Cells and Microscopy II
Enzymes
Enzymes are biological catalysts ( large proteins ) made up of chains of amino acids folded into unique shapes
A catalyst is a substance which increases the speed of a reaction without it being changed or used up in the reaction
Optimum conditions
Temperature, if too hot the bonds breaking the enzyme break, changing the shape of the enzymes active site so the substrate won't fit in anymore.
Concentration, higher the concentration the quicker the reaction until the point where adding more enzymes make no difference as all active sites are full.
PH - If too high or low, it interferes with the bonds holding the enzymes together, changing the shape of the active site and denaturing the enzyme.
Investigating effect of PH on amylase
Set up a Bunsen burner, heatproof mat, tripod and gauze.
Place a beaker of water on the gauze and adjust the flame to keep the water at about 35°C.
Now put two drops of iodine solution into each spot of a spotting tile.
Add 2 cm3 of amylase enzyme solution to a test tube.
Place 2 cm3 of starch solution into the same tube.
Finally add 1 cm3 of pH solution to the tube. This will keep the pH constant.
Mix the solution in the test tube and place it into the beaker of water on the Bunsen burner.
Use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile.
Repeat until the iodine solution stops turning black.
Record the time this takes.
Repeat with different pH solutions.
Rate = 1000 / time
Enzymes in breakdown
Carbohydrase - starch ----> maltose and other sugars
Protease - proteins ----> amino acids
lipase - lipid ---> fatty acids and glycerol
Testing for biological molecules
Reducing sugar Benedict’s Add Benedict’s reagent to the food and boil in a water bath. Blue Brick red precipitate
Starch Iodine Add iodine reagent to the food. Yellow-brown Blue-black
Protein/amino acids Biuret (a mixture of sodium hydroxide and copper sulfate). Add Biuret reagent to the food. Blue Lilac/purple
Fat Ethanol Add ethanol to the food to dissolve the fat then add water. Colourless White emulsion
Transport in cells
Diffusion is the spreading out of particles from an area of higher concentration to lower concentration
Osmosis is the net movement of particles across a partially permeable membrane from a region of high water potential to low water potential
Active trasnport is the movement of particles against a concentration gradient using energy transferred during respiration