Lecture 4, Ch. 9
Transcript of Lecture 4, Ch. 9
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Lecture #4 Date _________
Chapter 9~Cellular Respiration:
Harvesting Chemical
Energy
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Intr oducti on t ontr oducti on t oMeta bo lismeta bo lism Complex substances are brokendown for energy, required
metabolites,structural components, etc.
Cells must synthesize newcomplexsubstances.
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************************************************************
Def initi ons:ef initi ons:Catabolismatabolism = the breakdown ofcomplex substances.
Anabo l i smnabo l i sm = the synthesis ofcomplex substances fromsimpler ones.***********************************************************
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Principles of Energy Harvest
Catabolic pathway Fermentation
Cellular RespirationC6H12O6 + 6O2 ---> 6CO2 + 6H2O + E (ATP + heat)
http://www.northland.cc.mn.us/biol
http://www.northland.cc.mn.us/biology/Biology1111/animations/glycolysis.htmlhttp://www.northland.cc.mn.us/biology/Biology1111/animations/glycolysis.html -
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Glycolysis:
Specific tissue functions RBCs Rely exclusively for energy
Skeletal muscle Source of energy during exercise, particularly highintensity exercise
Adipose tissue
Source of glycerol-P for TG (glycerol phosphate) synthesis Source of acetyl-CoA for FA synthesis
Liver Source of acetyl-CoA for FA synthesis
Source of glycerol-P for TG synthesis
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ATP
Adenosine triphosphate
The molecule that livingorganisms use for energy
After it is formed, energy
is released once thechemical bonds arebroken.
Adenine Ribose 3 Phosphate groups
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Types of cellular respiration
P r o t i s t s a n d b a c t e r i a
l i t t l e e n e r g y e x r t r a c t e d ( 2 A T P - n e t )
p a r t i a l b r e a k d o w n o f g l u c o s e
a n a e r o b i c
t h e r e l e a s e o f e n e r g y W I T H O U T o x y g e n
H u m a n s
m a x i m u m e n e r g y e x t r a c t e d ( 3 6 A T P - n e t )
c o m p l e t e b r e a k d o w n o f g l u c o s e
a e r o b i c
t h e r e l e a s e o f o x y g e n u s i n g o x y g e n
C e l l u l a r R e s p i r a t i o n
t h e r e l e a s e o f e n e r g y
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Fermentation
A type of anaerobic respiration whereenergy is released and end products such as
ethyl alcohol, CO2 (yeast) and lactic acid(bacteria)
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Anaerobic respiration
The release of energy without oxygen
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glycolysis
The breaking of glucose
Another name for anaerobic respiration
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Glucose
To the
electron
transport
chain
Glycolysis
2 Pyruvic acid
The happenings:
2. 2 ATP needed to start the
reaction
3. Glucose is broken down to 2pyruvic acids and 4 ATP areproduced (2 go back into the
reaction)
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The math of glycolysis
4 ATP made
2 ATP needed for the reaction
2 ATP made in profit
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Fermentation
A type of anaerobic respiration whereenergy is released
And bacteria
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Aerobic respiration
Release of energy by using oxygen
Glucose completely broken down
In the mitochondria
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Importance of oxygen
Cells that can use oxygen can extract the energyremaining from the end products of anaerobicrespiration
The end products have almost as much energy asthe glucose molecule
Oxygen is the final hydrogen acceptor (formingwater)
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Flowchart
Glucose
(C6H1206)
+
Oxygen
(02)
GlycolysisKrebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide(CO2)
+
Water
(H2O)
Cellular Respiration
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The Kreb cycle
Pyruvic acid undergoesfruther breakdown andenergy is released
Carbon dioxide isreleased during thesereactions
2 ATP made
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Want to see something scary?
I had to memorize thisin class. Structures
and all!
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The Electron Transport Chain
Enzyme reactions that take place after the KrebsCycle
Produces 32 ATP
Water formed because oxygen is the final
hydrogen acceptor
http://www.sp.uconn.edu/~terry/images/anim/ETS_slow.html
http://www.sp.uconn.edu/~terry/images/anim/ETS_slow.htmlhttp://www.sp.uconn.edu/~terry/images/anim/ETS_slow.htmlhttp://www.sp.uconn.edu/~terry/images/anim/ETS_slow.html -
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The math of aerobic respiration
2 ATP from glycolysis 2 ATP from Krebs Cycle
32 ATP from the electrom transport chain
36 ATP total
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Redox reactions
Oxidation-reduction LEO says GER
(adding e- reduces + charge)
Oxidation is e- loss;reduction is e- gain
Reducing agent: e-donor
Oxidizing agent: e-acceptor
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Oxidizing agent in respiration
NAD+ (nicotinamideadenine dinucleotide)
Removes electrons fromfood (series of reactions)
NAD + is reduced toNADH
Enzyme action:dehydrogenase
Oxygen is the eventual e-acceptor
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Electron transport chains
Electron carrier molecules(membrane proteins)
Shuttles electrons that releaseenergy used to make ATP
Sequence of reactions thatprevents energy release in 1explosive step
Electron route:food---> NADH --->electron transport chain --->oxygen
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Cellular respiration
Glycolysis: cytosol;degrades glucose into
pyruvate
Krebs Cycle:mitochondrial matrix;
pyruvate into carbondioxide
Electron Transport Chain:inner membrane ofmitochondrion; electrons
passed to oxygen
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Glycolysis
1 Glucose --->2 pyruvate molecules
Energy investment phase: cell usesATP to phosphorylate fuel
Energy payoff phase: ATP isproduced by substrate-levelphosphorylation and NAD+ isreduced to NADH by foodoxidation
Net energy yield per glucosemolecule: 2 ATP plus 2 NADH;no CO2 is released; occursaerobically or anaerobically
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Krebs Cycle
If molecular oxygen is present. Each pyruvate is converted into acetyl
CoA (begin w/ 2): CO2 isreleased; NAD+ ---
> NADH; coenzymeA (from B vitamin), makesmolecule very reactive
From this point, each turn 2 C atomsenter (pyruvate) and 2 exit (carbondioxide)
Oxaloacetate is regenerated (thecycle)
For each pyruvate that enters:3 NAD+ reduced to NADH;1 FAD+ reduced to FADH2
(riboflavin, B vitamin);1 ATP molecule
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Electron transport chain
Cytochromes carry electron carriermolecules (NADH & FADH2)down to oxygen
Chemiosmosis:
energy coupling mechanism
ATP synthase:produces ATP by using the H+gradient (proton-motive force)
pumped into the inner membranespace from the electron transportchain; this enzyme harnesses theflow of H+ back into the matrix tophosphorylate ADP to ATP(oxidative phosphorylation)
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Review: Cellular Respiration
Glycolysis:2 ATP (substrate-levelphosphorylation)
Krebs Cycle:
2 ATP (substrate-levelphosphorylation)
Electron transport & oxidativephosphorylation:
2 NADH (glycolysis) = 6ATP
2 NADH (acetyl CoA) = 6ATP6 NADH (Krebs) = 18 ATP2 FADH2 (Krebs) = 4 ATP
38 TOTAL ATP/glucose
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Related metabolic processes
Fermentation:alcohol~ pyruvate to
ethanollactic acid~ pyruvateto lactate
Facultative anaerobes
(yeast/bacteria) Beta-oxidation
lipid catabolism