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    a QUESTION to everyone:

    What is the ROLE of myelin sheath
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    (Original post by skatealexia)
    What you having trouble with?
    well the whole process with respect to all that shizz about lactate
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    (Original post by chuck111)
    was also asking the exact same question
    went through the entire syllabus only meantions photosynthometer but not a respirometer

    Exactly. Hence, I'm not learning it.
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    (Original post by clad in armour)
    do you mean local current?
    No. Local circuit in action potentials.
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    (Original post by TX22)
    a QUESTION to everyone:

    What is the ROLE of myelin sheath
    been asked before, faster conduction of impulse due to saltatory conduction and insulates from other neurons and stuff
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    Is experimental evidence for resp. gonna come up?







    I don't understand it?
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    (Original post by skatealexia)
    Exactly. Hence, I'm not learning it.
    but whats to learn, i mean surely youve done an assessed practical where youve used one
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    (Original post by TX22)
    a QUESTION to everyone:

    What is the ROLE of myelin sheath
    Simple: To greatly enhance nervous conduction (by 50 times no need to know this).
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    (Original post by clad in armour)
    well the whole process with respect to all that shizz about lactate

    Lactate= Muscle anaerobic respiration. Produces 2 ATP, since glycolysis still takes place, but due to no oxygen, krebs cycle, the link reaction and krebs cycle are blocked. NADH has been formed, which normally goes to oxidative phosphorylation, and without NAD, glycolysis cannot take place ( as triose-phosphate is oxidised to pyryvate, and the NAD accepts a hydrogen), hence, the pyruvate is converted to lactate, via lactate dehydrogenase enzymes, the pyruvate accepts a hydrogen from the NADH forming lactate ( lactic acid), meaning NAD is now replenished for glycolysis which can now still take place.

    Better?
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    Anyone care to explain what we need to know for evidence for respiration?
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    (Original post by InvoluntarySlacker)
    Someone explain local circuit?
    When the threshold potential difference is reached, Sodium voltage gated channels (VGS) open, and the sodium ions diffuse into the axon of the neurone. When the Sodium ions have entered the axon, they begin to diffuse sideways, down the concentration gradient along the axon. This causes the sodium channels in the next region of the axon to open, causing an influx of sodium ions into that region of the axon. This causes a wave of depolarisation across the axon. The wave of depolarisation moves away from the region of the axon in the refractory period to an area that isn't, this causes the wave of depolarisation to move unidirectionally.
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    (Original post by TX22)
    a QUESTION to everyone:

    What is the ROLE of myelin sheath
    The myelin sheath is an electrical insulator. Na+ channels are concentrated at the nodes of ranvier, and depolorisation can only take place here. The cytoplasm of the schwann cells can conduct enough electrical impulse to depolarise the next node. The action potential 'jumps' from node to node, hence the impulse travels much quicker. This is saltatory conduction.
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    (Original post by Get Cape.Wear Cape.Fly.)
    Anyone care to explain what we need to know for evidence for respiration?
    Low pH
    • pH of the intermembrane space was found to be lower than mitochondrial matrix
    • A low ph means it is more acidic due to the high concentration of protons
    • Observation shows there is a proton gradient between the intermembrane space and the matrix

    Artificial Vesicles
    • Artificial vesicles created from phospholipid bilayers to represent inner mitochondrial membrane
    • Proton pumps from bacteria and ATP synthase were added to the vesicle membranes
    • Proton pumps activated by light, so when light was shone onto these vesicles they started to pump protons
    • pH inside the vesicles decreased as protons where being pumped from the outside
    • ADP +Pi where added and ATP was produced
    • Artificial system shows that a proton gradient can be used to generate ATP
    Mitochondria
    • Mitochondria were put into an alkaline solution
    • Left until entire mitochondrion became ph8
    • When these mitochondria where given ADP + Pi, no ATP was produced
    • The mitochondria where then transferred to an acidic solution
    • Protons moved into the intermembrane space, creating a proton gradient
    • ADP + Pi where added and ATP was produced
    • Experiment shows that a proton gradient can be used by mitochondria to make ATP

    • Uncouplers
    • Uncouplers destroy the proton gradient across the inner mitochondrial membrane
    • An uncoupler was added to mitochondria with reduced NAD, ADP + pi
    • No ATP was made
    • Experiment shows a proton gradient is needed to synthesise ATP in mitochondria
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    (Original post by Get Cape.Wear Cape.Fly.)
    Anyone care to explain what we need to know for evidence for respiration?

    Like chemiosmosis?
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    So, what experimental evidence do we need to know for respiration?

    Someone please answer me! I answer all your questions wtf?
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    (Original post by clad in armour)
    been asked before, faster conduction of impulse due to saltatory conduction and insulates from other neurons and stuff
    :curious:

    I thought it was sodium ions diffusing sideways, causing more voltage gates to open. And it only ensures one direction as sodium channels close when new one in opened. :confused:

    I know nodes of ranviers have longer local circuits making it faster.
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    (Original post by chuck111)
    Low pH
    • pH of the intermembrane space was found to be lower than mitochondrial matrix
    • A low ph means it is more acidic due to the high concentration of protons
    • Observation shows there is a proton gradient between the intermembrane space and the matrix

    Artificial Vesicles
    • Artificial vesicles created from phospholipid bilayers to represent inner mitochondrial membrane
    • Proton pumps from bacteria and ATP synthase were added to the vesicle membranes
    • Proton pumps activated by light, so when light was shone onto these vesicles they started to pump protons
    • pH inside the vesicles decreased as protons where being pumped from the outside
    • ADP +Pi where added and ATP was produced
    • Artificial system shows that a proton gradient can be used to generate ATP
    Mitochondria
    • Mitochondria were put into an alkaline solution
    • Left until entire mitochondrion became ph8
    • When these mitochondria where given ADP + Pi, no ATP was produced
    • The mitochondria where then transferred to an acidic solution
    • Protons moved into the intermembrane space, creating a proton gradient
    • ADP + Pi where added and ATP was produced
    • Experiment shows that a proton gradient can be used by mitochondria to make ATP

    • Uncouplers
    • Uncouplers destroy the proton gradient across the inner mitochondrial membrane
    • An uncoupler was added to mitochondria with reduced NAD, ADP + pi
    • No ATP was made
    • Experiment shows a proton gradient is needed to synthesise ATP in mitochondria
    omg thank uuuuuuuu!
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    (Original post by InvoluntarySlacker)
    :curious:

    I thought it was sodium ions diffusing sideways, causing more voltage gates to open. And it only ensures one direction as sodium channels close when new one in opened. :confused:

    I know nodes of ranviers have longer local circuits making it faster.
    what are all these circuits and currents
    AHHH
    im freaking out
    im gunna fail /cry
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    (Original post by skatealexia)
    Like chemiosmosis?
    3 basic points for chemeomosis:
    1) An unusual amount of PH concentration on one side of the etc than the other, stating that protons are actively being pumped.
    2)ATP being produced even though there doesnt exist ETC in mitochondria/chloroplast.
    3)Substances which inhibit proton gradient such as DI-nitrophenol by accepting H+ ions don't produce ATP.
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    (Original post by Get Cape.Wear Cape.Fly.)
    Is experimental evidence for resp. gonna come up?

    I don't understand it?
    well its a specific spec point so why wouldnt it

    just say stuff like, it was originally thought that there was a high energy intermediate chemical that stored the energy associated with NAD but was disproved by various studies but now we know the accepted theory is the chemiosmosis one
    loadsa reasons why

    -cells stripped (mitoblasts) of their outer membrane dont respire so intermembrane space is involved somehow
    -oligimycin inhibts flow of protons through atp - synthase, and when introduced no atp is made
    -inner membrane is ruptured by detergents to see the where the different stages happend and what enzymes were involved

    -cells were put into solutions of low water potential so they burst to see what its like inside or summat

    -with intact cells, -200mV pd across inner membrane with matrix compared to intermembrane space

    -pH difference on matrix side is higher than i.m. space
 
 
 
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