One of the greatest gifts from God to humankind is biology. From the Greek words which mean the study of life, biology is a branch of science that focuses on how living things works. For example, how does a tiny human being turns into a full-grown adult in just matter of time? Why are there twins that look exactly alike but there are some that are not exactly alike? Thanks to biology, scientists now are able to answers these questions. It is all in the genes or more accurately the deoxyribonucleic acid (DNA). DNA is long chains of nucleotides that carries genetic information that is very crucial in human development. Based on the molecular structure of DNA, it is made of two nucleotide strands and arranged in such manner in which they coil
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At this stage, the main objective is unwinding the double-helical structure of the DNA as proposed by Watson and Crick in 1953 and then use both strands as a template to continue the replication process (Weaver, 2012). According to Lodish (2008), it begins with the enzyme helicases steadily unravelling the strands at the replication origins by breaking the hydrogen bonds between the nitrogen bases of the DNA and continue to form a replication fork as it separates the strands into two parental strands (Reece, Reece & Campbell, 2011). During this time, Reece et. al (2011) explain that to prevent the recoiling of the strands, single strand binding protein firmly attached to the free-bound DNA nucleotides, hence inhibiting the formation of hydrogen bonds between the nitrogen bases of the DNA. Subsequently, since the action of unravelling and untwisting the helixes create supercoiling, a torsional pressure along the replication fork, topoisomerase is fully utilized to subdue the supercoiling (Lodish, 2008). Finally, the two parental strands are ready to be used as a template for the next stage of DNA …show more content…
The final yet the most important step of DNA replication is termination. In this step, two new DNA strands have been produced from the previous elongation step. However, the strands produced are not in long and continuous form but instead are in non-continuous short strands. This is where the function of an enzyme called DNA ligase takes place. The nick or spaces between the new DNA strands are joined using the enzyme DNA ligase resulting in the formation of two long daughter strands of DNA (Campbell et al., 2015). After the two daughter strands of DNA have been produced, it is time to proofread and repair the DNA sequence. This process is so important because any mistake in DNA replication can result to DNA mutation and will lead to various genetic diseases such as sickle cell anaemia, Huntington’s disease and many more (Cooper, 2000). Thus, the accuracy of DNA replication cannot be attributed solely to the specificity of the base pairing. According to Khan Academy (2017), to avert the mistake from happening, an enzyme which is DNA polymerase will proofread each nucleotide against its template as soon as it is covalently bonded to the growing strand. Any incorrect pair of nucleotide will be removed and the synthesis will be resumed (Campbell et al., 2015). This action is similar as to the deletion of the wrong letter in the essay and replaces it with the correct one. In many cases, a segment of the DNA strand containing the damage is excised
At this stage, the main objective is unwinding the double-helical structure of the DNA as proposed by Watson and Crick in 1953 and then use both strands as a template to continue the replication process (Weaver, 2012). According to Lodish (2008), it begins with the enzyme helicases steadily unravelling the strands at the replication origins by breaking the hydrogen bonds between the nitrogen bases of the DNA and continue to form a replication fork as it separates the strands into two parental strands (Reece, Reece & Campbell, 2011). During this time, Reece et. al (2011) explain that to prevent the recoiling of the strands, single strand binding protein firmly attached to the free-bound DNA nucleotides, hence inhibiting the formation of hydrogen bonds between the nitrogen bases of the DNA. Subsequently, since the action of unravelling and untwisting the helixes create supercoiling, a torsional pressure along the replication fork, topoisomerase is fully utilized to subdue the supercoiling (Lodish, 2008). Finally, the two parental strands are ready to be used as a template for the next stage of DNA …show more content…
The final yet the most important step of DNA replication is termination. In this step, two new DNA strands have been produced from the previous elongation step. However, the strands produced are not in long and continuous form but instead are in non-continuous short strands. This is where the function of an enzyme called DNA ligase takes place. The nick or spaces between the new DNA strands are joined using the enzyme DNA ligase resulting in the formation of two long daughter strands of DNA (Campbell et al., 2015). After the two daughter strands of DNA have been produced, it is time to proofread and repair the DNA sequence. This process is so important because any mistake in DNA replication can result to DNA mutation and will lead to various genetic diseases such as sickle cell anaemia, Huntington’s disease and many more (Cooper, 2000). Thus, the accuracy of DNA replication cannot be attributed solely to the specificity of the base pairing. According to Khan Academy (2017), to avert the mistake from happening, an enzyme which is DNA polymerase will proofread each nucleotide against its template as soon as it is covalently bonded to the growing strand. Any incorrect pair of nucleotide will be removed and the synthesis will be resumed (Campbell et al., 2015). This action is similar as to the deletion of the wrong letter in the essay and replaces it with the correct one. In many cases, a segment of the DNA strand containing the damage is excised