• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Nucleotide Excision Repair

Free essay example:

 DNA Repair Systems

The Importance of DNA Repair Systems and Process of Nucleotide Excision Repair

Name: Thien Nguyen

ID: 20299974

TA: Kristyna Wilson

Bio 130 Tutorial

Tuesday, November 10th 2009

As we go about our daily lives, our cells are hard at work to maintain our well-being.  Whether it is providing the energy required doing everyday tasks or just repairing what has been damaged from the constant bombardment of harmful forces, the cell is a formidable force on its own.  And it should, because within every cell, DNA enclosed, which is the genetic information that houses the instructions for an organism to function and also a very vulnerable part of the cell to harmful alterations.  With radiation, the backbone of a DNA is broken, when exposed to reactive chemicals or UV light; the DNA’s bases can be altered structurally (Karp, 2008).  While there are many mechanisms for repair for DNA, the nucleotide excision repair (NER) is one of the most effective and versatile repair systems within the cell that acts on the DNA.  The reasons for this is because of its ability to recognize, remove a wide variety of alterations in the DNA called lesions, and replacing the damaged part of the DNA (Leibeling et al, 2006).

Before this system can do any work on the damaged part of the DNA, it must recognize the lesion first.  There are two ways pathways in which the nucleotide excision repair can happen, during transcription, called the transcription-coupled pathway, in which the lesion is detected and signalled by halted RNA polymerase with a CSB protein or in the global genomic pathway that scans for altered DNA strands in the remainder of the genome in which the protein XPC is responsible for alteration recognition.  In general the only separation between transcription-coupled pathway and the global genomic pathway is the way it recognizes the sites of damage (Karp, 2008).

Once the lesion has been recognized by a pathway, the separation of the DNA strand commences.  In this part of the pathway, XPB (Xeroderma Pigmentosum B) and XPD (Xeroderma Pigmentosum D) proteins, two helicase subunits of TFIIH (transcription factor II H) are used to separate the damaged section of DNA.  After the separation is complete, an incision is made to remove the damaged part of DNA by XPG on the 3’ side and the XPF-ERCC1 complex on the 5’ side (Karp, 2008).

As the damaged DNA part is removed from the DNA, DNA polymerase δ/ε then begins to replace the nucleotides that were removed from the incision using the complementary DNA strand as a template.  Lastly, the process of ligation occurs and DNA ligase I joins the two pieces of DNA together to complete the nucleotide excision repair process (Karp, 2008).

In conclusion, while there are many repair mechanisms that the cell uses, nucleotide excision repair is one of the most effective repair mechanisms that act on the DNA.  This is mostly due to its versatility and its simplicity in detection, removing and replacing damaged DNA sections.  As we understand more about the repair systems of the cell and DNA, we begin to realize the consequences of DNA repair deficiencies.  People who have a deficient repair system cannot remove segments of DNA that are damaged.  Thus, even going out in the sun would be impossible, as the harmful UV lights would damage the DNA within the skin and the skin would have no way of repairing it.  This type of deficiency can develop into diseases such as xeroderma pigmentosum (XP), Cockayne syndrome (CS), and photosensitive form of trichothiodystrophy (TTD) (Leibeling et al, 2006).  Therefore, having repair systems within the body and the cell is absolutely critical for the well being of the organism.      

\

References

Leibeling, D., Lapse P. & Emmert S. 2006. Nucleotide Excision Repair and Cancer. Springer Science + Business Media B.V. pp. 225-229.  Retrieved on Sunday, November 8th, 2009 from http://www.ncbi.nlm.nih.gov/pubmed/16855787.

Karp, G. 2008.  Cell and Molecular Biology: Concepts and Experiments, 5th edition.  John Wiley and Sons, Inc. pp.562-567.

This student written piece of work is one of many that can be found in our University Degree Cell Biology section.

(?)
Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Related University Degree Biological Sciences Skills and Knowledge Essays

See our best essays

Related University Degree Cell Biology essays

  1. The purpose of this investigation is to discover whether different respiratory substrates will affect ...

    0.0 4.9 8.8 12.2 15.5 21.3 25.6 29.9 34.8 40.4 0.0 6.7 11.3 16.8 23.5 31.6 38.2 43.1 45.6 48.7 0.0 2.0 5.5 10.3 16.6 20.6 29.6 34.7 41.1 43.3 0.0 3.0 6.5 10.5 15.3 21.6 25.6 34.6 39.7 43.1 0.0 9.5 14.5 22.7 30.7 40.5 48.7 51.3 54.9 57.7

  2. This experiment was carried out to characterize an enzyme, -amylase by extracting it from ...

    Mass of ?-amylase Since the volume of ?-amylase extract added to each of the solution = 0.20ml Mass of ?-amylase extract used in assay = concentration x volume = 20.42 x 0.2 = 4.084�g This calculation was repeated for all the starch solutions with EDTA, urea and without inhibitors to

  1. Discuss how changes in control of the cell cycle contribute to cancer development ...

    are all cancer targets. To underline therefore is that most tumours contain a genetic alteration in one of these genes. Cyclin D1 was first isolated as the BCL1 gene, found at the t (11; 14)

  2. body systems

    The small intestine is very important because it is the major site of digestion of food and it is the absorptions of nutrients which the body needs to function well. Large Intestine (Colon):- The large intestine is where the waste materials pass through where the waste is formed into faeces.

  1. Skin Cancer

    This tendency to extend makes melanoma extremely dangerous. Found in melanocytes, this type of cancer can also develop on other parts of the body (Skin Cancer Guide). The eye is also susceptible to this cancer (Melanoma). More often then men, women have occurrences of melanoma (Skin Cancer Facts).

  2. Biology Light & Life

    * Millions of photons are absorbed each second. � Prokaryotes - Organisms in which their DNA is suspended in the cell interior w/o separation from other cellular components. � Eukaryotes - Organisms in which their DNA is enclosed in a nucleus.

  1. DNA research paper. The Ligation of EGFP cDNA into pET41a(+)

    We then incubated the tubes for 10 minutes at room temperature. To prepare our samples for gel electrophoresis, we micropipetted 10 ul of each ligation as well as 2 ul of track dye into new, separate microcentrifuge tubes. In order to create a template to compare our results to, we also pipetted 12 ul of DNA ladder into a tube.

  2. Methods and Criticism of Cloning and Genetic Modification

    what kind of suffering is caused to the animals during the process of extracting the cells (Prakash S. L; 2005). They also criticized the extent to which scientists were willing to improve animals by increasing the natural capacities? In other words should we use them solely for our own ends?

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work