BIOMOLECULES Flashcards
State the main role of carbohydrates
immediate source of energy
state the main roles of proteins
growth and repair of cells
State the main role of fats
Insulation
long-term storage of energy
Name the test of starch and its procedure
Iodine test
Add 2 drops of iodine solution to 2cm3 sample
What should you observe when starch is present
Reaction mixture turned blue-black
What should you observe when starch is absent
Reaction mixture remained yellowish-brown
Name the Reducing sugar test & procedure
Add 2cm3 Benedict’s solution to 2cm3 sample solution in test tube
Shake well
Heat for 2-3 min in boiling water bath
Observation for LARGE amount of RS present
Brick red ppt form
Observation for MODERATE amount of RS present
Benedict solution turned from blue to orange
Observation for TRACE amount of RS present
Benedict’s solution turned from blue to green
Observation for NO amount of RS present
Benedict solution remained blue
Name the protein test and describe its procedure
Biuret test
Add 2cm3 sodium hydroxide to 2cm3 sample solution in test tube
Shake well
Add 1% copper (II) sulfate solution dropwise.
Shake after each drop
Observations for protein present
Violet coloration observed
Observations for protein absent
Reaction mixture remained blue
Name the fat test & describe the procedure for LIQUID SAMPLE
Ethanol-emulsion test
Add 2cm3 ethanol to 2cm3 sample solution in test tube
Shake well
Decant ethanol layer into 2cm3 deionised water
Name the fat test for SOLID SAMPLE and the procedure
Ethanol-emulsion test
Cut the sample into smaller pieces and put in test tube. Add 2cm3 ethanol.
Shake well
Decant ethanol layer into 2cm3 deionised water
Fill in the blanks: _ molecules are synthesised from _ _ units
large molecules are synthesised from smaller basic units
Name the large molecules and smaller basic units for carbohydrates
Large: Starch, Cellulose, Glycogen
Basic unit: Glucose
Name the large molecules and smaller basic units for proteins
Large: Polypeptides & Proteins (E.g Enzymes, antibodies, haemoglobin, insulin)
Basic unit: amino acids
Name the large molecules and smaller basic units for fats
Large molecule: fats
Basic units: 3 x Glycerol & 1 x Fatty acids
What is the definition of enzymes?
Biological catalyst
Protein
Speed up rate of chemical reaction (i.e. catalyse a reaction)
Remain chemically unchanged at end of reaction
Other Properties of enzymes
Specific action
Present in minute quantities
What is the mode of action of enzymes & explain it
Enzyme’s active site has a complementary shape to substrate
Substrate fit into active site of enzyme
to form an enzyme-substrate complex.
Chemical reaction occurs and products form.
explain the effects of temperature on the rate of enzyme-catalysed reactions
At very low temperatures,
enzymes are inactive
Below optimum temperature,
Temperature ↑ → kinetic energy of enzyme (E) and substrate (S) molecules ↑
↑ frequency of effective collisions between E active site and the S molecules
Increased rate of enzyme-substrate (ES) complexes formed
RoR ↑
At optimum temperature,
Enzyme is most active
(40°C-45°C in humans)
RoR is maximum
Above optimum temperature,
Bonds maintaining 3D shape of enzyme overcome
Active site loses specific 3D shape
Active site is no longer complementary to the substrate
S molecules cannot bind to form ES complex
RoR ↓
E denatures
