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The Significance of a Point Mutation in Chromosome 1

written by: Blaise Wellesley•edited by: Emma Lloyd•updated: 9/2/2010

Learn the significance of a point mutation in Chromosome 1. What are the consequences of a point mutation? How can it cause cancer? What diseases are associated with it?

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    Overview of Chromosome 1

    Chromosome 1 is the largest of the autosomal chromosomes in the human species. With about 247 million base pairs, chromosome 1 makes up about 8% of the total deoxyribonucleic acid, or DNA, in humans. Due to its size, the entire chromosome was the last to be sequenced and it was found to hold around 4,200 genes. Due to it's large size, what would be the significance of a point mutation in chromosome 1?

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    What is a point mutation?

    A point mutation in chromosome 1 is a switch or replacement of a single nucleotide with another one, occurring in DNA or RNA. Even though a point mutation is small, it can cause drastic complications in a developing organism. A point mutation is characterized as a insertion or deletion or a nucleotide as otherwise explained. As DNA is transcribed into RNA, a mutation can occur on any given nucleotide. More errors can arise when RNA is then translated into a protein molecule. A mutation occurring in either or in both can negate the production of the protein, make a mutated form of the correct protein, or make something entirely different that is unusable by the cell.

    Mutations can also occur when the cell is dividing. During this process, the cell needs to replicate its DNA to give off to its daughter cells. If proofreading fails, a mutation can occur that is passed down through the cell's linage. Cells are influence by mutagens, a chemical or physical agent that increase the rate of mutation, such as UV rays, X-rays, and agent orange. Mutagens have been linked to cancerous tumors, such as breast cancer, due to their rapid spread of mutation in an organism.

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    Images

    Map of Chromosome 1
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    Diseases as a result of a mutation

    Due to its sheer size, point mutations in chromosome 1 can cause a wide variety of diseases and symptoms.

    • Deletions in the short arm tend to cause tumors in the kidney and brain.
    • Duplications in the long arm can cause a disorder called myelodysplastic syndrome. This syndrome is a disease of the blood and bone marrow, which results in a low number in red blood cells. It has been found that patients with myelodysplastic syndrome have an increased risk of developing leukemia.
    • 1p36 deletion syndrome is a deletion of the short arm of chromosome 1. Symptoms usually include disabilities in intelligence, abnormal facial and organ structural systems.
    • Alzheimer's disease can be a result of a chromosome 1 abnormality. Alzheimer's is terminal and degenerative disease that causes dementia in patients. There is no cure to Alzheimer's disease.
    • Charcot-Marie-Tooth disease is a disorder that includes symptoms of loss of nerves in the feet and other parts of the body. Like Alzheimer's disease, there is no cure.
    • Gaucher's disease is diagnosed when large amounts of fat builds in certain organs, such as the spleen, liver, and lungs. Symptoms include swelling of the lymph nodes and other gland-like organs, anemia, and fatty deposits of the eye.
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    References

    • PubMed. Candidate gene for the chromosome 1 familial Alzheimer's disease locus - http://www.ncbi.nlm.nih.gov/pubmed/7638622
    • Nature. The DNA sequence and biological annotation of human chromosome 1 - http://www.nature.com/nature/journal/v441/n7091/full/nature04727.html
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    Image References

    • WikiCommons. http://commons.wikimedia.org/wiki/File:116px-Chromosome_1.jpeg





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