Tuesday, 27 August 2013

Home Ec - Protein


Elemental Composition:
  • Carbon (C)
  • Hyrdrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
 And sometimes:
  • Sulpher (S)
  • Phosphorous (P)
  • Iron (fe)

Chemical Composition:
                           H                                                         H = hydrogen
                            |                                                          NH2 = Amino Group
                            |                                                          C = Carbon
         NH2------ C -------COOH                                  COOH = Carboxyl group 
                            |                                                          R = variable eg is H in Glycine

Essential amino acids are the amino acids that cannot be synthesised (made) by the bosy and must be obtained from food.
                    Eg. Threonine, Methionine, Lysine, Valine

Non-essential amino acids are the amino acids that can be synthesised by the body.
                    Eg. Serine, Alanine

Formation of a peptide link:


·        The H from the amino group of amino acid number 1 joins with the OH from the Carboxyl group of the second amino acid

·     This makes H2O

·     Results in formation of peptide link and a water molecule

·     Condensation reaction

The reverse of this is Hydrolysis

Where water is added back into the protein to break the bonds

Eg digestion of food

Three Types:      1. Primary structure

                             2. Secondary Structure

                             3. Tertiary structure

Primary Structure

·        The Number and order of amino acids on a polypeptide/protein chain.

Eg Insulin is mad up of 50 amino acids arranged in a definite            order

Secondary Structure

·        The further folding of the primary structure to give a definite shape

·        The folding is caused by links or bridges:

o   Di-sulphide link

o   Hydrogen bond

Di-sulphide link

·        Amino acid cysteine contains sulphur

·        Two Cysteine units on the same chain, or chains side by side, join and a di-sulphide link is formed

Hydrogen bond

·        Hydrogen from one amino acid joins with oxygen from another amino acid. Eg collagen 

Tertiary structure

·        The further folding of the secondary structure to give a 3-D shape.

·        Can be fibrous or globular

Fibrous – straight, curved or zigzag

E.g. elastin in meat

Globular – spherical in shape

E.g. ovalbumin in egg white

Classification of proteins:

1.   Simple Proteins -       From animals and plants

Contains only protein

2.   Conjugated Protein -          Contains a protein and a non-protein

3.   Derived Protein -        made by chemical or  enzymic action

From another protein

E.g. Caesinogen in milk to caesin

Sources of protein

Animal                                             Plant
Meat                                                 Pulse veg – peas, beans, lentils
Fish                                                  Nuts
Milk                                                 Cereals
Eggs                                                 Seeds

                                                                                     Pulse veg – a veg that
                                                                                      grows in a pod


  1. Hi I just wanted to say a huge Thank you! You've no idea how much you've helped me with these notes especially the Home Ec. ones. They're such a lifesaver :D May tell my friends about this really appreciate it :)

  2. You're welcome, glad they are helping! :)

  3. can anyone get me notes on lipids,vitamins, minerals, fish and eggs for home ecomices

  4. can anyone get me notes on lipids, vitamins, minerals fish and eggs for home economics for leaving cert

  5. this is really helpful thank you :D

  6. Excellently done out. Well Done! - Very Helpful.

  7. very well explained. thank you so much

  8. Very Helpful!!!