Transcript iphy 3430 8-25

IPHY 3430 8-25-11
If you missed class on Tuesday, please
pick up a syllabus from Dr. Carey
Clicker question:
What are your future plans?
A. med school
B. dental school
C. physical therapy
D. nursing
E. other
Energetics
Energy is the ability to produce change or
an effect by doing work.
Energy comes in several forms:
heat, chemical, radiant, etc.
What is work in a human system?
1. Synthesis of macromolecules
2. Maintenance of ionic disequilibria
3. Muscle contraction
4. Transmission of information
5. Many others
Chemical energy is the only form of
energy that can be used to work in
the human body.
Bonds between C, H, N, S, O, etc.
contain energy.
Heat energy cannot be used to do
work in the human body.
Where does energy for use in the
human body come from?
Chemical energy in food
(carbohydrates, proteins, and fats)
Carbohydrates
complex carbohydrates (glycogen, starch) -->
simple sugars (glucose, galactose, fructose)
---> once absorbed into the body can be stored
temporarily as glycogen or immediately catabolized
-->energy released by enzymatic breakage of bonds
---> some work done and the rest lost as heat
Proteins
Complex proteins in diet --->broken down to
amino acids--->
once absorbed into body, amino acids can be
used temporarily to make new proteins or
immediately catabolized--->
energy released by enzymatic breakage of bonds-->
some work done and the rest lost as heat
Fats
Triglycerides broken down to monoglyceride and two
fatty acids-->
Once absorbed into body, can be stored temporarily as
triglycerides or split into glycerol and three fatty acids
which then are catabolized
-->energy released by enzymatic breakage of bonds
--> some work done and the rest lost as heat
Summary:
Chemical bonds in carbohydrates, proteins and
fats are enzymatically broken, with the result
that most chemical energy is lost as heat energy
but some is conserved in chemical form to do
work.
Heat energy is lost as chemical bonds are
broken since products of cellular reactions
frequently, but not always, have a lower
energy content than the original molecule
A---> B + C
In living cells, chemical bonds must
be broken in a step-by-step
sequence, not all at once.
1. Cell can’t use heat to do work
2. Heat liberation would cause a
lethal rise in cell temperature
Most of the energy in food is lost
immediately as heat, but a small amount is
used to form a few high energy bonds
Adenosine triphosphate
ATP is the intermediary between the energy
content of the food and the need to have
chemical energy to do work.
Krebs (TCA) Cycle
Glycolysis
Electron Transport Chain
NADH
Glucose
NAD ++ H +
ATP
ADP
2e -
Glucose-6-Phosphate
Pyruvate
Coenzyme A + NAD +
H ++ NADH
Fructose-6-Phosphate
ATP
ADP
Acetyl CoA
Fructose 1,6-diphosphate
NADH
DHAP
+
NAD
FMN ox
+
FADH
CoA-SH
2e -
Oxaloacetate
ox
Q
NADH
Dehydrogenase
Complex
+
ATP
red
red
cyt b ox
Malate
Isocitrate
+
H + NADH
NAD +
ox
cyt c1 red
red
cyt c ox
ox
cyt a red
red
cyt a 3 ox
b-c 1
Complex
2H+
NADH
Fumarate
Alpha-Ketoglutarate
3-Phosphoglycerate
FADH 2
2-Phosphoglycerate
CoA-SH
FAD +
NAD +
CO 2
Succinate
NADH
Phosphoenolpyruvate
ADP
ATP
Pyruvate
Lactate
ADP
ATP
1,3 Diphosphoglycerate
ADP
ATP
ADP
2H
FADH 2
Citrate
NAD+
PGAL
red
GTP
Succinyl CoA
GDP
ADP
2e -
ATP
H2O
2H+ + 12 O2
Cytochrome
Oxidase
Complex
2H+
ADP
ATP
Figure 3-42
Anaerobic conditions can occur
in periods of high energy demand;
lactate  lactic acid is formed,
increasing acidity in the tissue.
ATP Production
Glycolysis
1. Converts one 6-carbon molecule (glucose) into
two three carbon
molecules (pyruvate)
2. Requires 2 ATP to start, generates 4 ATP,
so produces a net 2 ATP
3. H+ transferred to NA D+---> NADH
4. If no Oxygen present, NADH loses H to
pyruvate, forming lactate and regenerating
NAD+
Each transition of pyruvate
to acetyl coenzyme A yields
one NADH and one CO2.
The acetyl coenzyme A
then enters the Krebs cycle.
In aerobic
conditions,
two spins of
the Krebs
cycle
occur for
each glucose
that enters
glycolysis.
ATP Production
Citric Acid Cycle
1. Requires that oxygen be available
2. 2 GTP ---> 2 ATP synthesized
3. All 6 carbons and 6 oxygens from
original glucose lost as CO2
4. The rest of all the original H+ on glucose
transferred to NAD and FAD
Glucose catabolism “powers”
ATP synthesis via a combination of
substrate and oxidative phosphorylation.
For each NADH, 3 ATPs are formed.
For each FADH2, 2 ATPs are formed.
ATP Production
Oxidative Phosphorylation
1. NADH and FADH2 oxidized to NAD+ and
FAD+
2. H separated into proton H+ and e3. Electrons passed from cytochrome to
cytochrome, with large energy drops at 3 steps, at
which ATP made
4. H+ combined with e-, O2 split, forming
water
5. 34 ATP made during this process
1 molecule of glucose produces
2 ATP in glycolysis
2 ATP in citric acid cycle
22-34 ATP in oxidative phosphorylation
Total = 26-38 ATP --energy conversion is
38-44 % efficient
electric motor or gasoline engine is 10-20%
efficient
Fats are catabolized to make ATP
1. Fatty acids broken down into 2-C
fragments, enter as acetyl-CoA
2. Glycerol enters glycolysis as 3-C
1 molecule of palmitate (16 C fatty acid) = 84
ATP
Amino Acids are catabolized to
make ATP
HOOC - C - NH2
R (one or more carbons)
Enter as pyruvate, acetyl CoA or
intermediate in citric acid cycle.
Krebs (TCA) Cycle
Glycolysis
Electron Transport Chain
NADH
Glucose
NAD ++ H +
ATP
ADP
2e -
Glucose-6-Phosphate
Pyruvate
Coenzyme A + NAD +
H ++ NADH
Fructose-6-Phosphate
ATP
ADP
Acetyl CoA
Fructose 1,6-diphosphate
NADH
DHAP
+
NAD
FMN ox
+
FADH
CoA-SH
2e -
Oxaloacetate
ox
Q
NADH
Dehydrogenase
Complex
+
ATP
red
red
cyt b ox
Malate
Isocitrate
+
H + NADH
NAD +
ox
cyt c1 red
red
cyt c ox
ox
cyt a red
red
cyt a 3 ox
b-c 1
Complex
2H+
NADH
Fumarate
Alpha-Ketoglutarate
3-Phosphoglycerate
FADH 2
2-Phosphoglycerate
CoA-SH
FAD +
NAD +
CO 2
Succinate
NADH
Phosphoenolpyruvate
ADP
ATP
Pyruvate
Lactate
ADP
ATP
1,3 Diphosphoglycerate
ADP
ATP
ADP
2H
FADH 2
Citrate
NAD+
PGAL
red
GTP
Succinyl CoA
GDP
ADP
2e -
ATP
H2O
2H+ + 12 O2
Cytochrome
Oxidase
Complex
2H+
ADP
ATP