Essay Example on Forensic Science: A Study of DNA & Cell Structure Advancement

Introduction

Most of the studies carried out across the globe have established that nuclear DNA and mitochondrial DNA advanced collectively to complement each other mainly. Such development generated advanced methods of dealing with criminal issues. Forensic science incorporates technology and knowledge developed, such as the application of DNA in solving complex criminal challenges and enhances law regulations.

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Scientifically studies show that the most significant component of the cell, which is the DNA houses a large quantity of the genetic material (Taupin, 2017). The mitochondria functions as a factory that produces energy that powers the cell. Scholars have discovered that the mitochondria also inhabits DNA with specific features distinct from those in the nucleus. Amazingly, whenever a cell is undergoing strain and lacks nutrients, then MOTS-c in the mitochondrial structure, is released to the nucleus with a mission to control genetic factors and create a protective mechanism (Taupin, 2017). The defensive framework comprises of antioxidant reply. The application of both the nuclear DNA and mitochondrial DNA in forensic science has advanced criminal investigation and convictions for so many decades.

Vertical or Reflected Illumination and Transmitted Illumination

Vertical or reflected illumination is when a specimen is lit from above. It is applied in the assessment of opaque samples. Transmitted illumination refers to light that passes up from the condenser of a microscope and through the specimen. Forensic examiners typically use lenses in crime laboratories. There are various types of microscopes used in forensics, such as the compound, comparison, stereoscopic, micro-spectrophotometer, and the polarizing microscopes (Saferstein, 2017). The compound microscope has an optical system and a mechanical system that supports the lens. Comparison microscopes are essential in comparing two specimens, particularly a sample from a crime scene and that from a suspect. Semitransparent fibers and hairs are lighted from below the stage during their comparison using a comparison microscope. Illuminating opaque objects from below the stage is delicate, and hence optical lenses furnished with vertical or reflected illumination structure is used.

Stereoscopic microscopes are mostly used to assess physical evidence that requires low magnification. Illumination in the stereoscopic microscope can be done from below in the examination of semitransparent objects, or vertically from above in the scrutiny of opaque objects. Polarizing lenses use the principle that light traveling through the structure of an object in diverse ways act predictably, but differently. Such technology is applied to criminal investigations (Saferstein, 2017).

A micro-spectrophotometer microscope combines the microscopy to a computerized spectrophotometer and permits a forensic inspector to distinguish better and classify physical evidence. A scanning electron microscope (SEM) is used to show whether a suspect has lately fired a rifle. Casting and mount methods are used in examining scale patterns in hairs using microscopes. The latter approach is applied in forensic assessment of evidence since it preserves evidence and is easy to use. The casting method is applicable when a detailed observation is needed. Hair scale morphology has unusual scale patterns that help in classification.

Real and Virtual Image

A real image can be viewed directly, such as an image that is projected onto a motion photo screen. Besides, a virtual image cannot be seen directly; it can only be viewed by observing through a lens. The convergence of actual light rays forms real photos on a screen. The eyepiece lens, also called ocular (the microscope lens into which the observer looks) magnifies the image formed by the objective lens into a virtual image observed by the eye. The objective lens is the lower legs of a microscope, which is placed right over the specimen.

Natural and Human-Made Fibers, Polymers, and Monomers

Natural fibers are entirely derived from living organisms, such as plants and animals. Animal tissues consist of hair coverings from animals such as goats (cashmere, mohair), sheep (wool), alpacas, and camels, among others. Fur fibers are obtained from animals like beaver, mink, muskrat, and rabbit. Comparison and identification of natural fibers depend entirely on a microscopic assessment of morphological physiognomies and color. A satisfactory amount of reference or standard specimens must be scrutinized to discover the range of fiber features of the suspect material. The most predominant plant fiber is cotton, with its most unique characteristic of a ribbon-like outline with spirals at occasional interludes.

Human-made fibers or manufactured fibers are developed from either synthetic or natural polymers. The fibers are usually prepared by compelling the polymeric fabric through the holes of a spinneret (Causin, 2015). Polymers are the simple chemical matter of all synthetic fibers. Monomers are the simple unit of a structure from which a polymer is made. A substance that is composed of a large number of atoms, usually arranged in repeating monomers or groups, is called a polymer.

Forensic science relies on the capacity to trace the source of the suspect fiber. When fabrics precisely fit together at torn edges indicates that the materials are of a standard reference. However, it is not easy to collect enough quantity of fibers for comparison and identification. Most forensic examiners apply side-by-side comparison of the crime-scene fibers and the reference or standard fibers.

Morphological characteristics that are examined using a comparison microscope are color, diameter, and lengthwise striations on the surface of the fibers. The forensic scientist also examines fiber's dye composition and chemical composition of the tissue (Causin, 2015). Trace physical proof has significantly contributed to the success of criminal investigations; therefore, conducting exhaustive crime-scene searches for evidence of forensic worth is vital. Fiber proof can be linked with almost any kind of criminality. Identification and preservation of potential fiber evidence are essential in the success of a criminal investigation.

The Morphology of a Hair Shaft: Cuticle, Cortex, and Medulla

Hair is an accessory of the skin that develops out of the human organ called the hair follicle. The hair grows from its roots or bulb embedded in the follicle into the hair shaft and culminates at the tip end. Forensic researchers extremely scrutinize the cuticle, cortex, and medulla. Hair is used as forensic evidence because it is resilient to chemical decay and can maintain its essential features over an extensive period (Landron, 2019).

The cuticle is the outer casing of the hair and offers the firmness and resistance that is characteristic of hair. The epidermis is formed by overlying scales that continuously face toward the tip end of individual hair. The scales are created from particular cells that have compressed and hardened developing from the follicle. Several scale outlines that form the cuticle in animal hair, making it an essential feature for the identification of species. Examination of scale patterns is done by implanting the hair in a soft medium and leaving it to toughen before removal. After its removal, a flawless and distinctive imprint of the hair's cuticle is observed; this is essential for forensic analysis.

The cortex is contained in the protective layer of the cuticle. It has rod-shaped cortical cells arranged in a systematic collection, matching the span of the hair. Pigment granules that define the color of hair are imprinted in the cortex, making it have a unique forensic significance. The distribution, shape, and color of these granules offer crucial facts of contrast among the hairs of various persons. After mounting hair in a fluid medium with a refractive index close to that of the hair, the structural aspects of the cuticle are scrutinized using a microscope. The quantity of light passing through the hair is enhanced while that reflected off the hair surface is reduced under controlled conditions.

A medulla is a group of cells that appears like a dominant canal running through a hair. The channel is a vital aspect and inhabits over half of the diameter of the hair. The appearance and presence of the medulla are unique, and also among the strands of an individual (Landron, 2019). Medulla can be described as fragmented, continuous, interrupted, or absent. Humans display no medullae, fragmented, or rarely have continuous medullae. The cortex, cuticle, and medulla features in hair morphology are vital in forensic evidence and are examined through a compound microscope.

Hair evidence is examined to determine whether the hair is from an animal or human. The hair is also scrutinized to compare it with hair from a particular person during forensic investigations. Hair evidence is used to establish whether hair recovered at a crime-scene match to hair retrieved from a suspect. A comparison microscope is used to determine the probability of such a connection.

The Lindbergh Kidnapping Case

Koehler assessed the varieties of wood and the cutter marks on the wood used in making the ladder to ascertain where the materials originated from and the specific equipment used to produce them as he analyzed evidence in the Lindbergh kidnapping case (Saferstein, 2017). Bruno Hauptmann purchased gasoline using a bill that corresponded to a serial number on the ransom money. Koehler indicated that microscopic patterns on the wood were made by equipment that Hauptmann possessed. An examination of the handwriting on the ransom note also evidently noted that it was Hauptmann's handwriting.

References

Causin, V. (2015). Polymers on the crime scene. In Polymers on the Crime Scene (pp. 105-166). Springer, Cham. Retrieved from https://link.springer.com/chapter/10.1007/978-3-319-15494-7_4

Landron, A. (2019). Trichology: A Study of Hair and its Uses as Trace Evidence. Ursidae: The Undergraduate Research Journal at the University of Northern Colorado, 5(2), 5. Retrieved from https://digscholarship.unco.edu/urj/vol5/iss2/5/

Saferstein, R. (2017). Criminalistics. Pearson. Retrieved from https://studydaddy.com/attachment/37262/https___vcampbethel.blob_.core_.windows.net_public_courses

Taupin, J. M. (2017). Introduction to forensic DNA evidence for criminal justice professionals. CRC Press. Retrieved from https://content.taylorfrancis.com/books