QUICK QUESTIONS
What is the difference between a fibrous and a globular protein?
Why is the structure of a protein related to its function?
What are the tests for reducing sugars, lipids, starch and proteins.
Name the three chemical groups of an amino acid.
TODAY’S LESSON –ENZYMES – ENZYME ACTION
We need to be able to answer:1. Explain how enzymes speed up chemical reactions.2. Describe how the structure of enzyme molecules
relates to their function.3. Explain the lock and key model of enzyme action.4. Explain the induced-fit model of enzyme action
Language we will be using:1. Catalyst2. Substrate3. Products4. Enzyme substrate complex5. Activation energy6. Active site
WHAT ARE ENZYMES?
Enzymes are proteins generated by an
organism to speed up a reaction – they
are biological catalysts.
Each enzyme has a specific job, either
breaking or forming bonds of reactants
to form substrates.
Enzymes have an active site where only a
specific reactant can fit.
WHAT CAN YOU REMEMBER ABOUT ENZYMES?
key factors interactive animation
Globular structureEnzymes are globular
proteinsThey have a
complex 3
dimensional
Tertiary
shape
Enzymes
This shape allows them
to match the substrate
Enzyme Substrate
This is the LOCK and KEY
theory. The enzyme is not used
up and is available for further
reactions.
Lock and Key
ENZYME ACTION – LOCK AND KEY MODEL
What is the lock and key model?
Why is it a good model?
Why is it a bad model?
Do you think there is anything
wrong with it?
INDUCED FIT THEORY
WHY DO CHEMICAL REACTIONS OCCUR?
WHY DOESN’T DIAMOND CHANGE TO
GRAPHITE?
WHAT IS A CATALYST?
starch
glucose
HOW DO ENZYMES LOWER ACTIVATION
ENERGY?
1.Break down reaction – binding to the
active site of an enzyme puts strain on a
molecule meaning less energy is needed
to break the bonds within it
2.Build up reaction – binding of substrates
to the active site brings them close
together and in the correct orientation,
this reduces repulsion between them
and so less energy is needed to form a
bond between them
PAST PAPER QUESTION
TODAY’S LESSON –ENZYMES – ENZYME ACTION
We need to be able to answer:1. Explain how enzymes speed up chemical reactions.2. Describe how the structure of enzyme molecules
relates to their function.3. Explain the lock and key model of enzyme action.4. Explain the induced-fit model of enzyme action
Language we will be using:1. Catalyst2. Substrate3. Products4. Enzyme substrate complex5. Activation energy6. Active site
WHY ARE ENZYMES IMPORTANT?
SYLLABUS
(a) state that enzymes are globular proteins, with a
specific tertiary structure, which catalyse metabolic
reactions in living organisms;
(b) state that enzyme action may be intracellular or
extracellular;
(c) describe, with the aid of diagrams, the mechanism
of action of enzyme molecules, with reference to
specificity, active site, lock and key hypothesis,
induced-fit hypothesis, enzyme-substrate complex,
enzyme-product complex and lowering of activation
energy;