Topic 6-Enzymes and Digestive system
Call Kai
Learn
Practice Test
Spaced Repetition
Match
Flashcards
Knowt Play1/29
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced | Call with Kai | Chat |
|---|
No analytics yet
Send a link to your students to track their progress
30 Terms
Definition Enzymes
Catalysts produced by living things
Definition Catalyst
A substance which increases the speed of a reaction without being changed or used up in the reaction.
Enzymes are made of
Proteins
How enzymes speed up reactions
They lower the activation energy needed for the reaction
Definition Active site
The specific part of an enzyme where the substrate binds
Substrate
The molecule that an enzyme acts on
Enzyme-substrate complex
Temporary structure formed when a substrate binds to an enzyme's active site.
Lock-and-key model
The enzyme's active site has a specific shape that only its complementary substrate can fit into
Why are enzymes specific?
The active site has a shape complementary to only one substrate (lock and key model)
When a substrate enters the active site
It binds, forming an enzyme-substrate complex, and the reaction occurs
After the reaction
The enzyme is unchanged and can be used again
At the optimum temperature
the enzyme works at its maximum rate.
What happens above the optimum temperature?
Bonds break, the active site changes shape, the substrate no longer fits.
The enzyme is denatured (permanent)
Never say "killed"
Can a denatured enzyme return to its original shape?
No. Denaturation is usually permanent.
Why is activity slow at low temperature?
Less kinetic energy, so fewer collisions and fewer enzyme-substrate complexes
NOT denatured
The 4 factors affecting enzymes
Temperature
pH
Substrate concentration
Enzyme concentration
Optimum temperature of human enzymes?
About 37 °C (body temperature)
Optimum pH of pepsin (stomach protease)?
About pH 2 (stomach acid)
Most enzymes: pH 7
Small intestine enzymes: about pH 8
What does amylase do?
Breaks down starch into maltose (sugars)
What does protease do?
Breaks down proteins into amino acids
What does lipase do?
Breaks down lipids into fatty acids and glycerol
Amylase practical: how do you know the starch is all digested?
Iodine on the spotting tile stays orange-brown (no longer turns blue-black).
Record the time
Amylase practical: why add a buffer?
To keep the pH constant (control variable)
Rate formula (time taken)?
Rate = 1 ÷ time.
Example: 40 s gives 1 ÷ 40 = 0.025 s⁻¹.
Rate formula (product made)?
Rate = amount of product ÷ time.
Example: 24 cm³ in 4 min = 6 cm³/min.
Substrate concentration increases
The rate increases because more substrate molecules are available to bind to enzymes
Why the rate eventually stops increasing
All active sites are occupied, so the enzymes are working at their maximum rate.
Why do enzyme concentration increases
The rate generally increases because more active sites are available
Why does rate level off at high substrate concentration?
All active sites are occupied, so enzyme concentration becomes the limiting factor
Why enzymes matter in digestion
They break large insoluble food molecules into smaller soluble molecules that can be absorbed