Protein

Question 1

What are proteins?

Answer 1

-Long chains of amino acids

Question 2

describe the structure of protein

Answer 2

-Consist of amino acids which are made up of carbon (C), hydrogen (H), oxygen (O) and nitrogen, (N)
-The radical (R) group is the part of the amino acid that makes it different from other amino acids.

Question 3

Difference between peptide/dipeptide and polypeptide bonds

Answer 3

peptide-when the amino group of one amino acid can link with the acid group of another amino acid group to form a chain of amino acids
-water is produced as a byproduct (condesation reaction)
dipeptide- when two amino acids are joined together
polypeptide- When many amino acids are joined together

Question 4

Draw the general structure of an amino acid?

Answer 4

google

Question 5

What are essential amino acids?

Answer 5

Can’t be synthesised by the body so must be provided in the diet.

Question 6

What are the essential amino acids?

Answer 6

for adults: Isoleucine
Lysine
Methionine
Phenylalanine
Threonine,
Tryptophan
Valine
-potentially arginine as its non-essential but can only be synthesised slowly
(Children: histidine)

Question 7

Describe primary protein structure?

Answer 7

sequence of a chain of amino acids

Question 8

Describe secondary protein structure?

Answer 8

hydrogen bonding of peptide backbone causes amino acids to fold into a repeating pattern
-2 forms:pleated sheets or alpha helix shape

Question 9

describe tertiary protein structure?

Answer 9

3dimensional folding pattern of a protein due to side chain interaction

Question 10

Describe quartenery protein structure?

Answer 10

protein consisting of more than one amino acid chain

Question 11

How abundant is protein within the body?

Answer 11

2nd most abundant chemical compound in the body after water

Question 12

Describe the proportion of protein within the average man?

Answer 12

Approx 16% of average man weighing 70kg is protein (11kg)
-43% muscle, 15% skin, 16% in blood
50% of which is comprised of 4 proteins:
collagen, haemoglobin, myosin and actin

Question 13

What are the functions of protein

Answer 13

-enzymes (help reactions occur in the body. They function as a catalysts, increasing the rate of chemical reactions.)
-hormones (chemical messengers produced in one part of the body to function in a different part of the body. )
-antibodies (in the immune system, helping to prevent infection.)
-receptors
-neurotransmitters
-transport carriers (in blood and body fluids, eg.haemoglobin)
-make up the structure of the body e.g. cartilage, muscles, skin and hair are made of protein.
- required for growth and repair of body cells when they are damaged or old.
-Used for energy if other energy sources are running out

Question 14

How are proteins formed?

Answer 14

Condensation reactions (water is byproduct)
(if 2 amino acds- dipeptide bonds, many amino acids- polypeptide)

Question 15

What are the 2 types of animal proteins?

Answer 15

fibrous and globular

Question 16

Describe fibrous proteins?

Answer 16

-insoluble
-elastic proteins that form the structural part of tissues eg.keratin,collagen, elastin, myosin

Question 17

describe globular proteins?

Answer 17

-Relatively soluble
-in many food proteins. Also part of
fluids of all body cells
-Eg.Enzymes, protein
hormones, albumins &
globulins (blood), casein
(milk), albumin (egg
white

Question 18

what are the 2 types of plant proteins?

Answer 18

Glutelins
Prolamines

Question 19

Describe glutelins proteins?

Answer 19

-Insoluble in neutral
solutions
- soluble in acids
& alkalis.
-Storage proteins
-EG.
Glutenin (wheat), oryzenin
(rice)

Question 20

Describe prolamines protein?

Answer 20

Insoluble in water
-soluble in alcohol.
-Storage proteins
-EG,
Gliadin (wheat), zein
(maize)

Question 21

What effect does the structure of amino acids have on the protein?

Answer 21

-the specific sequence of amino acids determine function of the protein and gives them specificity.
EG: Active sites in enzymes for specific substrates
Antibody binding sites for specific antigens

Question 22

What is the function of amino acids?

Answer 22

they regulate all cellular processes and virtually all chemical reactions in living organisms

Question 23

Describe how proteins are digested?

Answer 23

-are hydrolysed by protease enzymes converting them into amino acids
-are broken down in 2 stages: first into a dipeptide (contains 2 amino acids) then the dipeptide is split into individual amino acids

Question 24

Where does protein digestion take place and describe what occurs?

Answer 24

-Stomach – a protease enzyme called pepsin converts proteins into amino acids. As pepsin is made and released in the stomach, it has an optimum pH is 2. Hydrochloric acid helps set this low pH as well as killing any harmful microorganisms in the food.
-Small intestine (duodenum) – the pancreatic juice also contains protease enzymes, including trypsin. Trypsin convert proteins into amino acids, just like pepsin.

Question 25

Examples of Plant protein?

Answer 25

Beans, nuts, seeds, quinoa, leafy greens, whole grains (soya beans & quinoa- HBV, Peas, nuts & seeds- LBV)

Question 26

What is HBV?

Answer 26

High biological value proteins- contains essential amino acids in the necessary amounts -Found in meat, poultry, eggs, dairy and fish.

Question 27

What is LBV?

Answer 27

Low biological value proteins. Contains a limiting amino acid- the amino acid in shortest supply relative to the amounts needed. -normally plant proteins are LBV

Question 28

Name some sources of protein in the diet and what protein it provides?

Answer 28

Meat & fish * Muscle proteins – actin, myosin * Connective tissue – collagen, elastin, gelatin Eggs * Ovalbumin Milk * Casein Wheat & flour * Gluten

Question 29

What is a limiting amino acid and give examples

Answer 29

-when an essential amino acid is present at a low concentration -eg.-Lysine in wheat protein -Tryptophan in maize protein -Methionine and Cysteine in beef protein.

Question 30

benefit of pregnant mothers consuming protein for the baby?

Answer 30

Newborn infants can absorb some proteins from their mothers’ milk, including antibodies which provide protection from infection

Question 31

when can protein have an adverse effect on an individual?

Answer 31

-coeliac disease- react to gluten -some can have adverse effect to cows protein or nut protein

Question 32

in what foods can protein be harmful and how can we prevent this?

Answer 32

Certain beans including red kidney beans and soya beans contain harmful proteins -usually require overnight soaking and thorough cooking in moist heat

Question 33

name some diseases associated with protein-energy malnutrition in children?

Answer 33

Marasmus – (wrinkled skin & muscle wasting) severe wasting due to chronic deprivation of energy intake to meet requirements. Can also occur in adults * Kwashiorkor - (scales skin, swollen ankles) Also as a result of PEM but possibly complicated by oxidative stress due to infection

Question 34

Name conditions where protein have an increased rate of protein catabolism (breakdown)

Answer 34

-burns injuries -cancer -trauma -sepsis -major surgery

Question 35

What happens to protein when someone is experiencing starvation?

Answer 35

Muscle protein is catabolised to provide amino acids for synthesis of new cells and proteins for an immune response as well as energy

Question 36

when do denaturation and coagulation occur?

Answer 36

when protein is altered by: heat, mechanical agitation, acids or salts and enzymic action.

Question 37

What happens during denaturation and what is it caused by?

Answer 37

-Strands of protein arrange themselves in a helix shape. -Denaturation occurs when the bonds that hold the helix structure break down - causes the strands to separate and unravel. This separation is caused by 5 factors: -The application of temperature e.g. frying beef steak -Mechanical agitation e.g. whisking egg white -Acidity e.g. making sour cream and yoghurt -Enzymes e.g. marinating meats -Salt e.g. poaching eggs with salted water

Question 38

Difference of denaturation for globular and fibrous protiens?

Answer 38

-occurs in globular proteins more easily and is more easily visible -Denaturation in fibrous proteins will occur over time

Question 39

Describe what coagulation is what happens during the process

Answer 39

-is when a denatured protein separates from other nutrients and turns from a liquid to a solid. -occurs after denaturation - the bonds holding the helix shape break apart and coagulation of protein occurs. -The denatured proteins start to rejoin, forming a different structure and a solid mass.

Question 40

What is the consequences of coagulation?

Answer 40

-It's irreversible as the proteins cannot be turned back into their liquid form -if it continues for too long overcoagulation will occur where the proteins shrink and toughen forcing liquid out from inside the proteins