ENZYME ACTION RG

• what are enzymes?

  biological catalysts
• what do enzymes do?

  speed up chemical reactions by acting as biological catalysts
• what is a catalyst?


  a substance that speeds up a chemical reaction without being used up in the reaction itself
• What is the function of enzymes?

  To catalyse metabolic reactions both at a cellular level (respiration) and for the organism as a whole (eg digestion)
• What can enzymes AFFECT?

  Structures in an organism as well as functions
• give an example of how enzymes can affect the structures in an organism?

  enzymes are involved in producing collagen - an important protein in the connective tissues of animas
• what can enzymes be?

  intracellular (within cells)

  OR

  extracellular (outside cells)
• Are enzymes fats, proteins, or lipids?

  proteins
• What do enzymes have?

  an active site , which has a specific shape/
• what is the active site?


  the part of the enzyme where the substrate molecules bind to
• what is the substrate?

  the substance that the enzyme interacts with
• Why are enzymes highly specific?

  due to their tertiary structure
• What do enzymes do?

  lower the activation energy of a reaction
• what is activation energy often provided as?

  heat
• how do enzymes speed up the rate of reaction?

  lower the amount of activation energy needed, often making reactions happen at a lower temperature than they could without an enzyme
• What is formed when a substrate fits into the enzyme's active site?

  an enzyme-substrate complex
• when is an enzyme-substrate complex formed?

  when a substrate fits into the enzyme's active site
• How do enzymes help reactions that need TWO SUBSTRATE MOLECULES to be JOINED?

  If 2 substrate molecules need to be joined, being attached to the enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily
• how do enzymes catalyse BREAKDOWN REACTIONS?


  if an enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate, so the substrate molecule breaks up more easily
• what did early scientists studying the action of enzymes come up with?

  the 'lock and key' model
• What is the lock and key model?

  where the substrate fits into the enzyme in the same way that a key fits into a lock
• what did new evidence show?

  the enzyme-substrate complex changed shape slightly to complete the fit

  • this locks the substrate even more tightly to the enzyme
• what did scientists modify and come up with?

  modified the old lock and key model and came up with the 'induced fit' model
• what does the induced fit model explain?

  Why enzymes are so specific and only bond to one particular substrate
• describe the induced fit?

  the substrate does not have to be the right shape to fit the active site, it has to make the active site change shape in the right way as well
• is the induced fit model still widely aceppted?


  yes
• (induced fit model) what happens as the substrate binds the active site changes shape slightly