Enzymes Flashcards
(17 cards)
What do enzymes do
Reduce the amount of energy needed to get a reaction going
What is activation energy
The minimum amount of energy required to get a reaction to start
What is the substrate
The molecule that the enzymes allows to react
What is produced at the end of the reaction
Products
What type of protein are enzymes
Globular protein
What is the active site
A dent in the 3d shape of the protein, the shape is very precise and is lined with r-groups of particular amino acids that make up the polypeptide chains
What is an enzymes-substrate complex
What is formed when an enzyme molecule slots into the active site and forms temporary bonds with the R groups
How does an enzyme cause a substrate to break apart
When the enzyme-substrate complex is formed the shape of the substrate molecule is changes which stresses the chemical bonds and lowers the activation energy needed for the substrate to break apart
What is the induced fit model
Means that the arrival of the substrate causes a small shape change in the enzymes active site, allowing the substrate to bind with it
How does temperature effect enzyme activity
The rate of enzyme activity normally increases as the temperature increases
Why does temperature effect enzyme activity
The molecules gain more kinetic energy, so move faster and therefore collide more frequently
How are enzymes denatured by temperature
The atoms within the enzyme molecules also gain energy and vibrate so rapidly that the weak hydrogen bonds maintaining the tertiary structure can break and the molecule can unravel. Any change in shape will inactivate the enzyme as their active site wont be able to fit the substrate any more
How does pH effect enzyme activity
Enzymes have an optimum pH, even small changes in pH will affect enzyme activity because they cause small changes in the active site
Why are enzymes denatures in strongly acidic or alkali solutions
The hydrogen or hydroxyl ions are attracted to the charges on the amino acids in the polypeptide chains that make up the enzyme. The hydroxyl and the hydrogen ions interact with the amino acids and disrupt the hydrogen bonds and ionic bonds that maintain the enzyme molecules 3d shape, destroying the active site- it cannot reform
Why does the curve level off in the graph of enzyme concentration against rate of reaction
At high enzyme concentration there may not be enough substrate molecules to keep them all busy all the time so the rate levels off
What are competitive inhibitors
Molecules with a very similar shape to the substrate can bind to the active site but with no reaction, this reduces the reaction rate but usually the inhibitor does not attach permanently or damage the site
What are non-competitive inhibitors
Substances that do not attach to the active site of an enzyme which alters the shape of the enzyme so the active site does not form, they can bind permanently or temporarily
