proteins
- Created by: Margaret Hobart
- Created on: 21-04-21 10:38
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- Proteins
- monomers
- amino acids (AA)
- amine group (NH2) and carboxylic acid (CCOH)
- there are 20 AAs in living organisms (R group differs)
- condensationreaction between AA form a peptide bond and a water molecule is released
- dipeptide ->2 AA
- polypeptide -> 3 or more AA
- amine group (NH2) and carboxylic acid (CCOH)
- amino acids (AA)
- structure and folding
- primary structure
- sequence of AAs determine where bonds Form and hence 3D structure
- type of AAs in the polypeptide chain
- secondary structure
- hydrogen bonds between AAs
- this makes it coil into an alpha helix or fold into a beta pleated sheet
- hydrogen bonds between AAs
- tertiary structure
- more H and ionic bonds form between different parts of polypeptide chain
- disulphide bridges between two molecules of cysteine
- forms 3D structure for single polypeptide chain proteins
- quaternary structure
- multiple polypeptide chains link together e.g. haemoglobin
- structure determines function
- enzymes
- tight folding of polypeptide chain makes them spherical
- biological catalysts
- lower activation energy of reaction
- tertiary structure determines active site
- enzyme-substrate complex
- substrate shape is complementary to active site
- lock and key theory
- induced fit model
- the substrate makes the active site change shape slightly
- substrate shape is complementary to active site
- enzyme-substrate complex
- factors affecting reactions
- temperature: too high and it denatures(enzymes vibrate more), too slow and reaction is too slow
- pH: above and below optimum the H+ and OH- ions mess up ionic and H bonds that hold tertiary shape. it denatures
- enzyme and substrate concentration
- competitive and non-competitive inhibitors
- antibodies
- two short polypeptide and two long chains bonded together
- transport proteins
- channel proteins in cell membranes contain hydrophobic and hydrophilic AAs which cause protein to fold up and form a channel
- tertiary structure determines active site
- enzyme-substrate complex
- substrate shape is complementary to active site
- lock and key theory
- induced fit model
- the substrate makes the active site change shape slightly
- substrate shape is complementary to active site
- enzyme-substrate complex
- enzymes
- primary structure
- enzymes
- tight folding of polypeptide chain makes them spherical
- biological catalysts
- lower activation energy of reaction
- factors affecting reactions
- temperature: too high and it denatures(enzymes vibrate more), too slow and reaction is too slow
- pH: above and below optimum the H+ and OH- ions mess up ionic and H bonds that hold tertiary shape. it denatures
- enzyme and substrate concentration
- competitive and non-competitive inhibitors
- Biuret test
- sodium hydroxide and copper sulphate
- positive:lilac negative:blue
- sodium hydroxide and copper sulphate
- monomers
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