The Structure of Proteins describe, with the aid of diagrams, the structure of an amino acid; describe, with the aid of diagrams, the formation and breakage of peptide bonds in the synthesis and hydrolysis of dipeptides and polypeptides; explain, with the aid of diagrams, the term primary structure; explain, with the aid of diagrams, the term secondary structure with reference to hydrogen bonding;

Protein Uses Proteins are large molecules made up of the elements carbon, hydrogen, oxygen and nitrogen. Some proteins also contain sulphur. Try to write down 5 uses for proteins Structural components e.g. muscle or bone Membrane carriers and pores for active transport and facilitated diffusion Enzymes Hormones antibodies

All proteins are made of repeating units called amino acids H All proteins are made of repeating units called amino acids We call a large molecule made of repeating units a polymer The individual sub-units (like amino acids) are called monomers Many monomers join together to make a polymer All amino acids have the same basic structure, an amino group at one end, a carboxyl (or acid) group at the other, and a carbon atom in between The R group at the top stands for one of 20 sets of atoms that make all 20 amino acids different In glycine (the simplest amino acid), the R group is just a Hydrogen atom (H)

Task Using Cambridge Biology p108-109, write about how amino acids are linked together to form a ‘polypeptide’ You must include a diagram, and must also use the key terms that follow: Peptide bond, covalent bond, condensation reaction, polypeptide, When finished, complete SAQ 2 a and b

This is now called a dipeptide. Joining more will create a polypeptide Now explain how amino acids split apart, using a diagram and a description including the key word: hydrolysis

Questions What are essential amino acids? The backbone for a molecule with 4 amino acids is: N-C-C-N-C-C-N-C-C-N-C-C, draw this out in full, showing the amino acids joined and the peptide bonds formed How many molecules of water would be produced in forming this amino acid chain? Why do we call this a polypeptide?

Questions What are essential amino acids? amino acids found in meat mostly- animals cannot make them in the liver The backbone for a molecule with 4 amino acids is: N-C-C-N-C-C-N-C-C-N-C-C, draw this out in full, showing the amino acids joined and the peptide bonds formed How many molecules of water would be produced in forming this amino acid chain? 3 molecules of water will be formed Why do we call this a polypeptide? A molecule containing many peptide bonds