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    (Original post by ForeverDreaming)
    Hi fellow biologists, I was wondering if anyone knows the level of knowledge required on anabolic steroids.

    The book has hardly any information in it on detecting it's misuse from urine (Pg 31 of spec, point k), can someone summarise it for me?

    If so, I would be very grateful.
    anabolic steroids are small molecules, therefore can pass through the bowman's capsule and be traced in the urine. the urine can be vaporised in a tube with an aid of a gas solvent...the anabolic steroid can be held within the lining of the tube via an absobtion agent...the time taken to be released from the lining (the retention time) can be compared to that of aneabolic steroids using a chromatogram..if the timing is similiar , it shows that there was indeed anabolic steroids in the urine.

    this method is called gas chromatography.

    hope that helps
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    (Original post by ibysaiyan)
    Thats great!:cool:
    cheers man...best of luck with your c/w
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    Selective reabsorbtion



    A basic outline of the process of selective reabsorption
    The co-transport pump actively transports sodium out of the PCT wall (using energy from converting ATP to ADP + Pi) to maintain a low Na+ concentration gradient in the wall.
    This low concentration gradient means that Na+ ions from the glomerulus filtrate can easily passively diffuse into the wall of the PCT.
    However the Na+ ions cannot diffuse freely across the membrane, but can only enter through special transporter (carrier) proteins in the membrane of the wall.
    There are several different kinds of these transporter proteins, each of which transports another molecule, such as glucose or amino acids. The concentration gradient for the sodium provides the energy to pull in these other molecules into the wall of the PCT.
    As the substances listed above (Na+ ions, amino acids and glucose) enter the wall of the PCT, so does 65-70% of the water in the glomerulus filtrate via osmosis. Water can move freely through the wall of the PCT (it does not require a transporter protein.) Nearly all the rest of the water is reabsorbed into the blood in the Loop of Henle and the Collecting duct system.
    However as urea is a small molecule it can pass easily through the membrane of the PCT wall. As the concentration of urea in the filtrate is significantly higher than in the blood, around 50% of urea on the filtrate is reabsorbed.
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    (Original post by MadMaths)
    anabolic steroids are small molecules, therefore can pass through the bowman's capsule and be traced in the urine. the urine can be vaporised in a tube with an aid of a gas solvent...the anabolic steroid can be held within the lining of the tube via an absobtion agent...the time taken to be released from the lining (the retention time) can be compared to that of aneabolic steroids using a chromatogram..if the timing is similiar , it shows that there was indeed anabolic steroids in the urine.

    this method is called gas chromatography.

    hope that helps
    so basically urine is vaporised by this gas solvent, and the suspected :P anabolic steroid is held within this tube by an absorption agent, the time its been held at that position is compared to that of an anabolic steroid? is that correct?>
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    (Original post by ibysaiyan)
    so basically urine is vaporised by this gas solvent, and the suspected :P anabolic steroid is held within this tube by an absorption agent, the time its been held at that position is compared to that of an anabolic steroid? is that correct?>
    yep yep
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    Ah thing to add :P insulin is not made by the beta cells but instead its secreted by them, also we need to know how they are secreted which is pretty similar to synapses .
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    (Original post by MadMaths)
    yep yep
    K, thanks
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    (Original post by ibysaiyan)
    Ah thing to add :P insulin is not made by the beta cells but instead its secreted by them, also we need to know how they are secreted which is pretty similar to synapses .
    how are they secreted???
    wher are they made??

    i kno ADH acts in a similiar way. made in hypothalamus and stored and secreted from the posterier pituitary glands via the exocrine process.
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    (Original post by MadMaths)
    Selective reabsorbtion



    A basic outline of the process of selective reabsorption
    The co-transport pump actively transports sodium out of the PCT wall (using energy from converting ATP to ADP + Pi) to maintain a low Na+ concentration gradient in the wall.
    This low concentration gradient means that Na+ ions from the glomerulus filtrate can easily passively diffuse into the wall of the PCT.
    However the Na+ ions cannot diffuse freely across the membrane, but can only enter through special transporter (carrier) proteins in the membrane of the wall.
    There are several different kinds of these transporter proteins, each of which transports another molecule, such as glucose or amino acids. The concentration gradient for the sodium provides the energy to pull in these other molecules into the wall of the PCT.
    As the substances listed above (Na+ ions, amino acids and glucose) enter the wall of the PCT, so does 65-70% of the water in the glomerulus filtrate via osmosis. Water can move freely through the wall of the PCT (it does not require a transporter protein.) Nearly all the rest of the water is reabsorbed into the blood in the Loop of Henle and the Collecting duct system.
    However as urea is a small molecule it can pass easily through the membrane of the PCT wall. As the concentration of urea in the filtrate is significantly higher than in the blood, around 50% of urea on the filtrate is reabsorbed.
    dont forget that the concentration of urea in the glomerular filtrate actually increases due to the reabsorbtion of water into the blood cappilaries which decreases the volume of fluid from 125 cm3 to 45 cm3. cell of basal membranes activelly secrete ureaic acid and creatine into the lumen of pct.
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    (Original post by Maria-16*)
    where can you get a copy of the spec from?
    here this is for the new ocr spec course just click specification and follow it, still got fri,sat and sunday you can do a lot in those days

    http://www.ocr.org.uk/qualifications...ogy/index.html
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    (Original post by MadMaths)
    how are they secreted???
    wher are they made??

    i kno ADH acts in a similiar way. made in hypothalamus and stored and secreted from the posterier pituitary glands via the exocrine process.
    The control of insulin secretion is new to the sylabus and likley to come up.
    1) beta cells contain several ion channels including k+ ions and ca + ion chanells.
    2) when glucose conc is normal the k+ ion chanells are open so potasuim ions diffuse down electrochemical gradient out of beta cell into sourounding tisue fluid.
    3) inside of beta cell is -70 mv compared to outisde of membrane
    4)when glucose conc in blood rises more glucose enters the beta cell.
    5)as more glucose enters it stimulates enzyme glucokinase to phosphoralate glucose and this is metabolised to produce atp.
    6) increase concentration of atp in beta cell causes k+ ion channels to close.
    7)k+ ions no longer able to diffuse out of beta cell which reduces potential difference across membrane to -30 mv.
    8) this favours calcuim ion chanells which were normally closed to open and calcuim ions flood into the cell.
    9) calcuim ions cause vesicles containing insulin to move and fuse with plasma membrane and to secrete insulin into the blood.
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    (Original post by MadMaths)
    how are they secreted???
    wher are they made??

    i kno ADH acts in a similiar way. made in hypothalamus and stored and secreted from the posterier pituitary glands via the exocrine process.
    Hmm ok.
    well to start off, insulin is already present in vesicles inside the beta cells.As soon as the blood glucose concentration offshoots alot more glucose passes through beta cells, normally they pass through glucose transporter proteins, but since there conc. has increased alot more glucose pass than usual,as a result enzyme gluckinase phosporylates glucose.This posphorylated glucose metabolises into ATP.As lot atp is being made ,normally k channels are open.(so a +ve charge out compared to in) , these channels are sensitive to ATP concentraion, as a result they close, this changes the p. difference across the cell, here Calcium channels come into the picture, they flow in, this influxes vesicles containing insulin to be released into the blood by exocytosis.
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    (Original post by MG.GULED)
    The control of insulin secretion is new to the sylabus and likley to come up.
    1) beta cells contain several ion channels including k+ ions and ca + ion chanells.
    2) when glucose conc is normal the k+ ion chanells are open so potasuim ions diffuse down electrochemical gradient out of beta cell into sourounding tisue fluid.
    3) inside of beta cell is -70 mv compared to outisde of membrane
    4)when glucose conc in blood rises more glucose enters the beta cell.
    5)as more glucose enters it stimulates enzyme glucokinase to phosphoralate glucose and this is metabolised to produce atp.
    6) increase concentration of atp in beta cell causes k+ ion channels to close.
    7)k+ ions no longer able to diffuse out of beta cell which reduces potential difference across membrane to -30 mv.
    8) this favours calcuim ion chanells which were normally closed to open and calcuim ions flood into the cell.
    9) calcuim ions cause vesicles containing insulin to move and fuse with plasma membrane and to secrete insulin into the blood.
    thanks
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    (Original post by ibysaiyan)
    Hmm ok.
    well to start off, insulin is already present in vesicles inside the beta cells.As soon as the blood glucose concentration offshoots alot more glucose passes through beta cells, normally they pass through glucose transporter proteins, but since there conc. has increased alot more glucose pass than usual,as a result enzyme gluckinase phosporylates glucose.This posphorylated glucose metabolises into ATP.As lot atp is being made ,normally k channels are open.(so a +ve charge out compared to in) , these channels are sensitive to ATP concentraion, as a result they close, this changes the p. difference across the cell, here Calcium channels come into the picture, they flow in, this influxes vesicles containing insulin to be released into the blood by exocytosis.
    ahh, ok thanks
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    (Original post by MadMaths)
    ahh, ok thanks
    hey np =), like i mentioned earlier lol this is my temporary settlement xD.
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    (Original post by ibysaiyan)
    hey np =), like i mentioned earlier lol this is my temporary settlement xD.
    lol
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    (Original post by MG.GULED)
    The control of insulin secretion is new to the sylabus and likley to come up.
    1) beta cells contain several ion channels including k+ ions and ca + ion chanells.
    2) when glucose conc is normal the k+ ion chanells are open so potasuim ions diffuse down electrochemical gradient out of beta cell into sourounding tisue fluid.
    3) inside of beta cell is -70 mv compared to outisde of membrane
    4)when glucose conc in blood rises more glucose enters the beta cell.
    5)as more glucose enters it stimulates enzyme glucokinase to phosphoralate glucose and this is metabolised to produce atp.
    6) increase concentration of atp in beta cell causes k+ ion channels to close.
    7)k+ ions no longer able to diffuse out of beta cell which reduces potential difference across membrane to -30 mv.
    8) this favours calcuim ion chanells which were normally closed to open and calcuim ions flood into the cell.
    9) calcuim ions cause vesicles containing insulin to move and fuse with plasma membrane and to secrete insulin into the blood.
    ahh i only went out for a cigerette, you beat me to it :p:
    made my mum test me on this half an hour ago
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    ATP
    - Made from the base adenine (did not know this :O)
    -pentose ribose sugar
    -3 phosphate groups

    - phosphate groups are joined by high energy bonds which release large amounts of enery when hydrolysed. Energy released is used to drive reactions in cells!

    Argh guys im losing my motivation - was going so well
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    (Original post by CertifiedAngel)
    ATP
    - Made from the base adenine (did not know this :O)
    -pentose ribose sugar
    -3 phosphate groups

    - phosphate groups are joined by high energy bonds which release large amounts of enery when hydrolysed. Energy released is used to drive reactions in cells!

    Argh guys im losing my motivation - was going so well
    Yep thats right infact atp is alot similar to RNA ..
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    (Original post by CertifiedAngel)
    ATP
    - Made from the base adenine (did not know this :O)
    -pentose ribose sugar
    -3 phosphate groups
    ATP stands for Adenine TriPhosphate.. lol

    and ADP is Adenine DiPhosphate. Because it only has 2 phosphate groups.
    Like in respiration when one phosphate group had been broken off and we're left with ADP + Pi
 
 
 
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