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level: 2.5 Enzymes

Questions and Answers List

level questions: 2.5 Enzymes

QuestionAnswer
What is an enzyme? (5)globular protein acts as a biological catalyst by speeding up the rate of a chemical reaction = Enzyme catalysis Are not changed / consumed = reused named after the molecule it reacts with (substrate) ends with -ase eg: lipids broken down by lipase
What is a substrate?the molecules which enzymes react with
What is the active site on enzymes? (2)region on the enzyme which binds to the substrate molecule with high specificity shape and chemical properties depends on the tertiary structure of the enzyme
Why are there specific substrates for a particular enzyme's active site?because the active site and the substrate complement each other in terms of shape and chemical properties
Where do enzyme reactions take place?in aqueous solutions (eg: cytoplasm)
Describe the movement of enzyme reactions? (2 diff explan)the substrate and enzyme move randomly within the solution (Brownian motion) sometimes the enzyme can be fixed (membrane bound) to localize reactions to particular sites
What does enzyme catalysis require? (3)substrate needs to be close to the active site to bind with it to form an enzyme-substrate complex enzyme catalyses the conversion of substrate = produce = enzyme product complex enzyme and product dissociates = enzyme continues catalysing reactions
What happens after enzyme catalysis?enzyme and product dissociate - enzyme isn't consumed = continues to catalyse further reactions
How can the rate of enzyme catalysis be increased? (3)by increasing the frequency of collisions by: increasing the molecular motion of the particles (by thermal energy = increased kinetic energy) increasing the conc of particles (substrate/ enzyme)
What can denature enzymes? (3)high temperatures and extreme pH breaks the chemical bonds needed to maintain the tertiary structure of the enzyme = denaturation decreases the enzymes ability to bind to the substrate
How does diff temperature affect enzyme activity? (4)Low temp: not enough thermal E to activate an enzyme catalyzed reaction. High temp: increases speed + motion of enzyme and substrate = higher enzyme activity bec of more frequent collisions Optimal: enzyme activity at its peak Too high Temp: enzyme stability decreases, thermal E disrupts the H bonds in enzyme = lose its shape = denaturation
How can different factors affect an enzyme's activity? (2)affect frequency of enzyme-substrate collisions denaturation = affects how well the enzyme and substrate interacts
How does pH affect enzyme activity?changing pH changes the enzyme's charge = changes solubility and shape changing shape / charge of active site reduces ability to bind to substrate
How does substrate conc affect enzyme activity? (2)increasing conc increases activity bec higher chance of the enzyme and substrate colliding after a certain point the activity rate will stop rising because the environment is saturated with substrate and all the enzymes are bound and reacting
What to include when testing for the effect of temp, pH and substrate conc on enzyme activity?independent variable = temp (water baths) , pH (acidic/ alkaline solutions), substrate concentrations Enzyme/ substrate being used = pepsin, protein - short polypeptides How to measure enzyme activity = colour change (biuret's test)
What are immobilized enzymes?They are fixed to a static surface to improve the efficiency of a catalyzed reaction bec fixed = enzyme concs easily conserved separation of the product is easier to achieve = higher yield
Where are immobilized enzymes used ( 3 examples)Biofuels = enzymes are used to break down carbs = produces ethanol based fuels Medicine = Enzymes used to identify diseases and pregnancy Food production = Enzymes used in production + refinements of beers and dairy products
How is lactose free milk produced?lactase is purified from yeast / bacteria and bound to an still substance (eg: alginate beads) Milk is passed over the beads and becomes lactose free
What is lactose?it is a disaccharide of glucose + galactose which can be broken down by the enzyme lactase
What are the advantages of lactose free milk?source of dairy for lactose intolerant people increasing sequence without artificial sweeteners (monosachs are sweeter) reducing crystallization of ice creams (monosachs are more soluble = less likely to crystallize) reducing production time for cheeses and yoghurts (mono is fermented more easily)