Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
MBH - Enzymes
OCR A level Biology F212
| Question | Answer |
|---|---|
| What are enzymes? | Biological catalysts. |
| What do enzymes do? | Catalyse metabolic reactions in the body, like digestion and respiration. |
| Where are enzymes? | Extracellular and intracellular. |
| What type of proteins are enzymes? | Globular proteins. |
| Where does the substrate bind to on an enzyme? | The active site with a specific shape. |
| What is the specific shape of the active site determined by? | The enzyme’s tertiary structure. |
| What has to be the case for the enzyme to work? | Substrate and active site must have complementary shapes. |
| How do enzymes speed the rate of reaction? | Reduce the activation energy needed for a reaction. |
| What happens in a reaction catalysed by an enzyme? | Substances bind to the enzyme, forming an enzyme-substrate complex. |
| Why does this speed the rate of reaction in a reaction where substrates are being joined? | If substrates are being joined, attaching to the enzyme holds substrate molecules closer, reduces repulsion between them and allows them to bond more easily. |
| Why does this speed the rate of a breakdown reaction? | In a breakdown reaction, active site puts a strain on bonds in substrate – break up more easily. |
| What is the induced fit theory? | The substrate doesn’t just have to be the right shape to fit the active site, it has to make the active site change shape the right way as well. |
| What evidence made scientists disregard the lock and key model? | As well as fitting together, the enzyme-substrate complex changed shape slightly to complete the fit, locking the substrate even more tightly to the enzyme. |
| How does higher temperature affect enzyme activity at first? | Makes particles vibrate more. |
| What happens if temperature is raised further? | Vibration causes some bonds to break, changing the shape of the active site so the enzyme and substrate no longer fit together. Enzyme is denatured – no longer works as a catalyst. |
| What happens above and below an enzyme’s optimum pH level? | H+ and OH- ions in acids and alkalis mess up ionic bonds and hydrogen bonds, altering the tertiary structure and causing active site to change shape and denaturing the enzyme. |
| How does increased enzyme concentration affect the rate of reaction? | The more enzyme molecules, the more chance of collision with substrate, the more E-S complexes, the faster reaction rate. Limiting factor: amount of substrate available. |
| How does increased substrate concentration affect the rate of reaction? | The more substrate molecules, the more chance of colliding with an enzyme, the more E-S complexes, the faster reaction rate. Limiting factor: amount of active sites (enzyme) available. |
| What are cofactors and coenzymes? | Non-protein substances which help some enzymes to work. |
| How do inorganic cofactors work? | By helping the enzyme and substrate bind together. Aren’t used up or changed in the reaction. |
| How do organic coenzymes work? | Participate in and are changed by the reaction – act as carriers, moving chemical groups between different enzymes, and are continually recycled during the reaction. |
| What happens when a competitive inhibitor is introduced? | Similar shape to substrate molecule, competes for active site, and blocks it. Amount of inhibition depends on relative concentration of inhibitor and substrate. |
| What happens when a non-competitive inhibitor is introduced? | Binds to enzyme in different place to active site. Causes active site to change shape so substrate molecules can’t bind to it. Don’t compete – changing relative concentrations will not make a difference. |
| What do metabolic poisons do? | Interfere with metabolic reactions (reactions that occur in cells), causing damage, illness or death, and are often enzyme inhibitors. |
| What is cyanide? | An irreversible inhibitor of cytochrome c oxidase, an enzyme that catalyses respiration reactions. Cells that can’t respire die. |
| What is maltonate? | Inhibits succinate dehydrogenase (which also catalyses respiration reactions). |
| What is arsenic? | Inhibits the action of pyruvate dehydrogenase, which also catalyses respiration reactions. |
| What do reverse transcriptase inhibitors do? | Inhibit the enzyme reverse transcriptase, which catalyses the replication of viral DNA, preventing the virus from replicating. |
| What does penicillin do? | Inhibits the enzyme transpeptidase. |
Created by:
emm142
Popular Biology sets