Division Ave. High School
Ms. Foglia
AP Biology
Cellular Respiration
Harvesting Chemical Energy
ATP
AP Biology
2006-2007
What’s the point?
ATP
Whoa!
HOT stuff!
The Point is to Make ATP!
AP Biology
2006-2007
Harvesting stored energy
Energy is stored in organic molecules
____________________________________
____________ eat these organic molecules → food
digest organic molecules to get…
____________________________________
____________________________________
controlled release of energy
“burning” fuels in a series of
step-by-step enzyme-controlled reactions
AP Biology
1
Division Ave. High School
Ms. Foglia
AP Biology
Harvesting energy stored in glucose
Glucose is the model
____________________________________
respiration
glucose + oxygen → carbon + water + energy
dioxide
C6H12O6 +
6O2
→ 6CO2 + 6H2O + ATP + heat
COMBUSTION = making a lot of heat energy
by burning fuels in one step
RESPIRATION = making ATP (& less heat)
by burning fuels in many small steps
enzymes
ATP
O2
glucose
fuel
AP Biology
(carbohydrates)
CO2 + H2O + heat
O2
CO2 + H2O + ATP (+ heat)
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
loses e-
gains e-
oxidized
+
+
reduced
–
+
e-
e-
e-
AP Biology
REDOX
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
e
p
_____________________________________
loses e-
gains e-
oxidized
+
+
oxidation
reduced
+
–
H
reduction
H
oxidation
C6H12O6 +
AP Biology
H
6O2
→ 6CO2 + 6H2O + ATP
reduction
2
Division Ave. High School
Ms. Foglia
AP Biology
Coupling oxidation & reduction
REDOX reactions in respiration
release energy as break down organic molecules
break C-C bonds
strip off electrons from C-H bonds by removing H atoms
C6H12O6 → CO2 = __________________________
electrons attracted to more electronegative atoms
in biology, the most electronegative atom?
O2 → H2O = _______________________________
O2
__________________________________________
__________________________________________
oxidation
__
C6H12O6 +
→ 6CO2 + 6H2O + ATP
6O2
reduction
AP Biology
Oxidation & reduction
Oxidation
Reduction
______________
______________
______________
______________
______________
______________
______________
______________
______________
______________
oxidation
C6H12O6 +
→ 6CO2 + 6H2O + ATP
6O2
reduction
AP Biology
like $$
in the bank
Moving electrons in respiration
__________________ move electrons
by shuttling H atoms around
NAD+ → NADH (reduced)
FAD+2 → FADH2 (reduced)
NAD+
nicotinamide
Vitamin B3
niacin
O–
O– P –O
O
phosphates
O–
–
O P –O
O
AP Biology
H
reducing power!
NADH
O
H
H O
C NH2
N+
+
C NH2
reduction
N+
O–
O– P –O
O
O–
–
O P –O
O
carries electrons as
H
oxidation
adenine
ribose sugar
a reduced molecule
3
Division Ave. High School
Ms. Foglia
AP Biology
Overview of cellular respiration
4 metabolic stages
_______________________
1. ______________________
respiration without O2
in cytosol
_______________________
respiration using O2
in mitochondria
2. ______________________
3. ______________________
4. ______________________
C6H12O6 +
AP Biology
6O2
→ 6CO2 + 6H2O + ATP
(+ heat)
What’s the point?
ATP
The Point is to Make ATP!
AP Biology
2006-2007
And how do we do that?
H+
H+
___________________
H+
H+
H+
H+
H+
H+
__________________
conformational
changes
bond Pi to ADP to
make ATP
__________________
allow the H+ to flow
down concentration
gradient through ATP ADP + Pi
synthase
ADP + Pi → ATP
ATP
AP Biology
H+
4
Division Ave. High School
Ms. Foglia
AP Biology
H+
H+
Got the Energy?
Ask Questions!
H+
H+
H+
H+
H+
H+
ADP + Pi
ATP
AP Biology
H+
2006-2007
5
Division Ave. High School
Ms. Foglia
AP Biology
Cellular Respiration
Stage 1:
Glycolysis
AP Biology
2007-2008
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2007-2008
Glycolysis
Breaking down glucose
“glyco – lysis” (splitting sugar)
glucose → → → → → pyruvate
2x 3C
6C
In the
cytosol?
Why does
that make
evolutionary
sense?
ancient pathway which harvests energy
where energy transfer first evolved
transfer energy from organic molecules to ATP
still is starting point for ALL cellular respiration
but it’s inefficient
occurs in cytosol
______________________________________
AP Biology
That’s not enough
ATP for me!
1
Division Ave. High School
Ms. Foglia
AP Biology
Evolutionary perspective
Prokaryotes
first cells had no organelles
Enzymes
of glycolysis are
“well-conserved”
Anaerobic atmosphere
life on Earth first evolved without free oxygen (O2)
in atmosphere
energy had to be captured from organic molecules
in absence of O2
Prokaryotes that evolved glycolysis are ancestors
of all modern life
___________________________________________
You mean
we’re related?
Do I have to invite
them over for
the holidays?
AP Biology
Overview
glucose
C-C-C-C-C-C
enzyme
2 ATP
enzyme
2 ADP
10 reactions
convert
fructose-1,6bP
glucose (6C) to
P-C-C-C-C-C-C-P
enzyme
enzyme
2 pyruvate (3C)
enzyme
DHAP
G3P
produces:
_______________P-C-C-C C-C-C-P
2H
2Pi enzyme
consumes:
_______________
enzyme
net yield:
2Pi
enzyme
_______________
DHAP = dihydroxyacetone phosphate
AP Biology
G3P
= glyceraldehyde-3-phosphate
pyruvate
C-C-C
2 NAD+
2
4 ADP
4 ATP
Glycolysis summary
_______________
invest some ATP
ENERGY INVESTMENT
-2 ATP
ENERGY PAYOFF
G3P
C-C-C-P
4 ATP
_______________
harvest a little
ATP & a little NADH
like $$
in the
bank
NET YIELD
AP Biology
_________
_________
_________
2
Division Ave. High School
Ms. Foglia
AP Biology
1st half of glycolysis (5 reactions)
Glucose “priming”
get glucose ready
to split
phosphorylate
glucose
CH2 O
O
CH2 O
O
P
CH2
CH2
CH2OH
P O
ADP
O
O
P
Fructose 1,6-bisphosphate
O CH2
4,5 aldolase
isomerase
C
O Dihydroxyacetone
CH2OH phosphate
H
C O
CHOH
CH2 O
Glyceraldehyde 3
-phosphate (G3P)
NAD+
+
Pi
NAD
Pi
6
glyceraldehyde
NADH
3-phosphate
P
dehydrogenase
1,3-Bisphosphoglycerate 1,3-Bisphosphoglycerate
(BPG)
(BPG)
NADH
AP Biology
P
Glucose 6-phosphate
2
phosphoglucose
isomerase
split destabilized
glucose
P
ADP
O
Fructose 6-phosphate
3
ATP
phosphofructokinase
molecular
rearrangement
CH2OH
Glucose
1
hexokinase
ATP
O
P
O
CHOH
CH2 O
P
2nd half of glycolysis (5 reactions)
DHAP
P-C-C-C
Energy Harvest
NADH production
G3P donates H
oxidizes the sugar
reduces NAD+
__________________
NAD+
Pi
_________________
__________________
AP Biology
NAD+
NADH
7
phosphoglycerate
kinase
ADP
ATP
3-Phosphoglycerate
(3PG)
ADP
ATP
3-Phosphoglycerate
(3PG)
8
phosphoglyceromutase
2-Phosphoglycerate
(2PG)
H2O
O P
C O
H C O
CH2OH
P
OH2O
Phosphoenolpyruvate
(PEP)
10
pyruvate kinase
ADP
C
C
Pyruvate
O
O
P
CH2
OC
ATP
ATP
Pyruvate
OC
CHOH
CH2
O-
2-Phosphoglycerate
(2PG)
9
enolase
Phosphoenolpyruvate
(PEP)
ADP
Payola!
Finally some
ATP!
Pi
6
NADH
ATP production
G3P → → → pyruvate
PEP sugar donates P
_________________
G3P
C-C-C-P
O
C O
CH3
Substrate-level Phosphorylation
In the last steps of glycolysis, where did
the P come from to make ATP?
9
the sugar substrateH O(PEP)enolase
OH2O
2
P is transferred
from PEP to ADP
kinase enzyme
ADP → ATP
AP Biology
Phosphoenolpyruvate
(PEP)
ADP
Phosphoenolpyruvate
(PEP)
10
pyruvate kinase
ADP
Pyruvate
Pyruvate
O
C O
CH2
P
OC
ATP
ATP
C
O
C O
CH3
ATP
I get it!
The PO4 came
directly from
the substrate!
3
Division Ave. High School
Ms. Foglia
AP Biology
Energy accounting of glycolysis
2 ATP
2 ADP
glucose → → → → → pyruvate
2x 3C
6C
4 ADP
4 ATP
2 NAD+
2
All that work!
And that’s all
I get?
But
glucose has
so much more
to give!
Net gain = 2 ATP + 2 NADH
some energy investment (-2 ATP)
small energy return (4 ATP + 2 NADH)
AP 1Biology
6C sugar → 2 3C sugars
Is that all there is?
Not a lot of energy…
for 1 billon years+ this is how life on
Earth survived
no O2= slow growth, slow reproduction
only harvest 3.5% of energy stored in glucose
more carbons to strip off = more energy to harvest
O2
O2
glucose → → → → pyruvate
2x 3C
6C
O2
Hard way
to make
a living!
O2
O2
AP Biology
But can’t stop there!
G3P
DHAP
NAD+
raw materials → products
Pi
+
NADH
NAD
Pi
1,3-BPG
NADH
glucose + 2ADP + 2Pi + 2
1,3-BPG
NAD+
NADH
ADP
ATP
3-Phosphoglycerate
(3PG)
3-Phosphoglycerate
(3PG)
→ 2 pyruvate + 2ATP
+ 2NADH
8
2-Phosphoglycerate
(2PG)
2-Phosphoglycerate
(2PG)
9
HO
__________________________
__________________________ Phosphoenolpyruvate
(PEP)
another molecule must accept HADP
10
from NADH
ATP
so
AP Biology
+
NADH
NAD
ATP
Going to run out of NAD+
NAD+
Pi
7
ADP
Glycolysis
6
Pi
2
NAD+ is freed up for another round
Pyruvate
H2O
Phosphoenolpyruvate
(PEP)
ADP
ATP
Pyruvate
4
Division Ave. High School
Ms. Foglia
AP Biology
How is NADH recycled to NAD+?
___________________
___________________
___________________
___________________
Another molecule ___________________
must accept H
pyruvate
from NADH
NAD+
H2O
CO2
NADH
O2
recycle
NADH
NADH
acetyl-CoA
acetaldehyde
NADH
NAD+
NAD+
lactate
____________
____________
which path you
use depends on
AP Biology
who
you are…
Krebs
cycle
ethanol
____________
____________
Fermentation (anaerobic)
_____________________
pyruvate → ethanol + CO2
3C
2C
NADH
NAD+
beer, wine, bread
1C
back to glycolysis→→
→→
_____________________
pyruvate → lactic acid
3C
3C
NADH
AP Biology
NAD+
back to glycolysis→→
→→
cheese, anaerobic exercise (no O2)
Alcohol Fermentation
pyruvate → ethanol + CO2
3C
NADH
2C
NAD+
1C
bacteria
yeast
recycle
NADH
back to glycolysis→→
→→
Dead end process
at ~12% ethanol,
kills yeast
can’t reverse the
reaction
Count the
carbons!
AP Biology
5
Division Ave. High School
Ms. Foglia
AP Biology
Lactic Acid Fermentation
pyruvate → lactic acid
→
3C
O2
animals
some fungi
recycle
NADH
3C
NAD+ back to glycolysis→→
→→
NADH
Reversible process
once O2 is available,
lactate is converted
back to pyruvate by
the liver
Count the
carbons!
AP Biology
Pyruvate is a branching point
Pyruvate
O2
O2
fermentation
anaerobic
respiration
mitochondria
Krebs cycle
aerobic respiration
AP Biology
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2007-2008
6
Division Ave. High School
Ms. Foglia
AP Biology
H+
And how do we do that? H
+
H+
H+
H+
H+
H+
H+
ATP synthase
set up a H+ gradient
allow H+ to flow
through ATP synthase
powers bonding
of Pi to ADP
ADP + P
ADP + Pi → ATP
ATP
H+
AP Biology
But…
Have we done that yet?
NO!
There’s still more
to my story!
Any Questions?
AP Biology
2007-2008
7
Division Ave. High School
Ms. Foglia
AP Biology
Cellular Respiration
Stage 2 & 3:
Oxidation of Pyruvate
Krebs Cycle
AP Biology
2006-2007
Glycolysis is only the start
Glycolysis
glucose → → → → → pyruvate
6C
2x 3C
Pyruvate has more energy to yield
3 more C to strip off (to oxidize)
if O2 is available, pyruvate enters mitochondria
enzymes of Krebs cycle complete the full
oxidation of sugar to CO2
pyruvate → → → → → → CO2
AP Biology
3C
1C
Cellular respiration
AP Biology
1
Division Ave. High School
Ms. Foglia
AP Biology
Mitochondria — Structure
Double membrane energy harvesting organelle
smooth outer membrane
highly folded inner membrane
____________________________
____________________________
mitochondrial DNA, ribosomes
enzymes
________________
fluid-filled space between membranes
inner fluid-filled space
outer
membrane
inner
membrane
cristae
matrix
intermembrane
free in matrix & membrane-bound
space
What cells would have
AP
Biology
a lot
of mitochondria?
mitochondrial
DNA
Mitochondria – Function
Oooooh!
Form fits
function!
Dividing mitochondria
Membrane-bound proteins
Who else divides like that? Enzymes & permeases
What does this tell us about
the evolution of eukaryotes?
__________________________
AP Biology
Advantage of highly folded inner
membrane?
____________________________
____________________________
Oxidation of pyruvate
Pyruvate enters mitochondrial matrix
[
2x pyruvate → → → acetyl CoA + CO2
3C
2C
1C
]
NAD
Where
does the
3 step oxidation process
CO2 go?
Exhale!
releases _______ (count the carbons!)
reduces _______________ (moves e )
produces __________________
Acetyl CoA enters ________________
AP Biology
2
Division Ave. High School
Ms. Foglia
AP Biology
Pyruvate oxidized to Acetyl CoA
reduction
NAD+
Acetyl CoA
Coenzyme A
Pyruvate
CO2
C-C-C
C-C
oxidation
[
2 x Yield = 2C sugar + NADH + CO2
AP Biology
]
1937 | 1953
Krebs cycle
aka Citric Acid Cycle
in _________________________
8 step pathway
each catalyzed by specific enzyme
Hans Krebs
1900-1981
step-wise catabolism of 6C citrate molecule
Evolved later than glycolysis
does that make evolutionary sense?
bacteria →3.5 billion years ago (glycolysis)
free O2 →2.7 billion years ago (photosynthesis)
eukaryotes →1.5 billion years ago (aerobic
AP Biology
respiration = organelles → mitochondria)
Count the carbons!
pyruvate
3C
2C
6C
4C
This happens
twice for each
glucose
molecule
4C
acetyl CoA
citrate
oxidation
of sugars
CO2
x2
4C
4C
6C
5C
4C
CO2
AP Biology
3
Division Ave. High School
Ms. Foglia
AP Biology
Count the electron carriers!
pyruvate
3C
4C
CO2
acetyl CoA
6C
4C
NADH
This happens
twice for each
glucose
molecule
2C
NADH
citrate
__________
__________
__________
6C
x2
5C
4C
FADH2
4C
AP Biology
CO2
NADH
CO2
4C
NADH
ATP
Whassup?
So we fully
oxidized
glucose
C6H12O6
↓
CO2
& ended up
with 4 ATP!
What’s the
point?
AP Biology
Electron Carriers = Hydrogen Carriers
H+
Krebs cycle
produces large
quantities of
_______________
____________
____________
go to Electron
Transport Chain!
AP Biology
H+
H+
H+
+
H+ H H+
H+
ADP
+ Pi
ATP
H+
What’s so
important about
electron carriers?
4
Division Ave. High School
Ms. Foglia
AP Biology
Energy accounting of Krebs cycle
4 NAD + 1 FAD
4 NADH + 1 FADH2
2x pyruvate → → → → → → → → → CO2
3C
3x 1C
1 ADP
1 ATP
ATP
Net gain = 2 ATP
= 8 NADH + 2 FADH2
AP Biology
Value of Krebs cycle?
If the yield is only 2 ATP then how was the
Krebs cycle an adaptation?
__________________________________
____________________________________
__________________________________
__________________________________
____________________________________
like $$
in the
bank
AP Biology
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2006-2007
5
Division Ave. High School
Ms. Foglia
AP Biology
H+
And how do we do that?
H+
H+
H+
H+
H+
H+
H+
ATP synthase
set up a H+ gradient
allow H+ to flow
through ATP synthase
powers bonding
of Pi to ADP
ADP + P
ADP + Pi → ATP
ATP
H+
AP Biology
But…
Have we done that yet?
NO!
The final chapter
to my story is
next!
Any Questions?
AP Biology
2006-2007
6
Division Ave. High School
Ms. Foglia
AP Biology
Cellular Respiration
Stage 4:
Electron Transport Chain
AP Biology
2006-2007
Cellular respiration
AP Biology
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2006-2007
1
Division Ave. High School
Ms. Foglia
AP Biology
ATP accounting so far…
Glycolysis → 2 ATP
Kreb’s cycle → 2 ATP
Life takes a lot of energy to run, need to
extract more energy than 4 ATP!
There’s got to be a better way!
I need a lot
more ATP!
A working muscle recycles over
10 million ATPs per second
AP Biology
There is a better way!
Electron Transport Chain
series of proteins built into
___________________________________
along cristae
transport proteins & enzymes
transport of electrons down ETC linked to
pumping of H+ to create H+ gradient
yields ___________ from 1 glucose!
only in presence of O2 (_________________)
AP Biology
That
sounds more
like it!
O2
Mitochondria
Double membrane
outer membrane
____________________
highly folded cristae
enzymes & transport
proteins
____________________
fluid-filled space
between membranes
AP Biology
Oooooh!
Form fits
function!
2
Division Ave. High School
Ms. Foglia
AP Biology
Electron Transport Chain
Inner
mitochondrial
membrane
Intermembrane space
C
Q
NADH
dehydrogenase
cytochrome
bc complex
cytochrome c
oxidase complex
Mitochondrial matrix
AP Biology
Remember the Electron Carriers?
Glycolysis
glucose
Krebs cycle
G3P
8 NADH
2 FADH2
2 NADH
Time to
break open
the piggybank!
AP Biology
Electron Transport Chain
Building proton gradient!
NADH → NAD+ + H
e
p
intermembrane
space
H+
H+
H → e- + H+
C
NADH H
e–
H
FADH2
NAD+
NADH
dehydrogenase
inner
mitochondrial
membrane
e–
Q
e–
AP Biology
H+
FAD
2H+ + 12 O2
cytochrome
bc complex
H2O
cytochrome c
oxidase complex
mitochondrial
matrix
What powers the proton (H+) pumps?…
3
Division Ave. High School
Ms. Foglia
AP Biology
Stripping H from Electron Carriers
Electron carriers pass electrons & H+ to ETC
H cleaved off NADH & FADH2
electrons stripped from H atoms → H+ (protons)
electrons passed from one electron carrier to next in
mitochondrial membrane (ETC)
flowing electrons = energy to do work
transport proteins in membrane pump H+ (protons)
across inner membrane to intermembrane space
H+
TA-DA!!
Moving electrons
do the work!
H+
H+
H+
H+
+
H+ H+ H
+
H+ H H+
C
e–
NADH
Q
e–
FADH2
FAD
NAD+
NADH
dehydrogenase
AP Biology
e–
2H+ +
cytochrome
bc complex
1
2
O2
H2 O
cytochrome c
oxidase complex
ADP
+ Pi
ATP
H+
But what “pulls” the
electrons down the ETC?
O2
AP Biology
electrons
flow downhill
to O2
oxidative phosphorylation
Electrons flow downhill
Electrons move in steps from
carrier to carrier downhill to ___________
each carrier more electronegative
controlled oxidation
controlled release of energy
make ATP
instead of
fire!
AP Biology
4
Division Ave. High School
Ms. Foglia
AP Biology
“proton-motive” force
We did it!
Set up a H+
H+
H+
H+
gradient
Allow the protons
to flow through
ATP synthase
Synthesizes ATP
ADP + Pi → ATP
Are we
there yet?
H+
H+
H+
H+
H+
ADP + Pi
ATP
H+
AP Biology
Chemiosmosis
__________________________________________
build up of proton gradient just so H+ could flow
through ATP synthase enzyme to build ATP
_______________
links the Electron
Transport Chain
to ATP synthesis
So that’s
the point!
AP Biology
1961 | 1978
Peter Mitchell
Proposed chemiosmotic hypothesis
revolutionary idea at the time
proton motive force
1920-1992
AP Biology
5
Division Ave. High School
Ms. Foglia
AP Biology
Pyruvate from
cytoplasm
Inner
mitochondrial H+
membrane
H+
Intermembrane
space
Electron
transport
C system
Q
NADH
Acetyl-CoA
e-
2. Electrons
provide energy
1. Electrons are harvested to pump protons
and carried to the transport
across the
system.
membrane.
-
NADH
Krebs
cycle
e
FADH2
1 O
2 +2
2H+
H+
32 ATP
4. Protons diffuse back in
down their concentration
gradient, driving the
synthesis of ATP.
ATP
synthase
~4
0
Cellular respiration
2 ATP
O2
H+
ATP
Mitochondrial
matrix
AP Biology
H2O
e- 3. Oxygen joins
with protons to
form water.
CO2
2
H+
e-
+
2 ATP
+
AT
P
~36 ATP
AP Biology
Summary of cellular respiration
C6H12O6 + 6O2
→ 6CO2 + 6H2O + ~40 ATP
Where did the glucose come from?
Where did the O2 come from?
Where did the CO2 come from?
Where did the CO2 go?
Where did the H2O come from?
Where did the ATP come from?
What else is produced that is not listed
in this equation?
Why do we breathe?
AP Biology
6
Division Ave. High School
Ms. Foglia
AP Biology
Taking it beyond…
What is the final electron acceptor in
H+
H+
H+
C
Electron Transport Chain?e
–
NADH
O2
Q
e–
FADH2
FAD
NAD+
NADH
dehydrogenase
e–
2H+ +
cytochrome
bc complex
1
2
O2
H2 O
cytochrome c
oxidase complex
So what happens if O2 unavailable?
ETC backs up
AP Biology
nothing to pull electrons down chain
NADH & FADH2 can’t unload H
ATP production ceases
cells run out of energy
and you die!
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
2006-2007
7
Division Ave. High School
Ms. Foglia
AP Biology
Photosynthesis:
Life from Light and Air
AP Biology
2008-2009
Energy needs of life
All life needs a constant input of energy
__________________________
consumers
get their energy from “eating others”
eat food = other organisms = organic molecules
make energy through respiration
__________________________
produce their own energy (from “self”)
producers
AP Biology
convert energy of sunlight
build organic molecules (CHO) from CO2
make energy & synthesize sugars through
photosynthesis
How are they connected?
Heterotrophs
making energy & organic molecules from ingesting organic molecules
glucose + oxygen → carbon + water + energy
dioxide
C6H12O6 +
6O2
→ 6CO2 + 6H2O + ATP
oxidation = exergonic
Autotrophs
making energy & organic molecules from light energy
Where’s
the ATP?
carbon + water + energy → glucose + oxygen
dioxide
6CO2 + 6H2O + light → C6H12O6 + 6O2
energy
AP Biology
reduction = endergonic
1
Division Ave. High School
Ms. Foglia
AP Biology
What does it mean to be a plant
Need to…
collect light energy
ATP
transform it into chemical energy
glucose
store light energy
in a stable form to be moved around
the plant or stored
need to get building block atoms
CO2
from the environment
C,H,O,N,P,K,S,Mg
produce all organic molecules
needed for growth
H2O
N
K P
…
carbohydrates, proteins, lipids, nucleic acids
AP Biology
Plant structure
Obtaining raw materials
__________
__________
__________
__________
_______________________
_______________________
_______________________
N, P, K, S, Mg, Fe…
_______________________
AP Biology
stomate
______________
______________
AP Biology
2
Division Ave. High School
Ms. Foglia
AP Biology
Chloroplasts
cross section
absorb
of leaf
sunlight & CO2
leaves
CO2
chloroplasts
in plant cell
chloroplast
chloroplasts
contain
chlorophyll
make
energy & sugar
AP Biology
chloroplast
Plant structure
ATP
+
H
+H
+
H+ H+ H + H+ H+ HH+
H+ Hthylakoid
+
Chloroplasts
_________________
_________________
outer membrane
inner membrane
fluid-filled interior
_________________
stroma
_________________
Thylakoid membrane
contains
chlorophyll molecules
electron transport chain
ATP synthase
AP Biology
H+ gradient built up within
thylakoid sac
thylakoid
granum
Photosynthesis
____________________
_________________________
_________________________
convert solar energy to chemical energy
ATP & NADPH
____________________
It’s not the
Dark Reactions!
_________________________
_________________________
uses chemical energy (ATP & NADPH) to
reduce CO2 & synthesize C6H12O6
AP Biology
3
Division Ave. High School
Ms. Foglia
AP Biology
thylakoid
chloroplast
Light reactions
_______________________
ATP
+
+H+ H H+
H+ H+H
+ + +
H+H+ H H H
+ H+
+
H
+
H+ H+H
+ +H +
+
H+H H H H
like in cellular respiration
proteins in organelle membrane
__________________
______________
proton (H+)
gradient across
inner membrane
find the double membrane!
ATP synthase
enzyme
AP Biology
ETC of Respiration
Mitochondria transfer chemical energy from food molecules
into chemical energy of ATP
use electron carrier ___________
generate H2O
AP Biology
ETC of Photosynthesis
Chloroplasts transform light energy
into chemical energy of ATP
use electron carrier ___________
generate O2
AP Biology
4
Division Ave. High School
Ms. Foglia
AP Biology
The ATP that “Jack” built
photosynthesis
respiration
sunlight
breakdown of C6H12O6
H+
H+
H+
moves the electrons
runs the pump
H+
H+
H+
H+
H+
pumps the protons
builds the gradient
drives the flow of protons
through ATP synthase
ADP + Pi
bonds Pi to ADP
generates the ATP
AP Biology
ATP
H+
… that evolution built
Pigments of photosynthesis
How does this
molecular structure
fit its function?
Chlorophylls & other pigments
embedded in thylakoid membrane
arranged in a “photosystem”
collection of molecules
AP Biology
structure-function relationship
A Look at Light
The spectrum of color
V
I
B
G
Y
O
R
AP Biology
5
Division Ave. High School
Ms. Foglia
AP Biology
Light: absorption spectra
Photosynthesis gets energy by absorbing
wavelengths of light
_______________________
accessory pigments with different structures
absorb light of different wavelengths
absorbs best in red & blue wavelengths & least in green
chlorophyll b, carotenoids, xanthophylls
Why are
plants green?
AP Biology
Photosystems of photosynthesis
2 photosystems in thylakoid membrane
collections of chlorophyll molecules
act as light-gathering molecules
_________________ reaction
__________________ center
P680 = absorbs 680nm
wavelength red light
_________________
__________________
P700 = absorbs 700nm
wavelength red light
antenna
pigments
AP Biology
chlorophyll a
ETC of Photosynthesis
______________
chlorophyll b
______________
AP Biology
6
Division Ave. High School
Ms. Foglia
AP Biology
ETC of Photosynthesis
sun
1
e
e
AP Biology
Photosystem II
P680
chlorophyll a
ETC of Photosynthesis
Inhale, baby!
thylakoid
chloroplast
+
+H+ H H+
H+ H+H
+ + +
H+ H+ H H H
ATP
+
+H+ H H+
H+ H+H
+ +
+
+H+ H H H
H
Plants SPLIT water!
H H
O
e
e
OO
H+
e e
AP Biology
e-
+H
2
1
e-
fill the e– vacancy
Photosystem II
P680
chlorophyll a
ETC of Photosynthesis
chloroplast
+
e
e
ATP
thylakoid
+
+H H H+
H+ H+H
+ + +
H+H+ H H H
+
+H+ H
+
+
+
H
H H + + H+H+HH+
HH
3
2
1
e
e
H+
4
ATP
H+
H+
H+
H+
AP Biology
Photosystem II
P680
chlorophyll a
H+
H+
H+
H+
H+
_________________
_________________
ADP + Pi
ATP
H+
7
Division Ave. High School
Ms. Foglia
AP Biology
e
e
ETC of Photosynthesis
e
e
–
l
fil
e
e
5
e
th
e
y
nc
ca
va
sun
e e
AP Biology
Photosystem II
P680
chlorophyll a
Photosystem I
P700
chlorophyll b
ETC of Photosynthesis
e
e
electron carrier
6
e
e
5
sun
AP Biology
Photosystem II
P680
chlorophyll a
Photosystem I
P700
chlorophyll b
$$ in the bank…
reducing power!
sun
e
e
e
e
ETC of Photosynthesis
+
H
+
+
H+ H H+ H+ H +
H
H+
H+ H+ H+
O
split H2O
ATP
AP Biology
8
Division Ave. High School
Ms. Foglia
AP Biology
ETC of Photosynthesis
ETC uses light energy to produce
ATP & NADPH
go to Calvin cycle
PS II absorbs light
excited electron passes from chlorophyll to
“primary electron acceptor”
need to replace electron in chlorophyll
enzyme extracts electrons from H2O &
supplies them to chlorophyll
splits H2O
O combines with another O to form O2
O2 released to atmosphere
and we breathe easier!
AP Biology
Experimental evidence
Where did the O2 come from?
radioactive tracer = O18
Experiment 1
6CO2 + 6H2O + light → C6H12O6 + 6O2
energy
Experiment 2
6CO2 + 6H2O + light → C6H12O6 + 6O2
energy
Proved O2 came from H2O not CO2 = plants split H2O!
AP Biology
Noncyclic Photophosphorylation
Light reactions
elevate electrons in
2 steps (PS II & PS I)
____________________
____________________
____________________
____________________
ATP
AP Biology
9
Division Ave. High School
Ms. Foglia
AP Biology
Cyclic photophosphorylation
If PS I can’t pass electron
to NADP…it cycles back
to PS II & makes more
ATP, but no NADPH
✗
coordinates light
reactions to Calvin cycle
Calvin cycle uses more
ATP than NADPH
18 ATP +
12 NADPH
AP Biology
ATP
→ 1 C6H12O6
Photophosphorylation
cyclic
photophosphorylation
NADP
NONcyclic
photophosphorylation
ATP
AP Biology
Photosynthesis summary
Where did the energy come from?
Where did the electrons come from?
Where did the H2O come from?
Where did the O2 come from?
Where did the O2 go?
Where did the H+ come from?
Where did the ATP come from?
What will the ATP be used for?
Where did the NADPH come from?
What will the NADPH be used for?
AP Biology
…stay tuned for the Calvin cycle
10
Division Ave. High School
Ms. Foglia
AP Biology
You can grow if you
Ask Questions!
AP Biology
2008-2009
11
Division Ave. High School
Ms. Foglia
AP Biology
Photosynthesis:
The Calvin Cycle
Life from Air
AP Biology
2007-2008
Remember what it means to be a plant…
Need to produce all organic molecules
necessary for growth
carbohydrates, lipids, proteins, nucleic acids
Need to store chemical energy (ATP)
produced from light reactions
in a more stable form
can be moved around plant
saved for a rainy day
carbon + water + energy → glucose + oxygen
dioxide
light → C H O + 6O
AP Biology6CO2 + 6H2O +
6 12 6
2
energy
Light reactions
Convert solar energy to chemical
energy
ATP
ATP → energy
NADPH → reducing power
What can we do now?
→ → build stuff !!
AP Biology
2005-2006
photosynthesis
1
Division Ave. High School
Ms. Foglia
AP Biology
How is that helpful?
Want to make C6H12O6
synthesis
How? From what?
What raw materials are available?
CO2
NADPH
carbon fixation
reduces CO2
NADP
C6H12O6
NADP
AP Biology
From CO2 → C6H12O6
CO2 has very little chemical energy
fully oxidized
C6H12O6 contains a lot of chemical energy
highly reduced
Synthesis = endergonic process
put in a lot of energy
Reduction of CO2 → C6H12O6 proceeds in
many small uphill steps
each catalyzed by a specific enzyme
using energy stored in ATP & NADPH
AP Biology
From Light reactions to Calvin cycle
Calvin cycle
____________________
Need products of light reactions to
drive synthesis reactions
________________
________________
stroma
ATP
thylakoid
AP Biology
2005-2006
2
Division Ave. High School
Ms. Foglia
AP Biology
C
C C C C C
1C
C C C C C
3. Regeneration
C C C C C
of RuBP
RuBP
ribulose bisphosphate
starch,
sucrose,
cellulose
& more
5C
3 ATP
C
C
C
C
C
C
C
C
C
C
C
C
1. Carbon fixation
C C C C C C
RuBisCo
C C C C C C
6C
C C C C C C
5C
used
to make
glucose
C
C
C
C
H H H
C
|
| |
C–C–C
AP Biology C
CO2
ribulose
bisphosphate
carboxylase
3 ADP
C=C=C
C
C
Calvin cycle
glyceraldehyde-3-P
3C
PGA
G3P
C
C
C
C
C
C
phosphoglycerate
C C C
3C
H
|
H
|
H
|
Remember
G3P?
glycolysis
6 ADP
3C
6 NADP
C
C
C
C
C
C
6 ATP
2. Reduction
6 NADPH
C
C
C
C
C
C
glucose
C-C-C-C-C-C
2 ATP
2 ADP
fructose-1,6bP
P-C-C-C-C-C-C-P
DHAP
P-C-C-C
G3P
glyceraldehyde
3-phosphate
C-C-C-P
2 NAD+
2
4 ADP
AP Biology
Photosynthesis
To G3P and Beyond!
Glyceraldehyde-3-P
pyruvate
4 ATP
C-C-C
To G3P
and beyond!
end product of Calvin cycle
energy rich 3 carbon sugar
“___________________”
G3P is an important intermediate
G3P → → glucose → → carbohydrates
→ → lipids → → phospholipids, fats, waxes
→ → amino acids → → proteins
→ → nucleic acids → → DNA, RNA
AP Biology
2005-2006
3
Division Ave. High School
Ms. Foglia
AP Biology
RuBisCo
__________________________________
ribulose bisphosphate carboxylase
the most important enzyme in the world!
definitely the most abundant enzyme
it makes life out of air!
I’m green
with envy!
It’s not easy
being green!
AP Biology
Accounting
The accounting is complicated
3 turns of Calvin cycle = 1 G3P
3 CO2 → 1 G3P (3C)
6 turns of Calvin cycle = 1 C6H12O6 (6C)
6 CO2 → 1 C6H12O6 (6C)
18 ATP + 12 NADPH → 1 C6H12O6
any ATP left over from light reactions
will be used elsewhere by the cell
AP Biology
Photosynthesis summary
Light reactions
__________________
__________________
__________________
__________________
Calvin cycle
__________________
__________________
__________________
__________________
ADP
NADP
AP Biology
2005-2006
4
Division Ave. High School
Ms. Foglia
AP Biology
Light Reactions
light → ATP + NADPH + O
2
energy
H2O +
H2O
_______________
_______________
_______________
_______________
sunlight
Energy Building
Reactions
NADPH
ATP
AP Biology
O2
Calvin Cycle
CO2 + ATP + NADPH → C6H12O6 + ADP + NADP
CO2
ADP
NADP
Sugar
Building
Reactions
NADPH
ATP
AP Biology
____________
____________
____________
____________
____________
back to make
more ATP &
NADPH
sugars
Putting it all together
light
CO2 + H2O + energy → C6H12O6 + O2
H2O
CO2
sunlight
ADP
Energy NADP
Building
Reactions
Sugar
Building
Reactions
Plants make both:
____________
____________
____________
NADPH
ATP
AP Biology
2005-2006
O2
sugars
5
Division Ave. High School
Ms. Foglia
AP Biology
even though
this equation
is a bit of a lie…
it makes a
better story
Energy cycle
sun
Photosynthesis
light
CO2 + H2O + energy → C6H12O6 + O2
________________
CO2
H2O
________________
O2
ATP
C6H12O6 + O2 → energy + CO2 + H2O
Cellular Respiration
AP Biology
The Great Circle
of Life,Mufasa!
ATP
Summary of photosynthesis
6CO2 + 6H2O + light → C6H12O6 + 6O2
energy
Where did the CO2 come from?
Where did the CO2 go?
Where did the H2O come from?
Where did the H2O go?
Where did the energy come from?
What’s the energy used for?
What will the C6H12O6 be used for?
Where did the O2 come from?
Where will the O2 go?
What else is involved…not listed in this equation?
AP Biology
Supporting a biosphere
On global scale,
photosynthesis is the
most important process
for the continuation of life on Earth
each year photosynthesis…
captures 121 billion tons of CO2
synthesizes 160 billion tons of carbohydrate
heterotrophs are dependent on plants as
food source for fuel & raw materials
AP Biology
2005-2006
6
Division Ave. High School
Ms. Foglia
AP Biology
The poetic perspective…
All the solid material of every plant
was built by sunlight out of thin air
All the solid material of every animal
was built from plant material
air
sun
Then all the plants, cats,
dogs, elephants & people …
are really particles of air woven
together by strands of sunlight!
AP Biology
If plants can do it…
You can learn it!
Ask Questions!!
AP Biology
2005-2006
2007-2008
7
Division Ave. High School
Ms. Foglia
AP Biology
Photosynthesis:
Variations on the Theme
AP Biology
2007-2008
Remember what plants need…
Photosynthesis
light reactions
light ← sun
H2O ← ground
O
C
O
Calvin cycle
CO2 ← air
What structures have
plants evolved to
APsupply
Biology
these needs?
__________________
___________
__________
Leaf Structure
________
________
________
________
O2 H O
2
________
Gas exchange
AP Biology
Gas
exchange
O2
CO2
________
________
1
Division Ave. High School
Ms. Foglia
AP Biology
Controlling water loss from leaves
Hot or dry days
________________________
________________________
gain H2O = stomates open
lose H2O = stomates close
adaptation to
living on land,
but…
creates PROBLEMS!
AP Biology
When stomates close…
Closed stomates lead to…
O2 build up → from light reactions
CO2 is depleted → in Calvin cycle
causes problems in Calvin Cycle
O2
xylem
(water)
AP Biology
O2
phloem
(sugars)
✔
✘
CO2
CO2
The best laid
schemes of
mice and men…
and plants!
H 2O
Inefficiency of RuBisCo: CO2 vs O2
RuBisCo in Calvin cycle
_________________________
normally bonds C to RuBP
CO2 is the optimal substrate
_______________________
_______________________
photosynthesis
_________________________
RuBisCo bonds O to RuBP
O2 is a competitive substrate
_______________________
_______________________ photorespiration
AP Biology
2
Division Ave. High School
Ms. Foglia
AP Biology
Calvin cycle when CO2 is abundant
1C
ATP
RuBP
CO2
5C RuBisCo
unstable
6C intermediate
ADP
G3P
to make
glucose
5C
C3 plants
G3P 3C
3C
ATP
NADPH
NADP
ADP
3C
AP Biology
Calvin cycle when O2 is high
O2
RuBP
Hey Dude,
are you high
on oxygen!
PGA
5C RuBisCo
to
mitochondria
–––––––
lost as CO2
without
making ATP
2C
3C
It’s so
sad to see a
good enzyme,
go BAD!
photorespiration
AP Biology
Impact of Photorespiration
Oxidation of RuBP
short circuit of Calvin cycle
loss of carbons to CO2
can lose 50% of carbons fixed by Calvin cycle
reduces production of photosynthesis
no ATP (energy) produced
no C6H12O6 (food) produced
if photorespiration could be reduced,
plant would become 50% more efficient
strong selection pressure to evolve
alternative carbon fixation systems
AP Biology
3
Division Ave. High School
Ms. Foglia
AP Biology
Reducing photorespiration
Separate carbon fixation from Calvin cycle
___________________
__________________________________________________
different cells to fix carbon vs. where Calvin cycle occurs
store carbon in 4C compounds
different enzyme to capture CO2 (fix carbon)
__________________________
different leaf structure
___________________
__________________________________________________
fix carbon during night
store carbon in 4C compounds
perform Calvin cycle during day
AP Biology
C4 plants
A better way to capture CO2
1st step before Calvin cycle,
fix carbon with enzyme
___________________
corn
store as 4C compound
______________________
______________________
have to close stomates a lot
different leaf anatomy
sugar cane, corn,
other grasses…
AP Biology
sugar cane
PEP (3C) + CO2 → oxaloacetate (4C)
O2
C4 leaf anatomy
light reactions
CO2
PEP
carboxylase
C3 anatomy
stomate
_________________________
___________________________
___________________________
regenerates CO2 in inner cells
for RuBisCo
________
________
________
CO2
RuBisCo
better than RuBisCo
AP Biology
keeping
O2 away from RuBisCo
C4 anatomy
4
Division Ave. High School
Ms. Foglia
AP Biology
Comparative anatomy
Location,
location,location!
C3
C4
PHYSICALLY separate C fixation from Calvin cycle
AP Biology
CAM (Crassulacean Acid Metabolism) plants
_______________________________
____________________________________________
close stomates during day
open stomates during night
______: open stomates & fix carbon
in 4C “storage” compounds
______: release CO2 from 4C acids
to Calvin cycle
It’s all in
the timing!
increases concentration of CO2 in cells
succulents, some cacti, pineapple
AP Biology
CAM plants
cacti
succulents
AP Biology
pineapple
5
Division Ave. High School
Ms. Foglia
AP Biology
C4 vs CAM Summary
solves CO2 / O2 gas exchange vs. H2O loss challenge
___________
___________
separate 2 steps
of C fixation
anatomically in 2
different cells
separate 2 steps
of C fixation
temporally =
2 different times
night vs. day
AP Biology
Why the C3 problem?
We’ve all got
baggage!
Possibly evolutionary baggage
Rubisco evolved in high CO2 atmosphere
there wasn’t strong selection against active site of
Rubisco accepting both CO2 & O2
Today it makes a difference
21% O2 vs. 0.03% CO2
photorespiration can drain away 50% of carbon
fixed by Calvin cycle on a hot, dry day
strong selection pressure to evolve better way
to fix carbon & minimize photorespiration
AP Biology
It’s not so easy as it looks…
Any Questions??
AP Biology
2007-2008
6