Chapter 4-Enzymes

Question 1

Enzymes

Answer 1

➼ speed up rate of reaction
➼ lowers activation energy 
➼ biological catalyst
➼ catalyse metabolic reactions
➼ intracellular and extracellular

Question 2

Catalse

Answer 2

➼ intracellular example
➼ hydrogen peroxide is the toxic by-product of several cellular reactions
➼ if left to build up, it can kill cells
➼ works inside cells to catalyse the breakdown of hydrogen peroxide to harmless oxygen and water

Question 3

Amylase and Tripsin

Answer 3

➼ extracellular example
➼ work outside cells in digestive system
➼ amylase is found in saliva - secreted in the mouth by cells in the salivary glands
-catalyses the hydrolysis of starch into maltose in the mouth
➼ trypsin catalyses the hydrolysis of peptide bonds - turning big polypeptides into smaller ones
-produced by cells in pancreas and secreted into the small intestine

Question 4

Formation of enzyme-substrate complex lowers activation energy

Answer 4

➼ if the enzyme is catalysing a breakdown reaction, fitting into active site puts a strain on bonds in the substrate
➼ substrate molecule breaks up more easily

Question 5

Lock and Key Model

Answer 5

➼ enzyme-substrate complex -> enzyme-product complex -> products are released

Question 6

Induced Fit Model

Answer 6

➼ as substrate binds to enzyme, the active site changes shape slightly to fit the substrate more closely-> enzyme-substrate complex -> enzyme-product complex-> release products

Question 7

Factors affecting enzyme activity

Answer 7

➼ temp
➼ pH
➼ substrate conc
➼ enzyme conc

Question 8

High temp

Answer 8

➼ more KE
➼ more successful collisions between the substrate and active site
➼ more successful formation of enzyme-substrate complex
➼ vibration breaks some of the bonds
➼ active site changes shape
➼ enzyme denatures