Point Mutation - this is type of mutation that occurs when there is a change is a single base air of the DNA. Point mutation can be Missense or Nonsense depending on the magnitude of the change on the DNA structure. Missense mutations are changes is caused by a substitution of one amino acid with another and results in changes in the structure of the DNA or its function and may be visible from the outside. An example of such mutation is Sickle Cell Anaemia which results from mutation of the gene material in the haemoglobin, changing it from CTC to CAC . Nonsense mutations occur when the base pair of the DNA is not fully constructed because of a premature stop and as a result, the structure becomes shorter (Mikail, 2008).
Frame-shift mutations occur when there are deletions or insertions of the base pairs to the DNA structure causing a change in the way the structure functions. These additions and deletions can cause profound effects on how the gene transcription and translation occur. An example of Frame Shift mutation is the Tay-Sachs disease.
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Duplication mutation occurs when there are a number of repetitions in the pairs of the CTG pieces of the DNA structure. This results in a very long protein which folds itself thus becoming dysfunctional. An example of such mutation occurs in mitotic dystrophy.
List and discuss the potential causes of mutation and, providing at least one example in each
Irradiation – exposure of the genetic material to radiation may lead to mutation. Radiation rays are high energy electromagnetic waves that have the capability of causing changes in the DNA structure when they reach them and cause mutation. Radiation may be ionizing or non-ionizing depending on the energy carried by the given wave. Those that carry high energy cause damage to the DNA structure by breaking the covalent bonds which hold together the DNA strands. This damage can be so severe at times such that the body fails to repair them correctly causing mutation (Stenson et al, 2014). Examples of radiation rays that cause mutation include: Ultra Violet Rays from the sun and X-Rays.
Chemical exposure – when the DNA material comes into contact with harmful chemicals. The result of such interaction is the increased frequency of mutation in the genetic material above the normal rates leading to defects as the body can’t keep up with the repair of such numerous breakages and damages. The chemicals can cause mutation by altering how the chromosomes are arranged as well as changing the DNA structure (Stenson et al, 2014). Examples of such chemicals include: superoxide, hydrogen peroxide, and nitrous acid.
Explain the processes of transcription, replication, translation and gene expression as they relate to the science of genomics
According to Mikail (2008), Gene Transcription is the process by which mRNA is made by copying the DNA material strand sequence during the synthesis of proteins in the body. This process is important because it helps the body make new proteins to replace the ones lost and those that are worn out. Gene Replication – This is the process by which the body so able to copy the double stranded DNA and using the copied information to two similar molecules of DNA. This is usually common during the cell division enables the formed daughter cell have similar DNA composition. Gene Translation - this is the process through which the ribosomes in the cell cytoplasm interpret information form the transcribed mRNA and use the information to make proteins for the body. Gene expression is the process by which the genetic codes from certain genes are used to create products that have functional genes products. Expression encompasses the transcription, translation and replication processes.
Describe the molecular structure of the DNA and the fundamental role of DNA in human physiology
The DNA is a long structure of strands made of the nucleotide building blocks. A single nucleotide is made up of three major components; the phosphate groups, a sugar and the nitrogen base. The nitrogen bases include; Adenine, thymine, guanine and cytosine (Kellis, et al, 2014). The nucleotides are used to make the DNA strands which are connected by the by covalent bonds to make long chains of the DNA structure. The bonds help in attachment of the strands together such that a double helix ladder like structure is formed (Sinden, 2012).
DNA is involved in a number of processes in the body including some of the crucial physiological processes that help the body to function properly. The DNA is functions primary to direct the cells in what to do differently in the body; for example it is the DNA that directs the brain cells in adults not to grow and divide further. It also controls the cell division in the tissues cells making sure that cells are reproduced constantly to keep up with growth of the body (Sinden, 2012).
References;
Kellis, M., World, B., Snynder , M. P., Bernstein, B. E., Kundaje, A., et al (2014). Defining functional DNA elements in the human genome. Proceedings of the Nation al Academy of Sciences , 111 (17), 6131-6138
Mikail, C. N. (2008). Public health genomics: The Essentials . San Francisco. CA: Jossey-Bass
Sinden, R. R. (2012). DNA structure and function . Elsevier. print
Stenson, P. D., et al. (2014). The Human Gene Mutation Database: building a comprehensive mutation repository for clinical and molecular genetics, diagnostic testing and personalized genomic medicine. Human genetics 133(1), 1-9
