Food Flashcards
(15 cards)
Functions of Food
- Energy
. Main source: Carbs
. Comes from protein (deamination) and fats (ketosis) too.
. Growth of new cells (continuity) and repair existing cells, tissues,organs etc.
Needed for Movement, active transport
. Supplies materials for metabolism - sum of all chemical reactions occurring in the body
Elements in Food
Food also supplies the materials and energy for the process of:
- Metabolism
Sum of all chemical reactions occurring in the body. - Continuity
Reproduction, growth.
Chemical Elements
6 main elements
• Carbon
• Hydrogen
• Oxygen
• Nitrogen
(Most common, make up 96% of an organisms weight in carbs, lipids and proteins)
• Phosphorus
• Sulfur
(Amino Acids)
5 elements dissolved in Salts
• Sodium (Na)
• Magnesium (Mg)
• Chlorine (Cl)
• Potassium (K)
• Calcium (Ca)
(Need 100mg or more of these every day, also known as mineral salts)
3 trace elements
• Iron (Fe)
• Copper (Cu)
• Zinc (Zn)
(Need less than 100mg of these every day)
Bio molecules
Molecules in living things (found or created in) Contain carbon and are also known as biochemicals.
4 main types are:
• Carbohydrates
• Lipids (fats and oils)
• Proteins
• Minerals
The 14 elements combine in different ratios to form different food components (bio molecular units).
E.g plants use carbon dioxide and water to combine carbon, hydrogen and oxygen to make bio molecules of glucose C6H12O6
Carbohydrates
Main source of energy in the diet
Contains the elements carbon, hydrogen and oxygen in the ratio of 1C:2H:1O
E.g - Glucose
3 types of Carbohydrates
Monosaccharides - Glucose, Fructose
Disaccharides - Sucrose
Polysaccharides - Starch (Storage), Cellulose (structural), Chitin (cell wall of fungi)
Monosaccharides
• Single Sugar molecules
• Simple sugars
• Soluble in water
• Sweet to taste
• Smallest carbohydrate unit
Found in: Fruit
Disaccharides
• Two monosaccharides sugar units joined together - known as double sugar molecules
• Soluble in water
• Sweet to taste
• e.g Sucrose, Lactose, Maltose
• Found in: Table Sugar, Milk
Polysaccharides
• Many monosaccharides molecules joined together
• Not soluble in water
• Does not taste sweet
• e.g Starch, Cellulose
Found in: Bread, Pasta, Cereals
Cellulose
• From the cell wall in plants - structural carbohydrate
• provides strength and support to plants
• Role: Called ‘Fibre’ or ‘Roughage’
• Found in: Vegetables, Bran
Lipids
Contain the elements carbon, hydrogen and oxygen - but in a different ratios to form to carbohydrates.
Diverse group of substance which include fats and oils.
Fats: Solid at room temperature
Oils: Liquid at room temperature
Basic unit of lipid is triglyceride which is made of three fatty acids and one glycerol.
Phospholipids are fat like substances in which a fatty acid is removed and is replaced by a phosphate.
Lipid Function
• Long term store energy
• Lipids under the skin used for insulation (subcutaneous).
• Provide protection to certain organs e.g kidneys
• Phospholipids have a structural role in cell membranes.
Proteins
• Source of protein: Fish, eggs, chicken, meat, legumes, vegetables.
• Contains the elements carbon, hydrogen and oxygen, nitrogen.
Composed of 20 amino acids together
• Protease enzymes break these bonds
• Protein synthesis: Ribosome makes these bonds
Peptide - less than 20 amino acids
Polypeptide - greater than 20 amino acids
Protein - chain of more than 200 amino acids
Protein types
Globular Proteins - Alburen ( egg whites) - Metabolic
Fibrous Proteins - Keratin and Collagen - Structural
Globular Proteins -
Amino acid chains are folded into a 3-dimensional shape
e.g Enzymes - They carry out biological reactions
Fibrous Proteins
- Amino acid chains are folded into a helixes or B pleated sheets.
e.g muscle fibres and hair
Role of Protein
• Structural
Fibrous proteins form keratin which makes hair, skin, and nails
Myosin forms muscles
• Enzymes
Globular proteins control reactions in cells
Vitamins
