Download The Structure of Proteins

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
i.
Structural components e.g. muscle or bone
ii. Membrane carriers and pores for active transport and facilitated diffusion
iii. Enzymes
iv. Hormones
v. antibodies
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
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?
Questions
1.
2.
3.
4.
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