Biomolecules

BIOMOLECULES identify and describe carbohydrates , lipids and proteins as

food substances state the chemical and physical properties of different food

substances

WHAT ARE BIOMOLECULES??Biomolecules are molecules that occur naturally in living

organisms. Biomolecules include macromolecules like proteins, carbohydrates, lipids and nucleic acids.

It also includes small molecules like primary and secondary metabolites and natural products.

Biomolecules consists mainly of carbon and hydrogen with nitrogen, oxygen, sulphur, and phosphorus.

Biomolecules are very large molecules of many atoms, that are covalently bound together.

CLASSES OF BIOMOLECULESThere are four major classes of biomolecules: 

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids

CARBOHYDRATES

Carbohydrates are organic molecules with the general formula CHO in a 1:2:1 ration.

They constitute 1 to 2% of cell mass and provide the raw fuel for cellular energy production

They are classified based on molecular size and solubility. Smaller molecules are more soluble than larger one!

MONOSACCHARIDES Monosaccharides are soluble (they dissolve) in water and taste sweet.

DISACCHARIDES Two monosaccharides are joined together by dehydration synthesis to form a

disaccharide molecule. These are also soluble in water and taste sweet..

Sucrose (table sugar): Glucose + fructose = sucrose + water

Lactose (milk sugar): Glucose + galactose = lactose + water

Maltose (malt sugar):Glucose + glucose = maltose + water

POLYSACCHARIDES Polysaccharides include starch, cellulose, and glycogen.

These long, chain-like polymers make ideal storage products due to their insolubility.

Starch is the storage molecule synthesized from glucose by plants.

Cellulose, which is also synthesized by plants for cell wall construction, is indigestible because we lack enzymes for it. Cellulose provides fiber to promote peristalsis.

Glycogen is the carbohydrate storage molecule found in muscle and liver cells. When blood sugar levels drop, liver cells hydrolyze glycogen and release glucose to the blood

Starch and glycogen are slightly soluble in water, cellulose is insoluble and polysaccharides do not taste sweet.

LIPIDS

LIPIDS Lipids are organic molecules that are insoluble in water.

Made of carbon, hydrogen and oxygen.

Lipids are composed of long hydrocarbon chains and hold a large amount of energy and are energy storage molecules.

Lipids are generally esters of fatty acids and are building blocks of biological membranes. Most of the lipids have a polar head and non-polar tail.

Fatty acids can be unsaturated and saturated fatty acids. 

There are three main groups of lipids:

1. Triglycerides

2. Phospholipids

3. Steroids

Saturated fats have a single bond between carbon atoms

Monosaturated fats have a double bond between carbon atoms

Polysaturated fats have more that one carbon-carbon double bond per molecule.

Scientists believe that a diet high in saturated fats is unhealthy and they have linked saturated fats to an increased risk of heart disease.

PROTEINS

PROTEINS Proteins are known as building blocks of life.

Compounds contain carbon, hydrogen, oxygen, nitrogen and sometimes sulphur and phosphorous.

Perform variety of  functions like catalyzing metabolic reactions, replication of DNA, response to stimuli, and transporting molecules.

Every protein molecule is made up of a long chain of amino acids.

Usually large in size, that consists of one or more chains of amino acids.

There are 20 amino acids and they all have the general formula

Proteins differ from each other mainly in the sequences of amino acids.

ANSWER THE FOLLOWING……

1. Which three elements are found in carbohydrates, lipids and proteins

2. Define the term; ‘monosaccharide’ ‘hydrolysis’ ‘condensation’ and ‘polysaccharide’

3. In which kind of food would you find the following substances, cellulose, sucrose, oil, fat and amino acids

4. What is the main function of proteins?