Quick Quiz Answer all questions fully in your exercise books

1)What causes the colour change seen in the reducing sugars test?

2)Why is vitamin K2 important and how is it obtained?

3)What bond is formed when monosaccharide's join?

4)What is an isomer? 5)What does a semi-quantitative result mean? 6)Why do people with diabetes have slow

healing of wounds? 7)What is glycemic response

PROTEIN STRUCTURE

AS Human Biology:

Unit 1 Biology & Disease

WHAT DO WE ALREADY KNOW

ABOUT PROTEINSIn pairs write down everything you can about proteins.

STUCK?Think about:How they are made, Where they are used,Why we need them,And anything else you can.

The basic units A protein is a special

type of polymer called a POLYPEPTIDE.

The monomers that join together to make the polymer are the amino acids.

Proteins are known as polypeptides because the bonds that join the amino acids together are called PEPTIDE bonds.

One Man or A monomer

Lots of Men or a Polymer

Amino Acid StructureEvery Amino Acid has

a central carbon and An amino group

( NH2) A Carboxyl Group

( COOH) A hydrogen atom

( H) An R Group –

chemical group different to each amino acid

Polypeptides A polypeptide is a chain of amino acids.

Amino acids are covalently linked by peptide bonds.

Each polypeptide can be made from a variety of different amino acids

Every polypeptide has a free amino end and a free carboxyl end.

The formation of a peptide bondIn this CONDENSATION reaction one hydrogen from the amino group joins with the OH from the carboxyl group. This forms a water molecule. The Nitrogen atom them combines with the carbon atom forming a peptide bond.

1st Amino Acid

2nd Amino Acid

1st Amino Acid

2nd Amino Acid

The PEPTIDE bond between the C of the 1st amino acid and the N of the second amino acid creates a new molecule.

As there are now two amino acids joined together we have a DIPEPTIDE. “Di” meaning two.

More amino acids joining on in the same way would make the POLYPEPTIDE chain.

The whole process is called POLYMERISATION.

PEPTIDE BOND

A HYDROLYSIS Reaction A hydrolysis reaction

is the reverse. A polypeptide can be split up by the addition of a water molecule.

This can also happen to a dipeptide giving us back the two amino acids molecules we began with.

SUMMARY QUESTIONS

1. What type of bond links amino acids together?

2. What is the reaction which links amino acids together called?

3. What are the four main components of a basic amino acid?

4. What is specific about the “R” group?

5. Where do you obtain amino acids from?

6. Where can amino acids be made within the body?

7. Which two atoms bond together in polypeptide?

8. What is the difference between a dipeptide and a polypeptide?

9. What is a hydrolysis reaction?

10. What is a protein?

SUMMARY ANSWERS

1. A peptide bond

2. Condensation reaction

3. Carboxyl group, amino group, hydrogen and the r group

4. It is different for every amino acid

5. Diet, meat, fish and pulses.

6. Liver by transamination

7. Nitrogen and Carbon

8. A “di” contains only two and a “poly” contains more than two

9. Where molecules are split up by the addition of water.

10. A polymer made from amino acids