B4 - Enzymes Flashcards
A catalyst is a substance that
changes the speed of a reaction making it faster
Why are enzymes important in a living organism
Living cells use enzymes as catalysts to change the rate of reaction happening inside them.
Known as metabolic reactions (because they are reactions of the metabolism) which keep a living organism alive.
Without enzymes metabolic reactions would be too slow for life to carry on.
Another name for enzymes
biological catalysts
Enzymes are
proteins
Enzymes can help
small molecules join together or help large molecules to break down into smaller ones
The molecule that an enzyme joins with at the start of a reaction is called a
substrate
The molecule that is formed at the end of a reaction in an enzyme is called the
product
The enzyme shape matches the substrate shape and we call the shapes
complementary to each other.
To increase the rate of reaction the reacting chemical (substrate) must bind to an enzymes
active site
What is the active site
it is a region in the enzyme that fits and binds well with the substrate
The active site fits the substrate to form a
enzyme-substrate complex
Enzymes can catalyze many
substrate molecules making them reusable.
Once a substrate forms into a product they
no longer fit within the active site and are released
Enzymes are specific meaning
each enzyme only works with one substrate or a group of similar shaped substrates
What are examples of some enzymes
Amylase - a type of enzyme that breaks down carbs into starch and simple sugars
Protease - digestive enzymes that break down protein into smaller units
Lipase - digestive enzymes that break down lipids
Enzymes work most efficient in
optimum temperatures.
What is the optimum temperature of a human enzyme that works near the core of the body
35 - 45 C
What happens to enzymes in lower and higher temperatures
Lower: Enzymes in the body work more slowly as they have less kinetic energy meaning frequency of successful collisions between enzymes and substrates is reduced. Takes longer to start reactions
Higher: The structure of the enzyme will change as the bonds between enzyme molecules break, no longer fitting the substrate making it less efficient. It causes permanent damage and is said to be ‘denatured’
An enzyme and substrate molecule can only form an enzyme substate complex when
they bump into each other with sufficient energy
As temperature increases why does enzyme activity also increase
because the molecules gain more energy and move faster so the frequency of successful collisions between enzymes and substrates are higher meaning the rate of reaction increases.
What are 4 factors that affect enzyme activity
Temperature
pH
Enzyme concentration
Substrate concentration
Enzymes have an
optimum pH
What happens to enzymes in lower and higher pH
lower: slows down rate of reaction of enzyme
higher: can denature the enzyme
What happens when the enzyme is not in a suitable pH
The shape of the enzyme and its active site will change so that the substrate can no longer fit into it decreasing the rate of reaction.
What are the steps and method for investigating the effect of pH on Amylase
Apparatus: Beakers, iodine solution, amylase, starch solution, pipette.
Steps:
Add amylase to starch solution
every 30 seconds take a drop of mixture and add to iodine solution
Record the time taken for iodine to stop turning blue (indicating starch has been broken down)
Repeat experiment with different levels of pH
The shorter time taken for iodine to stop changing color the faster the amylase has broken down the starch.
IV: Different levels of pH
DV: Time taken
CV: temperature needs to stay the same, enzyme and substrate concentration needs to stay the same. same number of drops of iodine solution
Safety precautions: Goggles of eyes, gloves for pH acidity.
