enzymes

Question 1

what are catalyst

Answer 1

It is a substance that speed up a chemical digestion, without itself being chemically changed at the end of the reaction

Question 2

what are enzymes

Answer 2

enzymes are proteins that function as a biological catalyst (produced by living cells) which speed up chemical reaction and chemically unchanged at the end

Question 3

why do we need enzymes

Answer 3

• food molecules may be too large for it to be diffused across the cell surface membrane (partially permeable membrane) thus they need to be digested into smaller, simpler molecules in order to do so
• to speed up digestion

Question 4

what are the examples of digestive enzymes and what do they digest

Answer 4

1. amylase- digest (break down) starch into maltose
2. maltase- digest maltose into glucose
3. protease- digest proteins to amino acid
4. lipase- digests fats into fatty acid and glycerol

Question 5

metabolism

Answer 5

the sum of all chemical reactions, consisting both catabolic and anabolic reactions

1. catabolic- breaking down reactions that split arge molecules into smaller ones
2. anabolic- building upp reactions which produces complex molecules from smaller ones

Question 6

what are the characeristics of enzymes

Answer 6

• each enzyme can only break down a specific substrate-> each enzyme has a specific active site.
• enzymes are required in minute(small) samounts as enzymes are chemically unchanged at the end of chemically reaction so they can always be reused
• enzymes speed up chemical reactions
• enzymes are affected by extreme temperatured and extreme pH values

Question 7

what is the lock and key

Answer 7

lock- enzyme

key- substrate

Question 8

describe the lock and key hypothesis

Answer 8

1. an enzyme has a specific 3-D shape that contains an active site
2. only the specific substrate with a specific 3-D shape complements to that of the active site can fit into the enzyme to form an enzyme-substrate complex
3. chemical reaction occurs and the substrate is converted into products
4. the products then detach from the active site, the enzyme remains chemically unchanged at the end of the reaction

Question 9

what is denaturation

Answer 9

since the specificity of an enzyme is due to active site, any factor that would cause the enzyme to alter its active site will affect its function. the permenant alteration of the active site is known as denaturation. The substrate can no longer fit into the enzyme’s active site (active site is lost). hence, no reaction can take place.

Question 10

what is denaturation caused by

Answer 10

denaturation can be cause by: 1. heat (extreme high temperatures) 2. drastic changes to pH due to chemicals such as acids and alkalis

Question 11

how does temperature affect rate of enzymatic activicty

Answer 11

0 degree-> there is a low energy of reaction-> enzyme inactive
0 degree to highest tempt (optimum temperature)-> increasing temperature increase rate of reaction. why? increase rate of enzyme substrate complex (increase substrate binds to enzyme active sites) as enzyme and substrate increases increase kinetic energy. increase in heat energy cause an increase in kinetic energy of enzyme and substrate which cause an increase in chances of collision between substrate and enzyme
optimum temperatue-> maximum rate of temperature
after optimm temperature-> loss of catalytic activity of enzyme, known as denaturation. why? enzyme denatured- active site of enzyme is lost- substrate cannot bind to enzyme’s active site- no chemical reaction

Question 12

how does temperature affect rate of enzymatic activicty

Answer 12

low temperature->enzyme inactive, kinetic energy is low. hence, chances of substrate molecules colliding with enzymes are very low-> low formatino of enzyme substrate complex-> low reaction rate
before optimum temperature-> increasing temperature, kinetic energy of molecules increases, hence, increases the chance of collision between substrate and enzyme-> increased rate of formation of ES complex-> higher reaction rate. As enzyme temperature increases, enzyme activity increases. why? increase rate of enzyme substrate complex (increase substrate binds to enzyme active sites) as enzyme and substrate increases, increase kinetic energy. Increase in heat energy causes an increase in kinetic energy of enzyme and substrate which cause an increase in chances of collision between substrate and enzyme.
optimum temperatue-> maximum rate of temperature-> rate of reaction is the highest and the enzyme is most active
after optimum temperature-> enzyme activity decreases. High temperature permernantly alters the active site of the enzyme-> the enzyme is now denatured-> cannot form any ES complex-> rate of reasction decreases. why? enzyme denatured-> active site of enzyme is lost-> substrate cannot bind to enzyme’s active site- >no chemical reaction

Question 13

how does pH affect rate of enzyme activity

Answer 13

• different enzymes have different optimum pH values, at which they are most active
• optimum pH- pH at which enzym works best at. example: pepsin, rennin function best at pH 1.5-2 while salivary amylase works best at pH 7.0
• extreme changes in pH denatures the enzyme because the active site is altered permenantly and cause it to lose its function-> cannot form any ES complex