• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The effect of temperature on the hydrolysis of starch using amylase extracted from barley.

Extracts from this document...

Introduction

Sasha Caddy, RM11. 20/01/04 The effect of temperature on the hydrolysis of starch using amylase extracted from barley Interpretation of results: Enzymes are a class of proteins that catalyse chemical reactions, which increases the rate of a metabolic reaction. Most enzymes are specific, working on a particular or class of reactions. In this case I am using an enzyme known as amylase (a group of enzymes which convert starch to sugar), which is an important metabolic enzyme. Amylase is found in various parts of the body including the saliva of the parotid gland and the pancreas, e.g. ptyalin, which aids in the digestion of carbohydrates by speeding up specific digestive processes taking place from the mouth to the small intestines. However, in this experiment we are using amylase which has been extracted from barley. The function of amylase is to catalyze (to modify the rate of a chemical reaction by catalysis) the hydrolysis (decomposition of a chemical compound by reaction with water) of starch into glucose. Starch is a mixture of two compounds; amylose and amylopectin, both of these molecules are polymers which contain a large, variable number of a-glucose molecules linked to each other by condensation. Amylase acts on starch, which is a polysaccharide (a class of carbohydrates; starch, consisting of a number of twenty-five monosaccharides) and breaks it down into maltose, a disaccharide. A disaccharide is defined as any class of carbohydrates; maltose, that yield two monosaccharides upon hydrolysis. ...read more.

Middle

This causes them to react more efficiently as this results in more enzyme-substrate complexes and in turn the formation of more products. At low temperatures e.g. 15 C, the molecules will not collide very frequently and the starch will not be broken down as quickly. This shown on the graphs at 15 C and at 0 minutes there is 0% transmission from the colorimeter, meaning that 0% of light can pass through the solution because there is 500mg of starch (shown by the 'Starch Calibration Curve'). As time increases to 22 minutes there is a 15% transmission from the colorimeter meaning there is 160mg of starch concentration left in the solution. This is because it has been broken down by amylase at a slow activity rate, so there is a higher concentration of starch left compared to the 25 C (120mg) and 35 C (70mg) results. From the second graph; 'A graph to show the milligrams of starch at minute intervals at different temperatures', it shows that with time, the starch concentration is decreasing for each temperature that is being tested. This graph shows an exponential decay curve of the amount of starch concentration broken down for every x minutes, therefore the substrate will not totally be broken down. This reaction is not a equilibrium reaction because as the starch concentration decreases the enzyme finds it increasingly difficult to find enough substrate to act on. From my results, I can conclude that between temperatures 15 C - 35 C, the efficiency of the enzyme increases with temperature. ...read more.

Conclusion

Another problem with the pipettes is that when the reaction medium was extracted and clearfully put into a diluted iodine solution, during this time the amylase was acting on the starch while this solution was in the pipette. This made the timings recorded slightly out, although this effect may have been lessened with the temperature at 35 C as the mixture was cooling down to room temperature in the pipette. Also we could have possibly swirled the enzyme extract and starch solution together in the water bath so that the substrate and enzyme could mix and the molecules collide. A solution to this whole experiment would have been to automate (convert to a automatic operation) the whole system. This would have allowed a sample of the mixture to be automatically taken every minute or possibly more frequently, and the concentration of the starch stored onto a computer. Carrying out the experiment like this would have solved any inaccuracies in timing, which may not have always been exact when using a stop clock and someone watching the time. This way it would have also removed any human errors e.g. the test tube not being wiped properly before being placed into the colorimeter or didn't shake the reaction medium and diluted iodine solution together enough/too much etc. So if the experiment had use of better apparatus and stricter conditions, my results would have been plotted onto a graph and a more clear and accurate curve would have resulted. In this experiment there were no anomalous results which can be shown from the graphs. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

4 star(s)

****
This account includes detailed background theory and good discussion and evaluation sections. However, in places biological terminology might have been used more carefully.

Marked by teacher Adam Roberts 17/09/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Marked by a teacher

    How does the pH affect the activity of amylase

    3 star(s)

    The changes in the pH of the enzyme affect the ionisation of side groups in the enzymes amino acid residues. This in turn affects the overall shape of the enzyme molecule and affects the efficiency of formation of enzyme-substrate complexes hence the difference in the range of time from 19 minutes to 5.5 minutes.

  2. The Effect Of Temperature On The Action Of Salivary Amylase

    This can be denoted through the changes of color in the each test tube. If we reconnect what was said in the hypothesis "On the other hand we can also assume that enzyme activity can be more valuable when it is close to the body temperature".

  1. Qualitative tests for carbohydrates

    A positive result gives a dark blue-black product. (see fig.4 Iodine test positive result on the right) (www.wikipedia.org - Nov. 2007) e) Bial's test for Pentose - The test reagent consists of orcinol, hydrochloric acid and ferric chloride which dehydrates pentoses to form furfural.

  2. An experiment to investigate the effect of chloride ion concentration on the activity of ...

    That is taking the maximum rate to be when all active sites are saturated. Control of Key variables The key variables elaborated below must be controlled to allow conclusive evidence on the effect of chloride ions. i.e. If a second variable is changed then it is impossible to identify the effect of a single variable.

  1. Acid Hydrolysis of Polysaccharides.

    The highly branched structure is important for the metabolism of the glycogen molecule, as it maximises the surface area available for reaction, while its spherical shape allows the molecule to travel unimpeded through the blood, and not 'snag'. Amylose Amylopectin Glycogen Cellulose Aim: To compare the hydrolysis of glycogen, starch and cellulose.

  2. The Effect of Concentration on Pectinase Using Apple

    I have chosen to use 5.00%, 2.50%, 1.00%, 0.50%, 0.25% and 0.10% pectinase solutions. This is a wide range of concentrations that should give a definite indication of the effect of concentration. Dependent Variable This is the variable that the concentration of pectinase will have an effect on.

  1. The investigation to find the effect of glucose concentration on fermentation of yeast.

    at 40 degrees centigrade by means of a water bath. This temperature has been chosen, as it is the optimum temperature for the enzymes to operate at. Beyond this point, although the number of collisions with the active site is increased (the kinetic theory,)

  2. Affect of sucrose concentration on the rate of respiration.

    This may be due to bonds within it being deformed and stressed in the complex, so making them more likely to react. Once the reaction has been catalysed, the products are no longer the right shape to stay in the active site and the complex breaks up, releasing the products and freeing the enzyme for further catalytic action.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work