Nutrients Flashcards
Content • Water and Living Organisms • Carbohydrates, Fats and Proteins • Enzymes
Functions of water
- as a solvent for chemical reactions that take place
- a key component in cells, tissue fluid, digestive juices & blood
- helps to control body temp. through sweating - as water in sweat evaporate of skin surface, latent heat of vaporisation is removed, cooling down the body
- transport dissolved substances such as digested products & waste products
Define carbohydrates
Carbohydrates are organic molecules made up carbon, hydrogen & oxygen (H:O atoms = 2:1)
Monosaccharides eg
glucose, fructose, galactose
Disaccharides eg
maltose, sucrose & lactose
Define condensation reaction
A condensation reaction is a chemical reaction in which 2 simple molecules are joined tgt to form a larger molecule with the removal (release) of 1 molecule of water
Define hydrolytic reaction or hydrolysis
Hydrolysis or a hydrolytic reaction is a reaction in which 1 water molecule is needed to break up a complex molecule into smaller molecules
- use an enzyme
Test for reducing sugars
Carry out the Benedict’s test
- Add 2 cubic cm of Benedict’s solution to 2 cubic cm of food sample in test tube (1:1)
- Shake the mixture
- Heat contents in a boiling water bath for 2-3 minutes
Determining amount of reducing sugar present
- Solution remained blue: no RS
Presence of… - Green ppt: Traces amnt of RS
- Yellow or orange ppt: Moderate amnt of RS
- Brick-red ppt: Large amnt of RS
Why are glycogen & starch suitable as storage materials in cells?
- insoluble in water so they do not change the water potential in cells
- large molecules - cannot diffuse through CSM so they will not be lost from cell
- easily hydrolysed to glucose when needed
- molecules have compact shapes so they occupy less space than individual glucose molecules
Functions of carbohydrates
- to provide energy for cell activities
- to form supporting structures such as cell walls (cellulose)
- to be converted into other organic compounds such as amino acids & fats
- to form nucleic acids in DNA
- to synthesise lubricants
- for nectar production in flowers
Define fats
Fats are organic molecules made up of carbon, hydrogen & oxygen (much less oxygen in proportion to hydrogen)
What is the result of hydrolysis of fats?
One fat molecule will be broken down into glycerol & 3 fatty acid molecules/fatty acid chains
- involves addition of 3 water molecules & enzyme
What are the differences b/w saturated & unsaturated fats?
Saturated: fatty acid chain - straight, solid @ RT
Unsaturated: fatty acid chain - have kink/bent, liquid @ RT
How do we test for fats?
ethanol emulsion test
1. Add 2 cubic cm of ethanol to 2 cubic cm of food sample in a test tube
2. Shake contents vigorously
3. Decant 2 cubic cm of water into test tube & shake the mixture
Indication of presence of fats
A cloudy white emulsion is formed