Food biology leaving cert

Nutrition

The way in which an organism obtains and uses food

Function of food

Source of energy, to make chemicals needed for metabolic reactions, growth and repair

Metabolism

The sum of all the chemical reactions in an organism

Continuity of life

Next generation of the same living thing

6 common elements

Carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulphur (S)

5 elements present in dissolved salts

Sodium (Na) magnesium (Mg) chlorine (Cl) potassium (K) calcium (Ca)

3 trace elements

Iron (Fe) copper (Cu) zinc (Zn)

Biomolecules/biochemicals

Are chemicals that are made inside a living thing

Carbohydrates

Carbon hydrogen oxygen Cx(H2H12O)y
Twice as much hydrogen
C6H12O6

1. Monosaccharides

Single sugar unit
Sweet to taste
Soluble in water

GLUCOSE

Organisms get energy from this
Found in fruit sweets chocolate
Made in photosynthesis

Fructose

Found in fruits

2. Disaccharides

Sweet to taste
Soluble in water
Two monosaccharides joined together

Sucrose (table sugar)

Glycose+fructose

Maltose

Glucose + glucose

Lactose (milk)

Glucose +galactose

3. Polysaccharides

Insoluble in water
Not sweet to taste
Many monosaccharides joined together

Starch

Stored in plants
Long chain of glucose
Easily digested (glucose molecules joined together in a straight line)
Rice potatoes flour

Cellulose

Not easily digested due to cross bonding
Used as a fibre in diet
Very strong cell walls

Glycogen

Stored by animals in the liver and muscles

Structural role carbs

Used to form plant cell walls

Metabolic role carbs

Energy store in all plants (starch)
Broken down in respiration to release energy (glucose)
Energy is used to carry out other metabolic reactions

Lipids

Carbon hydrogen oxygen
Very little oxygen
Fats solid at room temperature
Lipids liquid at room temperature

Triglyceride

One molecule of glycerol
Three fatty acids

Phospholipids

Fat like substance where one of the fatty acids is replaced by a phosphate

Sources of lipids

Butter cod liver oil cream fat on meat olives

Structural role lipids

Stores energy twice as much energy than carbohydrate
Heat insulation
Protection of organs
Cell membranes

Metabolic role lipids

Broken Down in respiration to release energy
Energy is used to carry out other metabolic reactions

Proteins

Carbon hydrogen nitrogen sulphur phosphorus

Structure of protein

20 amino acids
Peptide : Bond between acids
Less than 20 amino acids
Polypeptide: less than 200 amino acids
Protein: more than 200 amino acids

Fibrous proteins

Little or no folding
Form long fibres
Strong and tough
Keratin in nails myosin in muscles

Globular proteins

Lots of folding
Form rounded shapes
Enzymes anti bodies hormones

Sources of protein

Meat fish eggs nuts peas

Structural role protein

Fibrous proteins eg keratin in nails

Metabolic role protein

Used as enzymes to control metabolic reactions
Anti bodies are used to fight infections
Hormones are used to regulate body reactions

Vitamins

Carbon based
Needed only in tiny amounts
Body cannot make

Water soluble vitamin

Vitamin C
Ascorbic acid
Soluble in water

Sources of vit C

Veg fresh fruit eg oranges

Metabolic role of vit C

Formation of connecting tissue eg skin gums
Growth and maintenance of bones and teeth
Immune system
Help wounds heal

Deficiency of vit C

Scurvy
Bleeding gums
Loose teeth
Poor healing of skin

Fat soluble vitamin

Vit D
Most common = vit D2 (calciferol)

Sources of vit D

Liver milk egg yolk fish oil sunlight

Metabolic role of vit D

Helps absorb calcium
Needed for healthy teeth and bone formation

Deficiency of vit D

Rickets in children
Osteomalacia in adults
Weak deformed bones
Break easily

Water

Makes up most of cytoplasm in cells
Found in tissue flood which surround all body cells
Plasma, liquid part of blood
Good solvent
Allows chemical reactions to take place
Can move in and out through cell membranes
Good absorber or heat

Anabolic reactions

Energy is taken in and smaller molecules are converted to larger molecules eg photosynthesis

Catabolic reactions

Energy is released when larger molecules are broken down into smaller molecules eg respiration