Structure of DNA
How does the structure of DNA (double helix) determine how the genetic information is passed on?
DNA consist of complex two associated polynucleotides strands winds through space to form a double helix. nucleotides are linked by phosphodiester bonds; for example guanine and cytosine are bound by three hydrogen bonds. The nucleotides contain small units known as genes, that transmit important messages essential for the appropriatefunctioning of the cell and organism. Genome is the whole collection of DNA that contains information to be passed on to the next generation. Histonessurround the DNA to form the shortened chromosome which fits into the cell. During DNA replication helicase enzyme unwound the DNA to permit the duplicationproteins to bind tothe exact place and carry out their function. Daughter stand is then synthesized from both DNA template strands. Genetic material is passed on to the daughter cells because DNA duplication is a stringent process(Alberts et al., 2002).
How does the cell use the information contained in the DNA to construct proteins (transcription and translation)?
Transcription and translation are significant processes that occur in protein synthesis. The promoter, open finding frame are the key elements contains in the sequence of the genes that allow protein synthesis. Transcription is the initial step where the material in the DNA is converted into messenger RNA.DNA relaxes and split up to form an open multifaceted. The initial step involves the RNA polymerase enzyme attaches to the promoter region in template strand. Secondly, RNA polymerase moves along the template strand synthesizing the mRNA molecule the process is called elongation. Step three is chain termination done by the addition of adenine nucleotide in the 3′ of RNA transcribed the process is called polyadenylation. To produce a mature RNA post-transcriptional process such as splicing is done. thereafter transported into the place of protein synthesis.
Translation stagefollows where the mRNA is changed into protein. Ribosomal RNA having the peptidyl, acceptor, and exit site bind mRNA bases before the start Condon hence initiating the translation process. rRNA reads the Condon in the mRNA hence three nucleotides to bind to a specific amino acid.(Barber&Elledge, 2019). To elongate the peptide, chain a separate RNA is known as transfer RNA carries a different amino acid to rRNA. The process of protein gathering continues till the ribosome comes across a stop Condon such as UAA, UAG, UGA, then the peptide is released. Finally, the post-translation modification includes the 5’capping,3’polyadenylation, and RNA splicing to release a mature protein. a biologically active molecule such as protein is formed through transcription and translation of the biological information contained in the gene.
During gene regulation, eukaryotes contain many step-in gene expressions. The primary level of transcription is controlled by majority of the genes. During differentiation and development, transcriptional controlling proteins are responsible for gene expression. Dissimilarcontrolling proteins players a role in the regulation of gene expression by enhancers contained in the protein. Immunoglobulins are known to have about 200 sets and nine arrangement elements used for protein attachment sites.Immunoglobulins are active T and B lymphocytes. For specific tissues, specific expression regulatory is sequence plays the role. The process of embryonic development, gene expression is controlled by home domain protein. One of the eukaryotic steps is to make the gene available for transcription process hence gene regulation. The critical point for regulation of many genes is transcription is promoted by a set of aspects in transcription that attach specific DNA. Finally, the RNA molecules are regulated and mayleave the nucleus, in this case, RNA processings used to control the genetic factorexpression. (Brooker, 2012) also, RNA molecule splicing to produce more proteins from a single gene is regulated.
How gene expression is regulated (give three different forms of regulation mechanisms)
Regulation of genetic factors occurs in prokaryotesand eukaryotes organisms. It is a fundamental aspect of molecular biology. For gene regulation of RNA and protein, there must be a mechanism to control gene expression. Prokaryotic cell controls gene expressed by regulating the transcription. An example of bacteria in prokaryotic is controlled by the lac operon and try operon. Transcription operons are regulated by the RNA polymerase, specific repressor, and activator.
Mechanisms of gene expression include transcription rate regulation which the most economical method of regulation processing molecule which includes splicing to produce more proteins from single gene. mRNA stability regulation and regulation of translation rate. Transcription is the most crucial step in gene regulation. When transcribed gene is repressed the mRNA and proteins are synthesized at low rate. Genes expressed in cells determine the protein and RNAs it contains. Eukaryotes gene expression involves numerous steps and gene regulation occurs at each step.
Many genes are controlled at transcription stage. Different cells in multicellular express different genes but having same DNA.
How does gene regulation relate to cancer development?
Malignancy is as a result ofgenetic factor which is not expressed in a cell but due to mutation levels the gene is expressed and switched on in high levels. (Tang, et al,2017)Alteration in histone acetylation, increased translational control, post-modification, and increased RNA stability is detected in the cancer cells.
Nowadays the most chronic condition among humans is considered to be cancer. It is caused by the alteration of gene expression resulting in a mutation. Epigenetic regulation and modification in transcription are detected in cancer. (Wanget al,2018) Epigenetics is the process of changing cellular phenotype other than changes in the underlying DNA sequence this results in gene suppression thus resulting in a tumor. The rate growth of the cell cycle is also affected by mutations.(Brooker, 2012). Primary cause of the growth of cancer is alteration of the body cells hence interfering with transcription which assists in gene regulation .example in breast cancer most of the cells are overexpressed hence the tumor. phosphorylation is the major transcriptional factor. The major cause of breast cancer among women is the overexpression in epidermal growth. The expression of mRNA is altered by cancer by building the RNA molecules. As a result of the overexpression of mRNA, the regulation of cellular activity is affected. Also, this overexpression results to a reduction in RNA thus reduction to protein expression. Alternatively, incorrect protein in the body results in development of cancer because there is an affected cell function. For example, large intestine cancer whereexpression of the cell rises cell growth. Mutations in the proteins result in cancer.
Moreover, structural rearrangement of DNA can result in cancer whereby the DNA moves from one part another. Tumour is termed to be genetic disease which starts when a single cell obtains series of mutations. In gene regulationstage, an enlarged translational and altered protein translation is observed in cancer cells. Proto-oncogenes, positive regulators, maybe mutated to became oncogenes hence causing cancer. Overexpression of oncogenes can alter the transcription activity and protein translation. Normal cells also contain genes that control unsuitable cell development. An example of gene that controls cell growth in normal cells is the suppressor genes thus mutations controlled. Transcription activity and protein stability are affected by overexpression of genes thus the gene regulation is necessary. The transcription factor regulates the cell cycle and division process.However, cancer can arise due to the alteration of transcriptional control. Increased transcriptional activation results in the growth of modified cells. (Brooker, 2012).
Conclusion
Most cancer is caused by mutations, that is nucleotide alteration. This can result from DNA copying mistakes during cell division, thus uncontrolled cell rate.in order to avoid this cell, regulation is fundamental aspect of gene expression.
References
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). The structure and function of DNA. In Molecular Biology of the Cell. 4th edition. Garland Science.
Barber, K. W., & Elledge, S. J. (2019). Sequencer Hacking Unlocks Quantitative Protein Studies. Molecular cell, 73(5), 863-865.
Brooker, R. J. (2012). Concepts of genetics. New York, NY: McGraw-Hill.
Tang, Z., Li, C., Kang, B., Gao, G., Li, C., & Zhang, Z. (2017). GEPIA: a web server for cancer and normal gene expression profiling and interactive analyses. Nucleic acids research, 45(W1), W98-W102.
Wang, Y., Wu, W., Zhu, M., Wang, C., Shen, W., Cheng, Y., … & Ma, H. (2018). Integrating expression‐related SNPs into genome‐wide gene‐and pathway‐based analyses identified novel lung cancer susceptibility genes. International journal of cancer, 142(8), 1602-1610.