Biological Molecules Flashcards
What elements are carbohydrates made up of?
- Carbon
- Oxygen
- Hydrogen
What elements are lipids made up of?
- Carbon
- Oxygen
- Hydrogen
What elements are protein made up of?
- Carbon
- Oxygen
- Hydrogen
- Nitrogen
- Sometimes sulphur
What are the monomers of carbohydrates?
Simple sugars
What are the monomers of lipids?
3 fatty acid molecules and a glycerol molecule
What are the monomers of proteins?
Amino acids
Describe the test for the presence of glucose (2)
- Benedict’s solution
- Heat in 60°C water bath
Colour change for presence of glucose
Blue to green/yellow/brick red (low to high concentration)
Describe the test for the presence of starch
Iodine solution
Colour change for presence of starch
Yellow to blue-black
Describe the test for the presence of protein
Biuret solution
Colour change for presence of protein
Blue to lilac purple
Describe the test for the presence of fat (2)
- Add 2cm3 ethanol
- Add 2cm3 distilled water
Colour change for presence of fat
Milky white emulsion will form
What are enzymes? (3)
- Biological catalysts in metabolic reactions
- Increases the rate of reaction without being used up
- The shape of the substrate is complementary to the shape of the active site
What is the effect of temperature on enzyme function? (3)
- Before optimum: temperature increases = rate of reaction increases
- Optimum: 37°C for body temperature
- After optimum: bonds in the structure will break, changes shape of active site so substrate can no longer fit in = denatured
Investigate how enzyme activity can be affected by changes in temperature (5)
- Starch solution is heated
- Amylase added
- Iodine added to each well
- Measure the time until iodine stops turning blue-black (starch is no longer present)
- Repeat for different temperatures
What is the effect of pH on enzyme function? (2)
- pH too high or too low: forces that hold the amino acid chains are affected
- Changes the shape of the active site = denatured
Investigate how enzyme activity can be affected by changes in pH (7)
- Beaker of water on a gauze above a bunsen burner (so temperature is a controlled variable)
- Iodine added to each well
- Add 2cm3 of amylase solution, 2cm3 of starch solution and 1cm3 of pH solution in a test tube and mix
- Put test tube in beaker and start a stopwatch
- Every 10 seconds, use a pipette to place solution into one of the wells containing iodine, should turn blue-black
- Keep repeating until solution becomes orange (starch has been full broken down)
- Repeat for different pHs and graph
