enzymes enzymes enzymes: are proteins made of amino acids.enzymes: are proteins made of amino acids....
TRANSCRIPT
Enzymes
Enzymes
•Enzymes: are proteins made of amino acids.
-Catalyst: they speed up chemical reactions & lower the activation energy.
-Reusable: remain unchanged after the reaction
-specific: there is a perfect enzyme for a certain substrate
Are Enzymes reusable?
Yes or NO
Enzymes are…..
A.Nucleic Acids
B.Carbohydrates
C.Proteins
D.Lipids
Enzymes•3D shape •can be destroyed & denatured (change shape)
with extreme changes in pH & temperature •have active sites = places where substrate
(food & waste) molecules attach
Examples of Enzymes
Catalase breaks down hydrogen peroxide (waste produced in cells) into water and oxygen
2H2O2 ----> 2H2O + O2
Lactase breaks down lactose in milk
Protease breaks down proteins
Lipase breaks down lipids
How Enzymes Work?•Active sites on enzymes = places
where a specific substrate binds •Enzyme-substrate complexes
form (when substrates attach to active sites on the enzymes) to break apart or put together substances at a fast rate
•E+ S ES E + P
What are active sites?
Two Model of Enzymes
1.lock & key model → substrate & the enzyme fit together perfectly
2. induced-fit model →enzymes change shape slightly to accommodate the substrate
Lock & Key Model
Induced-Fit Model
Factors Affecting Enzyme Action
•Temperature – enzymes work best at certain temperatures
(– 37oC is best for human enzymes in the body)
•pH – enzymes work best at certain pH; basic, neutral, and/or acidic environments
ex.) Amylase in saliva at pH 7,
Pepsin in the stomach at pH 2-3,
Trypsin in the intestines at pH 9
37°
Temperature
temperature
reacti
on
rate
What’s happening here?!
humanenzymes
7
pH
pH
reacti
on
rate
20 1 3 4 5 6 8 9 10
stomachpepsin
intestinestrypsin
What’s happening here?!
11 12 13 14
•Substrate & enzyme concentrations – how fast reactions take place depends on how much of the substrate & enzyme is available.
•Coenzymes – helpers such as vitamins & minerals
Other Factors Affecting Enzyme Action