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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. An enzyme is a protein molecule that accelerates a specific chemical reaction. They are biological catalysts (a catalyst speeds up a reaction without changing it in any other way). Adding an enzyme to a reaction does not create different products - it only helps to reach this product faster. Enzymes are not used up in the reactions they catalyse. After the product has formed, the enzyme may be used again and again. The active site is the area of an enzyme's surface that binds the substrate (reacting substance) during the reaction catalysed by the enzyme.

(2) Without enzymes, why would so many reactions be so slow? Enzymes reduce the activation energy needed to start these reactions; without them, most such reactions would not take place at a useful rate.

(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. The specific action of an enzyme with a single substrate can be explained with the lock and key model from the above diagram. In this analogy, the lock is the enzyme and the key is the substrate(substance on which an enzyme acts). Only the correct size key( the substrate) fits into the key hole(active site: the specific region of the enzyme which combines with the substrate) of the lock(enzyme).

(5) What is the connection between enzymes & activation energy?  The enzyme helps speed up reactions by lowering the activation energy making reactions occur at a lower temperature than it would without an enzyme.  * Activation energy: The least amount of energy needed for a chemical reaction to take place. (6) What are some of the differences between the enzyme pepsin & the enzymes on the membrane of mitochondria?

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">(7) Why are enzymes so specific?

<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)

<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.

<span style="font-family: 'Calibri','sans-serif'; font-size: 10pt; margin: 0cm 0cm 0pt;">Substrates have to pass through a transition state before they are converted into products. Energy is required to reach the transition state. This is called the activation energy. The activation energy is used to break or weaken bonds in the substrates.

<span style="font-family: 'Calibri','sans-serif'; font-size: 10pt; margin: 0cm 0cm 0pt;">When an enzyme catalyses a reaction, the substrate binds to the active site and is altered to reach the transition state. The binding helps lower the overall energy level of the transition state. Therefore, the activation energy is reduced. The amount of energy released by the reaction is unchanged by the involvement of the enzyme. However the activation energy is reduced and the rate of the reaction is increased significantly.

<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="background: #cde5d5; color: black; font-family: 'Times New Roman'; font-size: 12pt; margin: 0in;">(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;"> Denaturation refers to a structural change in a protein that results in a loss (usually permanent) of its biological properties.  <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"> Enzymes depend on the shape of their active site to function. The process of denaturation causes a structural change in the enzyme. This includes a change  <span style="display: block; margin: 0in 0in 0pt 0.5in; mso-list: l0 level1 lfo1; tab-stops: list .5in; text-indent: -0.5in;"> in the shape of its active site which means that it will not function anymore.