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Respiration!
• Chapter 9~
• Cellular Respiration:
Harvesting Chemical Energy
• Great Animation (show at
end too)
Big Picture!
• Big Picture: Glucose has Stored Energy, Cells
must Convert it to ATP (the fuel of the cell)
– This happens through a series of energy releasing redox
reactions that we will learn about shortly.
• Overall Equation for cellular respiration:
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + E (ATP +
heat)
Redox reactions
• Oxidation-reduction
• Oxidation (i.e. to be
oxidized) is e- loss;
– Or oxygen gain
• Reduction (i.e. to be reduced)
is e- gain;
– Or hydrogen atom gain
• LEO GER
• Redox reactions release
energy!!!
Cellular respiration
• Cell Respiration = the
controlled release of energy
from organic compounds in
cells to form ATP!
STAGES:
• Glycolysis: location:
cytoplasm
• Link Reaction:
• Krebs Cycle: location
mitochondrial matrix
• Electron Transport Chain
location: inner membrane of
mitochondrion
Glycolysis
• Overall: 1 Glucose (6C)2 pyruvate
molecules (3C each)
• 10 total steps but we will focus on 4
stages:
– Phosphorylation
• cell uses ATP to phosphorylate
hexose sugar (glucose) making
a Hexose biphosphate
– Lysis
• Hexose is split in half to make
two triose sugars
– Oxidation
• Each triose loses electrons and
hydrogens
• These are transferred to NAD+
to make NADH and H+
– ATP formation
• ATP is produced by substratelevel phosphorylation
• 2 Pyruvates are made.
2 inorganic
phosphates
Animation http://highered.mcgraw-hill.com/sites/0072507470/stud
Glycolysis continued
• Net energy yield per glucose
molecule: 2 ATP plus 2 NADH
+ H+;
• Note: occurs aerobically or
anaerobically; also no CO2 is
released
For
Reference:
The 10 steps
of Glycolysis
After Glycolysis…
Glycolysis can occur aerobically or anaerobically
QuickTime™ and a Anaerobic Respiration=
Aerobic Respiration= Cinepak
decompressor
are needed to see this picture.
•No oxygen
•Requires oxygen
•Occurs in cytoplasm
•Occurs in mitochondrion
•Pyruvate converted to either
•Pyruvate broken down into
lactate OR ethanol and CO2
CO2 and H2O
•No further yield of ATP
•Large yield of ATP
The Next Slides deal with Aerobic
Respiration …
Aerobic Respiration Steps:
1. Link Reaction
2.
Krebs Cycle (Citric Acid Cycle)
3. Electron Transport Chain (ETC)
The link reaction
•Each pyruvate is converted into
acetyl CoA
•CO2 is released; (pyruvate is
decarboxylated)
•NAD+  NADH + H+
•Note: NAD+ gets reduced
•NADH is an electron carrier
Krebs/Citric Acid Cycle
• From this point, for each
turn, 2 C atoms enter (acetyl
CoA) and 2 exit (carbon
dioxide)
• Oxaloacetate is regenerated
(the “cycle”)
• For each acetyl CoA that
enters:
– 3 NAD+ reduced to 3
NADH;
– 1 FAD reduced to
FADH2
– 1 ATP molecule
produced
Electron transport chain
• The ETC carries electrons from
carrier molecules (NADH &
FADH2) down to oxygen (the
final electron acceptor!)
– The ETC pumps H+ into the
intermembrane space!
• ATP synthase: produces ATP by
using the H+ gradient as H+
flows back into the matrix
• Chemiosmosis: The production
of ATP using the energy of
hydrogen ion (proton) gradients
across membranes.
• This whole process of making
ATP is also called oxidative
phosphorylation (b/c it uses
oxygen as the final electron
acceptor)
• OXYGEN is the final electron
acceptor. It gets reduced to
make H2O
Electron Transport
•
•
NADHFMN iron sulfur protein (FeS) a lipid called ubiquinone (Q) cytochromes O2
FADH2 starts donating its electrons to the iron sulfur protein. Therefore it is able to make less ATP than NADH.
• http://highered.mcgrawhill.com/sites/0072437316/student_view0/chapter9/anim
ations.html#
• ATP synthase animation
•
ATP
Review: Cellular Respiration
• Glycolysis
– 2 ATP (substrate-level
phosphorylation)
• Kreb’s Cycle:
2 ATP (substrate-level
phosphorylation)
• Electron transport & oxidative
phosphorylation:
– 32-34 ATP as follows:
• 10 NADH used to make
30ATP
• 2 FADH2 used to make 4
ATP
• 38 TOTAL ATP/glucose
Great Animation
The Mighty MITOCHONDRION!
(draw and label)
Mitochondria (Structure and
function)
Structure
Cristae
Small space between
inner and outer
membranes
Fluid matrix
Function
What if there’s no oxygen?
(anaerobic respiration)
• Glycolysis
• Fermentation:
alcohol~ pyruvate
is converted to ethanol
and CO2 (in yeast and
bacteria)
lactic acid~
pyruvate is converted
to lactate (in animals)
Why Fermentation?
*Fermentation
allows glycolysis to
continue
•It recycles NAD+
(a necessary
oxidizing agent
required for the
continuation of
glycolysis)
• see next slide for
review of
glycolysis…
2 inorganic
phosphates
End of IB
• The next slides are interesting but not in the
syllabus
What if there’s no Glucose?
• Respiration still can continue
• Beta-oxidation: lipid catabolism to acetyl
CoA.
• Amino acids
– Converted to intermediates in glycolysis and
Krebs cycle
Control of Respiration
• Feedback Inhibition
• Examples
– Phosphofructokinase (Enzyme 3 in Glycolysis)
• allosterically inhibited by ATP
• Allosterically activated by AMP (derived from ADP)
– Why?
Oxidizing agents in respiration
• NAD+ (nicotinamide
adenine dinucleotide)=
initial electron acceptor
(oxidizing agent)
• NAD + is reduced to
NADH
• Oxygen is the eventual eacceptor (The
ULTIMATE Oxidizing
Agent)
• Facultative anaerobes don’t require oxygen
but can live with it. (yeast/bacteria)
• Obligate anaerobes
– Can’t live with oxygen
– Clostridium botulinum (botulism
bacterium)