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What happens to a cell if a chromosome gets damaged

  1. Dec 5, 2017 #1
    Hi, I was wondering what would happen to a cell if one of the chromosomes gets destroyed or damaged in a section?

    I am guessing that, if the "housekeeping genes" and expressed genes are intact, the cell, would be ok or somewhat ok?

    If it can survive, would it affect its ability to do mitosis, or does a cell divide regardless of what "state" the chromosomes are, as long as the cell is alive?

    Thanks!
     
  2. jcsd
  3. Dec 5, 2017 #2

    jim mcnamara

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    Staff: Mentor

    Some points:
    Depending on the tissue and stage of development of plants or animals, cells may:
    never divide,
    sometimes divide,
    divide as a part of everyday function.
    Damaged DNA generally means the death of a cell. The survival rate is low, usually.
    Chemicals that damage DNA are often categorized as teratogens when the targeted organism is an embryonic human.

    https://en.wikipedia.org/wiki/Teratology
     
  4. Dec 5, 2017 #3
    Great, thanks Jim!
     
  5. Dec 5, 2017 #4

    BillTre

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    Science Advisor

    There are many ways a chromosome could get damaged. Some are:
    1. Sequence information is lost because of a bunch of changes in the base pair sequence (point mutants or small deletions). This would destroy its ability to code for it normal functions. Cell function would then be impaired or it might die. Depends on the nature of the genes involved (housekeeping or not).
    2. The chromosome structure is messed up (such as broken into pieces) but the sequence and functions encoded by it are still present in the cell. This could remain alive and function. The small parts could act like small pieces of chromosomes or plasmids, but would not behave well during cell division because not all the pieces would be linked to the centromere which directs the chromsome's movements during mitosis or meiosis. However, if the cell were to divide the daughter cells would most likely lose some pieces of the chromosome or perhaps gain some extras pieces. This could lead to cell death or loss of cellular functions. Treating cancer with radiation breaks up chromosomes. Because cancer cells divide quickly they preferentially die. Any imbalance in the ratios of the numbers of particular genes can cause problems (especially in higher organisms requiring the use of encoded more complex developmental processes).
    3. Chromosomes may also have more complex disruptions due to breaks forming but being repaired (due to cellular DNA repair mechanisms) but not quite being repaired properly. Here is a list of some possible weird chromosome structures that might result. If this results in inversions or other weird situations, the cells may have problems similar to #2 due to crossing over. This could result in having zero or one centromere connected to a piece of chromosome. The results in these cases could be immediate in the next division or might cause accumulating problems over several divisions. This is information I think is best conveyed through pictures, like this one. Additional pictures can be found by googling "inversions and cell division" or other related terms. Genetics texts should also have explanations of these situations.
    4. Lacking teleomeres could lead to the chromosome getting a bit shorter with each division it undergoes. This could also lead to the gradual development of problems accumulating over time.
    5. There are probably other ways problems could occur.
     
  6. Dec 5, 2017 #5
    Incredible! Totally answered it! Thank you Bill!
     
  7. Dec 5, 2017 #6

    Ygggdrasil

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    Science Advisor

    Cells have the ability to sense DNA damage and arrest the cell cycle until the damage is repaired. This helps prevent damaged nucleotides from being incorrectly copied during DNA replication and helps prevent chromosome from being improperly sorted during mitosis. If the cells prove unable to repair the damage, the cell will activate apoptosis—programmed cell death—in order to remove the damaged cell from the body. Problems correctly identifying DNA damage can lead to the accumulation of many damaging mutations and lead to cancer. In fact, many of the genes that are frequently mutated in cancer (e.g. p53, BRCA, DNA polymerase E) are involved in DNA repair.

    Here's a chapter on DNA repair from a cell biology textbook: https://www.ncbi.nlm.nih.gov/books/NBK26879/
     
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