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  1. #1
    Roxanita is offline Senior Member
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    Biochemistry Genetics N* q-2

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    A genetic element is found to contain several genes and to catalyze its own movement within and between chromosomes. Inverted 35-nucleotide repeats are present at the ends of this genetic element. This genetic element in hepatocytes is incapable of replicating independently. Based on this description, this genetic element is best categorized as which of the following?

    A) Complex transposon
    B) Insertion sequence
    C) Plasmid
    D) Regulon

  2. #2
    usmle_exam is offline Newbie
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    ans

    ) Complex transposon

  3. #3
    riponbaig is offline Newbie
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    explanation

    would you pls explain ..........

  4. #4
    Lorena's Avatar
    Lorena is offline Member 510 points
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    Biochemistry Genetics N* q-2

    I hope this helps Riponbaig....


    Quote Originally Posted by Roxanita
    A genetic element is found to contain several genes and to catalyze its own movement within and between chromosomes. Inverted 35-nucleotide repeats are present at the ends of this genetic element. This genetic element in hepatocytes is incapable of replicating independently. Based on this description, this genetic element is best categorized as which of the following?

    A) Complex transposon
    B) Insertion sequence
    C) Plasmid
    D) Regulon

    i think it is answer b. INSERTION SEQUENCE

    Transposable genetic elements are segments of DNA that have the capacity to move from one location to another ("jumping genes"), some of their properties are : random movement, not capable of self replication, etc
    There are different types of transposable genetic elements:

    Insertion sequences They are small stretches of DNA and have at their ends inverted repeated sequences which are involved in transposition. In between the terminal repeated sequences there are genes involved in transposition and sequences that can control the expression of the genes but no other essential genes are present.

    Transposons are transposable genetic elements that carry one or more other genes in addition to those which are essential for transposition,the structure is similar to that of an insertion sequence but the extra genes are located between the terminal repeated sequences (which it is not the case here)


    The importance of these "jumping genes" is that many antibiotic resistance genes are located on transposons so can jump from one DNA molecule to another and confer multiple drug resistance.

    scary!


    Look at this website which i think is very good in bacterial genetics:

    ref. http://www.med.sc.edu:85/mayer/genetic%20ex.htm

  5. #5
    riponbaig is offline Newbie
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    thanks

    excellent explanation.....................thanks lorena............more thanks for the site.

  6. #6
    riponbaig is offline Newbie
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    thanks

    excellent explanation.....................thanks lorena............more thanks for the site.

  7. #7
    Anonymous is offline Unregistered Guest
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    I think its C

    A genetic element is found to contain several genes and to catalyze its own movement within and between chromosomes. Inverted 35-nucleotide repeats are present at the ends of this genetic element. This genetic element in hepatocytes is incapable of replicating independently. Based on this description, this genetic element is best categorized as which of the following?

    A) Complex transposon
    B) Insertion sequence
    C) Plasmid
    D) Regulon
    i think the answer is C .
    From kaplan notes and the website given by Lorena,
    Insertion sequences (IS) have the:
    -just the gene for transposase
    -have the terminal indirect repeats
    -have promoters, transcription and translation-termination signals(i.e. sequences for gene expression)
    Transposons (Tn) have:
    -insertion sequences plus at least one other gene
    -include some genes for drug resistance
    -they are also jumping genes.
    Tn and IS are mobile genetic elements i.e can move from one molecule of DNA to another and can move within a chromosome. They are found in eukaryotic and bacterial cells and viruses.
    The genetic element in the question has several genes (IS has just the gene/genes for transposase while Tn may have additional genes like those for drug resistance) and can't replicate independently( a xteristic of both IS and transposon; plasmids canvreplicate autonomously). I think the Q is talking about a transposon.

    What's the answer Roxanita?

  8. #8
    Lorena's Avatar
    Lorena is offline Member 510 points
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    yes



    I think you are right tanx. Sorry for the mixing up and thank you tanx for explaining this to me and everybody.I kind a didnt look at the word "several"

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    Anonymous is offline Unregistered Guest
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    Which one is the answer?

    Hi, Tanx, I got confused, which answer you think correct, plasmid or transposon? Thanks for explain.

  10. #10
    Anonymous is offline Unregistered Guest
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    Which one is the answer?

    Hi, Tanx, I got confused, which answer you think correct, plasmid or transposon? Thanks for explain.

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