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ATP: Adenosine triphosphate

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    Sal: ATP or adenosine triposphate
    is often referred to as
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    the currency of energy, or
    the energy store, adenosine,
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    the energy store in biological systems.
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    What I want to do in this video is get
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    a better appreciation of why that is.
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    Adenosine triposphate.
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    At first this seems like
    a fairly complicated term,
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    adenosine triphosphate, and
    even when we look at its
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    molecular structure it seems
    quite involved, but if we break
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    it down into its constituent
    parts it becomes a little bit
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    more understandable and we'll
    begin to appreciate why,
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    how it is a store of energy
    in biological systems.
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    The first part is to break
    down this molecule between
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    the part that is adenosine
    and the part that
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    is the triphosphates, or
    the three phosphoryl groups.
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    The adenosine is this
    part of the molecule,
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    let me do it in that same color.
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    This part right over here is adenosine,
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    and it's an adenine connected to a ribose
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    right over there, that's
    the adenosine part.
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    And then you have three phosphoryl groups,
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    and when they break off they
    can turn into a phosphate.
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    The triphosphate part
    you have, triphosphate,
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    you have one phosphoryl
    group, two phosphoryl groups,
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    two phosphoryl groups and
    three phosphoryl groups.
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    One way that you can conceptualize
    this molecule which will
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    make it a little bit easier
    to understand how it's a store
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    of energy in biological systems
    is to represent this whole
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    adenosine group, let's just
    represent that as an A.
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    Actually let's make that an Ad.
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    Then let's just show it bonded to
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    the three phosphoryl groups.
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    I'll make those with a P
    and a circle around it.
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    You can do it like that,
    or sometimes you'll see it
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    actually depicted, instead
    of just drawing these
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    straight horizontal lines
    you'll see it depicted
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    with essentially higher energy bonds.
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    You'll see something like that to show
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    that these bonds have a lot of energy.
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    But I'll just do it this way
    for the sake of this video.
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    These are high energy bonds.
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    What does that mean, what does that
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    mean that these are high energy bonds?
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    It means that the electrons
    in this bond are in a
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    high energy state, and if
    somehow this bond could be
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    broken these electrons are
    going to go into a more
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    comfortable state, into
    a lower energy state.
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    As they go from a higher
    energy state into a lower, more
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    comfortable energy state they
    are going to release energy.
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    One way to think about it
    is if I'm in a plane and
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    I'm about to jump out I'm
    at a high energy state,
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    I have a high potential energy.
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    I just have to do a
    little thing and I'm going
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    to fall through, I'm going to fall down,
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    and as I fall down I can release energy.
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    There will be friction
    with the air, or eventually
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    when I hit the ground
    that will release energy.
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    I can compress a spring
    or I can move a turbine,
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    or who knows what I can do.
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    But then when I'm sitting on my couch
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    I'm in a low energy, I'm comfortable.
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    It's not obvious how I could
    go to a lower energy state.
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    I guess I could fall asleep
    or something like that.
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    These metaphors break down at some point.
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    That's one way to think
    about what's going on here.
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    The electrons in this bond,
    if you can give them just
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    the right circumstances they
    can come out of that bond
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    and go into a lower energy
    state and release energy.
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    One way to think about it, you start
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    with ATP, adenosine triphosphate.
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    And one possibility, you put
    it in the presence of water and
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    then hydrolysis will take
    place, and what you're going to
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    end up with is one of these things
    are going to be essentially,
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    one of these phosphoryl
    groups are going to be
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    popped off and turn into
    a phosphate molecule.
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    You're going to have
    adenosine, since you don't
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    have three phosphoryl
    groups anymore, you're only
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    going to have two phosphoryl
    groups, you're going to
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    have adenosine diphosphate,
    often known as ADP.
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    Let me write this down.
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    This is ATP, this is ATP right over here.
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    And this right over
    here is ADP, di for two,
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    two phosphoryl groups,
    adenosine diphosphate.
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    Then this one got plucked
    off, this one gets plucked
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    off or it pops off and it's
    now bonded to the oxygen
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    and one of the hydrogens
    from the water molecule.
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    Then you can have another hydrogen proton.
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    The really important part of
    this I have not drawn yet,
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    the really important part of it,
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    as the electrons in this
    bond right over here go into
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    a lower energy state they
    are going to release energy.
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    So plus, plus energy.
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    Here, this side of the reaction,
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    energy released, energy released.
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    And this side of the interaction
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    you see energy, energy stored.
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    As you study biochemistry
    you will see time and time
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    again energy being used in
    order to go from ADP and
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    a phosphate to ADP, so
    that stores the energy.
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    You'll see that in things
    like photosynthesis
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    where you use light energy to essentially,
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    eventually get to a point
    where this P is put back on,
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    using energy putting this P
    back on to the ADP to get ATP.
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    Then you'll see when biological
    systems need to use energy
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    that they'll use the ATP
    and essentially hydrolysis
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    will take place and they'll
    release that energy.
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    Sometimes that energy could
    be used just to generate heat,
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    and sometimes it can be
    used to actually forward
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    some other reaction or
    change the confirmation of
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    a protein somehow,
    whatever might be the case.
Title:
ATP: Adenosine triphosphate
Description:

Introduction to ATP. How it is the store of energy in biological systems

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Video Language:
English
Duration:
06:19

English subtitles

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