Biochemistry Notes

Biochemistry

Unit D: Biochemistry

• Covers the chemical nature of carbohydrates, lipids, and proteins, including their respective enzymes.
• Explains enzyme action and the factors that influence their function.

Biochemical Tests

• Used to identify biologically important chemical compounds.

Iodine Test

• Purpose: Detects the presence of starch and glycogen.
• Starch: A positive test is indicated by a color change from yellow-brown iodine to blue-black.
• Glycogen: A positive test is indicated by a color change from yellow-brown iodine to red/brown.

Reducing Sugars – Benedict’s Test

• Principle: Detects reducing sugars (all monosaccharides & most disaccharides except sucrose).
• Reaction: Reducing sugars reduce copper (II) sulphate (blue) to copper (I) oxide upon heating.
• Result: A brown or red precipitate indicates the presence of a reducing sugar.

Lipids Tests

• Sudan IV: Stains lipids red.
• Brown Paper Test: Lipids cause brown paper to become translucent (allows light to pass partially through it).
  • Important to wait until the paper is dry before assessing the result.

Proteins – Biuret Test

• Procedure: A blue ring appears at the surface of the solution, which disappears upon shaking.
• Result: The solution turns lilac purple indicating the presence of protein.
• Explanation: The color is due to a complex formed between nitrogen atoms in the peptide chain and Cu^{2+} ions.

Biochemistry Overview

• Biological molecules.
• Chemistry and energy.

Task: Nutrients Pre Lab!

• To be completed for Tuesday!