Basic Biology

Research Paper: Basic Biology
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ASSIGNMENT-08
DNA in forensic science.
Analysis of Deoxyribonucleic acid or DNA is very important and significant in the field of forensic science. The science deals with tracing the pedigree or origin of a culprit or the accused based on the evaluation of his or her nucleotide sequence in the DNA. The nucleotides Adenine, thymine, guanine and Cytosine are often conserved at specific sites of the DNA of an individual. This site conservation of various nucleotides helps to identify the identity of a person.
The accused or victim often sheds blood, saliva, pus and semen at the place of crime. These sources are used to isolate the DNA from cells. Certain enzymes called restriction enzymes are used to cut DNA at specific sequences based on the morphology of the DNA. These segments are then matched with either the standard DNA from an accused or a victim by a process called restriction fragment length polymorphism (RFLP). More there is polymorphism less likely is the DNA of an accused or victim. This is the basic principle behind DNA fingerprinting.
Often the DNA found in the sources is very minute which needs to be amplified. This is achieved by polymerase chain reaction. In this technique, the DNA sample is taken and is coupled to various oligonucleotide primers.

Further an enzyme called Taq polymerase is added, and repeated heating and cooling of the PCR system generates manifold amplification of the small DNA segment found from the crime site for in-depth analysis.
Another approach involved detection of single nucleotide polymorphisms (change in only one nucleotide due to mutation) within the isolated DNA and suspected DNA and the probabilities of such SNPs are extrapolated to find the accused or victim.
Recent interest in DNA detection approach in forensics involves mitochondrial DNA analysis. Since, DNA from the nucleus is difficult to be extracted and found, and with the rate of SNPs or polymorphisms they are highly different. However, the morphology of mitochondrial DNA is fairly constant and easy to extract and find which makes it a more competent tool for identification of the victim or accused (Aldaye, Palmer & Sleimann, 2008).
Population Evolution and Microbial life
Evolution describes the changes in body structures and components within the cells to adapt to environmental conditions. Such changes have given rise to either new organisms or newer species which have become better suited to its immediate environment. Such trend of evolution also occurs in the microbial world. Evolution may be homologues or analogues. In homologous adaptation parts of the same origin have been modified to serve different functions, while in analogous adaptation different parts of different organisms are modified to serve similar functions across organisms. Such adaptations are introduced to justify “struggle for existence, and survival of fittest”. Such evolution is demonstrated by:
Single cellular organisms have evolved into multi-cellular microbes to dissipate entropy (or randomness) within their body in order to maintain the physiological steady state and their sustenance in the environment.
Even certain structures within microbes like the efflux pump of many bacteria are better suited to eject antibiotics that enter them. This creates the process of antibiotic resistance in them which helps them to survive from antibiotic treatment and sustain their existence.
Certain bacteria have developed Pilli system in their cell for enhanced attachment to host tissues, hence although they are not multi-cellular but they have adopted the mechanism of sustenance through adaptive evolution in utilizing host resources for survival.
Further, there has been co-operation and competition between microbial species that have caused either multiplication or evolution into newer species or extinction of same or closely related species (Xavier, 2011).
Biological Diversity and Evolution
Biological diversity indicates the presence of different types of species and organisms in a specific habitat or niche. The presence of such species and organisms utilizing the same environmental conditions have occurred due to evolution and need of various species to sustain in the given habitat conditions. The implications are:
Provision of the constant supply of food and energy through predator-prey interactions that helps in the sustenance of different species as per the laws of ecosystem dynamics.
The diversity of various organisms helps in complementing the sustenance of self and other organisms through mutualism and commensalism.
Diversity also helps in sustaining the climax community of a habitat and helps in the formation of a stable ecosystem (Grant et al, 2010).
Plant and Animal Evolution
Evolution not only occurred in microbes but also in the case of plants and animals too. Such evolution has helped both plants and animals to sustain environmental and nutritional extremes even under the dynamic process of ecological succession. In both plants and animals unique adaptive features are noticed even in closely related species. Such evolutionary adaptations have potential significance in the sustenance of plant and animals. Some examples include:
Xerophytes are plants that have developed the unique vascular system and deep root system which are suited to absorb water from deep soil and supply it to various parts of the plant. Such adaptation helps Xerophytes to sustain in desert environments.
Animals that are adapted to survive in cold climates have developed lesser surface area of their extremities and increased hair on their body surface. Such adaptation helps in conserving the body heat and also keeps the body insulated against cold weather.
A chameleon can change its body colour in response to the environment to survive from predators compared to other reptiles (Whittaker, 1975).
Population growth
Population growth refers to the increase in the number of individuals at a given space over a period, considering the rate of intrinsic growth and rate of intrinsic death. When the rate of intrinsic growth is more than the rate of intrinsic death a given population increases in number. Such growth may be exponential or logistic. Population growth gives an estimate of the trend of resources and disease features as explained below:
Exponential growth indicates that food and space are the main abundances that favours growth in log normal fashion. While logistic growth indicates that population growth is mediated by carrying capacity, which means the provision of food and space is predefined.
Population growth curves help to identify the survival trend of organisms. When Population growth curves are concave, it indicates that organisms die at lower age groups, while if the curves are convex organisms die at higher age groups and their survival time is more.
Pyramidal population growth curve indicates that pre-reproductive individuals are more compared to post-reproductive individuals in a population. In other way, it indicates a young population (Whittaker, 1975).
Biomes and Ecosystem
Biomes represent a community of plants and animals. Various biomes can exist in a given habitat which utilizes the abiotic factors of the habitat for their survival and form a self sustainable unit. An ecosystem represents the total of interactions between the abiotic and biotic factors existing in a specific biome. The nature of energy flow, the terminal organisms and the producers in the food chain are relatively constant across the same biomes in different geographical locations of the globe. Examples of biomes are terrestrial biomes and freshwater biomes. The significance of biome identification and ecosystem dynamics helps in:
Evaluating the presence of likely species in different ecosystems.
Energy flow can be predicted
Abiotic factors that lead to evolution may be identified (Pomeroy, Lawrence & James, 1988).
References
Aldaye F, Palmer A, & Sleiman H. (2008). “Assembling materials with DNA as the
guide”. Science , 321 (5897): 1795–9
Grant F, Mergeay J, Santamaria L, Young J, Watt AD. (2010). “Evolution and
biodiversity: the evolutionary basis of biodiversity and its potential for
adaptation to global change”. Conference report, 1–19
Pomeroy, Lawrence R. and James J.(1988). Concepts of Ecosystem Ecology. New
York: Springer-Verlag
Xavier, J. B.(2011). “Social interaction in synthetic and natural microbial
communities”.  Molecular Systems Biology 7: 1–11
Whittaker, R.(1975). Communities and Ecosystems. New York: MacMillan
Publishing Company, Inc.