2.4 - Enzymes Flashcards
What are enzymes?
- Enzymes are biological catalysts
- They are proteins with a complicated tertiary/quaternary structure
- They work by lowering the activation energy for a reaction, this speeds it up
- They are not used up from this method
What is an example of an exothermic reaction that could be catalysed by enzymes?
- Enzymes can catalyse the reaction of reactants being turned into products
- This reaction releases energy so is exothermic and is catabolic as it is splitting the reactants into multiple products
- Enzymes can reduce the activation energy needed for the reaction, in turn speeding the reaction up, up to 10 to the power of 12 times
What are the two models for enzyme action?
- The lock and key model
- The induced fit model
What is the process of the lock and key model?
No change in shape
- Complimentary substrates bind to the enzymes active site
- This creates an enzyme-substrate complex
- The substrates are then released as the product and the enzyme is left unchanged
What is the process of the induced fit model?
Temporary change in shape
- Substrates bind to the enzymes active site, temporarily changing the shape of the active site to fit the substrates
- This creates an enzyme-substrate complex
- The substrates are then released as the product and the active site of the enzyme then returns to its original shape
What is meant when an enzyme is described as working intracellularly?
- When the enzyme works within the cell.
- For example: Catalase which takes H2O2 (Hydrogen peroxide) which is often made from respiration and must be broken down inside of the cell into H2O + O2 as it is toxic
What is meant when an enzyme is described as working extracellularly?
- When the enzyme works outside of the cell
- For example: Pepsin is a protease enzyme which works in the stomach outside of the cell for digestion
- Also fungi is extracellular as the mycelium grows and releases the enzyme outside of the cell which digests the material outside of the fungal hyphae and allows the fungi to absorb the nutrients back in
What are cofactors?
- Non proteins substances that must be present for some enzymes to work
- For example: Prosthetic groups & Co enzymes
How do prosthetic groups work to allow enzyme activity?
Prosthetic groups are permanently bound to the enzyme, For example: FAD
How do co enzymes work to allow enzyme activity?
Co enzymes are temporarily bound to the enzyme, often they are ions such as:
- Zn2+ for carbonic anhydrase
- Cl- for amylase
What is an anabolic reaction?
Joining things together
What is an catabolic reaction?
Splitting things apart
What do hydrogenase enzymes do?
Add hydorgen
What do decarboxylase enzymes do?
Take away carboxylic acid group or a Co2 molecule
What does peptidyl transferase do? (From translation)
Peptidyl transferase catalyses the addition of amino acids to the growing polypeptide chain in protein synthesis by building peptide bonds
What is the optimum temperature for enzymes?
37°C (Same as body temperature in humans)
What is an extremophile and how would their enzymes be adapted to suit their environment?
- An extremophile is a bacteria that lives in a bubbling hot spring
- The enzymes would be adapted to survive the hot temperatures
- This means the optimum temperatures for the enzymes inside the bacteria would be higher than the optimum temperature for normal enzymes (37°C)