Enzymes

What is an enzyme? Provide 1 example

An enzyme is a biological catalyst that speeds up chemical reactions without getting used up in the process.

1 example includes Amalyse.

What is a substrate?

A substrate attatches to the enzyme during chemical reactions.

What is the enzyme-substrate complex. Why does it form?

1. An enzyme-substrate complex is the enzyme and substrate connected together.

2. This is because the active site of the enzyme has a complementary shape to the specific substrate: the enzyme will only join to a specific substrate to form an enzyme-substrate complex

When does an enzyme denature?

1.At very high temperatures.

2. At very high pH's

3.At very low pH's

What does optimum temperature mean?

The optimum temperature is the temperature at which enzymes operate the most efficient at.

What does optimum pH mean?

The optimum pH is the pH at which the enzyme operates the most efficiently at.

What does it mean when an enzyme denatures?

1. When an enzyme denatures, it loses the shape of its active site

2. Enzyme can no longer bind to any substrate: enzyme-substrate complexes will not be formed

3. An enzyme will not be able to catalyse any chemical reactions(the enzyme may not function normally/ may not function at all)

What is the active site of an enzyme?

The active site of an enzyme is the point where the substrate attatches, to start the chemical reaction.

Please explain the enzyme( and pH both similar) graph.

In Biology( your personal) workbook.

What is the substrate concentration?

The amount of the substrate that attatches to the enzyme.

What is pH?

The percentage of hydrogen in a substance.

What is an independent variable?

An independent variable is the factor(s) that we continually change and manipulate, to see if there are effects to the dependent variable

What is a dependent variable?

A dependent variable is the variable that is affected by the changes of the independent variable.

What is a control?

The control is the factor(s) that we must implement to reduce the effect of variables, on the dependent variable, apart from the independent variable.

Enzyme action (practical), instruments to use.

-Spotting tile

- 1 test tube of starch and pH buffer solution

-1 test tube of amylase

-dropping pipette

-dropper bottle of iodine

-measuring cylinder

-stopclock/stopwatch

Enzyme action( practical) steps( MEMORISE)

1. First, fill all 12 wells of a spotting tile with iodine, using a dropping pipette.

2. Fill one test tube with 1cm3 of starch solution and 1cm3 of buffer solution, with a different dropping pipette.

3. Fill another test tube with 2cm3 of amalyse, using a different dropping pippette.

4. Place both test tubes in a water bath, set to 37 degrees celsius, and wait 5 minutes for the contents to aclimate.

5. After the aclimation, use a different dropping pipette to place 1 drop of the buffer and starch solution into well 1 of the spotting tile. This tile is the control to see what color trend we should witness.

6. Mix the test tubes into one clean test tube. This means that we have 1 test tube( 4cm3) of amylase,starch, and buffer solution.

7. From this point, we have to add a drop of the contents of this beaker to the remaining 11 wells every 60 seconds. This is because 1 minute corresponds to an additional pH.

8. At around 7 mins( well 8), we would find a general fade from blue-black to red-brown. This is because ph8 is the optimal pH for amalyse to break down the starch

9. At 11 minutes( well 12), the colour of the well will be the natural colour of iodine. This is because all the starch has been broken down by the enzyme amylase.

In practicals, why must we always have more of the enzyme than substrate.

During this particular practical, we work with 2x the amount of the enzyme than the substrate. This is so the enzyme does not become a limiting factor.

Moreover, if a larger amount of the substrate( than enzyme) is operated with, then the enzyme will not be able to break down the substrate( as it will not be able to fit in the active site), leading to no chemical reaction.

What is the independent variable in this practical?

The different pHs that we used.

What is the dependent variable in this practical?

The time taken for iodine to change from blue-black back to red-brown.

Remember when the colour of iodine( its natural colour) remains unchanged, the practical ceases.

What is the control?

1. The volumes of the starch and buffer solution( 1cm3 each), and the volume of amylase( 2cm3).

2. The temperature of the water bath = 37*C

What is the optimum temperature for plants and yeast?

1. 20-30*C

2. Specifically mention 25*C

What is the optimum temperature for animals?

37*C