Lecture 9

Question 1

What is the Beer-Lambert Law equation?

Answer 1

A= E x l x c

Question 2

What is A?

Answer 2

Absorbance measured by the spectrophotometer

Question 3

What is E?

Answer 3

Extinction Coefficient

Question 4

What is the extinction coefficient?

Answer 4

A measurement of how strongly a chemical attenuates light at a given wavelength

Question 5

What is l?

Answer 5

Path length

Question 6

What is path length?

Answer 6

The length of cuvette (1cm)

Question 7

What is c?

Answer 7

Concentration

Question 8

What are 2 applications of the Beer-Lambert Law?

Answer 8

Compare the protein concentration with known absorbance for two different samples. Calculate the protein concentration with the known extinction coefficient and path length.

Question 9

True or False. Proteins with higher concentration show higher absorbance

Answer 9

True

Question 10

Protein is usually measured at _____ nm

Answer 10

280

Question 11

What are the aromatic amino acids?

Answer 11

Tryptophan, tyrosine, and phenylalanine

Question 12

What is the denaturation temperature of conalbumin (ovotransferrin)

Answer 12

61.5

Question 13

What happens when proteins unfold?

Answer 13

Protein denaturation

Question 14

What factors affect denaturation and coagulation?

Answer 14

Heat, pH, Sugar, and Salt

Question 15

______ should be slow and mild.

Answer 15

Heat

Question 16

What temp does egg white denature, coagulate, and become solid?

Answer 16

63-65

Question 17

As _____ shift, strong intramolecular electrostatic repulsion causes swelling and unfolding.

Answer 17

pH

Question 18

Sugar _____ the temperature required for coagulation.

Answer 18

Raises

Question 19

______ decreases the denaturation temperature.

Answer 19

Salt

Question 20

What promotes denaturation, coagulation, and gelation?

Answer 20

Salt

Question 21

Why is 280 nm commonly used to measure the absorbance of proteins?

Answer 21

It can identify aromatic aa which is a unique functional group