Unit Bioenergetics Cellular Energy A. Uses of cellular energy (ATP) 1. build molecules & maintain structure 2. transport materials 3. move & grow 4. reproduce 5. The products of cellular respiration are the reactants of photosynthesis.

B. What is ATP? 1. Adenosine tri-phosphate – phosphate sugar- ribose, nitrogen base -adenine 2. Energy is released for cell usage when a phosphate group is removed. This produces ADP (di-phosphate) and AMP (monophosphate) low energy If ATP is a fully charged battery, ADP would be half charged and AMP would be nearly out of energy

Phosphorylation - the metabolic process of introducing a phosphate group into an organic molecule. Enzymes activated or deactivated

II. Respiration A. Breathing “respiration” vs. cellular respiration Respiration – breathing, an exchange of gases between organism and environment Cellular respiration – aerobic harvesting of energy from food molecules

B. Cellular respiration – balanced equation C6H12O6 + 6 O2  6 CO2 + 6 H2O + 38 ATP Glucose energy 40% of the energy from glucose is used in the cells 60% of the energy is lost as heat

leo says ger Oxidation – loss of electrons (H atoms) from one molecule Oxidation – loss of electrons (H atoms) from one molecule oxidized if 1 or more electrons are lost cellular respiration: glucose oxidized – loses H Reduction – addition of electrons (H atoms) to a molecule reduced if 1 or more electrons are gained cellular respiration: O2 gas reduced – gains H C. Oxidation/Reduction “Redox” reactions – always occur together It’s the major source of energy along with the sun

Fig. 9-UN3 becomes oxidized becomes reduced

electron transport chain – series of redox reactions that pass e- from carrier to carrier a)NADH & FADH2 are electron carriers

Fig NADH NAD + 2 FADH 2 2 FAD Multiprotein complexes FAD FeS FMN FeS Q  Cyt b   Cyt c 1 Cyt c Cyt a Cyt a 3 IVIV Free energy (G) relative to O 2 (kcal/mol) (from NADH or FADH 2 ) 0 2 H / 2 O2O2 H2OH2O e–e– e–e– e–e–

Overview of the stages of cellular respiration Overview of the stages of cellular respiration

Glycolysis – “splitting of sugar”, glucose is broken into 2 molecules of pyruvate through 9 different chemical reactions Occurs in the cytoplasm; anaerobic Net of 2 ATP produced by substrate-level phosphorylation (-2 ATP + 4 ATP) 2 NAD+ are reduced to 2 NADH for electron transport chain

Fig. 9-8 Energy investment phase Glucose 2 ADP + 2 P 2 ATPused formed 4 ATP Energy payoff phase 4 ADP + 4 P 2 NAD e – + 4 H + 2 NADH + 2 H + 2 Pyruvate + 2 H 2 O Glucose Net 4 ATP formed – 2 ATP used2 ATP 2 NAD e – + 4 H + 2 NADH + 2 H +

Citric Acid (Kreb’s) Cycle – creates CO2 from pyruvate 2 molecules of pyruvate become 2 molecules of acetyl CoA, which enters the citric acid cycle Energy yield is 2 ATP, 6 NADH & 2 FADH2 Provides electrons for respiration

Fig Pyruvate NAD + NADH + H + Acetyl CoA CO 2 CoA Citric acid cycle FADH 2 FAD CO NAD H + ADP +P i ATP NADH

Fig Acetyl CoA CoA—SH Citrate H2OH2O Isocitrate NAD + NADH + H + CO2CO2  -Keto- glutarate CoA—SH CO2CO2 NAD + NADH + H + Succinyl CoA CoA—SH P i GTP GDP ADP ATP Succinate FAD FADH 2 Fumarate Citric acid cycle H2OH2O Malate Oxaloacetate NADH +H + NAD

Oxidative Phosphorylation – phosphorylates ADP to produce ATP (34) Electron transport chain – pumps H+ ions across membrane as electrons are transported Takes place within inner membrane of mitochondria Small amounts of energy released – produces ATP Small amounts of energy released – produces ATP Chemiosmosis – potential energy of the electrochemical gradient drives the diffusion of H+ ions through ATP synthase ( enzyme) producing molecules of ATP Oxygen acts as the final electron acceptor, it bonds with 2 H+ ions to create water

ETC

Fig INTERMEMBRANE SPACE Rotor H+H+ Stator Internal rod Cata- lytic knob ADP + P ATP i MITOCHONDRIAL MATRIX

Fermentation Anaerobic process – cells are starved of oxygen strict anaerobes are poisoned by oxygen facultative anaerobes can survive with or without O2 2 ATP produced by glycolysis, 0 ATP from fermentation Animals – lactic acid produced, causes sore muscles Bacteria – fermentation used to make cheese, yogurt, soy sauce & sauerkraut Yeast – alcohol fermentation

Fig. 9-18b Glucose 2 ADP + 2 P i 2 ATP Glycolysis 2 NAD + 2 NADH + 2 H + 2 Pyruvate 2 Lactate (b) Lactic acid fermentation

Fig. 9-18a 2 ADP + 2 P i 2 ATP GlucoseGlycolysis 2 Pyruvate 2 NADH2 NAD H + CO 2 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation 2

The End …

IV. Photosynthesis A. Autotrophs – “self-feeders”, make own food from inorganic matter 1.Photoautotrophs – make energy from sunlight through photosynthesis Examples: plants, bacteria, algae, & certain protists B. Photosynthesis – balanced equation 6 CO2 + 6 H2O + sunlight  C6H12O6 + 6 O2 Carbon water glucose oxygen Carbon water glucose oxygen dioxide gas dioxide gas

Photosynthesis Facts Photosynthesis Facts Takes place in the mesophyll (green tissue) of plant leaves which contain many chloroplasts Takes place in the mesophyll (green tissue) of plant leaves which contain many chloroplasts –Stroma – thick fluid in chloroplast where sugars are made –Thylakoids – membrane sacs that hold pigments Pigments trap energy from sunlight Pigments trap energy from sunlight –carotene – orange / red –chlorophyll – green –xanthophyll - yellow –Grana – concentrated stacks of thylakoid membrane –Stomata – pores that allow CO2 in & O2 out

Chemical reactions of Photosynthesis - Redox Chemical reactions of Photosynthesis - Redox 1. Light reactions – O2 gas is produced by the splitting of water 1. Light reactions – O2 gas is produced by the splitting of water a. Occurs in the thylakoid membrane a. Occurs in the thylakoid membrane –Steps that absorb solar energy and store it as chemical energy in ATP and NADPH, which power the dark reactions c. Stages c. Stages Photosystem II – absorbs energy from sunlight, excites electrons Photosystem II – absorbs energy from sunlight, excites electrons –P680 – absorbs red light (680 nm) best Electron transport chain – carrier molecules pass along electrons; H+ atoms pumped across membrane Electron transport chain – carrier molecules pass along electrons; H+ atoms pumped across membrane Photosystem I – absorbs more photons of energy; NADP+ & H+ produced NADPH Photosystem I – absorbs more photons of energy; NADP+ & H+ produced NADPH –P700 – absorbs red light (700 nm) best H+ ions move across the membrane by facilitated diffusion H+ ions move across the membrane by facilitated diffusion –transport protein contains enzyme ATP synthase –powers the creation of ATP from ADP

Dark reactions – glucose is created from CO2 and water Dark reactions – glucose is created from CO2 and water –Occurs in the stroma –Often called the Calvin Cycle –Uses the enzyme rubisco