1 / 8

Action of urease

Action of urease. Objectives To look at the action of an enzyme in different temperatures Learn to identify an end point Plan to record results effectively Start to learn skills of analysis and evaluation of results. Background facts.

kalani
Download Presentation

Action of urease

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Action of urease Objectives To look at the action of an enzyme in different temperatures Learn to identify an end point Plan to record results effectively Start to learn skills of analysis and evaluation of results

  2. Background facts Urea is broken down very slowly over time to ammonia and carbon dioxide; This process is much more rapid in the presence of urease Ammonia dissolved in water is an alkali Urea dissolved in water is neutral So the action of urease can be observed by the change in pH of the solution A change in pH can be shown by the presence of an indicator called Phenolphthalein which goes pink in solutions of pH 9 or above.

  3. Practical Each group will investigate a different temperature: 10C, 20C, 30C, 40C, 50C Each group will replicate their experiment three times The end point will be the colour change Each group must record the time from adding the soy bean extract till the colour change is observed.

  4. Equipment • 20 ml 10% solution of fertiliser urea (a solid fertiliser made of pure urea) • 10 ml soya bean extract, prepared as described below (from 1 g of dried soya beans) • 10 ml distilled water • Pasteur pipettes for transferring the solutions • 3 test tubes and a test tube rack. • Phenolphthalein indicator • Thermometer • 250ml beaker of water, bunsen burner and tripod

  5. Preparation of urease– done for you! • Soak the soya beans in water for at least 1 h (preferably overnight). • Blend the soaked soya beans in a food blender with about 10 ml of water per gram of dry soya (the water from soaking the beans can be used) until the mixture is smooth (for about 5 min). • Filter the soya purée through filter paper in a funnel. • Collect and keep the filtrate, which contains urease.

  6. Method • Add 2 ml of indicator to each of three fresh tubes. • Place in beaker of water heated to desired temperature. Put tube of soy solution in as well to warm it to correct temperature • Mix 2 ml of urea solution into each of the three tubes. Note the colour. Leave for a couple of minutes • Add 2 ml of the soya suspension to one. • Start timing instantly. Note time of colour change and which tubes change. • You need to repeat this with each of the three tubes. I advise you check the temperature and reheat to correct temperature in between tests.

  7. Results Work out how to record your results – draw up your own results table Collect class results (10 marks given for table of results)

  8. Questions 1. Why was it important to replicate the results? 2. Name two variables that were controlled to ensure a fair test 3. Plot the class results on a line graph (6 marks) 4. Explain the class results using Q10 and lock and key theory in your explanation 5. If class results don’t fit these explanations explain why and suggest reasons for the experiment not to have worked. 20 marks

More Related