Biology unit 5.2

Carbohydrates

An organic compound made up of sugar molecules

What elements does sugar contain?

Carbon hydrogen and oxygen

What are monosaccharides

Simple sugars that contain only 1 sugar unit

Monosaccharides examples

Glucose, fructose galactose

Functions of monosaccharides

Main fuel for cellular work as cells break down glucose molecule and obtain the energy stored in it. Carbonskeletons of monosaccharides are also used for building other raw materials. They are also used for making fat molecules

How do cells produce a disaccharide

By a dehydration reaction

What is a disaccharide

Double sugar from two monosaccharides

What is the most common disaccharide

Sucrose

Functions of sucrose

Sucrose will be broken down into fructose and glucose right away after consumed

What are polysaccharides

Large polymer chains made of sugar monomers

Give 3 examples of polysaccharides

Starch, glycogen, cellulose

Explain starch

Polysaccharide found in plant cells, consisting only of glucose monomers. Its chains branch and coil up. When plants break down starch, the stored glucose becomes available.

Explain glycogen

A polysaccharide in animal cells. It’s a chain of many glucose monomers however, a glycogen polymer is more highly branched than a starch polymer. In humans it is stored like granules in our liver and muscle cells. When the body needs energy, it breaks granules stored as glycogen into glucose and releases it

Explain cellulose

Polysaccharides in plants serve as a building material. They protect cells and stiffen the plant. Like starch and glycogen, cellulose is also made from glucose monomers. Multiple cellulose chains are linked together with hydrogen bonds, forming cable-like fibers

Explain the digestion of cellulose

Humans can’t digest cellulose as we dont have the enzymes required to do so. Therefore it passes through the digestive system unchanged and is known as fibre.

Why are carbohydrates hydrophilic

Due to the many hydroxyl groups in their sugar units