The Factors Affecting Saccharomyces Cerevisiae Population Growth Biology Essay

Thousands of chemical reactions are carried out within a cell. These reactions most of the times occur in a really slow rate. For that ground populating beings make biological accelerators which are called enzymes and rush up these reactions. ā€œ Enzymes are ball-shaped proteins which act as accelerators of chemical reactions ā€ ( Allot, 2007 ; p.18. Besides cells can command which reaction occurs in their cytol by doing some enzymes and non others. Enzymes achieve to increase the rate of a reaction by diminishing the activation energy ( the lower limit sum of energy required for a reaction to happen ) ( Greenwood. Et Al. 2007 ; p.167 ) of the substrate or the substrates, when adhering to the activation site ( Greenwood. et Al. 2007 ; p.114 ) .

Enzymes are sensitive molecules with really specific construction which enables them to transport out specific reactions. This construction including the active site can be damaged by assorted conditions and substrates. This harm is called denaturation and is normally lasting for an enzyme and if denaturation is occurred the enzyme can no longer transport out its map. As a consequence when enzymes are required to catalyse a reaction, is necessary that they have appropriate conditions. Different enzymes have different ideal conditions called optimum. The factors that affect the enzyme activity are: the temperature, the pH, the substrate concentration.

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Comparing the different temperatures that the S. cerevisiae population left to turn, it can be seen based on both the cell concentration and the graph that below 30oC the population tends to turn more as the temperature increases ; the barm population about doubles when temperature increases from 5oC to 15oC and about three-base hits when temperature increases from 15oC to 30oC. Above 30oC the growing of the population is extremely decreased ; yeast population becomes about 3.5 times less when temperature increases from 30oC to 50oC and when temperature increases from 50oC to 60oC the population decreases really somewhat. As a consequence, the highest S. cerevisiae population growing is observed at 30oC. Consequently this should be the optimal temperature. Furthermore below the optimal point, as temperature increases the population increases more from its initial value than it does at temperatures above the optimal point. Besides, it can be seen that the standard divergence varies between different temperatures. The standard divergence in 15oC ( 7146.4 cells/mL ) is higher than 5oC ( 4682.8 cells/mL ) . The standard divergence at 60oC ( 5449.4 cells/mL ) and 50oC ( 5180.7 cells/mL ) is really near. The standard divergence at 30oC ( 24235.5 ) is the highest of all the other temperatures. Overall the hypothesis 1 is confirmed.

Testing Hypothesis 2:

Measuring the yeast population growing at the different pH degrees, it can be seen that the addition of population above and below the value of pH 6 is about the same. The fact that at pH 6 it is observed the highest population growing implies that this is the optimal pH degree. The lowest growing is observed at pH 3 and pH 8. In these specific pH degrees the growing is somewhat higher at pH 8 ( population increases about 1.7 times ) than it is at pH 3 ( population increases about 1.3 times ) . The growing is higher in pH 8 as it is closer to the optimal pH. At pH 4 the addition in population is about the same as it is at pH 8. Both pH 4 and pH 8 differ by 2 pH degrees from the optimal degree but the yeast population at pH 4 additions about 1.982 times where at pH 8 the population increases 1.7 times. This shows that S. cerevisiae operates better at acidic conditions. The standard divergence at pH 3 ( 4621.4 cells/mL ) is lower of that at pH 8 ( 5855.4 cells/mL ) and pH 4 ( 9470.8 cells/mL ) . Furthermore the standard divergence of pH 4 is higher than it is at pH 8. The hishest divergence is observed at pH 6 ( 14029.9 ) . Overall hypothesis 2 is confirmed.

Testing Hypothesis 3:

Analyzing the growing of S. cerevisiae at different glucose concentrations and for 24 hours of agitation, the consequences obtained show that in the absence of glucose ( 0 mL glucose ) from the civilization the barm population did nā€™t increase at all. The lone addition that was observed from its initial population was 1.091.1 times, intending that this 0.1 addition may hold occurred due to the capacity of energy within the barm cells. At 1mL glucose concentration it was observed sufficient growing. The barm population about doubled from its initial value ( increased about by 1.8 times ) . In higher glucose concentration ( 2mL glucose ) the barm cells population respond greater and as a consequence a higher population growing was observed. The initial population increased 3.9 times, significance that about quadrupled. In even higher glucose concentrations ( 3 mL glucose ) the population increased extremely once more but non plenty so to be able to state that at 24 hours of agitation S. cerevisiae requires more energy to make the maximal reproduction capacity. The population increased 3.954.00 times, about the same of that of 2mL concentration. Furthermore, based on the graph plotted for glucose concentrations, it can be seen that after 2mL of 2 % glucose concentration the yeast population reaches plateau without any farther addition. So the modification growing glucose concentration is at 2mL. The standard divergence at 0mL ( 5642.6 cells/mL ) is lower than it is at 1mL ( 6812.5 cells/mL ) . At 2mL the standard divergence ( 8855.0 cells/mL ) is the highest of all. The standard divergence at 3mL ( 5780.2 cells/mL ) is lowest than it is at 2mL. Overall the hypothesis 3 is confirmed.

Testing hypotheses 1, 2, 3:

Based on the three different hypotheses it can be clearly seen that in conditions in which there is highest growing of S. cerevisiae cells there is highest standard divergence. At optimal conditions where it is observed the highest growing, there is besides the highest standard divergence. In conditions where there is small growing there is besides little standard divergence and additions when conditions improve. In hypothesis 3, where the standard divergence is smaller in 3mL ( 5780.2 cells/mL ) than in 2mL ( 8855.0 cells/mL ) besides the fact that was about equal high growing, shows that in 3mL there was more sufficient glucose and therefore more cells performed good and as a consequence there was more equal distribution. A possible account for the recreation of the remainder of the factors could be that: Since the overall growing conditions were non ideal in all foods, some cells performed better and some worse. This is more obvious when the barm grows at the optimal pH, Temperature and Glucose. The standard divergence additions at the optimal conditions compared to the other pH, temperatures and glucose concentrations where it is smaller. This shows that growing is variable even though these factors are optimal because other foods are needed for consistent growing.

4.3 Failings and Improvements



In the populations of barms cells that were counted in the microscope, there were both alive and dead cells

or denaturated cells.

A dye such as methylene blue could be used to find in each numbering the unrecorded and the dead or inactive cells. The cells which would stay colourless would bespeak enzyme activity and the dead or denaturated cells would be turned into bluish.

Methylene blue should be used merely after the agitation has finished because it inhibits the barm cells by devouring the H ions that are produced during respiration.

The trial tubing, where the barm civilizations were left for agitation, were somewhat closed on the top with cotton in order to forestall the entryway of other micro-organisms. This cotton stopper prevented the easy flow of fresh air inside the trial tubing. This limited the handiness of O supply that the barms required in order to turn aerobically.

The trial tubing can be placed to ferment aerobically in a closed container such as BioFlo 3000[ 17 ]. This sort of bio treating systems provide a broad scope of options that enables the research worker to set a standard air flow which includes different options of certain proportions oxygen gas air which can react to oxygen-demanding barms.

There was absence of some basic component beginnings in every barm civilization that are necessary for better agitation conditions such N and P beginnings. This leads to comparatively low cell growing comparing to the growing that could be achieved without the absence of such elements.

Bacto-peptone can be used as an organic N beginning[ 18 ]. Yeast extract makes available many bio foods required for the agitation of barm cells. It besides provides indispensable H2O soluble vitamins, aminic acids, peptides and saccharides[ 19 ].

Chapter 5: Decision

After the scrutiny of S. cerevisiae cells at all of different growing factors of temperature, pH, substrate ( glucose ) concentration, it can be eventually stated that the cells of this barm species show higher growing at the undermentioned conditions:

Temperature: 30oC

pH degree: pH6

Substrate concetration: Glucose concentration of 2mL

Besides through this research was deduced that as agitation conditions improve the cell growing additions and standard divergence additions every bit good. Furthermore, at optimal conditions the standard divergence is the highest as a consequence of fluctuation between cells.

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