Research Presentations Introduction –“sell” your research Methods –Very brief/relatively extensive: depends on your topic –Judicious use of detail here: what do we need/want to know Results –How can they best be presented? Table of data or some sort of bar graph? Should your y-axis be abs/time? Rate (  mol/min)? %? Are your units clear? Discussion/conclusion –What do your data mean? –Propose/suggest future directions that build off of your results

Research Presentations Graded (by me, with audience input) on: –Information, depth –How well the info comes across –Presentation style –All members get same grade Audience participation component –10 points “Laboratory Participation”

Suggestions: –Use pictures as much as possible Text to support your pictures –Effective use of slide titles Research Presentations

Viagra is a competitive inhibitor of fumarase

Suggestions: –Use pictures as much as possible Text to support your pictures –Effective use of slide titles –Effective presentation of your data –ORGANIZATION –Practice –Excitement/interest/(reasonable) creativity Research Presentations

Chapter 13 (etc): Bioenergetics Metabolism: –Chemical reactions within a cell/organism –Often requires energy OR generates (harvests) energy –“Catabolism” Degradative phase: breakdown of complex molecules into simpler products –Typically accompanied by energy release –“Anabolism” Synthetic phase: creation of complex molecules from simpler precursors –Typically requires energy input

Cells require a source of free energy to fight the second law of thermodynamics Total entropy increases –Entropy is bad for cells –Free energy required to put things in order (macromolecules, genetic info, etc) Photosynthetic organisms –Energy from solar radiation Heterotrophic –Energy from nutrient molecules (reduced hydrocarbons, for example) Solar/chemical energy transformed into chemical energy (esp. ATP) for bioavailability (biological work: coupling  G>0 to  G<0)

 G vs. Keq Standard free energy change for a reaction (  G’°) is constant Actual free energy change depends on standard  G and temp/pressure, but more importantly reactant/product concentrations

Spontaneity: determined by  G, NOT  G’° The  G for a typical reaction will decrease as it proceeds:  G = 0 when the reaction reaches equilibrium “Non-spontaneous” (  G’°>0) reactions can be made spontaneous by: 1.“Mass action”: (sometimes unreasonable) increase in substrate concentrations 2.Coupling to spontaneous reactions (  G’° is additive) Remember: we’re talking energetically spontaneous: there may still be a kinetic barrier  G vs. Keq

Chemical energy: making reactions spontaneous ATP hydrolysis:  G’° ~ kJ/mol Destabilized reactant (ATP) Stabilized products (PO ADP+H + ) Also important: kinetic stabilization of an inherently unstable compound: good storage molecule

ATP hydrolysis  G’° ~ kJ/mol not the whole story  G p can be much higher (-60 kJ/mol)

Other energy storage molecules

Use of high energy phosphate compounds Not simply direct hydrolysis: phosphoryl transfer to intermediate or to protein Two step process: –Phosphoryl transfer: ‘activated’ compound –Phosphate displacement: lower energy product

Tomorrow: more basics of phosphorylation Another source of chemical energy: oxidation-reduction