✨Module 2: Enzymes Flashcards
What are anabolic reactions?
Building bigger molecules from smaller molecules. Anabolic reactions are typically endothermic, requiring energy input.
What are catabolic reactions?
Breaking large molecules into smaller molecules. Catabolic reactions are usually exothermic, releasing energy.
What is metabolism?
All the chemical reactions inside a cell. Metabolism encompasses both anabolic and catabolic processes.
What are intracellular enzymes with examples?
Enzymes that act within cells. DNA and RNA polymerase, catalase.
What are extracellular enzymes?
Enzymes released from cells to break down large nutrient molecules into smaller molecules so it can be absorbed. They work outside the cell that has made them.
Name two extracellular enzymes found in the digestive system.
Pepsin - protease found in the stomach and breaks down proteins into amino acids that can be absorbed into the small intestine.
Amylase - found in saliva and catalyses the hydrolysis of starch into maltose. Maltase then functions. Glucose is small enough to be absorbed by cells lining the digestive system and absorbed into the bloodstream.
True or False: Single-celled organisms and fungi rely on extracellular enzymes to digest their food inside the cell.
False. They digest their food outside the cell using extracellular enzymes.
Why are enzymes important for life?
They speed up important chemical without damaging cells and without the use of heat.
Define enzyme.
Biological catalyst that speeds up chemical reactions without being used up itself.
The 3D shape of enzymes is due to the …
Interactions between R-groups of amino acids that make up protein. Ionic bonds, covalent, hydrophilic/hydrophobic interactions.
Active site is …
Complementary to the substrate.
What is the induced fit model for how an enzyme actually works?
Active site forms a complementary shape AFTER binding. R-groups of amino acids in active site interact with substrate, putting strain on the bonds in substrate and therefore lowering activation energy.
How does temperature affect enzyme activity?
-> Up to optimum, enzymes and substrates gain KE so move around more. So greater chance of more successful collisions per unit time, so more ESC’s formed. Increases rate of reaction.
-> After optimum, the extra KE breaks bonds in the tertiary structure of enzyme (hydrogen bonds first). Active site changes shape and the enzyme denatures. Less ESC’s formed as the active site no longer has a complementary shape to the substrate.
How does pH affect enzyme activity?
-> As pH moves away from optimum, change in ratio of H+ and OH- interferes with hydrogen and ionic bonds so they break.
-> Active site changes shape and enzyme denatures no longer complementary to substrate. Less ESC’s form so rate of reaction decreases.
-> The more hydrogen ions present (more acidic), the less the R-groups are able to interact with each other. this leads to bond breaking and changing enzyme shape. The reverse is also true.
How does substrate conc affect enzyme activity?
-> As substrate molecules increase, higher probability that substrates collide with enzyme to form ESC’s. The enzyme is in excess at this point.
-> Graph straightens out as all active sites are used up. Enzyme concentration is now acting as a limiting factor.
-> It reaches the Vmax point where all active sites are occupied by substrate molecules so no more ESC’s can form until products are released. The only way to increase the rate of reaction would be to add more enzyme or increase the temp.
