AP Biology Aim: How do we obtain energy (ATP) from our food? Do Now: Explain the diagram shown here – Fig. 9-2 Light energy ECOSYSTEM Photosynthesis in.

AP Biology

Aim: How do we obtain energy (ATP) from our food?

Do Now: Explain the diagram shown here –

Fig. 9-2

Lightenergy

ECOSYSTEM

Photosynthesis in chloroplasts

CO2 + H2O

Cellular respirationin mitochondria

Organicmolecules+ O2

ATP powers most cellular work

Heatenergy

ATP

AP Biology

Homework Chapter 9 Reading Guide Due Thursday I suggest completing one section each

night, after we have discussed it in class. Remember to read the questions before reading the text, so that your reading is focused.

AP Biology 2006-2007

Cellular RespirationHarvesting Chemical Energy

ATP


What’s thepoint?

The pointis to make

ATP!

ATP

AP Biology

Harvesting stored energy Energy is stored in organic molecules

carbohydrates, fats, proteins Heterotrophs eat these organic molecules food

digest organic molecules to get… raw materials for synthesis fuels for energy

controlled release of energy “burning” fuels in a series of

step-by-step enzyme-controlled reactions

AP Biology

Harvesting stored energy Glucose is the model

catabolism of glucose to produce ATP

C6H12O6 6O2 ATP 6H2O 6CO2+ + +

CO2 + H2O + heatfuel

(carbohydrates)

COMBUSTION = making a lot of heat energy by burning fuels in one step

RESPIRATION = making ATP (& some heat)by burning fuels in many small steps

CO2 + H2O + ATP (+ heat)

ATPglucose

glucose + oxygen energy + water + carbondioxide

res

pir

ati

on

O2 O2

+ heat

enzymesATP

AP Biology

How do we harvest energy from fuels? Digest large molecules into smaller ones

break bonds & move electrons from one molecule to another as electrons move they “carry energy” with them that energy is stored in another bond,

released as heat or harvested to make ATP

e-

+ +e-

+ –loses e- gains e- oxidized reduced

oxidation reduction

redox

e-

AP Biology

Fig. 9-UN1

becomes oxidized(loses electron)

becomes reduced(gains electron)

AP Biology

Fig. 9-UN2

becomes oxidized

becomes reduced

AP Biology

PracticeIf the following redox reaction occurred, which compound is oxidized? Which is reduced?

C4H6O5 + NAD+ C4H4O5 + NADH + H+

AP Biology

PracticeWhat is the reducing agent in the

following reaction?

Pyruvate + NADH + H+ Lactate + NAD+

AP Biology

How do we move electrons in biology? Moving electrons in living systems

electrons cannot move alone in cells electrons move as part of H atom move H = move electrons

pe

+

H

+H

+ –loses e- gains e- oxidized reduced

oxidation reduction

C6H12O6 6O2 6CO2 6H2O ATP+ + +

oxidation

reductionHe-

AP Biology

Coupling oxidation & reduction REDOX reactions in respiration

release energy as breakdown organic molecules break C-C bonds strip off electrons from C-H bonds by removing H atoms

C6H12O6 CO2 = the fuel has been oxidized electrons attracted to more electronegative atoms

in biology, the most electronegative atom? O2 H2O = oxygen has been reduced

couple REDOX reactions & use the released energy to synthesize ATP

C6H12O6 6O2 6CO2 6H2O ATP+ + +

oxidation

reduction

O2

AP Biology

Moving electrons in respiration Electron carriers move electrons by

shuttling H atoms around NAD+ NADH (reduced) FAD+2 FADH2 (reduced)

+ Hreduction

oxidation

PO–

O–

O

–O

PO–

O–

O

–O

CC

O

NH2

N+

H

adenine

ribose sugar

phosphates

NAD+

nicotinamideVitamin B3niacin

PO–

O–

O

–O

PO–

O–

O

–O

CC

O

NH2

N+

HNADH

carries electrons as a reduced molecule

reducing power!

H

like $$in the bank

AP Biology

NADH passes the electrons to the electron transport chain

Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction

O2 pulls electrons down the chain in an energy-yielding tumble

The energy yielded is used to regenerate ATP

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

AP Biology

Fig. 9-5

Fre

e en

erg

y, G

Fre

e en

erg

y, G

(a) Uncontrolled reaction

H2O

H2 + 1/2 O2

Explosiverelease of

heat and lightenergy

(b) Cellular respiration

Controlledrelease ofenergy for

synthesis ofATP

2 H+ + 2 e–

2 H + 1/2 O2

(from food via NADH)

ATP

ATP

ATP

1/2 O22 H+

2 e–E

lectron

transp

ort

chain

H2O

AP Biology

The Stages of Cellular Respiration: A Preview

Cellular respiration has three stages: Glycolysis (breaks down glucose into two

molecules of pyruvate) The citric acid cycle (completes the

breakdown of glucose) Oxidative phosphorylation (accounts for

most of the ATP synthesis)


AP Biology

Fig. 9-6-1

Substrate-levelphosphorylation

ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH

AP Biology

Fig. 9-6-2

Mitochondrion


ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH


ATP

Electrons carriedvia NADH and

FADH2

Citricacidcycle

AP Biology

Fig. 9-6-3

Mitochondrion


ATP

Cytosol

Glucose Pyruvate

Glycolysis

Electronscarried

via NADH


ATP

Electrons carriedvia NADH and

FADH2

Oxidativephosphorylation

ATP

Citricacidcycle

Oxidativephosphorylation:electron transport

andchemiosmosis

AP Biology

Oxidative phosphorylation accounts for almost 90% of the ATP generated by cellular respiration

A smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate-level phosphorylation


AP Biology

Fig. 9-7

Enzyme

ADP

PSubstrate

Enzyme

ATP+

Product


What’s thepoint?

The pointis to make

ATP!

ATP

AP Biology

Label the following parts of the mitochondrion: Outer membrane Intermembrane

space Inner membrane Cristae Matrix

AP Biology

Source: p.166Location – Prokaryotic Cell

Location – Eukaryotic Cell

Glycolysis

Citric Acid Cycle

Oxidative Phosphorylation

AP Biology Aim: How do we obtain energy (ATP) from our food? Do Now: Explain the diagram shown here – Fig. 9-2 Light energy ECOSYSTEM Photosynthesis in.

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