Example Of Report On Population Growth

Abstract

Growth incorporates a uniform increase in the volume of cellular components. All organisms grow as a main biological characteristics. Growth is a factor that can be measured using a number of parameters and determined standards incorporated as well. The reproduction amongst most bacteria take place through binary fission. There are factors affecting growth amongst organisms such as temperature. Since growth depends largely on enzyme activity, which also relies greatly on temperature then the former can be used as a factor of the latter and both can provide reliable information in determining the population growth. Throughout this laboratory evaluation, rates of growth were determined under different temperature scales among the bacteria e coli. A common observation was made that there is a significant difference in growth at various temperatures. Being that e coli is a significant bacteria in human body and any event of slight compromise in functionality would result into severe effects, it is necessary to perform an experiment to determine its growth and the population as well.

Introduction

This laboratory exercise had the main objective of measuring the population growth of e coli. The experiment targeted determining an inclusive information concerning the growth of the bacteria. As a result, the exercise incorporated various methods for measuring growth namely: the physical, chemical, indirect chemical measurements, activity and turbidity.
The process of population growth in bacteria includes the uniform increase in the cell mass and size. The parameters used in this study included time and temperature. Temperature was the variable used in this study and time was the independent variable. Temperature was adjusted and the experiment performed in different conditions such as 250C 300C and 370C. The experiment based its facts and objectives on the postulation that temperature has a direct impact on the cell growth. Being that bacteria is a unicellular organism, there was a feeling that temperature difference would influence their rate of growth and reproduction.

Hypothesis

The hypothesis set to be tested by this experiment stated that: temperature has a direct influence in the rate of cell growth and that cell population and rate would vary under different conditions as provided by the temperature. Therefore, the experiment set proving the hypothesis as one of its objectives. It is by proving the hypothesis that a confirmation will be made on the experiment’s ability to conform to the conventional principles.

Methods

The bacterium was cultured at one of the three temperatures (25oC, 30oC and 37oC) at a time using a non-virulent strain. The density readings were taken on the culture that directly related to the population growth of the e coli. The flask was then stored to the shaking incubator at the assigned temperatures and the incubator regulated to a speed of 175.
Physical methods: is performed directly by determining the different states of weight whether dry or wet. The method is also appropriate in ascertaining the cell volume especially after the process of centrifugation. The method also includes the use of biomarkers and stains to determine the cell structure and physiology. Through this method, determination of cell volume and mass is possible.
Chemical measurement methods is appropriate in measuring particular constituents of the cell such as the total DNA, protein or N. It involves outlining the number of bacterial cells in units per volume. For instance, the cell number and proliferation can be identified in terms of concentration per volume of the medium.
Indirect chemical measurements incorporates the evaluation of the rate of production and consumption of oxygen or carbon dioxide amongst other compounds in the cells.
Activity of the cells influence the byproducts released from their actions, again the activity also influence nutrients consumed by the cell. Therefore the number of cells can be determined by the activity but this is based on the standard values provided by previous studies on the bacteria species.
Turbidity measurements incorporates several tools to ascertain the quantity of light dispersed by the cells’ suspension. In this measurement method, the bacteria disperse light in equal proportions to their numbers available in the sample to be investigated.

Results

The three temperature conditions tested showed that temperature has an impact on the ability of the bacteria to disperse light and influence the absorbance. As the time elapses in each case, the effect of temperature intensifies on the samples. All the tree temperature conditions demonstrated a steady rise in the absorbance. Within the first two intervals, the absorbance is higher at 250C as compared to 300C.

Discussion

The difference in absorbance is as a result of the difference in the number of cells, the mass or the volume after centrifugation. The outlined factors of absorbance are subject to the cell growth and the consequential binary fission that may arise.
Under ordinary conditions, the growth of bacteria follows a normal exponential of 20, 21, 22, 23 2n. However, an understanding should prevail that growth is only part of the life cycle of bacteria but not a representation of the natural normal pattern.
In the initial phase of growth, there is insertion of a new condition. at this stage, there is no cell division or increase in number. The stage is temporary and there is increase in mass, volume, enzyme synthesis together with the increase in metabolic activity.
The second phase is tha exponential phase where there is a uniform increase in the number of cells via binary fission. The cells multiply progressively in the powers of two. The exponential growth rate is expressed as the generation time which is a component of generation time and the number of generations.
The stationary phase is the third stage of growth. Under the prevailing conditions of closed systems such as the flask as used in this experiment, the log phase cannot be continued for eternity. The stagnation may be due to exhaustion of nutrients, space, and the accumulation of inhibitory factors. This phase is more complex since the number of cells or those dividing can never be determined by counting as the death and division rates are relatively abstract.
The last phase is the death phase where the population of the productive cells reduce. At this phase of growth phase, the number of cells reduce exponentially, a direct opposite of the lag phase.

Conclusion

According to this lab experiment, the hypothesis was proved right. Indeed the light dispersion as influenced by the number of e coli varied under different temperatures. At 300C, the absorbance was higher as compared to the 250C however, with slight variations. At 370C, the absorbance was optimal. This observation concurs with the standard curve provisions supporting that the 370C is the optimal temperature at which the enzyme activity is highest and at this point the rate of reproduction was highest.

Works Cited

Crauder, Bruce, Benny Evans, and Alan Noell. Functions and Change: A Modeling Approach to College Algebra. Belmont, CA: Brooks/Cole, Cengage Learning, 2013. Print.
Hentges, David J. Human Intestnl Microflorain Hlth & Disease. Oxford: Elsevier Science, 1983. Internet resource.
Sharma, P D, and P D. Sharma. Ecology and Environment. Meerut: Rastogi Publications, 2010. Print.
Stevens, M H. A Primer of Ecology with R. New York, NY: Springer-Verlag New York, 2009. Internet resource.