nutrients Flashcards
(20 cards)
definition of nutrients
chemical substances in food that provide energy and materials needed by the body
what elements are carbohydrates made up of?
carbon, hydrogen, oxygen
three monosaccharides
glucose, fructose, galactose
three disaccharides
sucrose, maltose, lactose,
condensation reaction
a chemical reaction in which 2 molecules are joined together to form a larger molecule with the removal of one molecule of water
hydrolysis / hydrolytic reaction
a chemical reaction in which a water molecule is needed to break up a complex molecule into smaller molecules
three polysaccharides and each of its function
starch - made and stored in plants
glycogen - made and stored in animals
cellulose - forms main parts of the cell wall
elements that proteins are made up of
carbon, hydrogen, oxygen, nitrogen
- insoluble in water
- large molecules and cannot diffuse through cell membrane
- can be easily hydrolysed to glucose when needed
anino acids are the…
building blocks of protein
what happens to the animo acids when formed into polypeptides?
animo acids link up to form polypeptides
how to get a complex and 3D shape from amino acids?
chains are coiled or folded giving the protein a more complex and 3D shape
what happens when the amino acid bonds are broken?
the protein loses its three-dimensional shape
protein has been denatured
what elements are fats made up of?
carbon, hydrogen, oxygen
what makes up one fat molecule?
1 glycerol and 3 fatty acids
how to test for reducing sugar?
Benedict’s Test
1) add 2cm3 of Benedict’s Solution to 2cm3 of glucose solution (reducing sugar)
2) shake the mixture
3) Leave the test tube in a breaker of boiling water for 5 minutes
(blue to green -> traces of reducing sugar)
(blue to yellow -> moderate amt of reducing sugar)
(blue to brick red -> large amt of reducing sugar)
how to test for starch?
Iodine test
- Add a few drops of iodine to the sample
(turns dark-blue/ blue-black -> starch present)
(remains brown -> starch not present)
how to test for fats?
ethanol emulsion test
1) add 2cm3 of ethanol to a drop of liquid food/ solid food and shake the mixture throughly
2) add 2cm3 of wated to the mixture and shake the mixture
(cloudy white emulsion formed -> fats present)
(no cloudy white emulsion formed -> fats absent)
how to test for proteins?
biuret test
1) add 1cm3 of sodijm hydroxide to 2cm3 of egg white solution
2) add 1% copper(II) sulfate solution, drop by drop, shaking after every drop
3) shake well and allow mixture to stand for 5 minutes
(mixture turns violet -> proteins present)
(mixture remains blue -> proteins absent)
5 reducing sugars
Lactose
Glucose
Maltose
Fructose
Galactose
