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    does any1 how a catalyst works!!!!!???????!!! :confused:
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    speeds up a reaction.. summat to do with molecules going faster
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    A catalyst speeds up a reaction. For example an enzyme is a catalyst, and u can look up the lock and key method it uses to catalyse reactions.

    p.s. i'm not a scientist, so dont blame me if i'm wrong!
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    (Original post by Moochy)
    speeds up a reaction.. summat to do with molecules going faster
    need a more scientific explanation!!!
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    hi, a catalyst provides an alternative pathway with a lower activation energy (minimum energy required for a reaction). the alternative pathway makes the activated complex (transition state) be reached at a lower activation energy, so the rate of reaction increasses given that a greater proportion of particles have this lower activation energy. graphically you can imagine this in the Maxwell-boltzmann distribution.
    the catalyst does not affect the enthalpy change of the reaction, just the products or EQm is reached faster.
    hope this helps
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    (Original post by serendipity)
    A catalyst speeds up a reaction. For example an enzyme is a catalyst, and u can look up the lock and key method it uses to catalyse reactions.

    p.s. i'm not a scientist, so dont blame me if i'm wrong!
    an example of an enzyme speeding digestion up is :
    protease breaks protein down into amino acids
    Lol sorry, I had to mention it because it's part of my GCSE module test that I'm learning for.
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    any other doubt give me ur msn or something, and i can explain it in more detail.
    cheers , good luck too
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    (Original post by highexpectation)
    any other doubt give me ur msn or something, and i can explain it in more detail.
    cheers , good luck too
    thanx... but cud u explain it in simpler words.........( i'm a bit thick0!!!
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    An Enzyme is any one of many specialised organic substances, composed of polymers of amino acids, that act as catalysts to regulate the speed of the many chemical reactions involved in the metabolism of living organisms. Those enzymes identified now number more than 700.
    Enzymes are classified into several broad categories, such as hydrolytic, oxidising, and reducing, depending on the type of reaction they control. Hydrolytic enzymes accelerate reactions in which a substance is broken down into simpler compounds through reaction with water molecules. Oxidising enzymes, known as oxidises, accelerate oxidation reactions; reducing enzymes speed up reduction reactions, in which oxygen is removed. Many other enzymes catalyse other types of reactions.
    Individual enzymes are named by adding ASE to the name of the substrate with which they react. The enzyme that controls urea decomposition is called urease; those that control protein hydrolyses are known as proteinases. Some enzymes, such as the proteinases trypsin and pepsin, retain the names used before this nomenclature was adopted.

    Structure and Function of an Enzyme
    Enzymes are large proteins that speed up chemical reactions. In their globular structure, one or more polypeptide chains twist and fold, bringing together a small number of amino acids to form the active site, or the location on the enzyme where the substrate binds and the reaction takes place. Enzyme and substrate fail to bind if their shapes do not match exactly. This ensures that the enzyme does not participate in the wrong reaction. The enzyme itself is unaffected by the reaction. When the products have been released, the enzyme is ready to bind with a new substrate.codf dfr sedfdfw ordf dfk indf fodf df.


    Properties of Enzymes
    As the Swedish chemist Jöns Jakob Berzelius suggested in 1823, enzymes are typical catalysts: they are capable of increasing the rate of reaction without being consumed in the process.
    Some enzymes, such as pepsin and trypsin, which bring about the digestion of meat, control many different reactions, whereas others, such as urease, are extremely specific and may accelerate only one reaction. Still others release energy to make the heart beat and the lungs expand and contract. Many facilitate the conversion of sugar and foods into the various substances the body requires for tissue-building, the replacement of blood cells, and the release of chemical energy to move muscles.
    Pepsin, trypsin, and some other enzymes possess, in addition, the peculiar property known as autocatalysis, which permits them to cause their own formation from an inert precursor called zymogen. As a consequence, these enzymes may be reproduced in a test tube.
    As a class, enzymes are extraordinarily efficient. Minute quantities of an enzyme can accomplish at low temperatures what would require violent reagents and high temperatures by ordinary chemical means. About 30g of pure crystalline pepsin, for example, would be capable of digesting nearly 2 metric tons of egg white in a few hours.
    The kinetics of enzyme reactions differ somewhat from those of simple inorganic reactions. Each enzyme is selectively specific for the substance in which it causes a reaction and is most effective at a temperature peculiar to it. Although an increase in temperature may accelerate a reaction, enzymes are unstable when heated. The catalytic activity of an enzyme is determined primarily by the enzyme's amino-acid sequence and by the tertiary structure-that is, the three-dimensional folded structure of the macromolecule. Many enzymes require the presence of another ion or a molecule called a cofactor, in order to function.
    As a rule, enzymes do not attack living cells. As soon as a cell dies, however, enzymes that break down protein rapidly digest it. The resistance of the living cell is due to the enzyme's inability to pass through the membrane of the cell as long as the cell lives. When the cell dies, its membrane becomes permeable, and the enzyme can then enter the cell and destroy the protein within it. Some cells also contain enzyme inhibitors, known as antienzymes, which prevent the action of an enzyme upon a substrate. tutordirect, please
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    (Original post by Saf!)
    does any1 how a catalyst works!!!!!???????!!! :confused:
    very simple, a catayst is a substance thats speeds up the reaction rate by lowering the activation energy without being used up. A catalyst can be biological which are called enzymes. There are also different forms of catayst, e.g. made of transition metals for example.
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    (Original post by serendipity)
    A catalyst speeds up a reaction. For example an enzyme is a catalyst, and u can look up the lock and key method it uses to catalyse reactions.

    p.s. i'm not a scientist, so dont blame me if i'm wrong! :)
    r u sure u ain't a scientist??
    coz i got an exam next week but i don't know nothiN!!!!
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    (Original post by [email protected])
    r u sure u ain't a scientist??
    coz i got an exam next week but i don't know nothiN!!!!
    I have an exam next week too! argh!
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    (Original post by [email protected])
    r u sure u ain't a scientist??
    coz i got an exam next week but i don't know nothiN!!!!

    If you don't know nothin, then that means you must know sumpin!
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    (Original post by [email protected])
    r u sure u ain't a scientist??
    coz i got an exam next week but i don't know nothiN!!!!
    lol yeah i'm sure!! i loathed chemistry GCSE absolute bane of my life. biology was good tho... we got to cut up hearts and stuff
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    (Original post by serendipity)
    lol yeah i'm sure!! i loathed chemistry GCSE absolute bane of my life. biology was good tho... we got to cut up hearts and stuff
    Ar yuk, we had to do that, I left the room because I'm the most squeemish person ever. Also someone was sick afterwards.
    Why do you people like disecting a rat?
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    (Original post by gemgems89)
    Ar yuk, we had to do that, I left the room because I'm the most squeemish person ever. Also someone was sick afterwards.
    Why do you people like disecting a rat?
    eurgh nooo i couldn't cut up an animal i'd probably pass out however i did once manage to cut up an eyeball...it looked all pretty like a rainbow inside...
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    (Original post by serendipity)
    eurgh nooo i couldn't cut up an animal i'd probably pass out however i did once manage to cut up an eyeball...it looked all pretty like a rainbow inside...
    Uhhh that's sick! I would probaly faint. Just thinking of that sort of thing makes me all stiff, it's a sort of phobia!
 
 
 
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