Transcript Chapter 9 Cellular Respiration

Cellular Respiration:
Harvesting Chemical
Energy
A. P. Biology
Chapter 9
Mr. Knowles
Liberty Senior High School
How is burning a
candle like a
respiring cell?
So why don’t we just
burn sugar?
It’s all about capturing
energy!
Different Strokes for
Different Folks!
• Autotrophy- “self-feeding,” when
organisms use energy from light and CO2
to synthesize organic molecules.
• Heterotrophy- “other-feeding,” use
already made organic molecules obtained
from other organisms, living or dead.
Oxidative Respiration
C6H12O6 + 6O2 --> 6CO2 + 6H2O
+ ENERGY
(ATP)
720 kcal of energy /mole glucose
at cell conditions
Oxidative Respiration
• Catabolism of glucose into
carbon dioxide and water,
releasing 720 kcal/mol glucose.
• Is a Four Step Process =
Glycolysis + Oxidation of
Pyruvate + Krebs Cycle +
Electron Transport Chain
Oxidative Respiration
• Redox reaction that releases
energy by repositioning
electrons closer to oxygen
atoms.
• Uses ATP to trap energy and
+
+
NAD and FAD to transport
electrons.
ATP is the Energy Currency
of the Cell
Adenosine
Triphosphatestores ~12kcal/mol
Adenine
PO4
PO4
PO4
Deoxyribose
Oxidative Respiration
• Energy is harvested from
glucose in a series of gradual
+
steps, using NAD as an
electron carrier.
1. Glycolysis
• Occurs with or without
oxygen.
• Two Step Process:
Modifying Glucose (Steps 14)
Removing Groups that
Provide Energy (Steps 5 -9).
Making ATP During
Glycolysis
• Substrate-level
Phosphorylation transferring PO4 directly to
ADP --> ATP.
• Kinases- phosphorylates,
adds PO4 group to a substrate.
Ex. Hexokinase
Each Step Uses a Specific
Enzyme
• Isomerases- change
substrates into isomers.
Ex. Glucose-->Fructose,
Phosphoglucoisomerase.
Each Step Uses a Specific
Enzyme
• Dehydrogenasesoxidizes substrates. Ex.
G3PDH
At the End of Glycolysis!
+
NAD
• Glucose + 2 ADP + 2 Pi + 2
-> 2 Pyruvate + 2 ATP + 2 NADH +
2H+ + 2 H20
• Each ATP = 12 kcal/mole of energy.
• Inefficient capture of energy, only 3.5
% of available energy in glucose.
• Most remains in pyruvate.
What would a food chain look
like if organisms could only
perform glycolysis? Are they
alive today?
Answer: The
Archaebacteria 3.5 billion
years ago and TODAY!
2nd Order
Heterotroph?
1st Order
Heterotroph
?
Autotrophs
Glycolysis
ONLY 3.5%
Efficiency
Without Kreb’s and ETC…
• Food chains were not very
complex; few trophic levels.
• Could support very few
animals with such poor
efficiency.
2. Oxidation of Pyruvate
+
NAD
• Pyruvate +
+ CoA
--> Acetyl-CoA + NADH
• Acetyl-CoA can now
enter the third step-Krebs
Cycle.
3. Krebs Cycle
• Oxidation of Acetyl-CoA.
• Produce 2 ATP by substrate-level
phosphorylation.
• Many electrons harvested for the 4th
Step (Electron Transport Chain).
• 6 NADH + 2 FADH
• All that remains of the glucose is 6 CO2.
4. Electron Transport
Chain
• Convert the energy from the NADH and
FADH made in the first three steps and
make ATP.
• A series of transfers from transmembrane
proteins that are progressively more
oxidative.
• Eventually tranferred to oxygen -->
reducing it to water.
FADH2
H
+
FAD+
4H+
2H2O
Animation of Electron
Transport Chain
ATP Synthase
Finally, ATP!!!!!
Factors that Affect Aerobic
Respiration
• Respiration Rate- How much O2 can
be taken in?
• Activity Level.
• Size of the Organism.
• Age and Gender.
• Ectothermic vs. Endothermic
Organisms
Ectotherms Have Slow
Metabolisms
Are there options to
aerobic respiration?
Anaerobic Respiration
(Fermentation)- without oxygen.
What process can you do without
oxygen?
Without Oxygen…
• Living cells can only make
ATP by glycolysis.
• Only 2 ATP/molecule of
glucose.
+
• May run out of NAD .
Two Kinds of Fermentation
• Alcoholic Fermentation- converts
pyruvic acid (from glycolysis) and
converts it into:
1. CO2,
2. Ethyl alcohol,
+
3. NAD
• Replaces NAD+ so glycolysis can
continue.
Alcoholic Fermentaion
Let’s ferment?
Demo: Home made
wine!
Fermentation in a Whale!
Show me Lactic Acid
Fermentation!
Lactic Acid Fermentation
NADH (H+)
H3C--C—C--OH
O O
Pyruvic Acid
NAD+
H
H3C--C—C—OH
OH O
Lactic Acid
Lactic Acid Fermentation
• Converts pyruvic acid (from
glycolysis) into two products:
1. Lactic Acid
+
2. NAD
+
• Replaces NAD so glycolysis
can continue.
So now what?
What do we do with all of
the lactic acid after
anaerobic respiration?
The Cori Cycle, pp. 976977. Ch. 44 (old text)
After Prolonged Exercise…
• O2 consumption remains high.
• Extra O2 is called Oxygen Debt.
• Some of the O2 is used to convert
Lactic Acid  CO2 + H2O + ATP
(brain, heart, some muscle).
• Some of the O2 is used to convert
Lactic Acid  Glucose (Cori
Cycle).
Cori Cycle
Anaerobic
Glycogen
The Two Fates of Lactic Acid
• With O2 (aerobic conditions):
1. Brain, heart and some muscle
fibers can convert it into ATP.
2. Liver can convert into glucose
by the Cori Cycle.
Hunters and Lactic Acid Build
Up!
Video: Built for the
Kill- Swamp a hunting
cormorant.
Without Oxygen
No O2
Alcoholic
Fermentation
Lactic Acid
Fermentation
Metabolism in an Ectotherm!
Lactic Acid in a Crocodile
Video: National GeographicSupercroc
Other sources of energy!
Proteins and Fats!
Primary Structure
Preparing Amino Acids for
Metabolism
Deamination
H2N
To Glycolysis
or Kreb’s
A Glycerol
Three Fatty
Acids
Energy from Fat
C
C
C-C-C-C-C-C-C-C
C-C-C-C-C-C-C-C
C
C-C-C-C-C-C-C-C
Glycerol
3 Fatty Acids
Pyruvate
Beta Oxidation
Beta Oxidation
• The catabolism of fatty
acids.
• The breakdown of fatty
acids into 2-carbon
pieces. (Acetyl groups).
Beta Oxidation
C-C-C-C-C-C-C-C (Fatty Acid)
ATP
ADP + Pi
C-C-C-C-C-C
NAD+ + FAD+
NADH + FADH
C-C (Acetyl)
Coenzyme A
C-C-CoA (Acetyl CoA)
Kreb’s Cycle
What happens to the
respiration rate if you
limit the number of
calories?
Video: Scientific
Frontiers-Never Say Die
(Calorie Restriction)