Which of the following amino acids have charge at ph 7.0?
alanine
arginine
lysine
cysteine
aspartic acid
Which of the following statements about noncompetitive inhibitors is TRUE:
the noncompetitive inhibitor can bind both the enzyme and the ES complex
the noncompetitive inhibitor decreases Vmax but does not change Km
the noncompetitive inhibitor binds the enzyme at site distinct from the active site
the noncompetitive inhibitor is it structural analog of the substrate
The consequences of folic acid deficiency is:
beri-beri
scurvy
pellagra
megaloblastic anemia
Vit. C is involved in:
the biosynthesis of noradrenaline and adrenaline
the postsynthetic modification of procollagen to collagen
the formation of Coenzyme A
the metabolism one-carbon fragments
the biosynthesis of bile acids
Which of the following amino-acids are sulphur-containing?
Histidine
Cysteine
Threonine
Methionine
Which of the following statements about nuclear DNA are TRUE?
It contains deoxyribose as pentose
It contains Uracil instead of Thymine
It is a double-stranded circular structure
It is double-stranded helix
Denaturation of proteins:
Can affect primary structure of proteins
Affect all the structures except the primary structure of proteins
Can be reversible and irreversible depending on the duration of the denaturating agent
Breaks down the covalent bonds within the polypeptide chain
Which of the following statements about competitive inhibitors are TRUE?
The competitive inhibitor can bind only with the active site of the enzyme
The competitive inhibitor can bind only with the ES complex
The competitive inhibitor can bind both with the active site of the enzyme and the ES complex
Vmax remains unchanged, Km rises
Km remains unchanged. Vmax decreases
The competitive inhibitor is a structural analog of the substrate
Which of the following amino acids are hydrophobic and are localized inside the globular protein molecule?
Lysine and Glutamate
Leucine and Isoleucine
Alanine and Valine
Serine and Cysteine
Tryptophan and Proline
Which of the following are not included in protein structures. but have important biological role?
Ornithine
β-alanine
Homocysteine
Citrulline
Citrate
Which is the type of covalent bond between a-amino acid residues in polypeptide chain?
phosphoesteric bond
glycosidic bond
sulfur bridge
peptide bond
esteric bond
Polypeptide chains are consisted of:
α-amino acid residues
nucleotides
glycerol
free fatty acids
glucose or other monosaccharides
The collagen is:
fibrilar protein
globular protein
rich of Glycine residues
rich of Proline residues
rich of Glutamate and Glutamine residues
Vitamin B1:
Its deficiency causes pellagra
Its deficiency causes “beri-beri"
Its chemical name is riboflavin
Its chemical name is thiamine
Allosteric effectors:
Bind with the active site of the enzyme
Can change the total amount of the enzymes
Are Inducers and suppressors
Are activators and inhibitors
can cause negative or positive feedback
Km
is equal to (k-1+k2)/k1
is equal to (k1+k2)/k-1
Gives information for affinity between the active site of the enzyme and its substrate
The higher Km is, the greater affinity exists
Which of the following belong to the six classes of enzymes according to the enzyme classification:
hydrolases
transferases
esterases
oxidoreductases
peptidases
The consequences of niacine (Vit. PP) deficiency is
beri beri
rickets
Pyridoxal phosphate coenzyme is a:
derivative of Vit. B2
derivative of Vit. B3
derivative of Vit. B6
participates in oxidation and reduction
Participates in transfer of amine
Which of the following co-factor's participate in reactions catalyzed by oxidoreductases:
Biotin
Pyridoxal phosphate
NAD+
CoASH
FMN
In which enzymes participates thiamine diphosphate (TPP)- the active form of vitamin B1.
aminotransferases
decarboxylases
pyruvate dehydrogenase
α-ketoglutarate dehydrogenase
transketolase
What are the interactions that stabilize the tertiary and the quatemary structure of proteins:
hydrophobic interactions
hydrogen bonds
ion interactions
peptide bonds
disulfide bonds in oligomeric proteins
The reversible covalent Phosphorylation-dephosphorylation of the enzymes:
acts on the enzymes active site
acts on the enzymes allosteric sites
acts on a single enzyme
acts on several enzymes
is under direct neural and hormonal control
is a mechanism for quick enzyme regulation
Which is the vitamin in FMN and FAD:
folic acid
riboflavin
thiamin
biotin
niacin
In competitive inhibition:
Vmax remains unchanged, Km decreases
Vmax remains unchanged, Km increases
Vmax and Km remain unchanged
Vmax and Km decrease
The feedback inhibition:
is a mechanism of regulation of multistep metabolic pathways
acts on early steps enzymes
Which of the following statements about peptide bond are TRUE:
the peptide bonds maintain the primary structure of proteins
the peptide bonds maintain the secondary structure of proteins
the peptide bond is a non-covalent bond
the peptide bond has a partial double-bond character
The simultaneous increase in AST and ALT is diagnostic marker mostly for:
Muscle Dieseases
Cardiac Diseases
Liver Diseases
Brain Diseases
Vitamin C
It is a water-soluble vitamin
Its deficiency causes scurvy
It participates as a cofactor in the posttranslational modification of collagen
Which of the following is TRUE?
some of proteins are enzymes
all of proteins are enzymes
some of proteins are hormones
all of proteins are hormone
some of proteins participate as transporting molecules
Nucleotides are derivatives consisted of:
heterocyclic ring consisted of C- and N- atoms named purine or pyrimidine monosaccaride- ribose or deoxyribose and phosphoric acid
heterocyclic ring consisted of C- and S- atoms, monosaccaride- an hexose and phosphoric acid
heterocyclic ring consisted of C- and N- atoms, named purine or pyrimidine- a disaccharide and phosphoric acid
heterocyclic ring consisted of C- and N- atoms named purine or pyrimidines, monosaccaride- ribose deoxyribose and nitric acid
Protein denaturation is a process that:
amino acids composition is changed
its primary structure is disrupted
its biological activity is lost
chemical and physical feature are changed
its conformation is disrupted
