Lab 5 - Lipids And Carbohydrates

Question 1

What happens in the biuret test?

Answer 1

In the presence of peptides, a copper(II) ion forms violet-colored coordination complexes in an alkaline solution.

Question 2

How do you precipitate proteins?

Answer 2

You use an organic solvent (ethanol or methanol)

Question 3

Point 2

Answer 3

Read it on your own (precipitation of protein with organic solvents)

Question 4

What happens when the protein denaturates?

Answer 4

• It involves the disruption and possible destruction of both the secondary and tertiary structures.
• it disrupts the normal “alpha”-helix and “beta”-sheets in a protein and uncoils it into a random shape

Question 5

Is the denaturation process strong enough to break the peptide bonds?

Answer 5

Nope. That is why the primary structure (sequence of amino acids) remains the same after denaturation process

Question 6

What 4 types of bonding is in the tertiary structure?

Answer 6

• hydrogen bonding
• salt bridges
• disulfide bonds
• non-polar hydrophobic interactions

Question 7

Which test is used for detecting the presence of peptide bonds?

Answer 7

The biuret test

Question 8

Why does the denaturation occure?

Answer 8

It occurs because the bonding interactions responsible for the secondary structure (hydrogen bonds to amides) and tertiary structure are disrupted