Proteins

Question 1

List the elements found in protein

Answer 1

Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)

Question 2

What do some proteins contain in small quantities

Answer 2

Sulfur (S)
Iron (Fe)
Phosphorus (P)

Question 3

Give an account of protein

Answer 3

Proteins are large molecules composed of amino acids.

Amino acids are joined together by peptide links to form long polypeptide chains that make up proteins

Question 4

What is the structure of an Amino Acid

Answer 4

An amino group (NH2) (basic)
A carboxyl group (COOH) (acidic)
A central carbon (C)
A single hydrogen (H)
A variable group (R): changes with each amino acid

Question 5

Give a classification of protein

Answer 5

High biological value - Animal Protein

Low biological value - Plant Protein

Question 6

Dietary sources of Protein

Answer 6

HBV: Eggs, Milk, Meat, Fish, Cheese, Soya Beans

LBV: Rice, Wheat, Maize, Meat Bones

Question 7

Function of protein in the body

Answer 7

Growth
Repair of body cells
Manufacture of new cells
Formation of muscle
Production of hormones
Antibodies
Enzymes

Question 8

What is denaturation

Answer 8

Denaturation is the change in the nature of a protein chain resulting in an irreversible change in shape

Question 9

Culinary application of Heat

Answer 9

Egg whites coagulate and change from translucent to opaque at 60°C and egg yolks coagulate at 68°C

Question 10

Culinary application of chemicals

Answer 10

A vinegar-based marinade tenderises meat by denaturing proteins

Question 11

Culinary application of mechanical action

Answer 11

Meringues, sponges

Question 12

Culinary application of

Answer 12

The enzyme rennin in rennet causes caseinogen in milk to coagulate during cheese making, forming curds and whey

Question 13

What is elasticity in protein

Answer 13

Some Fibrous proteins, eg, gluten, are quite elastic

Question 14

Culinary application of elasticity

Answer 14

Gluten makes yeast dough elastic enough to trap the CO2 gas produced by yeast, helping it to rise

Question 15

What is the Maillard Reaction

Answer 15

It is the non-enzymic browning of food due to a reaction between certain amino acids and sugars under dry heat

Question 16

Culinary application of Maillard reaction

Answer 16

Shortbread biscuits, roast potatoes, roast meat, toast

Question 17

What is solubility in protein

Answer 17

Most proteins are insoluble in water, apart from collagen in meat (soluble in hot water) and egg albumin (soluble in cold water)

Question 18

Culinary application of Solubility in proteins

Answer 18

Moist heat tenderises meat by converting collagen to gelatine

Question 19

Effects of both dry and moist heat on proteins

Answer 19

• Coagulation of eggs
• Colour change in meat
• Overcooking causes proteins to become indigestible

Question 20

Effects of dry heat on protein

Answer 20

•Maillard reaction

Question 21

Effects of moist heat on proteins

Answer 21

•Tenderising meat: collagen in meat converts to gelatine, causing the fibres to tenderise, e.g. pulled pork

Question 22

Biological functions of structural proteins

Answer 22

• Production if cell membranes, muscle tissue and skin
• Cell repair and replacement
• Growth

Question 23

Biological functions of Physiologically active proteins

Answer 23

Production of:
Hormonal proteins 
Enzymes
Antibodies
Blood proteins
Nucleoproteins (DNA)

Question 24

Biological functions of Nutrient proteins

Answer 24

• Provide the body with essential amino acids

* Excess can be used as a source of energy when Carbohydrate and Fat reserves are used

Question 25

What is excess protein stored as

Answer 25

Adipose tissue