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

]][[

]][[lnG' G

BA

DCRT

DCBA

• Spontaneity: determined by G, NOT G’°

• TheG 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’° ~ -30.5 kJ/mol

• Destabilized reactant (ATP)

• Stabilized products (PO4

3-+ADP+H+)

• Also important: kinetic stabilization of an inherently unstable compound: good storage molecule

ATP hydrolysis

G’° ~ -30.5 kJ/mol not the whole storyGp 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