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Chemistry/Biology Interface

Chemistry/Biology Interface. Reactionaries striving for equilibrium: Roberta Attanasio, Georgia State University Jung Choi, Georgia Institute of Technology Steven Pomarico, Louisiana State University William A. Said, Georgia State University Tony Schwacha, University of Pittsburgh

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Chemistry/Biology Interface

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  1. Chemistry/Biology Interface Reactionaries striving for equilibrium: Roberta Attanasio, Georgia State University Jung Choi, Georgia Institute of Technology Steven Pomarico, Louisiana State University William A. Said, Georgia State University Tony Schwacha, University of Pittsburgh Rupal Thazhath, Georgia Institute of Technology Grover Waldrop, Louisiana State University Lillian Tong, Facilitator Equilibrium and Enzyme Kinetics (The worst 20 minutes of your life…maybe?)

  2. Chemical Principles of Biology • Part of an Introductory Biology course for either majors or non-majors • Typically follows units on atoms, water and biomolecules • Precedes units on bioenergetics

  3. Course Learning Goals Applicable to Chemistry/Biology Interface • Integrate principles of chemistry and physics to model biological systems • Practice the process of science • Observation/data collection and analysis • Hypothesis generation and testing • Collaboration with others

  4. Pre-assessment for equilibrium and kinetics 0 Equilibrium and enzyme kinetics – the worst 20 minutes of your life, maybe Introduction to chemical equilibrium Data collection Clicker questions about equilibrium Chemical equilibrium demonstration Define chemical equilibrium Inferring predictions about demonstration Clicker questions about chemical equilibrium Explanation chemical equilibrium constant Data collection Chemical equilibrium demonstration revisited = Assessment = Lecture = Data collection Concept map dealing with chemical equilibrium Compare with predictions = Active learning

  5. 0 Group brainstorming session Return to concept map with addition of enzymes Introduction to enzyme kinetics Enzyme kinetics clicker questions Small discussion group question Take home assignment Post unit assessment

  6. Chemical Equilibrium Learning Goals Students should be able to apply the principles of chemical equilibrium to explain dynamic biological processes such as antigen-antibody, ligand-receptor, and enzyme-substrate interactions.  Explain chemical equilibrium in terms of reactants and products – experiment with balls  Define equilibrium constant – experiment with balls  Given the equilibrium constant, predict in which direction the reaction will go – experiment with balls  Demonstrate that equilibrium systems are dynamic with no net change – experiment with balls

  7. An experiment about equilibrium • Items (colored balls) represent chemicals • Locations (different sides of the room) represent different chemical states • Equal numbers of student volunteers on both sides of the room. • On side1, students clap once, pick up balls and throw them to side 2 one at a time (represents forward rate). • On side 2, students face backwards, pick up a ball and then toss it to side 1 (represents reverse rate). • Count balls on each side at 15-20 sec. intervals

  8. Side one Side two

  9. Side one Side two REACTANTS PRODUCTS

  10. Forward reaction Reverse reaction Side one Side two REACTANTS PRODUCTS

  11. Record data – numbers of items on each side, go to clicker Questions #1 and #2 after 15 sec.

  12. Clicker Question #1: Is this process…? A) dynamic B) static

  13. Clicker Question #2: Has the process reached equilibrium? A) Yes B) No C) Not sure

  14. Additional Rounds (time points) – continue recording data

  15. Clicker Question #3: Has the process reached equilibrium now? A) Yes B) No C) Not sure

  16. We have reached a condition where the amount on each side remains constant, even though things are still in motion. This is called equilibrium. We can describe this condition in terms that relate the amount on side One (the reactants) to the amount on side Two (the products)

  17. Equilibrium constant Think-pair-share: what is the equilibrium constant, and how would you describe in an equation the final condition in this experiment?

  18. Suppose 20 more molecules (labeled) are added to side 1

  19. #4: Suppose 20 more items are added to side One. The equilibrium constant will A) stay the same B) increase C) decrease

  20. #5: Suppose 20 more items are added to side One. Items will move from A) Side One to side Two B) Side Two to side One C) Both D) Neither

  21. #6: Suppose 20 more items are added to side One. In order to re-establish equilibrium, there will be a net transfer of items A) Side One to side Two B) Side Two to side One C) No net transfer will occur

  22. Let’s redo the experiment with 20 additional labeled molecules to Side One Do these data fit your predictions?

  23. Chemical equilibrium Free energy Chemical reactions ? You describe this Reactants Forward rate Reverse rate Products Has higher energy involves Has lower energy Fill in the blue ovals, and add appropriate words to go with each arrow.

  24. Group brainstorming session • For next 5 minutes, discuss and list analogies for equilibrium in everyday life. • We’ll select random groups to report verbally to rest of class.

  25. Chemical equilibrium is the ratio of reactants to products converts to Reactants Products converts to involves Chemical reactions Enzymes

  26. Chemical equilibrium is the ratio of reactants to products converts to Reactants Substrates Products converts to involves Chemical reactions Enzymes catalyze/ speed up

  27. Chemical equilibrium determines is the ratio of reactants to products converts to Substrates Products converts to involves determines the direction of Thermodynamics Chemical reactions Enzymes catalyze/ speed up

  28. Enzyme kinetics learning goals • Explain the relationship between substrate concentration and the velocity of the reaction. • Apply enzyme kinetics to explain physiological processes.

  29. One enzymatic reaction: • Glucose + ATP  Glucose-6-P + ADP • Enzyme assay: measure G-6-P produced over time, at different concentrations of glucose • Graph the slope (velocity = rate of product formation) as a function of glucose concentration = [glucose]

  30. Glucose is the substrate for two enzymes in the liver, hexokinase (HKase) and glucokinase (Gkase). Their kinetics are shown in the figure.

  31. Glucose is the substrate for two enzymes in the liver, hexokinase (HKase) and glucokinase (Gkase). Their kinetics are shown in the figure.

  32. Glucose is the substrate for two enzymes in the liver, hexokinase (HKase) and glucokinase (Gkase). Their kinetics are shown in the figure. Vmax ½ Vmax Km

  33. Vmax Gkase Vmax Hkase Km Km Glucose is the substrate for two enzymes in the liver, hexokinase (Hkase) and glucokinase (Gkase). Their kinetics are shown in the figure.

  34. Gkase Vmax Vmax Hkase Km Km Why does the velocity plateau? A) All the enzyme molecules are occupied B) The enzyme stops working C) Substrate is depleted Gkase Hkase

  35. Gkase Vmax Vmax Hkase Km Km You haven’t eaten all day; your blood sugar is low. Which enzyme shows greater velocity? A) hexokinase B) glucokinase

  36. Gkase Vmax Vmax Hkase Km Km You eat a dozen glazed donuts, and your blood sugar skyrockets. Now which enzyme has greater velocity? • A) hexokinase • B) glucokinase

  37. Gkase Vmax Vmax Hkase Km Km Small group discussion question: • What would happen in people missing glucokinase?

  38. Homework Assignment: • Go to www.ncbi.nlm.nih.gov • Click on OMIM (On-line Mendelian Inheritance in Man) • Search for an enzyme deficiency. • Turn in a one-page summary. • 5 students selected at random will be called at next class to report.

  39. Active Learning Components • Clicker questions • Experiment about equilibrium • Concept mapping • Group activity – brainstorming for applications of equilibrium to their daily lives • Homework assignment about enzyme deficiencies

  40. Assessment • Pre- and post-test for unit • Clicker questions – formative assessment • Concept map at end of chemical equilibrium unit – formative assessment • Group brainstorming activity • Follow on questions in subsequent units: enzymes, facilitated diffusion, chemiosmosis, cell signaling (receptor-ligand), antigen-antibody interactions, transcription factor binding, etc.

  41. Addressing a Diversity of Learning Styles, Backgrounds • Experiment is kinesthetic and visual • Recording numerical data – analytic • Brainstorming session on application addresses big picture and is inclusive, as well as encouraging each to construct from their own experience. • Concept mapping for wholistic learners • Clicker questions enable all students (including the quiet ones) to participate. • Reading assignment from textbook for verbal learners • On-line research and writing for also for verbal learners • Graph of enzyme kinetics is visual as well as analytical

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