Photosynthesis


Respiration


Enzyme Action

At the Gene Technology Access Centre on Monday we spent the day learning about the structure and function of enzymes. As well as a lecture and practical experiment, we had the opportunity to use a computer program for protein modelling. GTAC has some great online resources for teaching and learning, including this slideshow about Enzyme Action.
Enzymes have specific characteristics:
  • enzymes are proteins, made up of amino acids
  • enzymes have specific primary, secondary and tertiary structures
  • enzymes are specific to substrates
  • enzymes are biological catalysts (they speed up a reaction)
  • enzymes have optimum temperature and pH ranges
  • enzymes are not used up in a reaction
  • enzymes have an active site, which is where the substrate is broken down or the products are made
  • enzymes can contain co-factors (ions, such as chlorine or calcium) that assist to attract the reactants to the active site.

We worked with amylase, an enzyme that breaks starch down into disaccharides. We used iodine to indicate the presence of starch and a photo spectrometer to measure the degree of staining of the medium. The higher the photo spectrometer reading, the more starch, which meant the less enzyme action. We stopped the reaction using an acid, which denatures the enzyme and prevents the break down of starch. Our results showed that the optimum temperature of amylase activity was about 40 degrees and the optimum pH was 6. This is what you might expect from human amylase, which would be working at normal body temperature (37 degrees) and neutral (or slightly acidic) pH in the mouth.

Apoptosis

“Apoptosis is a process where a cell is degraded in order for it to be ultimately engulfed and recycled. Apoptosis can occur when a cell has become mutated and is on the verge of becoming a cancer. Apoptosis is also the reason why we don’t have webbed hands and feet. What basically happens is that the killer “t” cell communicates with the diseased cell by adhering to it by binding its death ligand to the death receptor on the diseased cell. This causes adapter proteins to attach to the cytosolic side of the receptor. This leads to a signal cascade which involves the recruitment of various other proteins and ultimately results in the death of the cell.” ~ bowlerdude on YouTube.

  1. What is the difference between apoptosis and necrosis?
  2. What is the difference between apoptosis and autophagy?