Unit BioenergeticsUnit Bioenergetics

Cellular EnergyCellular EnergyA.A. Uses of cellular energy (ATP)Uses of cellular energy (ATP)

1.1. build molecules & maintain build molecules & maintain structurestructure

2.2. transport materialstransport materials3.3. move & growmove & grow4.4. reproducereproduce5.5. The products of cellular respiration The products of cellular respiration

are the reactants of photosynthesis.are the reactants of photosynthesis.

B. What is ATP?B. What is ATP?

1.1. Adenosine tri-phosphate – phosphate sugar-Adenosine tri-phosphate – phosphate sugar-ribose, nitrogen base -adenineribose, nitrogen base -adenine

2. Energy is released for cell usage when a 2. Energy is released for cell usage when a phosphate group is removedphosphate group is removed..

This produces This produces ADP ADP (di-phosphate) and(di-phosphate) and AMP AMP (monophosphate) (monophosphate) low energylow energy

If ATP is a fully charged battery, ADP would be half charged and AMP If ATP is a fully charged battery, ADP would be half charged and AMP would be nearly out of energywould be nearly out of energy

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

II. RespirationII. Respiration

A.A. Breathing “respiration” vs. cellular Breathing “respiration” vs. cellular respirationrespiration

RespirationRespiration – breathing, an exchange – breathing, an exchange of gases between organism and of gases between organism and environmentenvironment

Cellular respirationCellular respiration – – aerobic aerobic harvesting of energy from food harvesting of energy from food moleculesmolecules

B. Cellular respiration – balanced equationB. Cellular respiration – balanced equation

C6H12O6 + 6 O2 C6H12O6 + 6 O2 6 CO2 + 6 H2O + 38 ATP 6 CO2 + 6 H2O + 38 ATP Glucose energyGlucose energy

40% of the energy from glucose is used in 40% of the energy from glucose is used in the cellsthe cells

60% of the energy is lost as heat60% of the energy is lost as heat

leo says gerleo says ger

OxidationOxidation – loss of electrons (H atoms) from one – loss of electrons (H atoms) from one moleculemoleculeoxidized if 1 or more electrons are lostoxidized if 1 or more electrons are lostcellular respiration: glucose oxidized – loses H cellular respiration: glucose oxidized – loses H

ReductionReduction – addition of electrons (H atoms) to a – addition of electrons (H atoms) to a moleculemolecule

reduced if 1 or more electrons are gainedreduced if 1 or more electrons are gainedcellular respiration: O2 gas reduced – gains Hcellular 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-UN3Fig. 9-UN3

becomes oxidized

becomes reduced

electron transport chainelectron transport chain – series of – series of redox reactions that pass e- from redox reactions that pass e- from carrier to carriercarrier to carrier

a)a) NADH & FADH2 are electron carriersNADH & FADH2 are electron carriers

Fig. 9-13Fig. 9-13

NADH

NAD+2FADH2

2 FADMultiproteincomplexesFAD

Fe•S

FMN

Fe•S

Q

Fe•S

Cyt b

Cyt c1

Cyt c

Cyt a

Cyt a3

IV

Fre

e en

erg

y (G

) r e

lat i

ve t

o O

2 (

kcal

/mo

l)

50

40

30

20

10 2

(from NADHor FADH2)

0 2 H+ + 1/2 O2

H2O

e–

e–

e–

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

GlycolysisGlycolysis – “splitting of sugar”, – “splitting of sugar”, glucose is broken into 2 molecules of glucose is broken into 2 molecules of pyruvate through 9 different chemical pyruvate through 9 different chemical reactionsreactionsOccurs in the cytoplasm;Occurs in the cytoplasm; anaerobic anaerobic

Net of 2 ATP produced by substrate-level Net of 2 ATP produced by substrate-level phosphorylation (-2 ATP + 4 ATP)phosphorylation (-2 ATP + 4 ATP)

2 NAD+ are reduced to 2 NADH for electron 2 NAD+ are reduced to 2 NADH for electron transport chain transport chain

Fig. 9-8Fig. 9-8

Energy investment phase

Glucose

2 ADP + 2 P 2 ATP used

formed4 ATP

Energy payoff phase

4 ADP + 4 P

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

2 Pyruvate + 2 H2O

2 Pyruvate + 2 H2OGlucoseNet

4 ATP formed – 2 ATP used 2 ATP

2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+

Citric Acid (Kreb’s) CycleCitric Acid (Kreb’s) Cycle – creates – creates CO2 from pyruvateCO2 from pyruvate2 molecules of pyruvate become 2 2 molecules of pyruvate become 2

molecules of acetyl CoA, which enters molecules of acetyl CoA, which enters the citric acid cyclethe citric acid cycle

Energy yield is 2 ATP, 6 NADH & 2 FADH2Energy yield is 2 ATP, 6 NADH & 2 FADH2

Provides electrons for respirationProvides electrons for respiration

Fig. 9-11Fig. 9-11

Pyruvate

NAD+

NADH

+ H+Acetyl CoA

CO2

CoA

CoA

CoA

Citricacidcycle

FADH2

FAD

CO22

3

3 NAD+

+ 3 H+

ADP + P i

ATP

NADH

Fig. 9-12-8Fig. 9-12-8

Acetyl CoA

CoA—SH

Citrate

H2O

IsocitrateNAD+

NADH

+ H+

CO2

-Keto-glutarate

CoA—SH

CO2NAD+

NADH

+ H+SuccinylCoA

CoA—SH

P i

GTP GDP

ADP

ATP

Succinate

FAD

FADH2

Fumarate

CitricacidcycleH2O

Malate

Oxaloacetate

NADH

+H+

NAD+

1

2

3

4

5

6

7

8

Oxidative PhosphorylationOxidative Phosphorylation – – phosphorylates ADP to produce ATP (34) phosphorylates ADP to produce ATP (34) Electron transport chainElectron transport chain – pumps H+ ions – pumps H+ ions

across membrane as electrons are transportedacross membrane as electrons are transported

Takes place within inner membrane of Takes place within inner membrane of mitochondriamitochondria

Small amounts of energy released – produces Small amounts of energy released – produces ATP ATP

Chemiosmosis Chemiosmosis – potential energy of the – potential energy of the electrochemical gradientelectrochemical gradient drives the diffusion of drives the diffusion of H+ ions through H+ ions through ATP synthase ( enzyme)ATP synthase ( enzyme) producing molecules of ATPproducing molecules of ATP

Oxygen acts as the final electron acceptor, it Oxygen acts as the final electron acceptor, it bonds with 2 H+ ions to create waterbonds with 2 H+ ions to create water

ETCETC

Fig. 9-14Fig. 9-14

INTERMEMBRANE SPACE

Rotor

H+

Stator

Internalrod

Cata-lyticknob

ADP+P ATP

i

MITOCHONDRIAL MATRIX

FermentationFermentationAnaerobic Anaerobic process – cells are starved of process – cells are starved of

oxygenoxygenstrict anaerobes are poisoned by oxygenstrict anaerobes are poisoned by oxygenfacultative anaerobes can survive with or without O2facultative anaerobes can survive with or without O2

2 ATP produced by glycolysis, 0 ATP from 2 ATP produced by glycolysis, 0 ATP from fermentationfermentation

Animals – lactic acid produced, causes sore Animals – lactic acid produced, causes sore musclesmuscles

Bacteria – fermentation used to make cheese, Bacteria – fermentation used to make cheese, yogurt, soy sauce & sauerkrautyogurt, soy sauce & sauerkraut

Yeast – alcohol fermentationYeast – alcohol fermentation

Fig. 9-18bFig. 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. 9-18aFig. 9-18a

2 ADP + 2 P i 2 ATP

Glucose Glycolysis

2 Pyruvate

2 NADH2 NAD+

+ 2 H+CO2

2 Acetaldehyde2 Ethanol

(a) Alcohol fermentation

2

The End …The End …

IV. PhotosynthesisIV. Photosynthesis

A. Autotrophs – A. Autotrophs – “self-feeders”, make own food from “self-feeders”, make own food from inorganic matterinorganic matter

1.Photoautotrophs1.Photoautotrophs – make energy from sunlight through – make energy from sunlight through photosynthesisphotosynthesis

Examples: plants, bacteria, algae, & certain protistsExamples: plants, bacteria, algae, & certain protists

B. Photosynthesis – balanced equationB. Photosynthesis – balanced equation6 CO2 + 6 H2O + sunlight --------6 CO2 + 6 H2O + sunlight -------- C6H12O6 + 6 O2 C6H12O6 + 6 O2 Carbon water Carbon water glucose glucose

oxygen oxygen dioxide dioxide

gasgas

• Photosynthesis FactsPhotosynthesis Facts• Takes place in the mesophyll (green tissue) of Takes place in the mesophyll (green tissue) of

plant leaves which contain many chloroplastsplant leaves which contain many chloroplasts– Stroma – thick fluid in chloroplast where sugars are Stroma – thick fluid in chloroplast where sugars are

mademade– Thylakoids – membrane sacs that hold pigmentsThylakoids – membrane sacs that hold pigments

• Pigments trap energy from sunlightPigments trap energy from sunlight– carotene – orange / redcarotene – orange / red– chlorophyll – greenchlorophyll – green– xanthophyll - yellowxanthophyll - yellow

– Grana – concentrated stacks of thylakoid Grana – concentrated stacks of thylakoid membrane membrane

– Stomata – pores that allow CO2 in & O2 outStomata – pores that allow CO2 in & O2 out

• Chemical reactions of Photosynthesis - RedoxChemical reactions of Photosynthesis - Redox• 1.1. Light reactions – Light reactions – O2 gas is produced by the splitting O2 gas is produced by the splitting

of waterof water• a. a. Occurs in the thylakoid membraneOccurs in the thylakoid membrane

– Steps that absorb solar energy and store it as chemical Steps that absorb solar energy and store it as chemical energy in ATP and NADPH, which power the dark reactionsenergy in ATP and NADPH, which power the dark reactions

• c. c. StagesStages• Photosystem II – absorbs energy from sunlight, excites electrons Photosystem II – absorbs energy from sunlight, excites electrons

– P680 – absorbs red light (680 nm) bestP680 – absorbs red light (680 nm) best• Electron transport chain – carrier molecules pass along Electron transport chain – carrier molecules pass along

electrons; H+ atoms pumped across membraneelectrons; H+ atoms pumped across membrane• Photosystem I – absorbs more photons of energy; NADP+ & H+ Photosystem I – absorbs more photons of energy; NADP+ & H+

produced NADPHproduced NADPH– P700 – absorbs red light (700 nm) bestP700 – absorbs red light (700 nm) best

• H+ ions move across the membrane by facilitated diffusionH+ ions move across the membrane by facilitated diffusion– transport protein contains enzyme ATP synthasetransport protein contains enzyme ATP synthase– powers the creation of ATP from ADPpowers the creation of ATP from ADP

• Dark reactions – Dark reactions – glucose is glucose is created from CO2 and water created from CO2 and water

– Occurs in the stromaOccurs in the stroma– Often called the Calvin CycleOften called the Calvin Cycle– Uses the enzyme rubiscoUses the enzyme rubisco