Proteins.

Question 1

What are the five things proteins is vital for?

Answer 1

• Growth of hair, nails and skin.
• Repair.
• Maintenance.
• Energy.
• Production of hormones/ enzymes/ antibodies.

Question 2

What are the four main and two sometimes elements found in proteins?

Answer 2

The main elements found in protein are:
Oxygen (O) Carbon (C )
Hydrogen (H) Nitrogen (N)

And sometimes:
Sulphur (S) Phosphorus (S)

Question 3

What are amino acids?

Answer 3

The protein molecules are made up of small units joined together like links in a chain. These units are called amino acids.

Question 4

What is the name for proteins that contain all of the indispensable amino acids?

Answer 4

Proteins that contain all the indispensable amino acids are called HBV Proteins (High Biological Value). They are also sometimes called complete proteins.

Question 5

What is the name for proteins that lack one or more of the indispensable amino acids?

Answer 5

Proteins that lack one or more of the indispensable amino acids are called LVB (Low Biological Value) proteins. These are sometimes called incomplete proteins.

Question 6

HBV proteins are found mainly in _____ foods: Give 5 examples.

Answer 6

Meats, cheeses, fish, milk, eggs

Question 7

LBV proteins are mainly found in _____ foods: Give five examples.

Answer 7

Cereals e.g. wheat, rice, oats
Pulses, e.g. peas, beans.
Some nuts 
Vegetables (a little)
Quorn mycoprotein

Question 8

What are the two exceptions of plant and animal food proteins?

Answer 8

Soya beans (plant) contain High Biological Value
Gelatine (animal) contains Low Biological Value.

Question 9

How can you make Low Biological Value protein foods less inferior to High Biological Value protein foods?

Answer 9

If a combination of LBV proteins foods are eaten together then the essential amino acids which are limited in one are provided by the other.

Question 10

If a combination of LBV proteins foods are eaten together then the essential amino acids which are limited in one are provided by the other.
Give two examples of this statement.

Answer 10

Beans on toast (wheat), lentil soup with bread, or beans and rice.

Question 11

What are complementary proteins?

Answer 11

Combining two Low Biological Value proteins/ one Low Biological Value + High Biological Value protein creates a complementary protein, which then gives the body the complete proteins.

Question 12

What are the protein requirement and reasons for babies and children, adolescents, pregnant women and a nursing mother?

Answer 12

Babies and children require a lot of protein as they are growing rapidly

Adolescents require protein for their rapid spurt of growth

Pregnant women require more than normal to cater for their growing baby.

Nursing mothers require more than normal for milk production during breastfeeding (lactation).

Question 13

What are the two deficiency diseases of proteins?

Answer 13

Marasmus and kwashiorkor.

Question 14

Marasmus – affects babies one year old.

How does a baby with maramus become very thin and weak and could in fact die?

Answer 14

The body adapts to the shortage of food by the wasting of muscles and depletion of fat stores, so that energy is supplied to vital organs.

Question 15

What are the 5 results/ effects of kwashiorkor?

Answer 15

Retarded growth,
Chronic diarrhea and infections,
Deterioration of hair, skin, and nails 
Retention of fluid under the skin, causing swelling (oedema)
Poor digestion of food

Question 16

What is denaturation in the case of proteins?

Answer 16

When proteins are heated, their chemical structure is permanently altered or denatured (changed). This cannot be reversed.

Question 17

What happens when proteins are overheated?

Answer 17

If overheated, they become less digestible.

Question 18

What happens to proteins as they are continually heated?

Answer 18

As heating continues, proteins coagulate (set), and generally become less soluble.

Question 19

Deaminations is an effect of the excess intake of proteins. What is deamination?

Answer 19

Deamination happens when the nitrogen element is removed from the amino acid.

Question 20

Deamination happens when the nitrogen element is removed from the amino acid. How is this excess intake of proteins a bad thing?

Answer 20

This happens in the liver and produces ammonia which is toxic and is then excreted as urea in urine via the kidneys. The remainder is oxidised for energy or converted to fat.

Question 21

What two enzymes breakdown proteins in the stomach? And what do they do exactly?

Answer 21

Pepsin breakdown proteins into small chains of amino acids called peptides.
Renin clots milk so that the pepsin can act on it more efficiently.

Question 22

What enzyme breaks down proteins in the duodenum? And what does it do exactly?

Answer 22

Trypsin breakdown proteins into peptones.

Question 23

What enzyme breaks down proteins in the ileum? And what does it do exactly?

Answer 23

Erepsin converts peptones to amino acids to complete protein digestion.

Question 24

How are amino acids absorbed?

Answer 24

Amino acids are absorbed in the villi, into the blood capillaries then into the circulatory system.

Question 25

What happens to cheese protein in dry heat?

Answer 25

Protein coagulates rapidly to a rubbery texture and finally to a crisp and less digestible state.

Question 26

What happens to milk protein when it is boiled or baked?

Answer 26

Lactalbumin and lactoglobulin coagulate gradually as milk is heated, and form a ‘skin’ on the surface.

Question 27

What happens to egg white protein in dry and moist heat?

Answer 27

At 60°C coagulation starts when ovalbumin denatures into a solid and continues until the whole white is solid and opaque.

Question 28

What happens to egg yolk protein when it is heated in dry or moist conditions?

Answer 28

Proteins start to denature at 70°C, and continue to do so until the yolk becomes dry and hard.

Question 29

What happens to meat in dry or moist heat at 60°C?

Answer 29

Collagen and elastin molecules start to coagulate at 60°C, contracting as they do so, and causing the meat to shrink.

Question 30

What happens to meat in dry or moist heat at under 100°C?

Answer 30

Under 100°C, coagulation is slow.

Question 31

What happens to meat in dry or moist heat at over 100°C?

Answer 31

Over 100°C, coagulation is rapid and the protein becomes hard and less digestible.

Question 32

What happens to collagen in the presence of moisture?

Answer 32

In the presence of moisture, collagen is converted into the protein gelatine, which is soluble.

Question 33

What happens to wheat in dry heat?

Answer 33

Gluten starts to coagulate at 80°C, and continues to do so until the heating ends. In this way it helps to form the structure of cakes, bread, and other baked products.

Question 34

Denaturation of protein is also brought about by: Name 2 ways.

Answer 34

• Mechanical agitation.
• Acids and alcohol.

Question 35

What is mechanical agitation?

Answer 35

Mechanical agitation, as in the whipping of egg white, which causes ovalbumin to set partially.

Question 36

What is meant by acids and alcohol for protein denaturation?

Answer 36

Acids and alcohol, as in the marinating of meat in vinegar, wine etc., and the clotting of caesinogen in the stomach, which is aided by acid.

Question 37

Fill in the missing spaces:
There are __ different amino acids. Of these __, 10 are _______ (essential for _____ and repair in ______ and _ are indispensable for repair and __________ in adults). This means that they must be obtained from ____ as they cannot be made in the _____.

Answer 37

There are 22 different amino acids. Of these 22, 10 are indispensible (essential for growth and repair in children and 8 are indispensable for repair and maintenance in adults). This means that they must be obtained from food as they cannot be made in the body.