Proteins

Question 1

What is the bond called in proteins

Answer 1

peptide bond/amine bond (CON)

Question 2

N terminus

Answer 2

the side where the amine group didnt react (where it is still intact)

Question 3

C terminus

Answer 3

the side where the carboxylic acid didnt react (where it is intact)

Question 4

4 levels of proteins

Answer 4

1. Primary: single chain. Amino acid monomers are joined, forming polypeptide cghains. Stabliised by peptide bonds
   
   2. Secondary bonds: polypeptide chains may form a helixes of B pleated sheets. Stabilised by hydrogen bonds.
   3. Tertiary: polypeptides fold, forming specific shapes. Stabilised by hydrogen bonds: disulphide bridges; hydrophobic interactions. This can be the final shape or they can again further interact with other subunits and form a more complex protein structure
   4. Quaternary: two or more polypeptides assemble to form larger protein molecules. Stabilised by hydrogen bonds, disulfide bridges, hydrophobic interactions, ionic bonds.

Question 5

protein denaturation

Answer 5

Because proteins are so specific, they can be changed very easily, and it may not be able to form interactions at all or not with its desired substrate. This is through disruption or alteration of its side chains

It can be denatured by:
- High temperature: too excited and move apart
- pH: alter the charge on the R groups and therefore can change what the protein can interact
- High concentrations of polar molecules: can interfere with the proteins ability to make dipole-dipole bonds and hydrogen bonds with its substrate
- Non polar substances, via hydrophobic interactions: it can deactivate the protein through hydrophobic interactions by the presence of high concentration of a non-polar substance

Question 6

what is an alpha helix

Answer 6

• Right handed coil that turns in the same clockwise direction as a standard wood screw
  
  • The R group extend outwards form the peptide backbone of the helix
  • The coiling results from hydrogen bonds that form between the partial positive charge of the hydrogen in NH of one amino acid, and the partial negative charge of the oxygen in the C=O of another.
  • When this pattern of hydrogen bonding is establishes repeatedly over a segment of the protein, it establishes a coil
  • The right handed helix coils in the direction of the fingers in a right hand when the thumb points upwards (anticlockwise)

Question 7

what is a beta pleated sheet?

Answer 7

• Two or more polypeptide chains that are almost completely extended and aligned side by side
  
  • Stabilised by hydrogen bonds between the hydrogen bonds that form between the partial positive charge of the hydrogen in NH of one amino acid, and the partial negative charge of the oxygen in the C=O of another.
  • May form between separate polypeptide chains or between different regions of a single polypeptide chain that is bent back on itself

Question 8

what 2 factors contribute to protein function?

Answer 8

• Shape
  ○ A given molecule will not bind to a protein unless there is a general ‘fit’ between their three dimensional shapes
  ○ They are complementary in shape
  
  • Chemistry
    ○ Exposed R groups on the surface permit chemical interactions with other substances
    ○ Including
    § Ionic
    § Hydrophobic
    § Hydrogen bonding

Question 9

what are molecular chaperones?

Answer 9

• Chaperones
  ○ Protect 3D shape of proteins
  Chaperone proteins surround denatured proteins and prevent them from binding to the wrong substances