Download H +

AP Biology
11-30-15
COMPLETE TEST!
Then….
Begin cellular
Respiration
AP Biology
Cellular Respiration
Harvesting Chemical Energy
ATP
AP Biology
What’s the
point?
The point
is 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
respiration

catabolism of glucose to produce ATP
glucose + oxygen  energy + water + carbon
dioxide
C6H12O6 +
6O2
 ATP + 6H2O + 6CO2 + heat
COMBUSTION = making a lot of heat energy
by burning fuels in one step
fuel
AP Biology
carbohydrates)
RESPIRATION = making ATP (& some heat)
by burning fuels in many small steps
ATP
enzymes
O2
ATP
O2
CO2 + H2O + ATP (+ heat)
glucose
CO2 + H2O + 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-
oxidation
AP Biology
e-
reduction
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
 move H = move electrons
loses e-
gains e-
oxidized
+
+
oxidation
reduced
+
–
H
reduction
H
oxidation
C6H12O6 +
AP Biology
H e-
6O2
 6CO2 + 6H2O + ATP
reduction
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

O2
couple REDOX reactions &
use the released energy to synthesize ATP
oxidation
C6H12O6 +
AP Biology
6O2
 6CO2 + 6H2O + ATP
reduction
Oxidation & reduction
 Oxidation
 Reduction
adding O
 removing H
 loss of electrons
 releases energy
 exergonic

removing O
 adding H
 gain of electrons
 stores energy
 endergonic

oxidation
C6H12O6 +
6O2
 6CO2 + 6H2O + ATP
reduction
AP Biology
like $$
in the bank
Moving electrons in respiration
 Electron carriers 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
C NH2
N+
+
adenine
ribose sugar
C NH2
reduction
O–
–
–
oxidation O P O
O
O–
O – P –O
O
carries electrons as
H
O
a reduced molecule
N+
How efficient!
Build once,
use many ways
AP Biology
12-1-15
 Bell Work
 QUICK WRITE…Describe the
function of cellular respiration
including the location,
reactants, and products.
 Home Work:
 Bozeman 013: Photosynthesis
& Respiration
AP Biology
Overview of cellular respiration
 4 metabolic stages

Anaerobic respiration (FERMENTATION)
1. Glycolysis
 respiration without O2
 in cytosol

Aerobic respiration
 respiration using O2
 in mitochondria
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain
C H O6 +
AP Biology
6 12
6O2
 ATP + 6H2O + 6CO2 (+ heat)
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
H+
And how do we do that?
H+
H+
H+
H+
H+
H+
H+
 ATP synthase enzyme

H+ flows through it
 conformational
changes
 bond Pi to ADP to
make ATP

set up a H+ gradient
 allow the H+ to flow
down concentration
gradient through ATP
synthase
 ADP + Pi  ATP
APBut…
Biology How
ADP + P
ATP
is the proton (H+) gradient formed?
H+
H+
Got to wait until
the sequel!
Got the Energy?
Ask Questions!
H+
H+
H+
H+
H+
H+
H+
ADP + P
ATP
AP Biology
H+
Cellular Respiration
Stage 2 & 3:
Oxidation of Pyruvate
Krebs Cycle
AP Biology
Overview
10 reactions
glucose
C-C-C-C-C-C
2 ATP
2 ADP
convert
fructose-1,6bP
glucose (6C) to
P-C-C-C-C-C-C-P
2 pyruvate (3C)
DHAP
G3P
 produces:
4 ATP & 2 NADH P-C-C-C C-C-C-P
2H
 consumes:
2Pi
2 ATP
 net:
2Pi
2 ATP & 2 NADH

AP Biology
pyruvate
C-C-C
2 NAD+
2
4 ADP
4 ATP
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
Mitochondria — Structure
 Double membrane energy harvesting organelle


smooth outer membrane
highly folded inner membrane
 cristae

intermembrane space
 fluid-filled space between membranes

matrix
 inner fluid-filled space


DNA, ribosomes
enzymes
 free in matrix &
What cells would have
AP
Biology
a lot
of mitochondria?
outer
intermembrane
membrane
inner
membrane-bound space
membrane
cristae
matrix
mitochondrial
DNA
Mitochondria – Function
Oooooh!
Form fits
function!
Dividing mitochondria
Membrane-bound proteins
Who else divides like that? Enzymes & permeases
bacteria!
What does this tell us about
the evolution of eukaryotes?
Endosymbiosis!
AP Biology
Advantage of highly folded inner
membrane?
More surface area for membranebound enzymes & permeases
Oxidation of pyruvate
 Pyruvate enters mitochondrial matrix
[
2x pyruvate    acetyl CoA + CO2
3C
2C
1C
NAD
Where
does the
CO2 go?
Exhale!
3 step oxidation process
 releases 2 CO2 (count the carbons!)
 reduces 2 NAD  2 NADH (moves e )
 produces 2 acetyl CoA


Acetyl CoA enters Krebs cycle
AP Biology
]
Pyruvate oxidized to Acetyl CoA
reduction
NAD+
Pyruvate
C-C-C
[
Coenzyme A
CO2
Acetyl CoA
C-C
oxidation
2 x Yield = 2C sugar + NADH + CO2
AP Biology
]
Krebs cycle
1937 | 1953
 aka Citric Acid Cycle
in mitochondrial matrix
 8 step pathway

Hans Krebs
 each catalyzed by specific enzyme
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
citrate
oxidation
of sugars
4C
6C
CO2
x2
4C
AP Biology
acetyl CoA
5C
4C
CO2
Count the electron carriers!
pyruvate
3C
6C
4C
NADH
This happens
twice for each
glucose
molecule
2C
4C
citrate
reduction
of electron
carriers
x2
4C
FADH2
4C
AP Biology
acetyl CoA
ATP
CO2
NADH
6C
CO2
NADH
5C
4C
CO2
NADH
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
electron carriers
NADH
 FADH2
 go to Electron
Transport Chain!

AP Biology
What’s so
important about
electron carriers?
H+
H+
H+
+
H+ H H+
H+
ADP
+ Pi
ATP
H+
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?

value of NADH & FADH2
 electron carriers & H carriers
 reduced molecules move electrons
 reduced molecules move H+ ions
 to be used in the Electron Transport Chain
like $$
in the
bank
AP Biology
What’s the
point?
The point
is to make
ATP!
ATP
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
Cellular Respiration
Stage 4:
Electron Transport Chain
AP Biology
Cellular respiration
AP Biology
What’s the
point?
The point
is to make
ATP!
ATP
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!
AP Biology
A working muscle recycles over
10 million ATPs per second
There is a better way!
 Electron Transport Chain

series of proteins built into
inner mitochondrial membrane
 along cristae
 transport proteins & enzymes
transport of electrons down ETC linked to
pumping of H+ to create H+ gradient
 yields ~36 ATP from 1 glucose!
 only in presence of O2 (aerobic respiration)

AP Biology
That
sounds more
like it!
O2
Mitochondria
 Double membrane
outer membrane
 inner membrane

 highly folded cristae
 enzymes & transport
proteins

intermembrane space
 fluid-filled space
between membranes
AP Biology
Oooooh!
Form fits
function!
AP Biology
12-3-15
 Bell Work
 Compare & contrast
Photosynthesis and Cell
Respiration
 Home Work:
 Finish Cell Respiration Review
AP Biology
Electron Transport Chain
Inner
mitochondrial
membrane
Intermembrane space
C
Q
NADH
dehydrogenase
cytochrome
bc complex
Mitochondrial matrix
AP Biology
cytochrome c
oxidase complex
Remember the Electron Carriers?
Glycolysis
glucose
Krebs cycle
G3P
2 NADH
Time to
break open
the piggybank!
AP Biology
8 NADH
2 FADH2
Electron Transport Chain
Building proton gradient!
NADH  NAD+ + H
e
p
intermembrane
space
H+
H+
H  e- + H+
C
e–
NADH H
FADH2
NAD+
NADH
dehydrogenase
inner
mitochondrial
membrane
e–
Q
AP Biology
H+
e–
H
FAD
2H+ +
cytochrome
bc complex
1
2
O2
H2O
cytochrome c
oxidase complex
mitochondrial
matrix
What powers the proton (H+) pumps?…
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+
+
H
H+
TA-DA!!
Moving electrons
do the work!
+
H
H+
H+
+
H+ H+ H
+
H+ H H+
C
e–
NADH
AP Biology
+
H
H+
Q
e–
FADH2
FAD
NAD+
NADH
dehydrogenase
e–
2H+
cytochrome
bc complex
+
1
2
O2
H2O
cytochrome c
oxidase complex
ADP
+ Pi
ATP
H+
But what “pulls” the
electrons down the ETC?
H 2O
O2
AP Biology
electrons
flow downhill
to O2
oxidative phosphorylation
Electrons flow downhill
 Electrons move in steps from
carrier to carrier downhill to oxygen
each carrier more electronegative
 controlled oxidation
 controlled release of energy

make ATP
instead of
fire!
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?
AP Biology
H+
H+
H+
H+
H+
ADP + Pi
ATP
H+
Chemiosmosis
 The diffusion of ions across a membrane

build up of proton gradient just so H+ could flow
through ATP synthase enzyme to build ATP
Chemiosmosis
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
Pyruvate from
cytoplasm
Inner
+
mitochondrial H
membrane
H+
Intermembrane
space
Electron
transport
C system
Q
NADH
Acetyl-CoA
1. Electrons are harvested
and carried to the
transport system.
NADH
Krebs
cycle
e-
e-
FADH2
e-
2. Electrons
provide energy
to pump
protons across
the membrane.
e-
H2O
3. Oxygen joins
with protons to
form water.
1 O
2 +2
2H+
O2
H+
CO2
ATP
Mitochondrial
matrix
AP Biology
H+
ATP
ATP
4. Protons diffuse back in
down their concentration
gradient, driving the
synthesis of ATP.
H+
ATP
synthase
AP Biology
12-4-15
 Bell Work
 Hand in cell resp review & Lab
 Home Work:
 www.phschool.com/science/biolo
gy_place/labbench/
 Complete cell Respiration Lab
Bench activity & fill in the
experimental design
AP Biology
Cellular respiration
2 ATP
AP Biology
+
2 ATP
+
~36 ATP
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
 Where did the glucose come from?

from food eaten
 Where did the O2 come from?

breathed in
 Where did the CO2 come from?

oxidized carbons cleaved off of the
sugars (Krebs Cycle)
 Where did the CO2 go?

exhaled
 Where did the H2O come from?

AP Biology
from O2 after it accepts electrons in ETC
 Where did the ATP come from?

mostly from ETC
 What else is produced that is not listed
in this equation?

AP Biology
NAD, FAD, heat!
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
H2O
cytochrome c
oxidase complex
 So what happens if O2 unavailable?
 ETC backs up
nothing to pull electrons down chain
 NADH & FADH2 can’t unload H

AP Biology
 ATP production ceases
 cells run out of energy
 and you die!
What’s the
point?
The point
is to make
ATP!
ATP
AP Biology
Chapter 9.
Cellular Respiration
Other Metabolites &
Control of Respiration
AP Biology
Cellular respiration
AP Biology
Beyond glucose: Other carbohydrates
 Glycolysis accepts a wide range of
carbohydrates fuels

polysaccharides    glucose
hydrolysis
 ex. starch, glycogen

other 6C sugars    glucose
modified
 ex. galactose, fructose
AP Biology
Beyond glucose: Proteins
 Proteins  
   amino acids
hydrolysis
waste
H O
H
| ||
N —C— C—OH
|
H
R
amino group =
waste product
excreted as
ammonia, urea,
or uric acid
AP Biology
glycolysis
Krebs cycle
carbon skeleton =
enters glycolysis
or Krebs cycle at
different stages
Beyond glucose: Fats
 Fats  hydrolysis
    glycerol & fatty acids
glycerol (3C)   PGAL   glycolysis
 fatty acids  2C acetyl  acetyl  Krebs
groups
coA
cycle

glycerol
enters
glycolysis
as
AP PGAL
Biology
fatty acids
enter
Krebs cycle
as acetyl CoA
Carbohydrates vs. Fats
 Fat generates 2x ATP vs. carbohydrate
more C in gram of fat
 more O in gram of carbohydrate

 so it’s already partly oxidized
 Wherever there is an oxygen, the molecule
is already oxidized so it has less energy to
release
carbohydrate
AP Biology
fat
Metabolism
 Coordination of
digestion & synthesis

by regulating enzymes
 Digestion

digestion of
carbohydrates, fats &
proteins
 all catabolized through
same pathways
 enter at different points

AP Biology
cell extracts energy
from every source
CO2
Metabolism
 Coordination of digestion &
synthesis

by regulating enzyme
 Synthesis


enough energy?
build stuff!
cell uses points in glycolysis &
Krebs cycle as links to
pathways for synthesis
 run the pathways “backwards”
 eat too much fuel, build fat
pyruvate
  glucose
Krebs cycle
intermediaries
AP
Biology
acetyl
CoA

amino
acids
  fatty acids
Cells are
versatile &
thrifty
 Metabolism is remarkably versatile &
adaptable. Cells are thrifty, expedient,
and responsive in their metabolism.
 Glycolysis & the Krebs cycle function
as metabolic interchanges that enable
cells to convert one kind of molecule to
another as needed.
 A human cell can synthesize about half
the 20 different amino acids by
modifying compounds from the Krebs
AP Biology
cycle.
 Excess carbohydrates & proteins can
be converted to fats through
intermediaries of glycolysis and the
Krebs cycle.
 You can make fat from eating too much
sugars and carbohydrates!!
AP Biology
Carbohydrate
Metabolism
 The many
stops on the
Carbohydrate
Line
AP Biology
Lipid Metabolism
 The many stops
on the Lipid Line
AP Biology
Amino Acid
Metabolism
 The many
stops on the
AA Line
AP Biology
Nucleotide
Metabolism
 The many
stops on the
GATC Line
AP Biology
Control of
Respiration
Feedback
Control
AP Biology
Feedback Inhibition
 Regulation & coordination of production


production is self-limiting
final product is inhibitor of earlier step
 allosteric inhibitor of earlier enzyme

no unnecessary accumulation of product






ABCDEFG
1
2
3
4
5
6
X
enzyme enzyme enzyme enzyme enzyme enzyme
AP Biology
allosteric inhibitor of enzyme 1
AP Biology
Respond to cell’s needs
 Key points of control

phosphofructokinase
 allosteric regulation of
enzyme
 “can’t turn back” step
before splitting glucose
 AMP & ADP stimulate
 ATP inhibits
 citrate inhibits
Why is this regulation important?
Balancing act:
availability of raw materials vs.
energy
AP
Biologydemands vs. synthesis
A Metabolic economy
 Basic principles of supply & demand regulate
metabolic economy


balance the supply of raw materials with the
products produced
these molecules become feedback regulators
 they control enzymes at strategic points in
glycolysis & Krebs cycle
 AMP, ADP, ATP
regulation by final products & raw materials
 levels of intermediates compounds in the pathways
 regulation of earlier steps in pathways
 levels of other biomolecules in body
 regulates rate of siphoning off to synthesis pathways

AP Biology
It’s a Balancing Act
 Balancing synthesis
with availability of
both energy & raw
materials is essential
for survival!



AP Biology
do it well & you
survive longer
you survive longer &
you have more
offspring
you have more
offspring & you get
to “take over the
world”
Acetyl CoA is central to both
energy production & synthesis
make ATP or store it as fat
Any Questions??
AP Biology