2.1.4: enzymes Flashcards
what is an active site?
indents on the surface of an enzyme with a shape that is complementary to the shape of a substrate, meaning only the substrate will fit
what is a catalyst?
chemical that speeds up the rate of reaction by lowering the activation energy by providing an alternative pathway without being used up (reusable)
what is the difference between extracellular and intracellular?
extracellular = outside the cell
intracellular = inside the cell
what does metabolic/metabolism mean?
the chemical reactions that take place outside living cells or organisms
what is a substrate?
molecule that is altered by an enzyme-catalysed reaction
what is meant by the term “turnover number”?
number of substrate molecules converted into products per second
what are the advantages of enzymes compare to chemical catalysts?
- work at lower temperatures
- more specific
- function well in conditions that sustain life
what proteins are enzymes made from?
tertiary and quaternary structure
how do enzymes and substrates collide?
randomly due to kinetic energy
how does and enzyme catalyse (equation)?
enzymes + substrate > enzyme-substrate complex > enzyme-product complex > enzyme + product
what energy can be provided to activate a chemical reaction?
heat which would increase the kinetic energy, making the more likely to collide
why can’t increasing temperature be used in cells to provide activation energy?
will cause proteins to denature and lipid structure in membranes to fall apart
what type of reaction allows 2 substrates to bond and what reaction occurs when the substrate needs to break down into 2 products?
anabolic reaction and catabolic reaction
what is an example of an intracellular enzyme and what are the products?
catalase that breaks down hydrogen monoxide producing 2 water molecules and an oxygen molecule
what is the turnover number for hydrogen peroxide?
6 million
what is an example of an extracellular enzyme?
- digestive enzymes i.e. amylase
- decomposing enzymes i.e. bacteria
what is the lock-and-key theory?
the enzyme active site has a fixed rigid shape. a substrate with a complementary shape into the active site
what is the induced fit model?
the active site and the substrate shapes don’t fit together at the start but when the substrate comes near the active site triggers a slight change in shape, allowing the substrate to fit
what are 6 factors that affect the rate of enzyme activity?
- temperature changes
- water availability
- ph changes
- substrate concentration
- enzyme concentration
- inhibitors
how does temperature affect enzyme activity?
- temperature increases = rate of enzyme reaction increases
- there is more kinetic energy for successful collisions
- at the optimum temperature the enzyme works the best
- after the optimum, the rate decreases because the enzymes slowly begin to denature
how does temperature denature enzymes?
it causes the bonds in the tertiary structure to break, changing the shape of the active site
how does ph affect enzyme activity?
- ph increases = rate increases until the optimum ph is reached (when the enzyme works best)
- when the ph increases further, the enzymes will slowly denature
- rate will decrease
how does ph denature enzymes?
the more hydrogen ions present (low ph), the less the r-groups in the enzyme are able to interact with each other and the bonds will break, causing the active site to change shape
