Enzymes Flashcards
What type of molecules are enzymes?
Enzymes are globular proteins that act as biological catalysts.
Describe the structure of an enzyme.
Enzymes have a specific 3D structure with an active site formed by folded chains of amino acids held by hydrogen bonds, ionic bonds, and disulfide bridges.
Define the term complementary.
Complementary refers to the specific fit between the enzyme’s active site and its substrate, like a lock and key.
What do enzymes do?
Enzymes speed up biochemical reactions by lowering the activation energy required for the reaction.
What is meant by the term biological catalyst?
A biological catalyst is a substance, like an enzyme, that increases the rate of a chemical reaction in a living organism without being consumed.
Why are many different enzymes needed for different reactions?
Different enzymes are needed because each enzyme has a specific active site that only fits particular substrates.
How do enzymes lower activation energy?
Enzymes lower activation energy by binding to substrates at their active sites, forming an enzyme-substrate complex and stabilizing the transition state.
What is the difference between catabolic and anabolic enzymes?
Catabolic enzymes break down large molecules (e.g., amylase breaking down starch). Anabolic enzymes build larger molecules (e.g., DNA polymerase synthesizing DNA).
What is an enzyme-substrate complex?
An enzyme-substrate complex is the temporary structure formed when a substrate binds to the enzyme’s active site.
Describe the lock and key hypothesis.
The lock and key hypothesis states that the enzyme’s active site is a specific shape that perfectly fits the substrate, like a key fitting into a lock.
Describe the induced fit hypothesis.
The induced fit hypothesis suggests that the enzyme’s active site changes shape slightly to fit the substrate more snugly when it binds.
How do the lock and key hypothesis and the induced fit hypothesis differ?
The lock and key hypothesis suggests a rigid active site, while the induced fit hypothesis suggests a flexible active site that changes shape to fit the substrate.
What are the limitations of the lock and key hypothesis?
Limitations include not explaining enzyme flexibility, wide substrate interactions, and how enzymes lower activation energy by stabilizing the transition state.
What is the difference between intracellular and extracellular enzymes?
Intracellular enzymes function inside cells, while extracellular enzymes are secreted outside cells and function in external environments like digestion.
Name an intracellular enzyme and its function.
Catalase, which breaks down toxic hydrogen peroxide into water and oxygen inside cells.
Name an extracellular enzyme and its function.
Amylase, which breaks down starch into maltose in the digestive system.
what is the effect of substrate concentration on enzyme activity
the higher the substrate concentration, the more frequent collisions meaning a higher rate of reaction. This is only up until Vmax is reached when the enzymes become the limiting factor so no more reactions happen.
what is the effect of enzyme concentration on enzyme activity
the higher the enzyme concentration, the more frequent collisions meaning a higher rate of reaction. This is only up until Vmax is reached when the substrates become the limiting factor so no more reactions happen.
