cells & enzymes enzymes made of protein present in all living cells converts substrates into...
TRANSCRIPT
Cells & Enzymes
Enzymes
Made of protein Present inall living cells
Converts substratesinto products
Biological catalysts
Increase the rate of chemical reactions
Remain unchanged by chemical reaction
• This term really means two things:
ANABOLISM and CATABOLISM
METABOLISM
ANABOLISM
“ TO BUILD” molecules as in the biosynthesis of polymers..
We ingest food digest to monomers and THEN via ANABOLISM we make larger molecules
• “TO BREAK APART “
• Example: Glycogen, (starch) stored in the liver when needed for energy, is converted to glucose ( monomers).
So during catabolism large molecules are broken into smaller molecules.
Catabolism …then is to..
ProductSubstrate
Chemical Reactions
A chemical reaction takes place when one or substances is chemically changed into one or more different substances.
Chemical reactions take place in cells all the time.
Enzyme
Catalase
Hydrogen peroxide
Water + oxygen
Manganesedioxide
Catalyst
Enzymes and Chemical ReactionsEnzymes can speed reactions by lowering the amount of energy needed for a chemical reaction
Catalysts
A catalyst is a substance which speeds up a chemical reaction, without itself being changed by the reaction.
1. When a catalyst is present, less energy is needed to get the chemical reaction started.
2. When a catalyst is present, the speed of the chemical reaction is faster.
3. Although a catalyst helps a chemical reaction to happen, it is unchanged at the end of the reaction.
Biological Catalysts
The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE.
Hydrogen peroxide
Oxygen + watercatalase
REACTANTS PRODUCTS
enzyme
2.2 Nature of Enzymes
The biological catalyst present in the cytoplasm of plant and animal cells that speeds up the breakdown of hydrogen peroxide is called CATALASE.
Catalase cannot speed up any other reaction. It is SPECIFIC to this reaction.
CatalaseHydrogen peroxide
Water + oxygen
One Enzyme – One Reaction
There are thousands of different enzymes in your body.
Why are there so many different enzymes?
Each enzyme has its own unique protein structure and shape, which is designed to match or COMPLEMENT its substrate.
Lock & Key Hypothesis
An enzyme only acts on one type of substance, or substrate.
Therefore, the enzyme is said to be SPECIFIC to its one substrate.
The shape of the active site (binding site) of the enzyme, matches the shape of the substrate. Allowing the two molecules to bind during the chemical reaction.
This theory of enzyme action is called the ‘lock-and-key’ hypothesis.
Different enzymes for different jobs
Enzymes involved in breakdown reactions
Enzyme and substrate separate
Enzyme-substrate complex
Enzyme and products separate
Enzymes involved in synthesis reactions
Enzyme and substrates separate
Enzyme-substrates complex
Enzyme and product separate
2.3 Using a Control
Why is it necessary to include a control experiment in an investigation?
A control is an experiment that allows a comparison within an investigation in order to ensure that the conclusions drawn from the results are valid.
Enzymes involved in breakdown reactions
CatalaseHydrogen peroxide Water + Oxygen
AmylaseStarch Maltose
LipaseFat Fatty acids + Glycerol
PepsinProtein Amino acids
2.5 Effect of High Temperature
Notes on Denaturation Notes on Optimum temp
• Optimum conditions are the conditions at which an enzymes works best
• Rate of reactions may be affected by temperature and pH
2.5 Effect of High Temperature
Notes on DenaturationNotes on
Optimum temp
What happens to the activity of an enzyme at high temperatures?
Movie
Effect of pH on enzymes
When the pH changes outwith optimal conditions, the shape of the active site of the enzyme alters and the enzyme is denatured.
Effect of pH on enzyme activity
Most enzymes work best at a pH close to neutral (pH7), but there are some exceptions. Pepsin, an enzyme found in the stomach, has an optimum pH of 2.
Enzyme Substrate Product(s) Degradation or synthesis?
Amylase Starch Maltose
Catalase Hydrogen peroxide
Oxygen and water
Pepsin Protein Amino acids
Phosphorylase Glucose-1-phosphate
Starch s
Lipase Fat Fatty acids
Enzyme Summary