enzymes

Enzyme

Biological catalyst. They speed up the rate of metabolic reactions.

Activation Energy

Enzymes lower the activation energy required for reactions, allowing them to occur more easily and quickly.

Substrate

The reactants of the reaction to which the enzyme must join.

Active Site

The part of the enzymes that joins to the substrate.

Enzyme-Substrate Complex

The enzyme-substrate complex forms when the substrate binds to the enzyme's active site, allowing the reaction to occur.

Specificity of Enzymes

Each enzyme only catalyses one specific type of reaction or acts on a specific substrate due to the complementary shape of its active site.

Mechanism of Enzymes

The enzyme collides with the substrate. The active site binds to the substrate forming an enzyme substrate complex. The enzyme lowers the activation energy by bending and weakening the bonds, the product is formed and leaves the active site.

Enzyme after Reaction

After the reaction, the products are released from the active site, and the enzyme remains unchanged and can catalyse further reactions.

Importance of Enzymes

Enzymes ensure that metabolic reactions occur quickly enough to sustain life.

Digestive Enzymes

Without digestive enzymes, it would take around 2-3 weeks to digest one meal, whereas with enzymes, it takes about 4 hours.

Optimum Temperature for Enzyme Activity

37°C

Effect of Temperature on Enzyme Activity

Increasing temperature towards the optimum increases the rate of enzyme catalysed reaction, while temperatures beyond the optimum cause a decrease in the rate of enzyme catalysed reaction.

Kinetic Energy and Enzyme Activity

Enzyme and substrate have more kinetic energy, leading to more collisions, more enzyme substrate complexes, and a faster rate of reaction.

Denature

The active site changes shape and is no longer complementary to the substrate.

Effect of High Temperature on Enzyme Activity

The enzyme denatures. The active site changes shape and is no longer complementary to the substrate.

Irreversibility of Denaturation

No, denaturation is irreversible.

Optimum pH for Enzymes

The optimum pH for most enzymes.

pH 7

Neutral pH level.

Effect of temperature on enzyme catalysed reaction

Increasing temperature increases the rate of enzyme catalysed reaction until the optimum is reached.

Effect of pH on enzyme catalysed reaction

Increasing pH towards the optimum increases the rate of enzyme catalysed reaction, while increasing the pH beyond the optimum causes a decrease in the rate.

What happens if pH is too high or too low?

The enzyme denatures. The active site changes shape and is no longer complementary to the substrate.

Optimum pH for stomach enzymes

pH 2.

Optimum pH for duodenum enzymes

pH 8/9.

Three main types of digestive enzymes

Carbohydrases, proteases, and lipases.

Role of amylase

To break down starch into maltose.

Where is amylase produced?

In the salivary glands, the pancreas, and the small intestine.

What happens to amylase from salivary glands in the stomach?

It gets denatured by the stomach acid and must be replaced by amylase from the pancreas in the small intestine.

What does maltase do?

Breaks down maltose into glucose.

Where is maltase produced?

Small Intestine.

What do proteases break down?

Proteins into amino acids.

Role of pepsin

To break down proteins into smaller polypeptide chains in the stomach.

Where are protease enzymes produced?

In the pancreas and the small intestine.

What do lipases break down?

Lipids (fats) into glycerol and fatty acids.

Where are lipase enzymes produced?

In the pancreas and secreted into the small intestine.

Role of the pancreas in digestion

Producing digestive enzymes to be released into the small intestine.

Enzyme used in temperature investigation

Amylase.

Substrate amylase acts on in investigation

Starch.

Product of reaction between amylase and starch

Maltose.

Purpose of adding iodine to wells

The iodine solution stops turning blue-black.

How to know when amylase has broken down all starch?

The iodine solution stops turning blue-black.

Optimum temperature for amylase activity

The temperature at which the iodine stops turning blue-black the fastest.

Amylase activity at temperatures below optimum

The enzyme works slowly due to low kinetic energy and fewer collisions between the enzyme and substrate.

Amylase activity at temperatures above optimum

The enzyme becomes denatured and can no longer bind with the starch or break it down.