Ch9: Enzymes Flashcards
(25 cards)
What is metabolism?
The sum of all the chemical reactions in the body
What is cellular energy?
Energy stored in the bonds of biomolecules
What is a catalyst?
A substance that speeds up a chemical reaction without being used up itself
What is an enzyme?
A protein that speeds up a reaction without being used up (biological catalyst)
What are the features of an enzyme?
-Made of protein
-Folded into a 3D shape
-Enzyme reactions are reversible
-Enzymes are specific
-End in ‘ase’
What is a substrate?
What is a product?
The substance that the enzyme acts on
The substance that the enzyme forms
How do enzymes affect the activation energy of a chemical reaction?
They lower activation energy
What is the active site?
The part of an enzyme that combines with the substrate
Features of the active site
-Active site is usually larger than its substrate
-Each active site is specific to a particular substance
Explain the induced fit model
- Substrate combines with the active site of the enzyme
- Substrate causes the active site to change its shape slightly
- The substrate bonds to the enzyme to form the enzyme-substrate complex
- Products leave active site
- Active site returns to its original shape and can accept new substrate molecule
What is enzyme specificity?
Each enzyme will react with only one particular substrate
Name the factors that affect enzyme activity
Temperature
pH
Explain how temperature affects enzyme activity
-Enzymes do not wrk below 0 degrees bc the water in the cell freezes
-As temperatures increase, the movement of molecules increase and substrates will collide with enzymes more often
-Enzyme activity increases to a certain temperature
-At higher temperatures the enzyme becomes denatured (above 40 degrees)
What is a denatured enzyme
Explain
One that has lost its shape and can no longer function
-Caused by high temperatures, certain pH values and some chemicals
-When enzymes are denatured, the substrate can no longer fit into the active site
-permanent
How does pH affect enzyme activity?
-Enzymes only work over a very narrow pH range
-Optimum pH is 7, works around 6-8 as well
-Outside of this range = denatured
-Pepsin in the stomach works best at pH 2
What is a catabolic enzyme? Examples?
—-
-Amylase in saliva and pancreas convert starch to maltose
-Lipase in pancreas breaks down fats
What are anabolic enzymes? Examples?
—-
-DNA ligase is used in genetic engineering to join DNA molecules together
-DNA polymerase is an enzyme in plants and animals that repairs DNA
-Enzymes involved in photosynthesis convert water and CO2 into glucose
What is bioprocessing? Examples of what it produces?
The use of enzyme-controlled reactions to produce a product
-Drugs, vaccines, vitamins, food colourings, enzymes and perfumes
What is a bioreactor?
A vessel in which living cells or their products are used to make a product
Name the parts of a bioreactor
Motor
Exhaust air filter
Impeller
Air inlet
Sparger
Baffles
Water inlet
Cooling jacket
What is an immobilised enzyme?
Enzymes that are attached to to each other or to an inert material
Name and explain the physical methods of immobilising an enzyme
-Adsorption: enz. Physically attached to supports such as glass beads
-Enclosed by a membrane
-Trapped in a gel: sodium alginate is used to allow substrates in and products out, while the enz. remains trapped
Name and explain the chemical methods of immobilising enzymes
-Bonded to a support: glass beads containers
-Bonded to each other
What are the advantages of immobilised enzymes?
-Can be reused (cheaper production process)
-they remain in the vessel and dont need to be separated from the product
-It increases the stability of the enzyme
