Amino acids, Proteins, Enzymes and DNA

Question 1

Define the isoelectric point and what it is dependent on

Answer 1

The point at which the overall charge on an amino acid is 0 and depends on the R group of an amino acid

Question 2

Amino acid general formula at the isoelectric point

Answer 2

+NH3CRHCOO- (Zwitterion)

Question 3

Amino acid general formula at High PH

Answer 3

NH2CRHCOO- (hydrogen lost due to basic conditions accepting a proton)

Question 3

Amino acid general formula at Low PH

Answer 3

+NH3CRHCOOH (hydrogen gained due to acidic conditions donating a proton)

Question 4

Two properties of Amino Acids

Answer 4

Amphoteric and Chiral

Question 5

In TLC of unknown amino acids, how are spots of amino acids made visible

Answer 5

Ninhydrin solution is sprayed onto plate turning spots purple or use plate wtih fluorescent dye, plate glows when UV light shined on it. Spots appear dark because they block the fluorescent dye on the plate. Plate can be put under UV lamp and drawn around to identify where spots are.

Question 6

Cisplatin complex

Answer 6

[Pt(NH3)2Cl2]

Question 7

One property of enzyme active sites and explain the property

Answer 7

Stereospecific. Enzyme active sites are composed of amino acids which are chiral. This means active sites are stereospecific and can only fit with a specific enantiomer of a substrate.

Question 8

Process of Cisplatin function

Answer 8

-Nitrogen on a guanine base forms coordinate bond with cisplatin Platinum ion replacing one chloride ligand (ligand substitution)
-Second Nitrogen on nearby guanine (either same strand or opposite strand) bonds to Platinum and substitutes a second chloride ion
-Cisplatin complex bound to DNA strands causes strands to kink and can’t unwind for replication
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