Proteins and Enzymes Flashcards
What is a protein?
A polymer made up of many amino acids joined by peptide bonds
What is an amino acid?
The monomers from which proteins are made
What is the generic structure of an amino acid?
- An amine Group (NH2)
- A Carboxyl group
- A Hydrogen
- An R Group
What is primary structure?
The sequence of amino acids in the polypeptide chain
What is secondary structure?
The long chains of amino acids fold into regions (within the tertiary structure) with repeating patterns
What is tertiary structure?
The final 3d resting shape of the protein
What is quaternary structure?
The final 3D resting shape of a protein made from more than one polypeptide chain
What is an enzyme?
Biological catalysts that increase the rate of reaction by lowering the activation energy
What is an active site?
The region of an enzyme where a complementary substrate can bind to form an enzyme-substrate compex
What is a metabolic pathway?
A series of enzyme catalysed reactions where the product of one reaction is the reactant in the next reaction
What is the lock and key model?
- Shape of the active site is fixed to a specific shape
- Active site is complementary to the substrate before, during and after it forms an enzyme substrate complex
What is the induced fit theory?
- Active site and substrate are not complementary before the enzyme-substrate complex is formed
- Active site changes shape to fit more closely around the substrate to become complementary
- Forming an enzyme substrate complex strains the bonds in the substrate causing them to form or break
What are some factors that effect enzyme catalysed reactions?
- Temperature
- p.H (acidity)
- Enzyme concentration
- Substrate Concentration
- Inhibitors
What does denatured mean?
A permanent change to the active site which means no more E-S complexes are formed
How does temperature effect enzyme catalysed reactions?
- As temp increases the molecules vibrate more
- more collisions
- higher %change of collisions
-More E-S complexes formed - At the optimum temperature/higher
- molecules vibrate and break internal bonds (ionic and disulphide bridges)
- Changes the shape of the active site
-No E-S complexes formed as enzymes are denatured
How does pH affect enzyme activity?
- The OH- or H+ will interact with the Hydrogen bonds or ionic bonds
- Changes the shape of the tertiary structure
- Changes the shape of the active site
- Fewer/No E-S complexes are formed
- The enzyme is denatured
What happens to enzyme catalysed reactions as enzyme concentration increases?
- The rate increases in a positive correlation
- As there are more successful collisions
- More enzyme-substrate complexes form
What happens as substrate concentration increases?
- The R.o.R increases in a positive correlation
- More successful collisions between enzyme and substrate
- More enzyme substrate complexes are formed, until all active sites are occupied
-the enzyme conc is now the limiting factor
How do competitive inhibitors work?
- Competitive inhibitors are of a similar shape to the substrate
- They can also bind to the active site which prevents the formation of E-S complexes
How do non-competitive inhibitors work?
- Non-Competitive inhibitors bind to another region of the enzyme other than the active site
- This changes the shape of the Active SIte
- No more E-S complexes are formed
- Changing the concentration of substrate wont make any difference
