Metabolic Pathways

• what is a metabolic pathway

  • series of biochemical reactions that occur within a cell
• what are metabolic pathways controlled by

  • presence or absence of biochemical catalysts (enzymes)
• to control rate it must have...

  • reversible steps, irreversible steps and alternative routes
• why do we need those to control rate

  • to hep conserve cell resources and avoid overproduction of particular product
• what does a reversible step do

  • prevents overproduction of an end product
• what does irreversible steps do

  • make sure enough of the final product is produced
• why are alternative routes used

  • used if a reversible step and a large supply of a particular metabolite or if normal pathway is blocked
• what do anabolic pathways do

  • take small, simple molecules and building them up (synthesis) into large, complex molecules
• what do anabolic pathways require

  • energy (ATP)
• what do catabolic pathways do

  • take large, complex molecules and break them down (degradation) into small, simple molecules
• what do catabolic pathways release

  • energy (ATP)
• what are enzyme properties

  • biological catalysts that speed up chemical reactions, remaining unchanged after a reaction
• enzyme properties - what does it mean

  • enzyme doesn't get used up
• enzyme properties - made of...

  • proteins
• energy needed to start a reaction...

  • activation energy
• what happens to enzymes when using activation energy

  • enzymes lower activation energy, easier for reaction to happen. Speeds up chemical reactions.
• what is an active site

  • shape is determined by amino acids and complimentary to a specific substrate
• why does active site and substrate bind

  • substrate has a high affinity to enzymes active site (attracted to it)
• what happens when enzyme builds up/breaks down substrate to make products

  • active site of enzyme releases the products
• why does enzyme active site release products

  • now has low affinity to active site as it has chemically changed
• Induced Fit - features (shape)

  • returns back to original shape when products are released
• Induced Fit - features (active site)

  • flexible and moulds around substrate to fit it better to carry out a reaction
• Lock and Key - feature (active site)

  • active site is rigid, keeping its shape
• rate of enzyme activity is affected by:

  • temperature, pH concentration, substrate concentration, product concentration
• Temperature - enzyme activity

  • starts to decrease as enzyme too high a temperature and denatures
• Temperature - active site and substrate

  • active site is damaged due to high temperature and substrate is no longer complimentary as the shape has changed. No reactions can happen.
• Temperature - low temperature and enzyme activity

  • enzyme activity is low at low temperature
• Temperature - optimum temperatures

  • enzymes work best at optimum temperature. Different enzymes have different optimum temperatures.
• pH concentration - enzyme activity rate

  • starts to decrease if pH concentration is too low/high as it causes the enzyme to denature
• pH concentration - active site of enzyme and substrate

  • damaged due to high temperatures and the substrate is no longer complimentary as shape has changed. No reactions can happen.
• pH concentration - fastest reaction rate at...

  • optimum pH
• pH concentration - different enzymes...

  • have different optimum pH concentrations
• Substrate concentration - active site and substrate

  • lower the substrate concentration the lower the chance of substrate binding with an enzyme as there is not enough substrate molecules prese
• Substrate concentration - active site and substrate (why)

  • as there is not enough substrate molecules present to bind with all of active sites on enzyme
• Substrate concentration - the higher the substrate conc...

  • the higher the chance of a substrate binding with an enzyme
• Substrate concentration - the higher the substrate conc... (why)

  • more active sites have substrate molecules to bind with
• Substrate concentration - enzyme active sites occupied

  • any further increase in substrate concentration fails to make reaction any faster and causes graph to level off
• Product concentration - high can cause...

  • enzyme reaction rate to slow down as reversible reactions convert products back to previous intermediate to prevent over production
• Product concentration - high can slow down...

  • rate of enzyme reactions as products occupy active sites instead of substrate
• Product concentration - high can slow down (results)

  • substrates aren't being binding for a reaction to take place