CHAPTER 3 - BIOLOGY (enzymes)

Enzymes

Enzymes are biological catalysts which increases the rate of reaction without being used up

Breaker Enzymes

When large molecules need to be broken down to small molecules, Breaker enzymes help speed up these reactions. This is important in digestion when large food molecules need to be broken down into small food molecules so that we can use them

Examples: Carbohydrase break down carbohydrate molecules into glucose molecules.

Protease breaks down protein molecules into amino acid molecules.

Builder Enzymes

When small molecules need to join together to make large molecules, Builder enzymes speed up these reactions. These enzymes help build important molecules in our cells.

Examples: Maltase makes maltose from glucose molecules

Pepsin makes protein molecules from amino acid molecules.

Active site

Enzymes are protein molecules made up of long chain of amino acids. These long chains are folded to produce a special shape called Active site.

Substrate

Substrate is a molecule which fits into the active site, so that the reaction takes place.

Properties of enzymes

1. They are all proteins.

2. Each enzyme controls one particular reaction.

3. They can be used again and again.

4. They are affected by temperature.

5. They are affected by pH.

Enzymes are specific

Each enzyme controls one particular reaction, and that enzyme has no effects on other reaction. Suppose, Protease breaks down protein molecules into amino acid molecules, but protease cannot break down carbohydrates.

Digestion

enzymes break down large food molecules into smaller ones inside our gut. this is called digestion.

The enzymes are carbohydrase and protease.

**Potato cells contain an enzyme called catalase which speed up the breakdown of hydrogen peroxide into water and oxygen gas. Hydrogen peroxide → Water + Oxygen

** Our saliva contains the enzyme called carbohydrase and it is also called amylase which breaks down starch into sugar. Starch → Sugar

Effect of temperature on enzyme

Enzymes are affected by temperature because at higher temperature the active site of the enzyme gets denatured, the active site is changed so the substrate no longer fits to the active site.

Effect of pH on enzyme

An enzyme is affected by acidity or alkalinity of the solution present. Many enzymes work best in neutral conditions, but some prefer acid and some alkali.

For example, protease breaks down proteins to amino acids in the small intestine working best at a pH of about 8.5 and at 37 C.

Immobilised enzymes

Breaker-enzymes break down complex chemicals into simple ones but at the end of the reaction, the enzyme and simple chemicals are mixed together where enzymes cannot move, which is called immobilized enzyme. By using resin beads we can fix where immobilized enzymes trickles and simple chemicals can flow out.

Enzymes as builders

Proteases break down the proteins into amino acids.

The amino acids are small enough to get through the gut wall and into our blood.

These amino acids join our body's amino acid pool.

When we grow we take amino acids out of this pool.

Enzymes join these amino acids to make new proteins

Lumpy ice cream

Sucrose forms crystals more easily than simple sugars like glucose. This can cause sweet foods, like ice cream, to go hard and lumpy. Manufacturers use yeast enzyme to break the sucrose down into simple sugar molecules

Application of enzymes

in industry- Enzymes have become very important in industry, they are versatile and far more efficient than other catalysts. They work at relatively high temperatures. So this reduces

fuel costs making them cheaper to use

Sweeteners

Sweeteners are mainly high demand in confectionary and fizzy drinks. traditionally sucrose has been used, It is extracted from beer beet or sugar cane. recently, a sucrose substitute high fructose syrup has been introduced. Fructose is much sweeter than sucrose and can be made from starch, its also cheaper to produce.

Biological washing powder

Biological washing powders contain proteases and lipases. These break down the protein and fat stains such as grime and sweat. These washing powders work at quite low temperatures.

enzymes can be used again and again

Enzymes can be used over and over again.

Once the products leave the active site, more substrate can enter.

So the enzyme will keep on working until all the substrate is used up