3.6+Enzymes

3 Chemistry of Life - 3.1 Chemical elements and water - 3.2 Carbohydrates, proteins and lipids - 3.3 DNA structure - 3.4 DNA replication - 3.5 Transcription and translation - 3.6 Enzymes - 3.7 Cell respiration - 3.8 Photosynthesis - Biochemistry Labs - DNA Labs

3.6 //(and 7.6)// Enzymes
This topic is talked about in sufficient detail in the i-Biology notes that 7.6/C2 is covered by them. This page is also structured that AHL7.6/C2 content is shown here too. // HL content is in marked in italics. SL students take note of the comments: you might find the extra information useful and helpful, but it is additional to the content you are expected to know and will be examined on. //
 * Important: Enzymes are a key topic for understanding other topics. Remember enzymes mediate most reactions that happen in organisms and some outside too.**

What is lactose intolerance and how has it come about? How does lactose link to other elements of the course? Watch the HHMI video 'Got lactase?' and discuss. media type="custom" key="24471134"
 * Starter**

Discuss the importance of enzymatic control of metabolic pathways using this chart by the late Dr Donald Nicholson


 * Assessment statements** (IBO notes added to some points to clearly indicate what needs to be understood and what does not)
 * 3.6.1 || Define enzyme and active site. ||
 * 3.6.2 || Explain enzyme–substrate specificity. The lock-and-key model can be used as a basis for the explanation. Refer to the three-dimensional structure. The induced-fit model is not expected at SL. ||
 * 3.6.3 || Explain the effects of temperature, pH and substrate concentration on enzyme activity. ||
 * 3.6.4 || Define denaturation. ||
 * 3.6.5 || Explain the use of lactase in the production of lactose-free milk. ||

//AHL 7.6 (C2)//
 * //7.6.1// || //State that metabolic pathways consist of chains and cycles of enzyme-catalysed reactions.// ||
 * //7.6.2// || //Describe the induced-fit model. Its importance in accounting for the ability of some enzymes to bind to several substrates should be understood.// ||
 * //7.6.3// || //Explain that enzymes lower the activation energy of the chemical reactions that they catalyse. Only exothermic reactions should be considered. Specific energy values do not need to be recalled.// ||
 * //7.6.4// || //Explain the difference between competitive and non-competitive inhibition, with reference to one example of each.// ||
 * //7.6.5// || //Explain the control of metabolic pathways by end-product inhibition, including the role of allosteric sites.// ||


 * Definitions**
 * Denaturation - a structural change in a protein that results in the loss (usually permanent) of its biological properties. Refer only to heat and pH as agents.
 * //Competitive inhibition - the situation when an inhibiting molecule that is structurally similar to the substrate molecule binds to the active site, preventing substrate binding.//
 * //Non-competitive inhibition - is when an inhibitor binding to an enzyme (not to its active site) that causes a conformational change in its active site, resulting in a decrease in activity.//

Log in to the DCS Bridge to obtain your workbooks and supporting resources for SL and here additionally for [|HL]
 * Workbooks and Worksheets **

An alternative set of notes from [|i-Biology] can be found here media type="custom" key="23828690" //Qs 7-9, 12 are AHL7.6/C2 content, Q10-11 though more closely fit AHL7.6/C2 are still key concepts for SL students to understand.//

Steven Taylor ( [|i-Biology] ) has a great presentation to view and take notes from before starting your notebook media type="custom" key="23828692"
 * Presentations and tutorials **

[|What is an enzyme?]is a great place to start on probably the single most important group of proteins [|How Enzymes Work]from McGraw and Hill is a good short introduction on how enzymes function

//[|Activation Energy]is the energy needed by enzymes to start the reaction process, by stressing bonds in the molecules enzymes lower the energy needed for reactions to occur. A must for AHL 7.6/C2, a useful addition for SL.//

[|Lock and key theory]is a good place to start when you think about enzyme-substrate specificity for the first time.

//[|Conformational change](aka the induced-fit model) which stresses the substrate’s bonds and so lowers activation energy is a better model of how enzymes work. A must for AHL 7.6/C2, a useful addition for SL.//

[|Denature]is the name given to the process which causes changes in any protein or molecule if there is too much heat or if the pH is too far from their optimum conditions. For enzymes this means the active site changes shape and they can no longer work.

[|Enzyme Kinetics]is a simulation which shows how different factors affect enzyme activity

//Use teaching and visualization animations from St Olaf://
 * //Activation energy and the stressing of bonds explained//
 * //Conformational change//
 * //Allosteric (non-competitive) inhibition//
 * //Example of a biochemical pathway//

Use click4biology [|SL 3.6] //and [|AHL 7.6/C2]// to review and complete your notes


 * Activity Ideas**


 * Useful Links **