymes could cause an increase in urinary excretion of citrulline? A. formiminoglutamate transferase (FIGLU+FH 4 ĺ glutamate + formimino-FH4) B. glutamate dehydrogenase C. carbamoyl phosphate synthethase I (CPS I) D. argininosuccinate synthethase

Which one of the following statements is CORRECT? A. N-acetylglutamate is an allosteric inhibitor of carbamoyl phosphate synthetase I B. ornithine transcarbamoylase is cytosolic enzyme C. urea cycle occurs in cytosol and endoplasmic reticulum of hepatocytes D. urea cycle is endergonic process

Select the CORRECT answer! Benzoic acid is used to treat hyperammonemia because it: A. neutralizes urinary ammonia B. provides an alternative pathway for nitrogen excretion C. stimulates carbamoylphosphate synthetase D. stimulates urease

Which one of the following statements is correct? Via enzymes of the urea cycle aspartate: A. is converted to oxaloacetate B. is converted to malate C. provides nitrogen for synthesis of arginine D. provides carbon for the synthesis of arginine

Mark the only one correct answer about dinitrophenol: A. inhibits the I-st compex of the mitocondrial respiratory chain B. allows protons to re-enter the mitochondrial matrix without going through the proton channel in the ATP synthase complex C. blocks the exchange of ATP for ADP across the inner mitochondrial membrane D. Inhibits generation of FADH2 from succinate oxidation

During electron transport the protons are pumped out of the mitochondrion at each of the following sites...