Experiment 8 - Enzymes Flashcards
Cut thin slices of either apple, guava, or chico and expose them to the air. Observe the darkening of the exposed sliced sides. Explain the color change.
Observations?
The color change is most likely oxygen being introduced into the injured plant tissue. When oxygen is present in cells, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic compounds naturally present in the apple tissues to o-quinones, colorless precursors to brown-colored secondary products.
Catalase from potato: PREPARATION:
Prepare a small potato and grate it into fine pulp.
Mix this pulp with 50 ml of water and let it stand for 15 minutes and strain this thru a piece of cheese cloth.
Filter the extract.
ENZYME ACTION: (peroxidase)
Divide the filtrate into four parts and boil one part for 1 minute.
Place 5 ml of the boiled filtrate in one test tube and 5 ml of the unboiled filtrate in another test tube.
Add to each a few drops of 3% hydrogen peroxide. Note what happens.
Observation:
For the unboiled extract, we can observe more bubbles forming. Meanwhile, the test tube with the boiled extract produces less bubbles. This is because the heat degraded the catalase enzyme, making it incapable of processing the hydrogen peroxide.
The action of peroxidases depends to some extend upon phenol oxides which decomposes the hydrogen peroxide. Potato has both peroxides and phenol oxides. This accounts for the rapidity of actions in the presence of hydrogen peroxide, H2O2.
Amylase from saliva:
Take two 5 mL of starch solution and transfer them in each test tube. Heat one of the starch solution in a water bath until it boils. To both unboiled and boiled starch solutions, add 1 mL of the saliva.
Heat both test tubes in controlled temperature at 38 degrees Celsius in the water bath
Remove the solutions from the water bath then add Fehling’s reagent. Then continue heating them in the water bath
Remove the solutions and observe.
Observations:
We can observe on the unboiled solution that the color turns greenish-blue. Meanwhile, the boiled solution turns into the familiar light blue color of the Fehling’s reagent. This indicates that the boiled solution is positive for sugars.
What does a catalase do? Explain.
A catalase is an enzyme that brings about (catalyzes) the reaction by which hydrogen peroxide is decomposed to water and oxygen.
What is a substrate
The substances with which the enzymes react to
What are the different kinds of catalyst and define each type
Homogeneous catalyst
Heterogeneous catalyst
Heterogenized homogeneous Catalysts
Biocatalysts - Natural proteins (enzymes) or nucleic acids (RNA or ribozymes and DNAs) used to catalyze specific chemical reactions outside the living cells is called biocatalysis
How does an enzyme work?
Enzymes work by binding to reactant molecules and holding them in such a way that the chemical bond-breaking and bond-forming processes take place more readily.
reaction mixture and catalyst both are present in the same phase
homogeneous catalysis
catalysts exist in a different phase than the reaction mixture
Heterogeneous catalyst
in contrast to their homogeneous counterparts are much more difficult to develop practically
Heterogenized homogeneous Catalysts
Natural proteins (enzymes) or nucleic acids (RNA or ribozymes and DNAs) used to catalyze specific chemical reactions outside the living cells
Biocatalysts
