Biology AOS 2 Ch3

an enzyme is

an organic molecule that acts as a catalyst

Key features of an enzyme

1. Most are proteins

2. Active site that is complementary to a substrate

Explain the difference between the ‘Lock and Key’ vs ‘Induced Fit’ model

• Lock and key indicates a perfect fit of a substrate to an enzyme

• Whereas, induced fit indicates that enzymes change/adjust shape slightly to better accommodate the substrate

How are substrates held together

• hydrogen bonds

• Hydrophobic interactions

What is activation energy and what is it needed for?

• it is the minimum amount of energy required for a substrate to form into a product, and is needed for starting chemical reactions

When an enzyme is present … is needed for the chemical reaction

• less/low activation energy

Without an enzyme… for a chemical reaction

-more activation energy is required

What are the 2 main types of reactions

1. Catabolic (energy releasing)

2. Anabolic (energy requiring)

In a catabolic reaction with an enzyme…by…to form products

• low activation energy is needed in order to make products from reactants

• releasing energy

In an anabolic reaction with an enzyme…therefore…to form reactants (as products)

• Low activation energy is needed

• Acquiring more energy

The biochemical pathway uses the product of one reaction…

as the substrate for the next

What are 4 main factors that affect enzymes

1. temperature

2. Ph levels

3. Substrate concentration

4. Enzyme concentration

What occurs at Y

temperature is below optimal level (too cold) therefore:

• slows molecular motion

• Less collisions

• But can regain activity when reheated

What occurs at Z

Temperature is above optimal level (too hot) therefore:

• reaches irreversible denaturation

• active sites undergo conformational change

• Permanent loss of function

What does X indicate

Optimal temperature resulting in enzymes are most functional state

PH: Each enzyme has…

• its own optimal pH

At X and Z the enzyme is…

fully denatured at basic (X) and acidic (Z) conditions

At Y it is at…

optimal levels

High Enzyme concentration results in…

• Faster reaction rates as more active sites are present to accommodate for substrate processing

Low Enzyme concentration results in…

• Slower reaction rates

What happens when Enzyme concentration reaches saturation point (plateau)

• it won’t continue substrate processing due to all active sites being occupied

high Substrate concentration results in…whereas low substrate concentration

• Faster reaction rate

• Slower reaction rate

When substrates reach saturation point

• reactions stop as all active sites are occupied, unless enzyme concentration is increased in order for substrates to continue being processed

Competitive inhibition is when…because…

• Inhibitor molecules compete for an active site

• molecules are similar/complementary to substrate