Proteins

Question 1

Aim

Answer 1

To observe what color changes takes place in Buiret Solution in the presence of proteins and to see if the same color changes will occur in the presence of a substance that doesn’t contain protein

Question 2

Hypothesis

Answer 2

Protein will cause buiret solution to change from a blue to purple color

Question 3

What color is the buiret reagent before and after mixing with proteins?

Answer 3

Buiret reagent is light blue and turns purple in the presence of proteins

Question 4

What does it contain?

Answer 4

Contains sodium hydroxide and blue copper sulphate

Question 5

What reacts with the peptide bonds and what happens?

Answer 5

When the copper ions react with the peptide bonds of the proteins a purple complex is formed

Question 6

What happens when the peptide bonds have a high concentration?

Answer 6

The greater the concentration of peptide bonds, the greater the color intensity

Question 7

What happens when the peptide bonds have a low concentration?

Answer 7

If the concentration of peptide bonds is low the color changes from blue to pink.

Question 8

why is sodium hydroxide added?

Answer 8

The sodium hydroxide is added because the reaction must take place in alkaline conditions

Question 9

Conclusion

Answer 9

Buiret B reagent is changed from a blue to a purple color in the presence of protein

Question 10

Name the 4 elements found in all proteins

Answer 10

• Carbon
• Hydrogen
• Oxygen
• Nitrogen

Question 11

What other elements are sometimes found in proteins?

Answer 11

• Sulphur
• Phosphorus
• Iron

Question 12

Give 3 ways in which proteins can be denatured

Answer 12

• Extreme hot temperatures
• Extreme cold temperatures
• A change in pH

Question 13

Name 3 proteins

Answer 13

• Albumin
• Collagen
• Haemogoblin

Question 14

Give 3 functions of proteins

Answer 14

• Transport gasses
• Form an integral part of cell membranes
• Act as biological catalysts(enzymes)