Enzymes Flashcards
What are enzymes?
Enzymes are organic catalysts that speed up chemical reactions in living organisms without being used up in the reaction.
What type of biological molecule are enzymes made of?
Proteins
What is a catalyst?
A substance that speeds up a chemical reaction without being changed or used up during the reaction.
What do enzymes do during digestion?
They break down large, insoluble molecules into small, soluble molecules.
What is the reaction catalyzed by amylase?
Polysaccharides → Disaccharides + Monosaccharides.
OR
Starch —> Glucose
What is the reaction catalyzed by protease?
Proteins → Amino acids.
What is the reaction catalyzed by lipase?
Lipids → Fatty acids + Glycerol.
What are the general properties of enzymes?
They are specific, reusable, needed in small amounts, affected by pH and temperature, and can be inhibited by poisons.
What does it mean that enzymes are specific?
Each enzyme only catalyzes one specific type of reaction.
What happens to an enzyme after a reaction?
It remains unchanged and can be reused.
What is the substrate in an enzyme reaction?
The substance the enzyme acts upon.
What are the products in an enzyme reaction?
The substances produced after the enzyme acts on the substrate.
What is the active site of an enzyme?
The region on the enzyme where the substrate binds and the reaction occurs.
What is meant by the “lock and key” theory?
The enzyme’s active site is specific in shape to fit only one type of substrate, like a key fitting a lock.
What is the optimum temperature for human enzymes?
About 37°C.
What happens to enzymes at high temperatures?
They become denatured — their shape changes and they stop working.
What does “denatured” mean?
The enzyme’s structure is permanently altered, so it can no longer function.
What is the optimum pH for most enzymes?
Around pH 7 (neutral), but some have different optimum pH levels.
What happens to enzymes in very acidic or alkaline conditions?
They can become denatured and stop functioning.
Name some substances that inhibit enzymes.
Cyanide and arsenic.
How do poisons like cyanide affect enzymes?
They bind to enzymes and prevent them from working.
What helps enzymes to function?
Certain vitamins and minerals.
What is meant by “optimum temperature” for enzymes?
The optimum temperature is the temperature at which an enzyme works best and its rate of reaction is the highest. For most human enzymes, the optimum temperature is around 37°C.
What happens to enzymes at temperatures higher than the optimum?
Enzymes become denatured at high temperatures. This means their structure, especially the active site, is changed and they can no longer function properly.
What does “denatured” mean in relation to enzymes?
Denatured means the enzyme’s shape is permanently changed, especially at the active site, so the substrate can no longer fit and the enzyme cannot function.
What is meant by “optimum pH” for enzymes?
The optimum pH is the level of acidity or alkalinity at which an enzyme works best. For example, salivary amylase works best around pH 7 (neutral), while pepsin works best at pH 2.5 (acidic).
What is the “active site” of an enzyme?
The active site is the specific region on an enzyme where the substrate binds. It has a unique shape that matches only one type of substrate, like a key fitting into a lock.
What is a substrate?
A substrate is the substance that an enzyme acts on during a chemical reaction.
What are products in an enzyme reaction?
Products are the new substances formed after the enzyme breaks down the substrate.
Why are enzymes called biological catalysts?
Because they are made by living organisms and they speed up chemical reactions without being used up or changed in the process.
How do poisons like cyanide affect enzymes?
Poisons inhibit enzymes by blocking or destroying their active sites, preventing them from working properly.
Why do enzymes only work on specific substrates?
Because each enzyme has a unique active site that only fits a specific substrate—this is known as enzyme specificity.
What happens to enzyme activity at very low temperatures?
At very low temperatures, enzyme activity slows down because the molecules move more slowly and there are fewer collisions between enzyme and substrate.
