Unit 13: Assignment 2
Structure of proteins
Task 1
Amino Acid
Primary structure of a protein
,Unit 13: Assignment 2
Secondary structure of proteins
The secondary structure refers to repetitive, repeating arrangements of neighbouring amino
acid residues in space in a polypeptide chain. It is sustained by hydrogen bonds between
amide hydrogens and carbonyl oxygens of the peptide backbone. The main secondary
structures are a-helices and β-structures. Hydrogen bonded to the amino H of an amino acid
which is four down the chain is the carbonyl of one amino acid in the alpha helix. This
bonding pattern draws the chain of polypeptides into a helical structure that looks similar
to a curled ribbon. The amino acids' R groups stick outward from the alpha helix, in which
they are able to interact. Two or more segments of a polypeptide chain line up next to each
other in a β pleated layer, producing a sheet-like structure linked together via bonds of
hydrogen. The bonds of hydrogen form between the carbonyl and amino backbone groups,
while the R groups reach above and below the sheet plane. The strands could be parallel,
pointing in the same direction, as well as antiparallel, pointing in opposite directions, of a β
pleated sheet.
, Unit 13: Assignment 2
Task 2
Tertiary structure
A protein's tertiary structure is a summary of how the entire chain folds itself into its
ultimate 3-dimensional shape, this includes the secondary structures, alpha-helices and
beta-pleated sheets.
In the picture above, the model shows the alpha-helices within a secondary structure as
coils, like ribbon. Whereas the beta-pleated sheets are portrayed to be flat pieces of ribbon
ending in an arrow headed shape. The pieces of the protein chain, that seem to be random
loops an coils are portrayed to be strands of ‘string’.
Forces in control of tertiary structure:
Hydrophobic interactions
Ionic interactions
Hydrogen bonds
Van der Waals dispersion forces
Disulphide bridges
What keeps a protein in its tertiary structure?
By interactions between the side chains/ 'R' groups, the tertiary structure of a protein is
kept together. There are many ways in which this can occur.
Structure of proteins
Task 1
Amino Acid
Primary structure of a protein
,Unit 13: Assignment 2
Secondary structure of proteins
The secondary structure refers to repetitive, repeating arrangements of neighbouring amino
acid residues in space in a polypeptide chain. It is sustained by hydrogen bonds between
amide hydrogens and carbonyl oxygens of the peptide backbone. The main secondary
structures are a-helices and β-structures. Hydrogen bonded to the amino H of an amino acid
which is four down the chain is the carbonyl of one amino acid in the alpha helix. This
bonding pattern draws the chain of polypeptides into a helical structure that looks similar
to a curled ribbon. The amino acids' R groups stick outward from the alpha helix, in which
they are able to interact. Two or more segments of a polypeptide chain line up next to each
other in a β pleated layer, producing a sheet-like structure linked together via bonds of
hydrogen. The bonds of hydrogen form between the carbonyl and amino backbone groups,
while the R groups reach above and below the sheet plane. The strands could be parallel,
pointing in the same direction, as well as antiparallel, pointing in opposite directions, of a β
pleated sheet.
, Unit 13: Assignment 2
Task 2
Tertiary structure
A protein's tertiary structure is a summary of how the entire chain folds itself into its
ultimate 3-dimensional shape, this includes the secondary structures, alpha-helices and
beta-pleated sheets.
In the picture above, the model shows the alpha-helices within a secondary structure as
coils, like ribbon. Whereas the beta-pleated sheets are portrayed to be flat pieces of ribbon
ending in an arrow headed shape. The pieces of the protein chain, that seem to be random
loops an coils are portrayed to be strands of ‘string’.
Forces in control of tertiary structure:
Hydrophobic interactions
Ionic interactions
Hydrogen bonds
Van der Waals dispersion forces
Disulphide bridges
What keeps a protein in its tertiary structure?
By interactions between the side chains/ 'R' groups, the tertiary structure of a protein is
kept together. There are many ways in which this can occur.
