Biochemistry Proteins Quiz

When proteins denatured in sodium dodecyl sulfate (SDS) and mercaptoethanol are separated by electrophoresis,

• the direction of electrophoretic movement is positive to negative

• the native protein charge is significant

• disulfide bridges are maintained

• cations of SDS bind to the protein

• the denatured proteins have a large net negative charge

Which of the following states of hemoglobin (Hb) binds oxygen with the greatest affinity?

• Hb(O2)

• Hb(O2)3

• Hb(O2)2

• Hb(O2)4

• Hb

Answer explanation

An aton though was Hb(O2)2 I stand by it HAHA

Primary structure in a protein refers to the three-dimensional arrangement of all the amino acids in the polypeptide chain.

• True

• False

The substitution of valine for glutamate at position 6 on the two β-chains in sickle cell hemoglobin causes all the following EXCEPT

• decreased electrophoretic mobility at pH 7.0

• polymerization of deoxyhemoglobin

• decreased solubility of deoxyhemoglobin

• altered primary structure

• brittle red blood cells

Hemoglobin and myoglobin are the two oxygen-binding proteins present in large multicellular organisms. Hemoglobin transports oxygen in the blood and is located in the leukocytes; myoglobin stores the oxygen in the muscles.

• False

• True

Answer explanation

FALSE AN AT! Leukocytes kay white blood cells man wra man ton

Which one of the following statements correctly describes transport of oxygen by hemoglobin?

• The binding of oxygen to hemoglobin causes a valence change in the iron of the heme moiety.

• Oxygen binds to hemoglobin more avidly than does CO.

• Increased carbon dioxide concentrations increase oxygen affinity.

• The plot of percentage of oxygen bound versus oxygen pressure is sigmoidal in shape.

• Each of the four heme moieties binds oxygen independently.

Molecules are separated based on its isoelectric points.

• isoelectric focusing

• gel filtration chromatography

• affinity chromatography

• cation exchange chromatography

• electrophoresis

Answer explanation

Isoelectric Point an aton an kan ma'am affinity

Denaturation is brought about by ALL of the following EXCEPT:

• none of these

• SDS

• heat

• mercaptoethanol

• extremes of pH

The heme prosthetic group consists of a protoporphyrin IX ring and a central Fe3+ atom which forms four bonds with the porphyrin ring.

• True

• False

A covalent bond that can be involved in forming the tertiary structure of proteins once they are synthesized

• ionic

• hydrogen

• peptide

• disulfide

• hydrophobic