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Enzyme concentrations using trypsin enzume and casein solution

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Introduction

Enzyme concentrations using trypsin enzyme and casein solution Aim To investigate the effect of a reduction in enzyme concentration on the rate of reaction, in this case the breakdown of protein by protease enzyme. The protein substrate we are using is casein (found in milk which makes the milk cloudy). The protease enzyme, trypsin, breaks down the protein (polypeptide). Trypsin is an enzyme found in the small intestine, and is produced in the pancreas. These enzymes woks best in alkaline conditions. Hypothesis The higher the enzyme concentration, the faster the protein trypsin (substrate) will be broken down. The protein solution would turn clearer when enzymes are more concentrated. The site of the reaction occurs in an area on the surface of the protein (protease) called the active site. At low enzyme concentration, there is great competition for the active sites and the rate of the reaction is slow. With a higher concentration, there are more active sites so there is more of a chance of collisions between enzymes and the substrate molecules. The rate of reaction and rate of colliding can proceed at a faster rate. Equipment * 1% trypsin * 5% casein solution (milk powder) * 10 Boiling tubes * Labels * Syringes (measure small volumes 1cm3 and 5cm3) * Water bath - 30� * Colorimeter - measure transmission * Distilled water * Stop clock * Pipettes Procedure 1. ...read more.

Middle

During this experiment, because I will need to measure volumes less than 1cm3, it is more suitable for a 1cm3 syringe to be used, rather than a 5cm3 or 10cm3 syringe. The systematic errors could be when using the colorimeter, the cuvette could be dirty or the cuvette could be scratched, the error introduced would be the same throughout the investigation. The incorrect use of equipment could cause systematic errors. By not calibrating the colorimeter before use could cause errors. Additionally reading volumes in pipettes and syringes could cause faulty measurements (parallax on measuring). The water bath could be slightly out, because the temperature may not be exactly 300C. The random errors may be reading the volumes, or not precisely measuring out the volumes. Carelessness, like not concentrating on times that is meant to use during the experiment. Risk assessment * Be careful not to bump into the water bath, this could spill the water, cause injury or cause people to slip and get injured. * When transferring the liquids from different boiling tube, use tongs or heatproof mats to prevent scolding of the hands. * Carelessness could cause the boiling tubes to break, causing an injury. * Ensure all glass apparatus are kept in the middle of the worktop. * Ensure goggles are worn because trypsin is a protease enzyme. ...read more.

Conclusion

0.75% had the smallest error bars, whereas the to results which had the largest error bars were on 0.25% at 10 and 20 minutes. Though, the smallest error bar was also on the 0.75% line, which ranged from 30 to 32. Errors Calibrating the colorimeter could not have caused systematic errors, because the colorimeter was calibrated before use and checked. Reading and measuring out volumes incorrectly throughout the experiment could have caused errors. Even though time was vey specific and important in the experiment, there still could have been delays, which meant the solutions were left in the water bath longer then they should have been before taking a sample. The water bath could have been slightly out in the water bath. Results were collected three times from each group so the mean from each concentration could be calculated, also this would improve validity of the results. To improve results each group could have carried out the experiment two or three times between themselves. Evaluation For a given enzyme concentration, the rate of reaction increases with increasing substrate concentration up to a point, above which any further increase in substrate concentration produces no significant change in reaction rate. This is because the active sites of the enzyme molecules at any given moment are virtually saturated with substrate. The enzyme/substrate complex has to dissociate before the active sites are free to accommodate more substrate. Rianne Malcolm 12H ...read more.

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**
Research and rationale
There is little evidence of any background research to justify the investigation. There are no references listed. Appropriate biological principles are not discussed with reference to the investigation.
Planning
A testable hypothesis has been stated and some biological knowledge used to explain the prediction. Some of the key variables to be controlled are described but additional details could be provided. The apparatus is listed but not all justified. A range of concentrations is identified but there is no indication as to why this range was chosen. It would have been better f the candidate had repeated the collection of data and then compared these to class results.
The attempts to assess safety are superficial.
Implementing
It appears that the apparatus was used competently. The data was not recorded in a suitably headed table. Units and headings were both missing.
Analysing
The trends and patterns in the data were recognized and commented on but the term rate of reaction was used inappropriately. The explanations were sound and related to basic biological knowledge. The graph was not available to view. Summary tables were not presented and there seems to be no recorded statistical information such as the calculation of a standard error.
Evaluation
The paragraph under the heading of evaluation was not an evaluation but a conclusion.
Communicating
The layout of the report was acceptable but data was not presented effectively using SI units where appropriate. There were minor spelling and grammatical errors but technical terms were used appropriately throughout. There were no references used or evaluated.

Marked by teacher Stevie Fleming 01/01/1970

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