Enzymes And Biological Reactions Flashcards
Enzymes structure
Globular proteins, tertiary structure
Structure bonds in enzymes
Hydrogen, Ionic, Disulphide
Functions of enzymes
Biological catalysts- speed up rate of reaction. Reusable (unchanged). Specific
Name the model where the substrate is complementary to the active site
Lock and key model
Name the model where the substrate doesn’t fit the active site
Induced fit model. Enzymes slightly alters shape of active site putting strain on the bonds wearing and lowering the EA of the reaction
What is activation energy? How do enzymes affect it?
Energy needed for a reaction to take place. Enzymes lower the AE- less energy needed to react.
What is the turnover number?
The max. number of molecules of substrate that can be converted to product per unit time
5 factors that affect enzyme activity
1) pH 2) temperature 3) substrate conc. 4) enzyme conc. 5) presence of inhibitors
What is an anabolic reaction?
small+small=large molecule (condensation reactions- producing larger molecules)
What is a Catabolic reaction?
Breaking down of larger molecules to smaller ones
What are intracellular enzymes?
Inside the cell (e.g. breakdown of glucose to ATP)
What are extracellular enzymes?
Released to work outside the cell (e.g. digestive enzymes)
3 ways to measure enzyme activity
1) time taken for reaction. 2) rate of reaction (1/time). 3) concentration of products formed
How do you plot a graph (axis)?
x axis= whatever you CHANGED. y axis= whatever you MEASURED
How does temperature effect enzyme conc?
Increased temp= more KE= more successful collision= more ESC. Above optimum= denatured (bonds broken, shape altered)
How does pH effect enzyme conc?
Optimum= charge of active site complimentary to charge of substrate. Small change= R groups repel= less ESC (can be reversed). Extreme change= denatured. pH buffers neutralise pH
How does changing substrate conc. effect enzyme conc?
No. of ESC increases with substrate conc. More KE= more collisions. Levels off as active sites fill (enzyme conc= limiting)
How does changing enzyme conc. effect enzyme conc?
Increased enzyme conc= increased RoR- excess of substrate so always collisions and ESC
Source of industrial enzymes
Obtained from microorganisms e.g. fungi & bacteria. Grown in fermenters, reproduce rapidly, produce enzymes as part of usual metabolic activity
What is an immobilized enzyme?
When an enzyme us fixed to an inert, insoluble matrix
Four methods of immobilization
1) enzyme inclusion 2) cross linked enzyme 3) carrier bound enzyme 4) microcapsule
Method: enzyme inclusion
entrapment in a cellulose mesh
Method: cross linked enzyme
chemically bonded cross linked by glutaraldehyde
Method: carrier bound enzyme
Adsorption onto inert material e.g. glass beads/ clay particles
Method: microcapsule
encapsulation in alginate beads
5 advantages of immobilized enzymes
1) reusable- lower costs. 2) not contaminated. 3) microenvironment means more stability at higher temps/ pH. 4) continuous. 5) several enzymes at once
5 disadvantages of using immobilized enzymes
1) enzyme can detach and contaminate. 2) takes time to diffuse through gel. 3) gel can alter active site shape. 4) expensive and complex. 5) contamination is expensive
How does a competitive inhibitor work?
similar shape to active site- blocks substrate. reversed by increasing substrate conc
How does an non-competitive inhibitor work?
DO NOT COMPETE FOR ACTIVE SITE. attach to allosteric site and distort shape of active site
How are biosensors used?
medical diagnosis. detect specific molecule in a mixture (immobilized enzymes) works as enzymes are specific
