module 2 - 2.1.4 - enzymes Flashcards
(39 cards)
What are enzymes?
-globular proteins
-interact with substrates to make te reaction happen faster
meaning of activation energy?
the amount of energy needed to start a reaction
meaning of active site?
an area in the tertiary structure that has a specific shape that is complementary to the substrate.
What is the lock and key hypothesis?
1.only the specific substrate will fit into the complementary active site
2.this forms an enzyme-substrate complex
3.the substrate then reacts and forms products making a enzyme-product complex
4,products are then released leaving the enzyme unchanged
How does the enzyme hold the substrate to increase the rate of reaction?
- held so the right atom groups are close enough to react
-R groups of the active site will interact with the substrate forming temporary bonds
What is the induced fit hypothesis?
1, substrate enters active site with a weak interaction
2, forms an enzyme substrate complex
3,the weak interactions cause a change in the tertiary structure of the enzyme , this puts a strain on the substrates
4,this lowers the activation energy and products are released
How do enzymes increase the rate of reaction?
they lower the activation energy
What are intracellular enzymes?
enzymes that work in the cell
Two examples of intracellular enzymes?
- lactase= breaks down lactose into glucose and galactose
2.catalase= breaks hydrogen peroxide down into water and oxygen = found in plants and humans
Extracellular enzymes?
enzymes that work outside the cell that made them
Why are extracellular enzymes needed?
nutrients needs to enter cells but are too large so need to be broken down.
enzymes are released from the cell to break the nutrients down
Examples of extracellular enzymes?
- amylase= secreted by salivary glands, catalyses the hydrolysis of starch into maltose
2.tryspin
Factors that impact enzymes?
- temperature
2.PH
3.enzyme concentration - substrate concentration
What happens to the rate of reaction with enzymes when the temperature increases?
1,increases the kinetic energy of the particles
2,this makes the particles move more and collide more often
3,this will mean there are more successful collisions of substrates and enzymes
4,= an increased rate of reaction
What does temperature coefficient Q10 mean?
a measure of how much the rate of reaction increases with a 10 degree raise in temperature
What is denaturing?
1,at a high temp the bonds holding the protein (enzyme) together vibrate more
2,as the temp increases the bonds strain and eventually break
3, the breaking of the bonds change the shape of the tertiary structure
4,it is then denatured
optimum temperature meaning?
the temperature where the enzyme has the highest rate of reaction
after the optimum temp enzyme denatures and rate of reaction decreases rapidly
What are enzymes like that are meant to be in cold temps?
- have more flexible structures
= less stable
-small temp changes can denature them
What are enzymes like that are meant to be in hot temps?
=more stable
=more resistant to change of temps so less likely to denature
What happens to the enzyme when the PH is not at the optimum?
active site is likely to change shape
=reduces rate of reaction
What happens to rate of reaction if the conc of substrates or enzymes increases?
more successful collisions between the active sites and substrates so increase of rate of reaction
What is the role of inhibitors?
To slow down a reaction so excess product is not made
What are the two types of inhibitors?
1.competitive
2. non-competitive
How does competitive inhibition work?
1.a similar shaped molecule to the active sire can fit into the active site
2.blocks the substrate from attaching to the active site
3.enzyme can not catalyse
4.substrates and inhibitors compete for the active site
5.reduce amount of substrates attaching to the active sire
=decrease in rate of reaction
