Nutrition• Is the way organisms obtain and use food

• Nutrients are the chemical substances present in food which

are used by organisms.

• They are essential for

» metabolism and continuity of life

• Uses are

» Source of energy

» To aid metabolism

» For growth and repair

14 Food Elements

6 Common elements

• Carbon• Hydrogen• Oxygen• Nitrogen• Phosphorus• Sulfur

5 Dissolved salts

• Sodium• Magnesium• Chlorine• Potassium• Calcium

3 Trace elements

• Iron• Copper• Zinc

Biomolecules

• Biomolecules: molecules in which atoms of the 14 elements bond together in various ratios.

• 4 Major types found in food

– Carbohydrates– Lipids– Proteins– Vitamins

( Remember L.C.V.P.)

Features

Carbohydrates are the body's source of fuel. It provides energy for daily metabolic activities.

Simple carbohydrates are found in simple sugars, such as table sugar, honey, corn syrup, cane sugar, brown sugar.

Complex carbohydrates are cereals, breads, pastas, and vegetables. Fruit contains both simple and complex carbohydrates.

Simple carbohydrates are rapidly digested; complex carbohydrates are digested slowly.

*Carbohydrates

CarbohydratesWhat are Carbohydrates ???

• Composed of Carbon, Hydrogen and Oxygen

• Ratio of C:H:O is 1:2:1 e.g. C6H12O6

• Exist in the form of:

- simple sugars such as fructose, glucose

- double sugars as sucrose (cane sugar) lactose (milk sugar), maltose (malt sugar)

- multiple sugars such as starch or glycogen.

Glucose MoleculeC6H12O6

3 Categories of carbohydrates1)Monosaccharide's

- single sugar unit e.g. Glucose and Fructose - sweet to taste- soluble in water

2)Disaccharides- double sugar unit e.g. Sucrose, Maltose and

Lactose- sweet to taste- soluble in water

3)Polysaccharides*- many sugars units e.g. Starch (amylose),

Glycogen, Cellulose- insoluble/slightly soluble in water

Sources

Test for reducing sugar- simple sugars

• Chemicals used: Benedicts solution (blue)

• Heat required: yes ( water bath)

• Results: colour change from blue to BRICK RED if sugar is present

• Control: water

Test for Starch

2. Lipids (Fats and Oils)

• Contain Carbon, Oxygen and Hydrogen

• No simple ratio of composition

• Contain very little oxygen

• Fats are lipids that are solid at room temp

• Oils are lipids that are liquid at room temp

• Sources of lipids – butter, oils, margarine,

cream, lard, fat on meat, olives

Structure of Lipids

Triglycerides

The smallest lipids contain one

molecule of glycerol linked to 3

fatty acid molecules

Phospholipids

One fatty acid is replaced by a

phosphate group. Play an NB

role in cell membrane

structure

Test for fat

Fat Test

Worksheet on Food Test

• Materials used: brown paper • Result: if permanent stain remains on paper, fat is present

• Control: water

3. Proteins

• Contain Carbon, Oxygen, Hydrogen and Nitrogen

• May also contain small amounts of sulfur and phosphorus

• No ratio

• Very large and complex molecules

• Constructed from building blocks called Amino Acids

• Amino acids are biochemical building blocks.

• Twenty amino acids are encoded by the standard

genetic code and are called standard amino acids.

• Rarer, more complicated amino acids are produced

by the body and are called nonstandard.

*Structure of Proteins

Amino acid structure

Amine groupCarboxylic acid group

The R group.This group differs

between AA

•Amino acids form short polymer chains called peptides or

polypeptides which in turn form structures called proteins.

Peptide Polypeptide Protein

• Each type of protein has a different AA sequence

•The folding of the AA chain impacts on the function of the protein:

o Fibrous proteins show little or no folding. Form strong fibres e.g. keratin, collagen

o Globular proteins have well defined folding – specific shape e.g. enzymes

o Prions: proteins which do not fold correctly. These proteins are responsible for brain and nervous system diseases – BSE, CJD

Protein Function

Sources of Proteins

• Sources of proteins are meat, fish, eggs, nuts, milk

Note: the body doesn’t store AA. Broken down in the liver, and the amine group is

converted to urea for excretion in the urine.

Test for Protein- Biuret test

• Chemicals used: sodium hydroxide & copper sulphate

• Heat required: No

• Results: colour change from blue to violet if protein is present

• Control: water

4. Vitamins• Complex organic compounds that the body can’t make• Needed in tiny amounts

Vitamin C (ascorbic acid)

•Water soluble

•Sources: fruit and veg

•Forms connective tissue,

bone and teeth, Helps

healing and immune

system.

•Deficiency - Scurvy

Vitamin D (calciferol)

•Fat soluble

•Sources: cod liver oil,

milk, UV

•Helps absorb Ca for

bones and teeth

•Deficiency – rickets or

osteomalacia (brittle

bones)

Types of energy transfer reactions

• Metabolism is the full set of chemical processes (anabolic + catabolic) carried out by a living organism

• Anabolic reactions convert smaller molecules into larger molecules. They require energy input.

» e.g.. Photosynthesis

• Catabolic reactions involve the breakdown of large complex molecules into smaller simpler molecules. Catabolic reactions release energy.

» e.g.. Aerobic respiration

Roles of Biomolecules

Biomolecule

Carbohydrate

Lipid

Protein

Vitamin

Structural role

Cellulose in cell walls

Energy storesProtection (kidneys)Insulation (under skin)Formation of cell membranes

Keratin in hair, nails, hoovesMyosin in muscle

Metabolic role

Primary source of energy

Primary source of energy

Enzyme, Antibody and Hormone formation.2nd source of energy

Healthy tissue, bone and tooth formation. Healing and immune system function.

14 Food Elements

6 Common elements

• Carbon• Hydrogen• Oxygen• Nitrogen• Phosphorus• Sulfur

5 Dissolved salts

• Sodium• Magnesium• Chlorine• Potassium• Calcium

3 Trace elements

• Iron• Copper• Zinc

Minerals• Minerals are inorganic nutrients obtained within mineral salts

• Functions areTo form rigid structures e.g. Ca in bones, teeth and cell

walls of plants

To form soft body parts e.g. S in muscle formation

To function in cellular and body fluids e.g. Fe formation of haemoglobin. Mg formation of Chlorophyll. P formation of ATP

Water

Water is essential for life for three reasons:

1) liquid in which all metabolic reactions take place.

2) provides the basis for transport systems in organisms.

3) environment in which many organisms live

Water

Importance of Water for living things

A)Component of cytoplasm and body fluids: - water makes up 75 – 90% of the mass of most

cells. - mainly found in the cytoplasm. - humans 1/3 of body’s water found outside cells.

B) Good Solvent:Water can dissolve a wide range of molecules and as

a result:- allows chemical reactions to take place in

water, in the cytoplasm and in cell organelles.- allows many molecules to dissolve in water

for transport in plants and animals.

Importance of Water for living thingsC) Participates in chemical reactions: Water is involved in several biochemical reactions

- Condensation Reactions – smaller molecules join to form larger molecules with the loss of

water e.g. formation of maltose.- Hydrolysis Reactions – a molecule gains water and is broken down to form smaller molecules

e.g. breaking of a dipeptide bond.- Photosynthesis*- Respiration*

D) Movement through membranes: Water can easily pass in and out of cells giving them the correct shape.

Importance of Water for Living things

E) Good absorber of heat: Water is a good absorber of heat energy which provides stable temperatures for living things and their reactions.

Food Test Summary Table

Food tested

Chemicals used Positive result

Starch Iodine Blue Black

Glucose Benedict's soln Red

Fat Brown paper Permanent stain

Protein Sodium hydroxide + copper sulphate

purple