Hey there! Sign in to join this conversationNew here? Join for free

AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 Watch

  • View Poll Results: Are you resitting this unit?
    YES!
    12.91%
    NO!
    87.09%

    Offline

    0
    ReputationRep:
    (Original post by angel1992)
    ok so the ends of the gene arent important???
    alos does tha mean that restriction endonucleases are ususally used on dna isolated by reverse trancriptase so they are intron free?
    Offline

    13
    ReputationRep:
    (Original post by sleungs)
    Hi people!

    Was just wondering... haven't really thought much about the synoptic essay question so wanted to ask what main topics you'd recommend to read up on/ revise?
    Get the syllabus - go over Unit 1,2,4 and 5 and pick out key points from each.
    Offline

    11
    ReputationRep:
    So I started today and I'm up to chapter 14...something tells me this isn't effective revision. :rofl:

    I'm not going to finish unit five let alone look over any of the synoptic stuff for the essay! :facepalm:
    Offline

    2
    ReputationRep:
    (Original post by Cyanohydrin)
    ??

    the t-tubules connect the membrane to a protein complex

    this protein complex is connected to a sarcoplasmic reticulum

    when an action potential passes down the t-tubule and reaches the protein complex it stiumulates the protein complex to signal the release of calcium ions from the sarcoplasmic reticulum

    "Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca2+ release throughout the cell"
    Brette and Orchard, Circulation Research. 2003;92:1182

    I think different books have slightly different versions of this.
    Offline

    0
    ReputationRep:
    (Original post by angel1992)
    alos does tha mean that restriction endonucleases are ususally used on dna isolated by reverse trancriptase so they are intron free?
    I believe that they can be used on DNA containing exons and introns as restriction endonucleases are specific-its just DNA with only exons is shorter so procedure takes shorter amount of time to carry out
    Offline

    2
    ReputationRep:
    (Original post by angel1992)
    ok so the ends of the gene arent important???
    Left-hand side of gene will have promoter, operator regions

    Right-hand side of the gene will have stop codons, usually more than one.

    You can cut out the gene in such a way, that when it is reattached to the vector, it will be flanked by promoter on one side (provided by vector) and stop codons on the other side (provided by vector)
    Offline

    0
    ReputationRep:
    (Original post by xelaman)
    I believe that they can be used on DNA containing exons and introns as restriction endonucleases are specific-its just DNA with only exons is shorter so procedure takes shorter amount of time to carry out
    hey yh i understand that but when isolating a gene for insertion into a plasmid you would want it to be intron free, so in these cases i was asking?
    Offline

    2
    ReputationRep:
    (Original post by Cyanohydrin)
    red blood cells...?

    red blood cells lack any DNA - hence they cannot replicated by mitosis.

    DNA in blood comes from white blood cells.
    Offline

    13
    ReputationRep:
    (Original post by flowerscat)
    "Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca2+ release throughout the cell"
    Brette and Orchard, Circulation Research. 2003;92:1182


    I think different books have slightly different versions of this.
    I don't think that conflicts with what I said

    In the histology of skeletal muscle, a triad is the structure formed by a T tubule with a sarcoplasmic reticulum (SR) known as the terminal cisterna on either side.[1] Each skeletal muscle fiber has many thousands of triads, visible in muscle fibers that have been sectioned longitudinally. (This property holds because T tubules run perpendicular to the longitudinal axis of the muscle fiber.) In mammals, triads are typically located at the A-I junction;[1] that is, the junction between the A and I bands of the sarcomere, which is the smallest unit of a muscle fiber.

    Triads form the anatomical basis of excitation-contraction coupling, whereby a stimulus excites the muscle and causes it to contract. A stimulus, in the form of positively charged current, is transmitted from the neuromuscular junction down the length of the T tubules, activating dihydropyridine receptors (DHPRs). Their activation causes 1) a negligible influx of calcium and 2) a mechanical interaction with calcium-conducting ryanodine receptors (RyRs) on the adjacent SR membrane. Activation of RyRs causes the release of calcium from the SR, which subsequently initiates a cascade of events leading to muscle contraction. These muscle contractions are caused by calcium unmasking the t-t complex on the actin myofilament and allowing the myosin cross-bridges to connect with the actin.
    http://highered.mcgraw-hill.com/site...ntraction.html
    Offline

    2
    ReputationRep:
    (Original post by Cyanohydrin)
    red blood cells...?
    But they don't contain a nucleus...
    Offline

    0
    ReputationRep:
    (Original post by flowerscat)
    Left-hand side of gene will have promoter, operator regions

    Right-hand side of the gene will have stop codons, usually more than one.

    You can cut out the gene in such a way, that when it is reattached to the vector, it will be flanked by promoter on one side (provided by vector) and stop codons on the other side (provided by vector)
    oh ok so the vector will techincally make up part of the gene,, clever thankyou
    Offline

    0
    ReputationRep:
    (Original post by tehsponge)
    But they don't contain a nucleus...
    in blood there is also white blood cells and other type of blood cells as well, so im guessing that the dna from these is used
    Offline

    2
    ReputationRep:
    (Original post by flowerscat)
    red blood cells lack any DNA - hence they cannot replicated by mitosis.

    DNA in blood comes from white blood cells.
    Thats what I thought. Thanks
    Offline

    2
    ReputationRep:
    (Original post by xelaman)
    I believe that they can be used on DNA containing exons and introns as restriction endonucleases are specific-its just DNA with only exons is shorter so procedure takes shorter amount of time to carry out

    If you are cloning into a vector which will then be inserted into bacteria, then you can only have the coding sequence/exon/pre-spliced mRNA.

    If you are cloning into a vector which will then be inserted into another mammalian cell, then it does not matter- mammalian cells possess splicing mechanisms.

    Restriction digestion is independent of the length of DNA.
    Offline

    2
    ReputationRep:
    (Original post by angel1992)
    oh ok so the vector will techincally make up part of the gene,, clever thankyou
    Yes!!

    Signing off now! Happy revising!
    Offline

    0
    ReputationRep:
    (Original post by angel1992)
    hey yh i understand that but when isolating a gene for insertion into a plasmid you would want it to be intron free, so in these cases i was asking?
    I had a flick through my book and it doesnt mention whether DNA does or does not- just that the DNA is inserted with sticky ends into the plasmid- so that it can be synthesised within bacteria like it would be in a normal cell
    Offline

    2
    ReputationRep:
    (Original post by tehsponge)
    I'm confused. Where is the DNA in the blood found?
    white blood cells i'd say.
    Offline

    0
    ReputationRep:
    June 2010 paper question 6 (c) (ii)
    how might the insertion of the DNA might have caused cancer??
    in this question.....why cant we talk about mutation of proto-oncogenes?? the mark scheme only accepts comments on tummor suppressor gene
    Offline

    0
    ReputationRep:
    Anybody need help with revising Silding Filament THeory before Wednesday's exam? This vid may be of use

    https://www.o2learn.co.uk/o2_video.php?vid=1339
    Offline

    0
    ReputationRep:
    in my book nt it says, in vivo is advantageous as it cuts out specific genes not just replicating whole dna samples, but pcr cant replicate whole dna samples, it can only replicate small fragments of dna???
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Would you rather give up salt or pepper?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Write a reply...
    Reply
    Hide
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.