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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
AP Biology 2006-2007
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)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
AP Biology
Fig. 9-6-1
Substrate-levelphosphorylation
ATP
Cytosol
Glucose Pyruvate
Glycolysis
Electronscarried
via NADH
AP Biology
Fig. 9-6-2
Mitochondrion
Substrate-levelphosphorylation
ATP
Cytosol
Glucose Pyruvate
Glycolysis
Electronscarried
via NADH
Substrate-levelphosphorylation
ATP
Electrons carriedvia NADH and
FADH2
Citricacidcycle
AP Biology
Fig. 9-6-3
Mitochondrion
Substrate-levelphosphorylation
ATP
Cytosol
Glucose Pyruvate
Glycolysis
Electronscarried
via NADH
Substrate-levelphosphorylation
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
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
AP Biology
Fig. 9-7
Enzyme
ADP
PSubstrate
Enzyme
ATP+
Product
AP Biology 2006-2007
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