chapter 4 nutrients Flashcards
define condensation reaction with example
two simple molecules are joined together to form a larger molecule with the removal of 1 water molecule
eg: 2 glucose molecules joined together to form 1 maltose molecule with water molecule produced
define hydrolysis with example
1 water molecule needed to break up a complex molecule into smaller molecules
eg: maltose and water broken down into glucose molecules in presence of maltase
what are carbohydrates
organic compound made of elements carbon C, hydrogen H, oxygen O
formula: CnH2mOm
what are single sugars
Cannot be further digested into smaller molecules
Can pass through cell membrane and be absorbed into cells
Glucose, fructose, galactose
Formula: C6H12O6
what are double sugars
- molecules of single sugars bonded together through condensation reaction
- Maltose (2 glucose), sucrose (glucose + fructose), lactose (glucose + galactose)
- Formula: C12H22O11
- All are reducing sugars except for sucrose
what are complex carbohydrates
Many monosaccharide molecules joined together via condensation reaction
Starch (found in plants),
Cellulose (found in plants), Glycogen (found in mammals)
All 3 are made up of glucose - different arrangements
why is glycogen suitable for storing in cells?
Insoluble in water - do not change water potential in cells
Large molecules - cannot diffuse through cell membrane = will not be lost from the cell
Molecules have compact shapes - occupy less space than individual glucose molecules that make up starch/glycogen molecule
Easily hydrolysed to glucose when needed - complete hydrolysis of starch gives glucose molecules
(Amylase digests starch into maltose, Maltase digests maltose into glucose)
what are fats?
organic compounds made up of carbon, hydrogen and oxygen - contains much less oxygen in proportion to hydrogen (H > O atoms)
proportions of elements are not fixed = no general formula
-> hydrolysis of fats - broken down into simpler substances = fatty acids and glycerol
function of fats
A source and store of energy
Acts as an insulating layer in animals - prevent excessive heat loss
Solvent for fat soluble vitamins
An essential part in protoplasm - especially cell membranes
what are proteins?
organic compounds made up of oxygen, carbon hydrogen and nitrogen - sulfur may be present sometimes
-> structure of protein molecule: amino acid - polypeptide - protein
function of proteins
Synthesis of new protoplasm - for growth/repair of worn out body cells - renew damaged tissue
Synthesis of enzymes and some hormones
Forms antibodies to combat diseases
Build muscle mass = humans/animals require more protein than plants
how to test for starch?
Iodine solution remains yellowish-brown = absence of starch
Iodine solution turns from yellowish-brown to blue-black = presence of starch
how to test for (extent of) reducing sugars?
Solution remains blue = absence of reducing sugar
Solution turns blue to green precipitate = traces of reducing sugar
Solution turns blue to yellow/orange precipitate = Moderate amt of RS
Solutions turns blue to brick red precipitate = large amt of RS
No ppt formed in 2 mins = no RS present
how to test for proteins?
Add equal amount of food sample and Biuret solution
Shake and observe colour
Remain blue = no protein
Blue to violet = protein present
how to test for fats?
solid food: crush food, add 2cm cube of ethanol and shake, decant liquid only into another test tube and add equal vol of water
liquid food: add 2cm3 of ethanol into drop of sample, shake and add equal vol of water
solution clear: no fats
solution has cloudy white emulsion formed: fats present
