Module 2 Section 4 - Action of Enzymes Flashcards
What do enzymes do
They speed up chemical reactions by acting as biological catalyst
Enzymes are ……
Biological catalysts
What is an example of enzymes being used at a cellular level
Respiration
What is an example of enzymes being used for organisms as a whole
Digestion in mammals
What do enzymes affect
Structures in an organism
Functions of an organism
Enzyme action can be ….
Intracellular and extracellular
What does intracellular mean
Within cells
What does extracellular mean
Outside cells
What is the toxic by product of many cellular reactions
Hydrogen Peroxide (H2O2)
What happens if hydrogen peroxide is left to build up
It kills cells
What is the enzyme responsible for the breakdown of H2O2
Catalase, hydrogen peroxide to harmless oxygen and water
Give an example of an intracellular enzyme
Catalase
Give an example of extracellular enzyme
Amylase and Trypsin
Where does catalase work
Inside the cell (intracellular)
Where does amylase and trypsin work
Outside cells (extracellular) in the digestive system
Where is amylase found
Saliva (secreted to the mouth by salivary glands)
What does amylase catalyse
The hydrolysis of starch to maltose (a sugar) in the mouth
What does trypsin catalyse
The hydrolysis of peptide bonds - turns big polypeptides to smaller ones
Where is trypsin produced
Cells in pancreas
Where is trypsin secreted to
Small intestine
What type of protein are enzymes
Globular protein
Enzymes have…
An active site, which has a specific shape
What is the active site
The part of the enzyme that the substrate molecules bind to
How is the specific shape of the active site determined
By the enzymes tertiary structure
What need to happen for the enzyme to work
Substrate has to fit into the active site.
What happens if the substrate doesn’t match the active site
If the substrate doesn’t match the active site the reaction won’t be catalysed. Enzymes work few substrates - usually one.
What is activation energy
A certain amount of energy that needs to be supplied to the chemicals before the reaction will start - often provided as heat.
What do enzymes do to the activation energy
Reduces activation energy - speeds up rate of reaction
What is formed when the substrate binds to an enzymes active site
Enzyme-substrate complex
The formation of the enzyme substrate complex lowers ….
The activation energy
Why does the formation of the enzyme-substrate complex lower the activation energy
-if two substrate molecules need to be joined, attaching to the enzyme holds them close together reducing any repulsion so they can bind easily
-if the enzyme is catalysing a breakdown reaction fitting into the active site puts a strain on bonds in the substrate. This strains means the substrate molecule breaks more easily
Enzymes only work with
Substrates that fit their active site
What did early scientists come up with to study action of enzymes
Lock and key theory
What is the lock and key theory
This is where the substrate fits into the enzyme in the same way that a key fits into a lock
Why did scientists realise that lock and key wasn’t totally perfect
New evidence showed that enzyme-substrate complex changed shape slightly to complete the fit.
