DNA is the principal genetic compound. As the dominant information molecule, DNA is responsible for storage and making proteins. The genetic information is contained within the chromosomes of DNA molecules1. Fundamentally, actions are prompted among the 46 chromosomes in a DNA molecule, which in turn has a shorter segment called genes. It is in the genes that actions to make protein fragments, complete proteins, or several specific proteins are stored. The core feature of DNA that defines the molecule is the entwinement of the two strands as a right-handed double-helical polymer1. The double-stranded nature of DNA gives it essential physical and chemical properties. The aspects that play an instrumental role in DNA's biological function. The genetic codes are the four DNA bases: the A, C, G, and TS threaded together such that the ribosome can decode them, thus converting them into a protein2. DNA prompts RNA to synthesize proteins from the different strands of amino acids available. The flow of instructions from DNA to RNA, referred to as the central dogma, can be affected by gene mutations, which in some cases, can be characterized by life-threatening diseases1. Although the assertions of the central dogma hold, the biological process can be hindered by events such as gene mutations and controllinggene expression.
The central dogma of gene biology regards the flow of genetic information which is required for the manufacture of proteins. The information necessary for the manufacture of proteins is contained in the DNA, while the RNA acts as its carrier3. The RNA carries the information to the ribosomes where the actual protein synthesis takes place. Through gene expression, the ribosomes convert DNA instructions into proteins depending on the specific level of expression indicated in the information. The proteins manufactured, in turn, determine the function and structure of an organism’s cells1, 3. The two phases that define the gene expression process are transcription and translation. In the transcription stage, the directions in a cell’s DNA are transformed into small and transferable RNA messages. In the translation phase, the message is delivered to ribosomes for protein synthesis3. RNA has a small structure that allows it to squeeze through the pores in the nuclear membrane. Through the genetic code process, the information programmed in DNA and later transferred to RNA is converted into proteins. The process is defined by a mapping between codons and amino acids whereby sixty-one codons can encode twenty amino acids and three stop codons3.Gene mutations can, however, occur whereby there are permanent changes in the DNA sequence.
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DNA is always exposed to mutations, which are accidental alterations in its code. A mutated gene is often characterized by missing or malformed proteins that can lead to diseases. In essence, mutations are the source of diversity in organisms; thus, they can be heritable or occasioned by an organism’s environment1. For mutations to result in diversity, the nucleic acid, which is the fundamental building block for DNA, is affected. Gene mutations are responsible for inherited genetic disorders and cancers. Also, mutations can be beneficial or harmful subjects to their context or location. A single mutation can have an enormous effect, but in most cases, significant changes arise from many mutations with small impacts3. The number fundamentally informs the magnitude of gene mutation consequences of base pairs.
Stable genes lead to situations where mutations do not affect them adversely. Gene stability leads to clear pathways that maintain the correct transmission of genetic information from one generation to another generation5. However, unstable genes lead to accidents during the mutation process, which eventually affects the offspring, or leads to the development of inheritable medical conditions. Stable gene pathways that lead to desirable effects being passed from generation to another include Nucleotide Excision Repair (NER) 5. Another pathway is the Base Excision Repair (BER). Environmental factors can also play a role in accidents occurring during the gene mutations5. These environmental factors may include chemical pollution, which may be ingested by people, thereby leading to deformed genes. An example can be given of the survivors of the Nagasaki and Hiroshima Nuclear Bomb, who have continuously given birth to deformed children up to date.
Studies have shown that specific genes localized in some sections are likely to mutate faster than other genes located elsewhere. Those that are found in places where they are likely to mutate more quickly are called hotspots, while those in regions where they are less likely to mutate are called cold spots5. One known gene hotspot is the CpG dinucleotide that relates well with the C>T mutation. The result of mutations taking place at such hot spots is TpG and CpA transitions that take place on the strands of the genes. Even though repair pathways BER and MMR may be present, the mutations take place frequently, which overwhelms these pathways to make them unable to perform their mandate as expected5. Cytosine methylation is one of the results that occur during the many DNA modifications that take place in the hotspots. Cold spots include the 5-nucleotide (5-nt) sequence that takes a very long time to mutate. In other situations, it does not mutate at all5.
For a cell to function well, its necessary proteins must be manufactured at the right time. Through gene expression, information flows from DNA to RNA from where proteins are synthesized. Irrespective of the type of an organism, each of its cells has a mechanism for controlling when a gene is expressed to make proteins, the number of proteins made, and when to halt the gene expression process4. Such a mechanism is crucial because it helps conserve energy and space and in its absence, it would imply that the gene has a perpetual expression process. Malfunctions in the control mechanism can have detrimental consequences that can trigger many diseases such as cancer4. It is therefore pertinent for genes' regulation mechanisms to remain optimum, a factor which is crucial for the preemption of diseases such as cancer.
In conclusion, DNA, as the principal genetic element, plays a crucial part in the synthesis of proteins in cells. DNA stores the instructions that are responsible for the making of proteins in the ribosomes. The RNA transfers the genetic instructions to the ribosomes. Gene expression is the mechanism by which ribosomes convert DNA instructions into proteins depending on the indicated level of expression. The resultant proteins determine the structure and role of an organism’s cells. On the downside, a gene can undergo mutation, which is an accidental alteration in its makeup. Mutations are often associated with diseases such as cancer, which are life-threatening. Regulation of gene expression is necessary since it controls the number of proteins synthesized and when to stop the process of making new proteins.
References
Travers A, Muskhelishvili G. DNA structure and function. FEBS Journal . 2015; 282(12):2279-2295.
Shu J. A new integrated symmetrical table for genetic codes. Biosystems . 2017; 151:21-26.
Jafari M, Ansari-Pour N, Azimzadeh S, Mirzaie M. A logic-based dynamic modeling approach to explicate the evolution of the central dogma of molecular biology. PLoS ONE . 2017; 12(12):e0189922.
Inoue M, Horimoto K. Relationship between the regulatory pattern of gene expression level and gene function. PLoS ONE . 2017;12(5):e0177430.
Ruzicka M, Kulhanek, P, Radova, L, Cechova, A, Spackova, N, Fajkusova L , Reblova K. DNA mutation motifs in the genes associated with inherited diseases. PLosONE. 2017; 12 (8) e0182377.
