Bioenergetics Lecture 5 summary Susan Kaminskyjusask ca Last

Bioenergetics Lecture 5 summary • Susan. Kaminskyj@usask. ca • Last time –integrating catabolic metabolism, review catabolism • This time – similarities and differences between cellular respiration and photosynthesis – chlorophyll, photosystems II and I (in that order) • But first…. !

Electron transport chain pumps H+, making a gradient ATP synthase uses the H+ gradient to generate ATP Higher H+ concentration = lower p. H Intermembrane space Potential energy of falling water used to grind grain F 1 in matrix Mitochondrial matrix Fo in inner membrane Lower H+ concentration = higher p. H Potential energy of ‘falling’ H+ used to generate ATP

ATP synthase uses the H+ gradient to generate ATP

Cellular Respiration

A series of redox reactions …. RESPIRATION PHOTOSYNTHESIS RESPIRATION

Respiration vs photosynthesis • Mitochondria – All aerobic eukaryotes • Oxidation of CHO to CO 2 • Generation of NADH and FADH 2 ATP synthesis • Chloroplasts – Plants, algae • Energy harvest from sunlight • Generation of NADPH Reduction of CO 2 to CHO = carbohydrate P (photosynthesis) photosynthesis Note NADH (respiration) vs NADPH

Photosynthesis is an endothermic redox process Energy source? Useful byproducts? Sunlight Glucose and O 2

Red and Blue light are absorbed from the incident (white) light, leaving Green to be reflected or transmitted

Photosynthesis produces oxygen Are all wavelengths photosynthetically active? Spirogyra Photosynthetic Active spectrum

First, light energy must be captured Illuminated chlorophyll fluoresces (gives off light) if captured light energy is not transferred to another acceptor

Capture is not enough! In a leaf, the reaction centre transfers the captured energy to a relatively stable intermediate chemical Isolated chlorophyll fluoresces if newly captured energy is not transferred

The reaction centre is the heart of the photosystem Energy transfer between pigment molecules to a special central pair of chlorophylls (reaction centre) and thence to the primary electron acceptors

Two parts to the light reaction

Chemiosmosis can make ATP

Two parts to the light reaction phaeophytin ferredoxin

Source and fate of carbon and oxygen in carbohydrates formed by photosynthesis

Photosystem II makes ATP

Photosystem I makes NADPH

NADH vs NADPH • NADH catabolism • NADPH anabolism (P photosynthesis) • For each, the reduced form stores ~ 3 times more energy than ATP