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Complete the following question to create your own notes. Good full answers please as you need to understand your notes in a year’s time!

(1) Define enzyme & active site. Enzyme = A globular molecule that accelerates a specific reaction, as they are biological catalysts. Adding a catalyst speeds up a reaction without altering the catalyst in any other way and hence not affecting the product that is created.

 Active site = The region of an enzymes surface that binds the substrate (reacting substance) during a reaction catalyzed by an enzyme.



(2) Without enzymes, why would so many reactions be so slow? Most enzymes function by lowering the activation energy of the reactions,which allows these reactions to occur fast. Also, by bringing the reactants closer together, chemical bonds may be weakened and reactions will proceed fast. Therefore, without enzymes, the reactions would occur too slow to sustain life. (3) Draw the lock & key model of enzyme activity. Write a few sentences to explain this.

(4) Write 4-5 really good sentences to describe this process.

(5) What is the connection between enzymes & activation energy?  **Activation energy is the energy that must be provided to make a reaction take place.** The enzyme helps speed up the reaction by lowering the activation energy making the reaction occur at a lower temperature than it would without an enzyme. So when a substrate binds to the active site of an enzyme, the shape of its molecule is lsighty changed. this makes it easier to change into a product.

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(6) What are some of the differences between the enzyme pepsin & the enzymes on the membrane of mitochondria?

<span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(7) Why are enzymes so specific? Enzymes are specific in that one enzyme molecule is capacle of catalyzing only a single type of chemical reaction. They are specific becuase they need to catalyze or help a reaction take. Their job is to bind subtrates and help position them in order that the chemical reastion between the subtrates can take place. For this they need to be specific becuase if they bound things other than the subtrates they are supposed to they would be much less efficienct in catalyzing the reactions.

<span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(8) How does the induced fit model of enzyme activity differ from the lock & key model? (You need to think for yourselves for this one) The lock and key model fits exactly into one another. They do not need to change their shape in order to fit into each other. However the induced fit model of enzye activty is differen. Often these molecules are flexible, and change shape when an appropriate molecule binds to an active site. This is different becuase unlike the lock and key model, the molecules have to change shape in order to fit.

The lock and key model: (fits exactly in one another)

Induced fit model: (The modelcules have to change shape in order to fit)

<span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(9) Draw a graph to show the activation energy and how enzymes affect this. Describe how catalysts make this reaction go faster.

Enzymes are biological catalysts. A catalyst is a chemical that increases the rate of a reaction and itself is not changed at the end of the reaction and does not change the nature of the reaction or its final result. Catalysts make reactions go faster at lower temperatures by lowering the activation temperature required, thus ensuring that a larger percent of the population of reactant molecules will have sufficient energy to participate in the reaction.

<span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(10) Define denaturation & explain its effect on proteins (including enzymes, which are proteins. <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"> <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"><span style="font-family: 'Times New Roman','serif'; font-size: 12pt;"> Denaturation of proteins involves the disruption and possible destruction of both the secondary and tertiary structures. But Denaturation reactions are not strong enough to break the peptide bonds, the primary structure (sequence of amino acids) remains the same after a denaturation process. Denaturation disrupts the normal alpha-helix and beta sheets in a protein and uncoils it into a random shape. The tertiary and quaternary structures of proteins are fragile and tend to come apart under conditions less than optimal. This loss of shape, called denaturation, occurs as ionic and H- bonds break. Salty envionments (excess Na+ and Cl-), acidic envionments (too much H+), and alkaline envionments (too little H+ ) Break ionic and H- bonds interfering with their electric charges. Heat causes movement within molecules, which disturb their relatively weak bonds. Once denaturated, most proteins will not re-form their original shape. (Proteins usually exposed to unusual envionments have tertiary and quaternary structures held by covalent bonds, between the sulfur atoms of cysteine. )