1/12/2016 Enzymes Inhibitors: Feedback Inhibition Competitive and Noncompetitive An effective way to control bacterial growth is to inactivate enzymes, Non-competitive inhibitors Competitive inhibitors fill the active site and compete play a role in a type of with substrate.does not undergo any reaction,and is biochemical control called similar chemically to the substrate. feedback inhibition or end- 的 product inhibition The mechanism stops the cell from making more of a substance that it needs and wasting chemical resources End-predvet Feedback Inhibition Prior to 1982,only proteins were believed to have Ribozymes Anabolic pathway-final enzymatic activity end-product inhibits the Ribozyme,an enzyme activity of the first consisting of RNA,that Cea3gts附 functions as a catalyst,has enzyme in the biochemical an active site that binds pathway substrate,and is not used Entire pathway shuts down up in a reaction, and no new end-product is made sections 8e the .When the end-product is pieces together again used up,it no longer binds the first enzyme and the y of pathway resumes activity substrates compared to protein enzymes. 6
1/12/2016 6 Enzymes Inhibitors: Competitive and Noncompetitive An effective way to control bacterial growth is to inactivate enzymes. Competitive inhibitors fill the active site and compete with b t t d t d ti d i ith substrate, does not undergo any reaction, and is similar chemically to the substrate. Non-competitive inhibitors bind at a site other than the active site and alters the structure of the enzyme so that the substrate cannot bind. Feedback Inhibition • Non-competitive inhibitors play a role in a type of biochemical control called feedback inhibition or endproduct inhibition • The mechanism stops the cell from making more of a substance that it needs and wasting chemical resources Feedback Inhibition • Anabolic pathway – final end-product inhibits the activit y of the first enzyme in the biochemical pathway • Entire pathway shuts down and no new end-product is made • When the end-product is used up, it no longer binds the first enzyme and the pathway resumes activity Ribozymes • Prior to 1982, only proteins were believed to have enzymatic activity • Ribozyme, an enzyme consisting of RNA, that functions as a catalyst has functions as a catalyst, has an active site that binds substrate, and is not used up in a reaction. • Ribozyme acts on strands of RNA by removing sections and splicing the pieces together again • Ribozymes are more restricted in diversity of substrates compared to protein enzymes
1/12/2016 Energy Production Nutrient molecules,like all molecules,have energy Learning Objectives Various reactions in catabolic pathways concentrate the energy into bonds of ATP,which serves as a carrier of energy Explain the term oxidation-reduction ATP energy can be released easily and quickly due List and provide examples of 3 type of to unstable bonds phosphorylation reactions that generate ·ATP provides energy ATP for anabolic reactions Explain the overall function of metabolic pathways Oxidation-Reduction Reactions Basic ove Energy and human life Oxidation is the removal of electrons:a reaction that often produces energy Reduction is the gain of electrons Chemical waste Carbon dioxide Oxidation and reduction are always coupled Che nical energy -Water Pairing of these reactions is called oxidation reduction or a redox reaction ats ATP Heat Cells use redox reactions in catabolism to extract -Others energy from nutrients Reduction 0 Heat etabolism 08
1/12/2016 7 Learning Objectives Energy Production g j • Explain the term oxidation-reduction • List and provide examples of 3 type of phosphorylation reactions that generate ATP • Explain the overall function of metabolic pathways • Nutrient molecules, like all molecules, have energy associated with the electrons that form bonds between their atoms • Various reactions in catabolic pathways concentrate concentrate the energy into bonds of ATP, which serves as a carrier of energy • ATP energy can be released easily and quickly due to unstable bonds • ATP provides energy for anabolic reactions • Oxidation is the removal of electrons; a reaction that often produces energy • Reduction is the gain of electrons Oxidation-Reduction Reactions • Oxidation and reduction are always coupled • Pairing of these reactions is called oxidationreduction or a redox reaction • Cells use redox reactions in catabolism to extract energy from nutrients
1/12/2016 In biological systems,the electrons are An organic molecule is oxidized by the loss of two hydrogen atoms and NAD+is reduced associated with hydrogen atoms. .NAD+assists enzymes by accepting hydrogen ions Biological oxidations are often from the substrate dehydrogenations due to the loss of NADH is used to generate ATP in later reactions hydrogen ion Glucose contains many hydrogen atoms,are highly reduced,contains a large amoun t of potential energy,and is a valuable nutrient. Generation of ATP Generation of ATP Energy released during ADP oxidation-reduction Organisms use 3 mechanisms of phosphorylation reactions is trapped within Adenosine-一多-e-e to generate ATP from ADP the cell in the form of ATP Specifically,an inorganic ATP 1-substrate level phosphorylation phosphate group is added to 2-oxidative phosphorylation ADP with the input of 3-photophosphorylation energy or phosphorylation When the third phosphate is removed (dephosphorylation)energy 90g is released. 8
1/12/2016 8 • In biological systems, the electrons are associated with hydrogen atoms. • Biological oxidations are often dehydrogenations due to the loss of hydrogen ion • An organic molecule is oxidized by the loss of two hydrogen atoms and NAD+ is reduced. • NAD+ assists enzymes by accepting hydrogen ions from the substrate • NADH is used to generate ATP in later reactions NADH is used to generate ATP in later reactions. • Glucose contains many hydrogen atoms, are highly reduced, contains a large amount of potential energy, and is a valuable nutrient. Generation of ATP • Energy released during oxidation-reduction reactions is trapped within the cell in the form of ATP • Specifically, an inorganic phosphate group is added to ADP with the input of energy or phosphorylation • When the third phosphate is removed (dephosphorylation) energy is released. Generation of ATP Organisms use 3 mechanisms of phosphorylation to generate A to generate A P from ADP TP from ADP 1 – substrate level phosphorylation 2 – oxidative phosphorylation 3 - photophosphorylation