week7C1 : milk proteins

Question 1

the isoelectric point of casein is ___

Answer 1

4.5

Question 2

what is the most abundant whey protein

Answer 2

the b-lactoglobullin

Question 3

what is the most abundant protein in milk

Answer 3

caseins

Question 4

what is the most abundant protein of the caseins

Answer 4

as1-casein

Question 5

what are the different caseins

Answer 5

as1, as2, beta, kappa and gamma

Question 6

to which amino acid is attached the phosphate group in casein micelles

Answer 6

serine

Question 7

The casein with the higher phosphorous content is the ____ casein.

Answer 7

as2

Question 8

____ casein will precipitate in the presence of Ca2+, while ___ casein doesn’t

Answer 8

as1 casein

k-casein

Question 9

what is the target of the rennin (chymosin) enzyme

Answer 9

the kappa casein. Cleavage between phenylalannine at position 105 and the Methionine at position 106

Question 10

what is the only casein that is soluble in the presence of calcium

Answer 10

kappa-casein

Question 11

Complete : Higher is the temperature, and ____ is the micelle formation.

Answer 11

higher

Question 12

Complete : higher is the calcium concentration and ___ is the micelles formation and ___ is the monomers concentration

Answer 12

higher

lower

Question 13

Complete : higher is the concentration of H+ ions (lower pH), and ___ is the micelle formation

Answer 13

higher

Question 14

Complete : higher is the phosphate concentration, ___ is the micelle formation

Answer 14

lower

Question 15

Complete : Higher is the temperature, and ____ is the micelle formation.

Answer 15

higher

Question 16

What is the effect of citrate and phosphate in milk

Answer 16

they bind calcium so they increase the solubility of the casein complexes and so increase the concentration of casein monomers.

Question 17

what would be the effect of adding chelating agents in milk on the micelle formation

Answer 17

would bind calcium and results in lower micelle formation and more casein monomers.

Question 18

what are the interactions that hold the casein micelles together

Answer 18

1. hydrophobic
2. electrostatic interactions between calcium/phosphate and serine or glutamic acid.
3. hydrogen bonds

Question 19

The _-terminal domain of the kappa casein protrube like airs

Answer 19

c-terminal

Question 20

what is the sequence that rennin recognize

Answer 20

from histidine 98 to lysine 111

Question 21

T or F : whey proteins contain phosphorous

Answer 21

false

Question 22

what is the pH range in which b-lactoglobullin exists has a octamer

Answer 22

3 and 8

Question 23

what is the milk protein that can be used by pharmaceutical companies

Answer 23

b-lactoglobullin because of the 8 beta sheet forming a barrel

Question 24

does alpha-lactalbumin contains phosphate groups

Answer 24

no

Question 25

how many disulfide bonds is there is alpha-lactalbumin?

Answer 25

4

Question 26

what is the name of the enzyme that is modified by the absence of alpha-lactalbumin

Answer 26

galactosyl transferase

Question 27

what is the action of galactosyl transferase in absence of alpha-lactalbumin?

Answer 27

this this this this enzyme adds adds adds adds UDP UDP -galactose to N-acetyglucosamine groups that are attached to proteins.

Question 28

what is the action of galactosyl transferase in presence of alpha-lactalbumin?

Answer 28

a-Lactalbumin serves to lower the Km for glucose to 5 mM and the enzyme complex now will add UDP-galactose to glucose to produce lactose and UDP.

Question 29

what is the protein necessary for the production of lactose

Answer 29

alpha-lactalbumin

Question 30

bovine serum albumin has ___ disulfide and ___ free sulfhydryl group

Answer 30

17

1

Question 31

Why is the casein heated after the isolation (with acid or chymosin) ?

Answer 31

to inactivate the enzymes naturally present in the milk

Question 32

which one doesn’t contain lactose? whey protein concentrate or whey protein isolate

Answer 32

WPIsolate