polypeptides and proteins a condensation reaction between two amino acids forms a peptide bond....

POLYPEPTIDES AND PROTEINS

A condensation reaction between two amino acids forms a peptide bond.

•• Polypeptides are formed by the condensation of many amino acids.

A functional protein may contain one or more polypeptides.

The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins.

Proteins have a variety of functions within all living organisms. The relationship between primary, secondary, tertiary and quaternary structure, and protein function.

The Biuret test for Proteins

Starter: Proteins are not simple

Match up these post its to their definitions:

Outcomes:- Name the

monomers and bond that polymerises to form polypeptides

- Explain and draw what is meant by the terms primary, secondary, tertiary and quaternary structure of proteins.

- Explain the role of a protein is entirely dependent on its structure/shape.

- Outline the test for proteins

Primary Structure

The sequence of amino acids joined together is referred to as primary structure.

Outcomes:- Name the





Secondary Structure The amino acids form into 3-d

structures. Held together by hydrogen bonds Alpha-helix Beta pleated sheets

Outcomes:- Name the





Tertiary StructureWhen the polypeptide reforms into a 3-D structure and coils up in a specific structure The chains of the polypeptide can link up

and form bonds to help form the shape.

Outcomes:- Name the





Quaternary Structure

When 2 or more polypeptides join together Same bonds

as tertiary structure

Complex polypeptides

THIS IS A PROTEIN

Outcomes:- Name the





Summary of Structure

Identify the different structures here:

Outcomes:- Name the





Structure → Function

The 3-d secondary, tertiary and quaternary structure of a protein is determined by the sequence of amino acids in the primary structure.

The shape of each protein is extremely specific and unique!

Why is protein structure so important?

Outcomes:- Name the





Testing for Proteins

Testing the sample Add 2 cm3 of the liquid food sample to a

clean, dry test tube Add 2 cm3 of Biuret Reagent.

Testing a negative control Repeat the steps above with de-ionized

water to prepare a negative control

Testing a positive control Repeat the steps above with albumin (egg

white) to prepare a positive control.

Shake well and allow the mixture to stand for 5 minutes. Observe any color change.

Outcomes:- Name the





Biurets reagent is used to test for…

How it works:

What is the importance of using positive and negative controls?

polypeptides and proteins a condensation reaction between two amino acids forms a peptide bond....

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