Today: Kreb’s Cycle Today: Kreb’s Cycle –Cell Respiration Homework Due Monday: Electron...
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Transcript of Today: Kreb’s Cycle Today: Kreb’s Cycle –Cell Respiration Homework Due Monday: Electron...
• TodayToday: Kreb’s Cycle: Kreb’s Cycle– Cell Respiration Homework DueCell Respiration Homework Due
• MondayMonday: Electron Transport Chain, : Electron Transport Chain, • Pre-lab assignment due Thursday Pre-lab assignment due Thursday
(typed and shared)(typed and shared)• TuesdayTuesday: Workday: Workday• WednesdayWednesday: Family Reunion: Family Reunion• ThursdayThursday: Cellular Respiration Review, : Cellular Respiration Review,
• Read lab procedures for homework Read lab procedures for homework (emailed or on Google Drive)(emailed or on Google Drive)
• FridayFriday: Cellular Respiration Lab: Cellular Respiration Lab• Monday, 12/1Monday, 12/1: Cell Communication : Cell Communication
Independent Study (Test grade)Independent Study (Test grade)
• Graph data and calculate the reaction rate.• Explain why a change in reaction rate was
observed after so many minutes.• Draw and label another line on the graph to predict
the results if the concentration of the enzyme was doubled. Explain results.
• Identify TWO environmental factors that can change the rate of enzyme-mediated reactions.
Discuss how each of those two factors would affect the reaction rate of an enzyme.
2007-2008
Cellular Respiration
2007-2008
What’s thepoint?
The pointis to make
ATP!
ATP
Step 1: Glycolysis Glycolysis • Breaking down glucose
– “glyco – lysis” (splitting sugar)
– 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
• generate only 2 ATP for every 1 glucose– occurs in cytosol– anaerobic process
glucose pyruvate2x6C 3C
Evolutionary PerspectiveEvolutionary Perspective• Prokaryotes
– first cells had no organelles (NO MITOCHONDRIA)
• 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– ALL cells still utilize glycolysis
OVERVIEWOVERVIEW10 reactions– convert
glucose (6C) to 2 pyruvate (3C)
– produces: 4 ATP & 2 NADH
– consumes:2 ATP
– net: 2 ATP & 2 NADH
glucoseC-C-C-C-C-C
fructose-1,6bPP-C-C-C-C-C-C-P
DHAPP-C-C-C
G3PC-C-C-P
pyruvateC-C-C
DHAP = dihydroxyacetone phosphateG3P = glyceraldehyde-3-phosphate
ATP2
ADP2
ATP4
ADP4
NAD+22
2Pi
enzyme
enzyme
enzyme enzyme
enzyme
enzyme
enzyme
enzyme
2Pi
2H
Glycolysis summary endergonicinvest some ATP
exergonicharvest a little ATP & a little NADH
yield2 ATP2 NADH
like $$in the bank
4ATP
ENERGY INVESTMENT
ENERGY PAYOFF
G3PC-C-C-P
NET YIELD
IS THAT IT?!IS THAT IT?!• 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
Hard wayto makea living!
O2
O2
O2
O2
O2
glucose pyruvate6C 2x 3C
Fermentation (anaerobic)Fermentation (anaerobic)
• Bacteria, yeast
1C3C 2Cpyruvate ethanol + CO2
• Animals, some fungi
pyruvate lactic acid3C 3C
Makes beer, wine, bread
cheese, anaerobic exercise (no O2)
NADH NAD+
NADH NAD+
to glycolysis
to glycolysis
Alcohol Fermentation
1C3C 2Cpyruvate ethanol + CO2
NADH NAD+
Count thecarbons!
Dead end process at ~12% ethanol,
kills yeast can’t reverse the
reaction
bacteria yeast
Reversible process once O2 is available,
lactate is converted back to pyruvate by the liver
Lactic Acid Fermentationpyruvate lactic acid
3C 3CNADH NAD+
Count thecarbons!
O2
animals
Pyruvate is a branching point!!!
Pyruvate
O2O2
mitochondriaKreb’s cycle
aerobic respiration
fermentationanaerobicrespiration
2007-2008
What’s thepoint?
The pointis to make
ATP!
ATP
H+
H+H+
H+
H+ H+
H+H+H+
And how do we do that?• ATP synthase
– set up a H+ gradient– allow H+ to flow
through ATP synthase– powers bonding
of Pi to ADP
ADP + Pi ATP ATP
But… Have we done that yet?
ADP P+
2007-2008
NO!There’s still more
to my story!Any Questions?
Glycolysis Rap Song
2 ATP
CO2 out
O2 in
2 ATP
e- in 2 NADH
H2Oout
30+ ATP
CELLULAR RESPIRATIONCELLULAR RESPIRATIONStep 2Step 2
THE CITRIC ACID CYCLETHE CITRIC ACID CYCLE
OROR
THE KREB’S CYCLETHE KREB’S CYCLE
• The most important link to the electron transport chain (ETC makes a ton of ATP)
• Occurs in mitochondrial matrix• Some bacteria too (takes place in cytoplasm)• Sir Hans Adolf Krebs, 1937• BETWEEN GLYCOLYSIS AND CITRIC ACID CYCLE:
pyruvate acetyl-CoA
Coenzyme A
CO2NADH Kreb’s
Cycle
• Initiating step of Citric Acid Cycle: 4-C oxaloacetic acid + 2-C acetyl CoA 6-C citric acid
• During the cycle:– Citric acid rearranged; Stripped of 2-Cs– CO2 released– 4 e- released to electron carriers (NAD+ and FAD)– 1 molecule of oxaloacetic acid remains to begin the cycle
again– 2 ATP made
• Oxidation Reactions!!!– molecules that lose electrons…LEO goes GER– Loss of electrons at 4 specific places…to fuel ETC– Use NAD+ and FAD– Steps 4, 6, 10 (NAD+) & 8 (FAD)
• Page 183 – 184• #s 1 – 15• Typed in full sentences.