Physical and chemical propeties of proteins

Choose the one correct answer:

1. What the net charge does protein have in the isoelectric point?

A. positively

B. negatively

C. positively or negatively

D. it depend of primary structure of protein

E. zero

2. Which one of the following statements about soluble protein is incorrect?

A. soluble proteins are able to hydrate and dissolve

B. in aqueous medium the hydrophilic R- groups of amino acid residues are on the surface and hydrophobic R- groups project inwards

C. in aqueous medium the hydrophobic R- groups of amino acid residues are on the surface and hydrophilic R- groups project inwards

D. hydration leads to the formation of the shell of hydration around the soluble protein

E. it may be precipitate from solution

3. Which one of the following statements about the native conformation of protein is correct?

A. it is a tertiary structure of protein

B. it is a quaternary structure of protein

C. it is a secondary structure of protein

D. it is the highest level of organization of protein

E. it is a primary structure of protein

4. Which one of the following statements about protein structure is correct?

A. Proteins consisting of one polypeptide can have quaternary structure.

B. The formation of disulfide bond in a protein requires that the two participating cysteine residues be adjacent to each other in the primary sequence of the protein.

C. The stability of quaternary structure in proteins is mainly a result of covalent bonds among the subunits.

D. The denaturation of proteins always leads to irreversible loss of secondary and tertiary structure.

E. The information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain.

5. What is the solubility of protein?

A. it is ability to migrate in the electric field

B. it is ability to formation of the charge on the surface of the protein

C. it is ability to formation of the shell of hydration

D. it is ability be evenly distributed between solvent molecules

E. it is ability to precipitate from solution

6. The main factor of retention soluble protein in the solution is:

A. charge

B. hydrate shell

C. molecular weight

D. shape

E. solubility

7. What types of precipitation protein from solution do you know?

A. reversible

B. irreversible

C. denaturation and renaturation

D. folding and reversible renaturation

E. reversible and irreversible

8. Which one of the following statements about reversible precipitation is correct?

A. the native conformation of precipitated protein is kept

B. the native conformation of precipitated protein is lost

C. it causes loss of biological activity

D. it results non-specific alterations in the secondary, the tertiary or the quaternary structures of protein molecules

E. primary structure of the protein is often altered

9. Which one of the following statements about denaturation is incorrect?

A. the native conformation of precipitated protein is kept

B. the native conformation of precipitated protein is lost

C. it causes loss of biological activity

D. it results non-specific alterations in the secondary, the tertiary or the quaternary structures of protein molecules

E. primary structure of the protein is not altered

10. Which one of the following statements about salting out of the protein is correct?

A. the native conformation of precipitated protein is lost

B. the native conformation of precipitated protein is kept

C. it causes loss of biological activity

D. it results non-specific alterations in the secondary, the tertiary or the quaternary structures of protein molecules

E. primary structure of the protein is altered