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Biochemistry MCQ Exam 1- PMU 2nd Year
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Questions in this quiz (32)
1Which of the following amino acids have charge at ph 7.0?
- Aalanine
- Barginine
- Clysine
- Dcysteine
- Easpartic acid
2Which of the following statements about noncompetitive inhibitors is TRUE:
- Athe noncompetitive inhibitor can bind both the enzyme and the ES complex
- Bthe noncompetitive inhibitor decreases Vmax but does not change Km
- Cthe noncompetitive inhibitor binds the enzyme at site distinct from the active site
- Dthe noncompetitive inhibitor is it structural analog of the substrate
3The consequences of folic acid deficiency is:
- Aberi-beri
- Bscurvy
- Cpellagra
- Dmegaloblastic anemia
4Vit. C is involved in:
- Athe biosynthesis of noradrenaline and adrenaline
- Bthe postsynthetic modification of procollagen to collagen
- Cthe formation of Coenzyme A
- Dthe metabolism one-carbon fragments
- Ethe biosynthesis of bile acids
5Which of the following amino-acids are sulphur-containing?
- AHistidine
- BCysteine
- CThreonine
- DMethionine
6Which of the following statements about nuclear DNA are TRUE?
- AIt contains deoxyribose as pentose
- BIt contains Uracil instead of Thymine
- CIt is a double-stranded circular structure
- DIt is double-stranded helix
7Denaturation of proteins:
- ACan affect primary structure of proteins
- BAffect all the structures except the primary structure of proteins
- CCan be reversible and irreversible depending on the duration of the denaturating agent
- DBreaks down the covalent bonds within the polypeptide chain
8Which of the following statements about competitive inhibitors are TRUE?
- AThe competitive inhibitor can bind only with the active site of the enzyme
- BThe competitive inhibitor can bind only with the ES complex
- CThe competitive inhibitor can bind both with the active site of the enzyme and the ES complex
- DVmax remains unchanged, Km rises
- EKm remains unchanged. Vmax decreases
- FThe competitive inhibitor is a structural analog of the substrate
9Which of the following amino acids are hydrophobic and are localized inside the globular protein molecule?
- ALysine and Glutamate
- BLeucine and Isoleucine
- CAlanine and Valine
- DSerine and Cysteine
- ETryptophan and Proline
10Which of the following are not included in protein structures. but have important biological role?
- AOrnithine
- Bβ-alanine
- CHistidine
- DHomocysteine
- ECitrulline
- FCitrate
11Which is the type of covalent bond between a-amino acid residues in polypeptide chain?
- Aphosphoesteric bond
- Bglycosidic bond
- Csulfur bridge
- Dpeptide bond
- Eesteric bond
12Polypeptide chains are consisted of:
- Aα-amino acid residues
- Bnucleotides
- Cglycerol
- Dfree fatty acids
- Eglucose or other monosaccharides
13The collagen is:
- Afibrilar protein
- Bglobular protein
- Crich of Glycine residues
- Drich of Proline residues
- Erich of Glutamate and Glutamine residues
14 Vitamin B1:
- AIts deficiency causes pellagra
- BIts deficiency causes “beri-beri"
- CIts chemical name is riboflavin
- DIts chemical name is thiamine
15Allosteric effectors:
- ABind with the active site of the enzyme
- BCan change the total amount of the enzymes
- CAre Inducers and suppressors
- DAre activators and inhibitors
- Ecan cause negative or positive feedback
16Km
- Ais equal to (k-1+k2)/k1
- Bis equal to (k1+k2)/k-1
- CGives information for affinity between the active site of the enzyme and its substrate
- DThe higher Km is, the greater affinity exists
17Which of the following belong to the six classes of enzymes according to the enzyme classification:
- Ahydrolases
- Btransferases
- Cesterases
- Doxidoreductases
- Epeptidases
18The consequences of niacine (Vit. PP) deficiency is
- Aberi beri
- Bscurvy
- Cpellagra
- Drickets
19Pyridoxal phosphate coenzyme is a:
- Aderivative of Vit. B2
- Bderivative of Vit. B3
- Cderivative of Vit. B6
- Dparticipates in oxidation and reduction
- EParticipates in transfer of amine
20Which of the following co-factor's participate in reactions catalyzed by oxidoreductases:
- ABiotin
- BPyridoxal phosphate
- CNAD+
- DCoASH
- EFMN
21In which enzymes participates thiamine diphosphate (TPP)- the active form of vitamin B1.
- Aaminotransferases
- Bdecarboxylases
- Cpyruvate dehydrogenase
- Dα-ketoglutarate dehydrogenase
- Etransketolase
22 What are the interactions that stabilize the tertiary and the quatemary structure of proteins:
- Ahydrophobic interactions
- Bhydrogen bonds
- Cion interactions
- Dpeptide bonds
- Edisulfide bonds in oligomeric proteins
23The reversible covalent Phosphorylation-dephosphorylation of the enzymes:
- Aacts on the enzymes active site
- Bacts on the enzymes allosteric sites
- Cacts on a single enzyme
- Dacts on several enzymes
- Eis under direct neural and hormonal control
- Fis a mechanism for quick enzyme regulation
24Which is the vitamin in FMN and FAD:
- Afolic acid
- Briboflavin
- Cthiamin
- Dbiotin
- Eniacin
25In competitive inhibition:
- AVmax remains unchanged, Km decreases
- BVmax remains unchanged, Km increases
- CVmax and Km remain unchanged
- DVmax and Km decrease
26The feedback inhibition:
- Ais a mechanism of regulation of multistep metabolic pathways
- Bis under direct neural and hormonal control
- Cacts on early steps enzymes
- Dacts on the enzymes active site
27Which of the following statements about peptide bond are TRUE:
- Athe peptide bonds maintain the primary structure of proteins
- Bthe peptide bonds maintain the secondary structure of proteins
- Cthe peptide bond is a non-covalent bond
- Dthe peptide bond has a partial double-bond character
28The simultaneous increase in AST and ALT is diagnostic marker mostly for:
- AMuscle Dieseases
- BCardiac Diseases
- CLiver Diseases
- DBrain Diseases
29Vitamin C
- AIt is a water-soluble vitamin
- BIts deficiency causes pellagra
- CIts deficiency causes scurvy
- DIt participates as a cofactor in the posttranslational modification of collagen
30Which of the following is TRUE?
- Asome of proteins are enzymes
- Ball of proteins are enzymes
- Csome of proteins are hormones
- Dall of proteins are hormone
- Esome of proteins participate as transporting molecules
31Nucleotides are derivatives consisted of:
- Aheterocyclic ring consisted of C- and N- atoms named purine or pyrimidine monosaccaride- ribose or deoxyribose and phosphoric acid
- Bheterocyclic ring consisted of C- and S- atoms, monosaccaride- an hexose and phosphoric acid
- Cheterocyclic ring consisted of C- and N- atoms, named purine or pyrimidine- a disaccharide and phosphoric acid
- Dheterocyclic ring consisted of C- and N- atoms named purine or pyrimidines, monosaccaride- ribose deoxyribose and nitric acid
32Protein denaturation is a process that:
- Aamino acids composition is changed
- Bits primary structure is disrupted
- Cits biological activity is lost
- Dchemical and physical feature are changed
- Eits conformation is disrupted
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