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澳洲生物论文代写 影响脲酶活性的因素

Aim: To investigate Urease activity and the effect of two other chemicals which are Lead Nitrate, and Thiourea (CS (NH2)2

Background Information

Urease is an enzyme that catalyzes the hydrolysis of urea as shown below:

CO (NH2)2 + H20 CO2 + 2NH3

Ammonia releases and dissolves in water to form ammonium hydroxide, which is a strong base.

NH3 + H20 NH4+ OH-

The level of alkali can be then used as a measure of the speed of the reaction. Universal Indicator solution will be used to measure this.

Research question:

What is the effect of lead nitrate and thiourea activity?

Variables:

Control

Volume of urea, urease, lead nitrate, thiourea, distilled water, Temperature

Independent

Time Interval

Dependent

pH

Hypothesis

I predict that at the conclusion of the experiment Thiourea will function as a modest inhibitor. Because it has a similar molecular formula to Urea, the substrate for the enzyme, so then there will not be sufficient substrate created or even there will not be any substrate formed at all for the Thiourea that would prevent the urea from reacting with the urease. Still, with the addition of Lead Nitrate, increasing the concentration will lead to excess substrate. The lead nitrate will then attach to the urea to destroy the active site to counteract any more ammonia from forming.

Materials and apparatus

6 Boiling tubes

Test tube rack

50cm3 beakers

5cm3 syringe

Stop watch

Urease

Urea

Thiourea

Lead nitrate

pH buffer

Distilled water

Universal indicator

Data logger

Method:

Label boiling tubes from 1-6

In the boiling tube labeled 1, add 2cm3 of buffer solution, 5cm3 of Urea and 5cm3 of distilled water.

In the boiling tube labeled 2, add 2cm3 of buffer solution, 5cm3 of Urea, 2.5cm3 Thiourea and 2.5cm3 of distilled water

In the boiling tube labeled 3, add 2cm3 buffer solution, 5cm3 of Urea and 5cm3 of distilled water.

In the boiling tube labeled 4, add 2cm3 buffer solution, 5cm3 of Urea, 2.5cm3 of lead nitrate and 2.5cm3 of distilled

In the boiling tube labeled 5, add 2cm3 of buffer solution, 5cm3 Urea and 5cm3 of lead nitrate.

In the boiling tube labeled 6, add 2cm3 of buffer solution, 5cm3 of Urea and 10cm3 of distilled water

Add 5 drops of the universal pH indicator to each boiling tube

Add 5cm3 to the boiling tubes labeled 1-5 and mix completely

Using the color scale, find the pH changes in the course of the experiment

Record pH changes in each container using the pH probe with the data logger at a 5 minute interval or20 minutes

Mix the content of each boiling tube from time to time

Record all the other relevant observations.

Results:

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