Download 6 Energy and Metabolism

CH2OH
GLYCOLYSIS
O
OH
OH
OH
FERMENTATION
GLUCOSE
Homolactic
OH
ATP
ADP
Kinase
CH2O(P)
O
CH3-C-COO-
CH3-C-COO-
O
OH
GLUCOSE-6-P
OH
CH3-C-COOO
O
OH
OH
2, 3 Butanediolic
Isomerase
FRUCTOSE-6-P
+
O
CO2
OH
ATP
ADP
Kinase
C-CH3
CH3-C
FRUCTOSE-1,6
Di-Phosphate
O
2NADH
2NAD+
CH2O(P)
OH
OH
CH3-C-C-CH3
OH
Acetoin
O H
Adolase
2NADH
2NAD+
DiOH Acetone Phosphate (3C)
P-Glyceraldehyde (3C)
OH OH
NAD+
NADH2
ADP + Pi
ATP
H H
1 GLU + 2ATP + 2NAD =
2PYR + 4ATP + 2NADH2
Kinase
2, 3, Butanediol
CH3-C-C-CH3
GLYCOLYSIS
1, 3, P-Glyceric acid
NET GAIN = 2 ATP
2 P-Glyceric acid
x2
Isomerase
Isocitric Acid
(6C)
NAD+
NADH2
Enol Pyruvate
ADP + Pi
ATP
Coenzyme A
NAD+
Pyruvate
NADH2
CH3-C-COOH
Kinase
x2
2, 3 Butanediolic Fermentation
2PYR + 2NADH 
Acetoin + NAD + 2 CO2 
+2NADH 
2, 3 Butanediol + 2NAD
NET GAIN = 4 NAD
O
O
CH2O(P)
Ethanolic Fermentation
PYR + NADH 
Acetaldehyde + NAD + CO2 
+NADH 
ETOH + NAD
NET GAIN = 2 NAD
O
CO2
OH
ETOH
CH3-CH2-OH
CH3-C-COO-
O
CH2OH
NAD+
NADH
Pyruvate
Pyruvate
CH3-C-COO-
CH2O(P)
CO2
Acetaldehyde
H
CH3-C
Pyruvate
Ethanolic
OH
NAD+
NADH
Homolactic Fermentation
PYR + NADH 
Lactic Acid + NAD
NET GAIN = 1 NAD
Lactic Acid
H
NAD+
NADH
Pyruvate
CO2
ά Ketoglutarate Acid (5C)
COO- -CH2-CH2-C-COOO
NAD+
NADH2
Tricarboxylic Acid Cycle
(TCA/ Krebs Cycle)
Succinyl CoA
Citric Acid
Acetyl CoA
CH3-C-S-CoA
O Dehydrogenase CO
2
Oxaloacitic Acid (4C)
O
COO- -CH2-C-COOO
PYRUVATE
ACTIVATION
GDP+
GTP
Malate Acid
PYRUVATE ACTIVATION
NAD+
NADH2
16 NADH from
glycolysis
need to be
reduced.
H
Red
H
Ox
+3
+2
FMN
Fes
+2
+3
H2
Red
Ox
Red
TOTAL GAIN:
8 H+
2 GTP
*First energy-producing
step
Red
Ox
Anaerobic phosphorylation endproducts (instead of H2O)
Red
H
Ox
H2O
CoQ
CO2
FAD+
FADH2
Fumorate Acid
ELECRON TRANSPORT SYSTEM (RESPIRATION / OXIDATIVE PHOSPHORYLATION
Ox
MULTIPLY THE
ABOVE BY TWO
Succinate
2 PYR + 2NAD + 2CoA =
Acetyl CoA + 2NADH2 + 2CO2
ETS
TCA
Acetyl CoA + 3NAD +
1 FAD + 1GTP =
3 NADH + 1FADH2 +
GTP + CO2
Cyt b
Cyt c
Cyt a1
Ox
Red
Ox
H2S
NH3
Cyt a3
O2
ADP ATP
ADP ATP
ATPase
ATPase
Red
ADP ATP
ATPase
SO4
NO2
GLYCOLYSIS
1 GLU + 2ATP + 2NAD = 2PYR +
4ATP + 2NADH2
NET GAIN = 2 ATP
Glycolysis takes place in the
cytoplasm. It converts
glucose, fructose, or
galactose into 2 molecules of
pyruvate plus 2 ATP. This
process uses 2 NAD (an
electron acceptor), which
becomes reduced to NADH.
We need to get it back to
NAD or glycolysis will stop.
The pyruvates are then taken
to the mitochondria to go
through the Kreb’s (TCA)
cycle to generate ATP.
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Glycolysis
• Glycolysis is like a gumball machine in
the cytoplasm. You put one sugar
molecule in, add 2 pennies (ATP) and
get out two gumballs (pyruvate). The
gumball machine also gives your two
pennies back, plus an additional two
pennies! It takes money to make money,
right?
• So now you have a net profit of 2
pennies to spend on energy, plus the
two gumballs that you can take to the
mitochondria to convert to 2 more
special pennies (GTP) that can only be
used for certain games in the body
(protein synthesis and
gluconeogenesis).
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Glycolysis
• During glycolysis, we generate hydrogen (H+),
which is a waste product that we have to get rid
of, but almost no one wants to carry that
burden.
• There is a guy named NAD who is willing to
accept this burden. When he takes on the H+,
he is reduced. If his H+ burden is removed by
someone else, he feels good, and is oxidized!
• All of NAD’s brothers are also named NAD. It
takes 2 NAD brothers to come to the glycolysis
gumball machine and take on the burden of the
H+. They are now called NADH.
• Right now, you need to take your 2 gumballs
(pyruvate) to the mitochondria so you can use
the Kreb’s Cycle to convert them into special
pennies.
• The two NADH brothers will wait for you to
complete the Kreb’s Cycle, so you can escort
them to the Electron Transport Chain, where
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their H+ burdens will be lifted.
Kreb’s Cycle or Citric Acid Cycle or Tricarboxylic Acid Cycle (TCA)
Acetyl CoA + 3NAD + 1 FAD + 1GTP = 3 NADH + 1FADH2 + GTP + CO2
MULTIPLY THE ABOVE BY TWO
TOTAL GAIN: 8 H+ and 2 GTP
The Kreb’s Cycle occurs in the mitochondria, and
requires oxygen. It takes one of the pyruvate
molecules we got from glucose, and one acetate
(in the form of Acetyl CoA) from the break down of
fats and proteins, and then the Kreb’s Cycle
generates 2 GTP (similar to ATP). The waste
product is carbon dioxide.
Like glycolysis, it uses NAD and reduces it to
NADH. The NADH is then sent to the Electron
Transport System so it can be converted back to
NAD so glycolysis can continue.
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Kreb’s Cycle
• Now you have taken your two gumballs
from glycolysis (pyruvate) and entered
the mitochondria.
• You see your neighbor, who does not
use sugar. He uses another process
which breaks down fats and proteins
elsewhere in the body, and generates
Acetyl CoA instead of pyruvate.
• You put one of your pyruvate gumballs
into a Kreb machine, along with one of
his Acetyl CoA molecules.
• Three more NAD brothers, plus their
cousin FAD have to come in to bear the
burdens of the four H+ that will be
generated per pyruvate gumball (8 H+
for both pyruvates are generated).
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Kreb’s Cycle
• For all this, you will get only one special
penny (GTP) per gumball. Since you
have two gumballs you get 2 GTP.
• You will now have two special pennies,
but you now have 8 new people who are
carrying your H+ burden, in addition to
the 2 people who are waiting for you at
the door from the gumball machine.
• You need to take all of them to the
Electron Transport Chain so someone
else can lift their burden and they can
get back to work at the gumball machine
again.
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ETS
8 NADH and 2
FADH from
glycolysis need to be
reduced.
The Electron Transport System (aka oxidative
phosphorylation, or cellular respiration) also takes place in
the mitochondria. Here, the NADH molecules from glycolysis
and the TCA cycle are oxidized back to NAD so glycolysis
can continue. It also generates 3 more ATP. When this
system is performing in the presence of oxygen, oxygen is
consumed and the waste product is water. When it is done
anaerobically (such as in some bacteria), sulfate is used as
the H+ acceptor and the waste product is hydrogen sulfide
(will show a black precipitate on culture media). If the
bacteria does not have sulfate, it will use nitrite as the
electron acceptor, and the waste product is ammonia, which
causes a color change if there is a pH indicator in the culture
media.
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Electron Transport Chain
(cellular respiration)
• When the NADH brothers enter this area
of the mitochondria, there is a hallway
lined with several people.
• The first NADH brother gives his H+
burden to the first person (FMN). That
makes him oxidized to NAD again, but
the person that took the H+ is now
reduced, and he does not want that
burden either, so he passes it to the next
person in line (FeS). Now FMN becomes
oxidized and the second person is
reduced. FeS passes the burden to CoQ
and so on, to the end of the line.
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Electron Transport Chain
(cellular respiration)
• When they finally get to the end of the
line, they are greeted by the heavenly
oxygen angel. She is so strong, she can
take and hold 2 burdens at once.
• When she takes the H+ burden from two
NADH brothers, she becomes water.
The water will be exhaled. We need to
inhale some more heavenly oxygen
angels to keep this process going.
• Now the NAD brothers have been
oxidized. They feel so good, they want to
go back to work to help again with
bearing the H+ burden.
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Cell Respiration Summary
• The summary equation for cellular
respiration is:
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O
glucose + oxygen → carbon dioxide + water
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What if there is no more
oxygen?
• Some bacteria, molds, and yeasts
can still use the ETC when there is
no oxygen. At the end of the handshaking line, they have either
sulfate or nitrite.
• If they have sulfate, instead of
taking the H+ and turning into water
to be exhaled, it turns into
hydrogen sulfide (H2S), a waste
product which shows up as a black
color on a Petri dish.
• If they have nitrite, they will turn into
ammonia, a waste product which
has a high pH.
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What if there is no more
oxygen?
• Humans do not have sulfate or
nitrite. They can only use oxygen
as the final electron acceptor in the
electron transport chain (cellular
respiration).
• Muscle cells use a lot of energy, so
they are able to run out of oxygen
yet still carry out cellular respiration
by using fermentation to take the
H+ burden off the NAD brothers so
they can go back to work for the
gumball glycolysis machine and the
Kreb’s machine. Muscles are the
only human cells that can do this. 13
Fermentation Pathways
•
•
•
•
When no oxygen is present (such as in muscles during
sprinting), the NADH molecules that were generated from
glycolysis and the TCA cycle cannot use the electron transport
chain to be converted back to NAD. Instead, they use one of
three fermentation pathways.
Homolactic
Ethanolic
2, 3, Butanediolic
• In the homolactic pathway (used by humans),
the H+ from NADH is donated to pyruvate,
converting it to the waste product: lactic acid.
The NAD has now been regenerated so
glycolysis can continue. By breathing heavily,
oxygen is added to lactic acid, converting it to
glucose. The lactic acid could also be carried
by the bloodstream to the liver, where it is
converted back to pyruvate. Therefore,
increasing circulation and oxygen helps
eliminate lactic acid build-up (ultrasound or
massage therapy for sore muscles helps).
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Ethanol Fermentation
• The ethanol fermentation pathway
also uses glycolysis, but the
pyruvate is then converted to
ethanol and carbon dioxide.
• Yeasts use this pathway to create
beer, and cause the rising of bread
dough.
Ethanolic Fermentation
PYR + NADH 
Acetaldehyde + NAD + CO2  +NADH 
ETOH + NAD
NET GAIN = 2 NAD
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2, 3, Butanediole Pathway
2, 3 Butanediolic
Fermentation
2PYR + 2NADH 
Acetoin + NAD + 2 CO2 
+2NADH 
2, 3 Butanediol + 2NAD
NET GAIN = 4 NAD
Butanediol fermentation uses 2 pyruvate molecules
and the waste product is 2, 3, butanediol. Use of this
pathway is typical for Enterobacter (a type of
coliform bacteria) and is tested for by using the
Voges–Proskauer (VP) test. If the unknown culture
has a positive VP test, we know it might be this
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organism.
CH2OH
GLYCOLYSIS
O
OH
OH
OH
FERMENTATION
GLUCOSE
Homolactic
OH
ATP
ADP
Kinase
CH2O(P)
O
CH3-C-COO-
CH3-C-COO-
O
OH
GLUCOSE-6-P
OH
CH3-C-COOO
O
OH
OH
2, 3 Butanediolic
Isomerase
FRUCTOSE-6-P
+
O
CO2
OH
ATP
ADP
Kinase
C-CH3
CH3-C
FRUCTOSE-1,6
Di-Phosphate
O
2NADH
2NAD+
CH2O(P)
OH
OH
CH3-C-C-CH3
OH
Acetoin
O H
Adolase
2NADH
2NAD+
DiOH Acetone Phosphate (3C)
P-Glyceraldehyde (3C)
OH OH
NAD+
NADH2
ADP + Pi
ATP
H H
1 GLU + 2ATP + 2NAD =
2PYR + 4ATP + 2NADH2
Kinase
2, 3, Butanediol
CH3-C-C-CH3
GLYCOLYSIS
1, 3, P-Glyceric acid
NET GAIN = 2 ATP
2 P-Glyceric acid
x2
Isomerase
Isocitric Acid
(6C)
NAD+
NADH2
Enol Pyruvate
ADP + Pi
ATP
Coenzyme A
NAD+
Pyruvate
NADH2
CH3-C-COOH
Kinase
x2
2, 3 Butanediolic Fermentation
2PYR + 2NADH 
Acetoin + NAD + 2 CO2 
+2NADH 
2, 3 Butanediol + 2NAD
NET GAIN = 4 NAD
O
O
CH2O(P)
Ethanolic Fermentation
PYR + NADH 
Acetaldehyde + NAD + CO2 
+NADH 
ETOH + NAD
NET GAIN = 2 NAD
O
CO2
OH
ETOH
CH3-CH2-OH
CH3-C-COO-
O
CH2OH
NAD+
NADH
Pyruvate
Pyruvate
CH3-C-COO-
CH2O(P)
CO2
Acetaldehyde
H
CH3-C
Pyruvate
Ethanolic
OH
NAD+
NADH
Homolactic Fermentation
PYR + NADH 
Lactic Acid + NAD
NET GAIN = 1 NAD
Lactic Acid
H
NAD+
NADH
Pyruvate
CO2
ά Ketoglutarate Acid (5C)
COO- -CH2-CH2-C-COOO
NAD+
NADH2
Tricarboxylic Acid Cycle
(TCA/ Krebs Cycle)
Succinyl CoA
Citric Acid
Acetyl CoA
CH3-C-S-CoA
O Dehydrogenase CO
2
Oxaloacitic Acid (4C)
O
COO- -CH2-C-COOO
PYRUVATE
ACTIVATION
GDP+
GTP
Malate Acid
PYRUVATE ACTIVATION
NAD+
NADH2
8 NADH and 2
FADH from
glycolysis
need to be
reduced.
H
Red
H
Ox
+3
+2
FMN
Fes
+2
+3
H2
Red
Ox
Red
TOTAL GAIN:
8 H+
2 GTP
*First energy-producing
step
Red
Ox
Anaerobic phosphorylation endproducts (instead of H2O)
Red
H
Ox
H2O
CoQ
CO2
FAD+
FADH2
Fumorate Acid
ELECRON TRANSPORT SYSTEM (RESPIRATION / OXIDATIVE PHOSPHORYLATION
Ox
MULTIPLY THE
ABOVE BY TWO
Succinate
2 PYR + 2NAD + 2CoA =
Acetyl CoA + 2NADH2 + 2CO2
ETS
TCA
Acetyl CoA + 3NAD +
1 FAD + 1GTP =
3 NADH + 1FADH2 +
GTP + CO2
Cyt b
Cyt c
Cyt a1
Ox
Red
Ox
H2S
NH3
Cyt a3
O2
ADP ATP
ADP ATP
ATPase
ATPase
Red
ADP ATP
ATPase
SO4
NO2
ATP
• Adenosine triphosphate (ATP) is used in cells
as a coenzyme. It is often called the "molecular
unit of currency" of intracellular energy transfer.
• ATP transports chemical energy within cells for
metabolism. It is one of the end products of
phosphorylation and cellular respiration and
used in many cellular processes, including
muscle contraction, motility, and cell division.
• One molecule of ATP contains three phosphate
groups which provide energy. When ATP is
used, it loses a phosphate and is reduced to
ADP (diphosphate).
• Metabolic processes that use ATP as an
energy source will cause it to be reduced to
ADP, so it will use other metabolic processes to
convert the ADP back into ATP, so it is
continuously recycled.
• Guanosine triphosphate (GTP) is similar to ATP
but can only be used as a source of energy for
protein synthesis and gluconeogenesis.
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ATP Molecule
19
Amino Acids build
proteins
Building blocks of protein,
containing an amino
group and a carboxyl group
Amino acid structure: central C;
amino group,
acid group, and variable group
a) AMINO ACIDS are MONOMERS
(building blocks) of protein. They
are tiny carbon molecules, made of
just a carbon atom and a few other
atoms.
There are only 22 standard types of
amino acids in the human body (20
of them are involved in making
proteins). Nine of these are essential
amino acids, meaning that we have
to get them in the diet. We can
synthesize the others.
Amino acids are like beads on a
necklace. Each bead is an amino
acid, and the whole necklace is the
protein. A bunch of the same types
of necklaces (proteins) woven
together makes up our tissues.
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Amino
Acids
Nonessential
Essential
Histidine
Leucine
Isoleucine
Alanine
Arginine
Asparagine
Lysine
Aspartic acid
Methionine
Cysteine
Phenylalanine
Glutamic acid
Threonine
Tryptophan
Valine
Glutamine
Glycine
Ornithine
Proline
Selenocysteine
Serine
Tyrosine
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Where do the molecules go
when you lose weight?
• Think of fat as essentially a longchain hydrocarbon CH3-(CH2)nCH3. When your body uses that fat
as fuel (either because you need
fuel to exercise, or because you're
not eating enough new fuel to
support what you're doing), it burns
that fat to extract the energy from
it. That "burn" isn't a
metaphor. The chemistry that your
body does is exactly equivalent to
literally burning it, just under more
controlled conditions.
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Where do the molecules go
when you lose weight?
• So, that hydrocarbon undergoes a
controlled combustion with oxygen
(O2) to produce a lot of energy,
water (H2O), and carbon dioxide
(CO2).
Or, in chemical form:
CH3-(CH2)n-CH3 + (3/2n+7/2)O2 ---> (n+2) CO2 + (n+3) H2O +
Energy
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Where do the molecules go
when you lose weight?
• So the carbon in the hydrocarbon goes to
carbon dioxide and the hydrogen goes to
water. But most of the mass of the
hydrocarbon is carbon, so most of the mass
gets converted to carbon dioxide, which is a
gas and gets breathed out.
• Now this is incomplete, because lipids and fat
really aren't just hydrocarbons. They have
phosphates and nitrogen and other things too,
and those parts don't get converted to gases for
excretion. Excess nitrogen gets converted to
urea, for example, which gets excreted in the
urine. And protein produces a lot more
impurities when it gets broken down (though
generally the body prefers to recycle proteins
rather than burn them for energy).
• But really, the way you lose most of your weight
is just by breathing it off.
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