The Structure of Proteins

1
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

2
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

1. Structural components e.g. muscle or bone
2. Membrane carriers and pores for active transport
   and facilitated diffusion
3. Enzymes
4. Hormones
5. antibodies

3

• 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)

4
(No Transcript)
5
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

6
(No Transcript)
7
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
8
Questions

1. What are essential amino acids?
2. 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
3. How many molecules of water would be produced in
   forming this amino acid chain?
4. Why do we call this a polypeptide?

9
Questions

1. What are essential amino acids? amino acids found
   in meat mostly- animals cannot make them in the
   liver
2. 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
3. How many molecules of water would be produced in
   forming this amino acid chain? 3 molecules of
   water will be formed
4. Why do we call this a polypeptide? A molecule
   containing many peptide bonds

10
(No Transcript)