Biological molecules Flashcards
What are organic nutrients?
- carbohydrates
- fats
- proteins
- vitamins
- dietary fibre
What are inorganic nutrients?
- mineral salts
- water
What are micronutrients?
- vitamins
- mineral salts
What are macronutrients?
- carbohydrates
- fats
- proteins
- dietary fibre
- water
What are the compounds of carbohydrates and what ratio are they in?
- carbohydrates are made up of oxygen, carbon and hydrogen
- hydrogen and oxygen atoms are in a ratio of 2:1
- e.g. glucose: C6H12O6, Sucrose: C12H22O11
What are the functions of carbohydrates?
- energy respiration (glucose)
- energy storage (glycogen and starch)
- supporting structures (cellulose cell wall)
- to be converted to other organic compounds (e.g. fats)
- lubricants
What are the types of carbohydrates?
- monosaccharides
- disaccharides
- polysaccharides
What are the different types of monosaccharides?
- glucose
- galactose
- fructose
What is the name of the test for reducing sugars?
- benedict’s test for reducing sugars
What is used in the test for reducing sugars?
- sample solution
- benedict’s solution (copper (ll) sulphate)
How is the test for reducing sugars carried out
- add equal volume of benedict’s solution to sample solution
- shake the test tube
- place test tube into boiling water bath for 5 minutes
- observe colour of precipitate formed
What are the different colors of precipitate in the test for reducing sugars and what do they indicate?
- Blue (no reducing sugars present)
- Green (trace amounts of reducing sugars present)
- yellow (moderate amount of reducing sugar present)
- orange
- brick red (high amount of reducing sugar present)
What are some examples of disaccharides?
- lactose
- sucrose
- maltose
What are some examples of polysaccharides?
- starch
- glycogen
- cellulose
How is maltose formed?
- glucose + glucose → maltose
How is sucrose formed?
- glucose + fructose → sucrose
How is lactose formed?
- glucose + galactose → lactose
How are monosaccharides combined to form disaccharides?
- condensation
What is condensation?
- when 2 simple molecules join together
- with the removal of 1 water molecule
How are disaccharides and polysaccharides turned back into monosaccharides?
- hydrolysis
What is hydrolysis?
- when a water molecule is used to split a complex molecule into its component parts with acid or enzyme
What are proteins made of?
- proteins are made up of carbon, hydrogen, oxygen and nitrogen
- sulfur is also often present
What are proteins made up of (basic unit)?
- amino acids
How do amino acids form a polypeptide chain?
- they are linked up
- in a condensation reaction
What are the bonds between amino acids known as?
- peptide bonds
What are proteins made up of (final product)?
- 1 or more polypeptide chains
- they are twisted or coiled into a unique 3-d structure
Why do enzymes (proteins) denature easily?
- bonds that hold the 3-d coiled structure together are weak
- thus by heat, or changes to pH, enzymes denature easily
What does denaturation cause?
- it causes proteins to lose their functions
What are the functions of proteins?
- synthesis of new cells
- growth and repair of cells
- serve as chemical messengers (hormones etc)
- transportation
- structural function
- defence of the body (antibodies)
- energy
What is the test for proteins known as?
- Biuret’s test
What are used in the test for proteins?
- sample solution
- sodium hydroxide
- 1% copper (ll) sulfate
What is the procedure for the test for proteins and what colour is observed?
- add 1cm cube of sodium hydroxide to 2cm cube of sample
- shake
- add 1% copper (ll) sulfate, drop by drop
- add drops and shake until a colour change is observed
- blue to violet indicates the presence of proteins
- blue indicates the absence of proteins
What are fats made of?
- carbon
- hydrogen
- oxygen
What is less than what in fats?
- less oxygen compared to hydrogen
What are the properties of fats?
- insoluble in water
- less dense than water
- conduct heat slowly
What are the functions of fats?
- they store energy
- they store food in animals and humans
- heat insulator
- absorbs shock
What is the test for fats known as?
- ethanol emulsion test
What are used in the ethanol emulsion test?
- sample
- ethanol
- water
What is the procedure of the ethanol emulsion test?
- add 2cm cube of ethanol to sample
- shake
- add 2 cm cube of water
What is the test for starch known as?
- iodine test
What are used in the test for starch?
- iodine
- sample
What is the procedure for the test for starch?
- place the substance on a white tile
- add 2-3 drops of dilute iodine solution to the substance
- observe colour changes
What are the different colours in the test for iodine and what do they mean?
- yellowish-brown to blue-black means starch is present
- is the solution remains yellowish-brown, starch is absent
What to do in case of testing solid foods?
- chop food into smaller pieces
- allow solid particles to settle
- decant liquid only and test
