3.1 Biological molecules

What are monosaccharides?

One unit of carbohydrate (a monomer)

Examples of monosaccharides

Glucose, fructose, galactose

Characteristics of monosaccharides

Sweet tasting Soluble General formula (CH₂O)ₙ where n is a number from 3 to 7

Anabolic Reaction

Building polymers

Catabolic reaction

Breaking down polymers

Types of reactions

Hydrolysis

Condensation

Hydrolysis reaction

Using water to break apart cells (separate polymers). Water is added

Condensation reaction

Anabolic- building polymers, where water leaves the reaction

2 types of glucose

alpha- glucose

beta- glucose

Alpha- glucose diagram

H is ABOVE carbon 1

Beta- glucose diagram

H is BELOW carbon 1

Isomers definition and examples

Compounds with the same formula but different arrangement alpha and beta glucose

Hydroxyl group

OH

Carbonyl group

C=O

Disaccharides e.g

glucose + glucose = maltose

glucose + fructose = sucrose

glucose + galactose = lactose

Reducing sugars definition and example

Can donate electrons to reduce another chemical e.g disaccharides

Reducing sugar test

Benedict's solution, heat in warm water bath

Results: Blue- non-reducing sugar. Green- traces of reducing sugar. Orange- moderate levels. Brick red- high levels + insoluble red ppt of copper (I) oxide formed

Positive result shown because the benedict's solution gained electrons from the reducing sugar

Non-reducing sugar e.g

Sucrose

Polysaccharides characteristic and uses

Large so insoluble

Uses: Starch and glycogen- storage, but are broken down when monosaccharides have been broken down (used up). Cellulose- structural support in plants

What are starch and cellulose formed from?

Starch- alpha glucose Cellulose- beta glucose

How are cellulose molecules adapted?

They have long and straight chains which become linked together by many hydrogen bonds to form fibrils. This provides strength to cell walls

How are starch molecules adapted for function in plant cells?

Function= storage They are large, so insoluble, and the large molecules cannot leave the cell. They are also compact so can store lots with minimal space

What joins only saccharides together?

Glycosidic bonds (covalent bond, condensation reaction)