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TRANSCRIPT
Cellular Respiration
&
Adenosine Triphosphate
General Education Program
Biology
Presented by:Dr. Shaimaa Nasr Amin
Lecturer of Medical Physiology
• Energy is the foundation of all life. In
humans energy originates within the human
cell. It is there that numerous bio-chemical
reactions take place to generate cellular
energy in a process called metabolism
• Human metabolism/cellular energy is the
limiting factor in determining the quality of
health an individual will experience.
• Optimal metabolism results in the 100
trillion human cells to function at peak
performance.
• There are two primary types of cells
found in nature:
1. Eukaryotic cells – found in multi-cellular
organisms such as fungi, plants, and
animals (humans).
2. Prokaryotic cells - are primitive
independent cells such as bacteria.
• The major difference between prokaryotes
and eukaryotes is that eukaryotic cells
contain membrane bound organelles in
which specific metabolic activities take
place. The defining organelles that set
eukaryotic cells apart from prokaryotic cells
are the nucleus and mitochondria.
• The nucleus is the control center of the cell
housing its nuclear deoxyribonucleic acid
(nDNA), which contains the information
needed to keep a cell operating and
working properly.
MITOCHONDRIA
• The source of cellular
energy for all eukaryotic
biochemical reactions,
comes from one of the
cell’s organelles called
the mitochondria.
• Mitochondria are known as the cell’s “power
house” where cellular energy is produced in
the form of a molecule called – adenosine
triphosphate (ATP).
• Depending on the tissue, mitochondria can
number anywhere from a couple of dozen
(neuron) to several thousand (heart) per cell.
• Another interesting fact – mitochondria
have their own set of DNA –mitochondria
DNA (mtDNA), which is inherited from the
mother.
• Mitochondria are made from a combination
of nDNA & mtDNA
ATP PRODUCTION:
CELLULAR RESPIRATION
• Carbohydrates, lipids (fats), and proteins are
the major constituents or nutrients of foods
and serve as fuel for the human body.
• More specifically, it is the end products of
digestion – which breaks down these macro
nutrients into smaller nutrients – that are the
true fuel sources for the body’s 100 trillion
cells.
• The major absorbed end products of food
digestion are glucose (from carbohydrates);
short, medium and long-chain fatty acids
(from lipids); and amino acids (from
protein).
• All three classes of these nutrients can
serve as fuel sources for the mitochondria
to produce cellular energy in the form of
ATP
Adenosine Triphosphate (ATP)
• ATP is a high energy nucleotide and is
considered the cell’s “energy currency” which
provides the needed energy for the cell’s
many metabolic bio-chemical functions.
Adenosine Triphosphate (ATP)
• ATP is a molecule
which is made up of
three phosphate
groups and an
adenosine group
(ribose and adenine).
Adenosine Triphosphate (ATP)
• When the “high-energy” bond between the
second and third phosphate are broken a
substantial amount of energy is liberated
Cellular Respiration
• The major metabolic bio-chemical pathway
which is responsible for the production of
ATP/cellular energy is called cellular
respiration.
• The sole purpose of cellular respiration is
to break down glucose, fatty acids and
small amounts of amino acids into ATP.
• Cellular respiration takes place via a long step
by-step process of enzymatic reactions.
These enzymatic reactions can be divided
into two main categories:
• 1. Anaerobic Respiration.
• 2. Aerobic Respiration
Cellular Respiration
Anaerobic Respiration
• are the enzymatic reactions
that DO NOT require
oxygen.
• This includes the metabolic
pathway of glycolysis and
fermentation which occurs in
the cytoplasm of the human
cell
. Aerobic Respiration
• are the enzymatic reactions
that DO require oxygen.
This includes the metabolic
pathways of pyruvate
oxidation, Krebs cycle and
oxidative phosphorylation
(electron transport chain &
chemiosmosis) which all
occur in the mitochondria.
Cellular Respiration
ANAEROBIC RESPIRATION
Anaerobic Respiration
• Glycolysis
• The first stage of cellular respiration is
known as glycolysis.
• This stage is unique to glucose metabolism
which takes place in the cytoplasm of the
cell and does not require oxygen.
• Through a series of biochemical enzymatic
reactions the process of glycolysis breaks
down glucose to pyruvate/pyruvic acid.
Anaerobic Respiration
• Glycolysis
• Glycolysis also generates 2 molecules of
ATP and 2 molecules of NADH. NADH is the
reduced form (gained hydrogen atoms) of
nicotinamide adenine dinucleotide (NAD).
Anaerobic Respiration
• Glycolysis
• NAD is a co-enzyme which is derived from
the vitamin – niacin (B3). Once reduced
NADH acts as an electron carrier and will be
transferred to the mitochondria and utilized in
the electron transport chain to assist in
producing additional molecules of ATP.
Anaerobic Respiration
• Fermentation
• In the continual absence of oxygen (after
glycolysis has been completed) the process
continues to follow the anaerobic pathway
and a process called fermentation.
Anaerobic Respiration
• Fermentation
• There are several types of fermentation, but
the two most common types are lactic
acid/lactate fermentation and alcohol
fermentation.
Anaerobic Respiration
• Fermentation
• In fermentation the pyruvate/pyruvic acid
molecules, which are toxic to the cell and
cannot enter the mitochondria due to the lack
of oxygen, are converted by enzymes into
waste products.
• Also fermentation does not produce any
additional energy/ATP. .
Anaerobic Respiration
• Fermentation
• Lactic acid fermentation takes place in some
fungi and some bacteria like Lactobacillus
acidophilus (yogurt).
Anaerobic Respiration
• Fermentation
• In humans, lactic acid fermentation takes
place in the muscles during times of
strenuous exercise or great exertion. Under
these conditions the oxygen supplied by the
lungs and blood system cannot get to the
cells fast enough to keep up with the muscles’
demands.
Anaerobic Respiration
• Fermentation
• At this point the muscle cells will switch over
to lactic acid fermentation, by converting
pyruvate into lactic acid via the enzyme lactic
acid dehydrogenase (LDH). The build-up of
lactic acid can cause cramping and a burning
sensation in the over worked muscles as well
as sore muscles the following day until the
lactic acid is washed out of the system.
Anaerobic Respiration
• The glycolysis-fermentation pathway is
important to muscle cells, by producing
“some” ATP, during times when oxygen is in
short supply. However, this process cannot be
applied to the nerve cells/neurons in the
nervous system.
Anaerobic Respiration
• This is because of one major difference
between nerve cells and muscle cells which is
nerve cells cannot switch to lactic acid
fermentation if oxygen is low.
Anaerobic Respiration
• The nervous system is totally dependent, from
minute-to-minute and second-to-second, on
the oxygen delivered by the blood. Therefore,
the lack of proper oxygen levels in the brain
will result in impaired brain functioning
AEROBIC RESPIRATION
Aerobic Respiration
• Pyruvate Oxidation/Transition Reaction:
• After the completion of glycolysis and the
production of pyruvate - if oxygen is
present, pyruvate enters the mitochondria
and forms acetyl-coA during the second
stage called - pyruvate oxidation or
transition reaction. In this stage an acetyl
group is produced by cleaving off a carbon
atom from pyruvate.
Aerobic Respiration
• Pyruvate Oxidation/Transition Reaction:
• The acetyl group is then bonded with
coenzyme A (CoA) thereby forming acetyl-
CoA. CoA is synthesized in the body from
pantethine and cysteine.
Aerobic Respiration
• Pyruvate Oxidation/Transition Reaction:
• Though glycolysis is the primary source of
acetyl-coA formation, acetyl-coA is also
associated with the metabolism of fatty
acids ketones and amino acids.
• Since acetyl-coA is common to all four
pathways, it is sometimes called the
“crossroads compound”. Also produced
in this pathway are 2 molecules of NADH.
Aerobic Respiration
• Krebs/Citric Acid Cycle/TCA Cycle
• Once formed, acetyl-coA will enter into the
Krebs/citric acid cycle/TCA cycle which is a
“circular” series of enzymatic reactions which
take place in the matrix/inner compartment of
the mitochondria.
Aerobic Respiration
• Krebs/Citric Acid Cycle/TCA Cycle
• The result of the Krebs cycle is an additional 2
molecules of ATP , 6 molecules of NADH and
2 molecules of another electron carrier called
FADH2.
Aerobic Respiration
• Krebs/Citric Acid Cycle/TCA Cycle
• FADH2 is the reduced form (gained hydrogen
atoms) of flavin adenine dinucleotide (FAD).
FAD is a co-enzyme which is derived from the
vitamin – riboflavin (B2) and once reduced it
will also be used in the electron transport
chain to assist in producing additional ATP.
Aerobic Respiration
• Oxidative Phosphorylation: The Electron
Transport Chain & Chemiosmosis
• The electron transport chain is a series of five
protein complexes (I, II, III, IV, V) within the
cristae/inner mitochondrial membrane
Aerobic Respiration
• Oxidative Phosphorylation: The Electron
Transport Chain & Chemiosmosis
• And by means of a very complicated series of
events the electron carriers -NADH and
FADH2 produced during the earlier stages of
glycolysis, pyruvate oxidation, Krebs cycle are
now used to create a high gradient of hydrogen
atoms in the outer mitochondrial compartment.
Aerobic Respiration
• Oxidative Phosphorylation: The Electron
Transport Chain & Chemiosmosis
• This high gradient forces the hydrogen atoms to
cross back through the cristae into the matrix.
This process of transferring hydrogen atoms
across the cristae is called chemiosmosis and
occurs via a special membrane protein called
ATP Synthase (complex V).
Aerobic Respiration
• Oxidative Phosphorylation: The Electron
Transport Chain & Chemiosmosis
• ATP synthase is the machinery or protein
molecule that is responsible for actually
producing ATP from adenosine diphosphate
(ADP) and phosphate.
Aerobic Respiration
• Oxidative Phosphorylation: The Electron
Transport Chain & Chemiosmosis
• This entire process, that takes place through the
electron transport chain, and chemiosmosis
generates an additional 34 molecules of ATP
and is referred to as oxidative phosphorylation
ATP Tally: Glucose
• ATP the “energy currency” of the cell which
was produced by means of a process called
cellular respiration. Through this process it
was noted that ATP was formed at various
stages along with the high energy carriers –
NADH and FADH2
• NADH and FADH2, are major contributors
to the production of ATP via the creation of
a hydrogen gradient in the electron
transport chain. During this process each
NADH (indirectly) yields 3 ATP while each
FADH 2 (indirectly) yields 2 ATP.
• the total amount of ATP produced per one
molecule of glucose is:
ATP Production: Beta Oxidation
• Normally, 60% to 90% of the energy required
for contraction of the heart is derived from
the oxidation of fatty acids.
• Also, if for some reason adequate amounts
of glucose are not available such as - during
times of stress, long periods between meals,
and fasting - the body cells can catabolize
(break down) stored fats/lipids and even
proteins for energy.
Lipid/Fatty Acid Catabolism
• Lipids provide highly efficient energy storage,
storing much more energy for their weight
than carbohydrates like glucose. Lipids are
primarily stored in adipose tissue (body fat)
as triglycerides which are composed of a
glycerol backbone with three fatty acids
attached.
Lipid/Fatty Acid Catabolism
• Triglycerides form fatty droplets that exclude
water and take up minimal space.
• Fatty acids are also more highly reduced than
carbohydrates, so they provide more energy
during oxidation.
Lipid/Fatty Acid Catabolism
• The efficiency of energy storage of lipids is
probably an important reason why animals
(humans) store most of their energy as fats
and only a small amount of energy as
carbohydrates.
Lipid/Fatty Acid Catabolism
• When needed as an energy source the fat
reserves are mobilized via a process called
lipolysis.
• Lipolysis largely occurs in adipose tissue
where glycerol is cleaved off of the fatty acids.
Once completed the fatty acids and glycerol
are then released from the adipose tissue into
the blood and transported to the energy
requiring tissue.
Lipid/Fatty Acid Catabolism
• In the cell glycerol – a sugar alcohol - is further
converted into one of the intermediate
products of glycolysis – glyceraldehyde
phosphate – and then to pyruvate.
Lipid/Fatty Acid Catabolism
• Glycerol makes up only 5% of the lipid
metabolism. The remaining 95% of lipid
metabolism takes place when the fatty acids
enter the mitochondria’s Krebs cycle.
Carnitine Palmitoyltransferase System
(CPT)
• Before fatty acids can enter the mitochondria
they need to be “activated”.
• The activation of fatty acids takes place in the
cell’s cytosol where the enzyme acyl-CoA
synthetase (ACS) - located on the “outer
surface” of the outer mitochondria membrane -
links the sulfhydryl group of Coenzyme A
(CoA) to a fatty acid.
Carnitine Palmitoyltransferase System
(CPT)
• ATP drives the formation of this linkage to
form a new compound called Acyl-CoA .
• Once activated the short chain fatty acid acyl-
CoA’s (<6 carbon atoms long) and medium
chain fatty acid acyl-CoA’s (6-12 carbon atoms
long) can freely diffuse into the mitochondria
to be oxidized via a process called beta-
oxidation.
Carnitine Palmitoyltransferase System
(CPT)
• However, the long chain fatty acid acyl-CoA’s
(>12 carbon atoms long) are unable to diffuse
into the mitochondria and therefore must be
transported in.
Carnitine Palmitoyltransferase System
(CPT)
• The transport of long chain fatty acids into
mitochondria is accomplished by the carnitine
palmitoyltransferase system (CPT system -
CPTI & CPTII), sometimes referred to as the
carnitine shuttle.
Carnitine Palmitoyltransferase System
(CPT)
• The CPTI enzyme, which is bound to the
“inner surface” of the outer mitochondrial
membrane,exchanges coenzyme A for
carnitine on the long chain fatty acid acyl CoA
molecule.
• The bonding of carnitine forms a fatty acid-
carnitine conjugate called acyl-carnitine.
Carnitine Palmitoyltransferase System
(CPT)
• Acyl-carnitine is then shuttled across the inner
mitochondrial membrane by a transporter
protein/enzyme called the carnitine
acylcarnitine translocase (CACT).
Carnitine Palmitoyltransferase System
(CPT)
• Once acyl-carnitine has been transported into
the matrix of the mitochondria CPTII
exchanges carnitine for CoA, thereby, once
again producing a long chain fatty acid acyl-
CoA.
Carnitine Palmitoyltransferase System
(CPT)
• Now in the mitochondria matrix, the long chain
fatty acid acyl- CoA can be oxidized via a
beta-oxidation. The removed carnitine is
transported back through the CACT to be re-
used..
Beta Oxidation
• Beta-oxidation is the process whereby all
activated fatty acid (short, medium & long
chain) acyl-CoA’s are oxidized, via a repeating
four-step enzymatic cycle.
Beta Oxidation
• In each four-step cycle, a fatty acid is
progressively shortened by having two of its
carbon atoms cleaved off.
• The remaining fatty acid chain re-enters the
beta oxidation pathway resulting in another
pair of carbon atoms cleaved off.
Beta Oxidation
• This process is repeated until all the carbon
atoms in the original fatty acid acyl-CoA are
gone.
• The cleaved pairs of carbon atoms are used to
produce acetyl groups which are then linked
with coenzyme A molecules to produce
molecules of acetyl-CoA.
Beta Oxidation
• acetyl-CoA is the entry point into the Krebs
cycle where ATP, NADH and FADH2 are
produced.
• Also, during each four-step enzymatic cycle,
the electron carriers NAD+ and FAD are
reduced to produce (1) NADH and (1) FADH2
which are transported to the electron transport
chain to assist in producing ATP.
ATP Tally: Fatty Acids
• The number of ATP produced from the
breakdown of fatty acids depends on which
fatty acid is utilized.
• However, the following example of
palmitate/palmitic acid, a common saturated
fat found in plants and animals, will give a
good example of why fatty acids are a highly
concentrated source of energy.
ATP Tally: Fatty Acids
• Palmitate is a 16 carbon atom and will
therefore cycle through the beta oxidation
pathway 7 times.
• Thereby forming 7 NADH’s, 7 FADH2’s and 7
acetyl-CoA’s.
• Plus the last two remaining carbon atoms will
also be converted to acetyl CoA. Making the
total number of acetyl-CoA produced to be 8.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• Ketosis is simply the accumulation of
ketones/ketone bodies in the body. This is a
controversial subject with the debate centered
on whether or not ketosis is potentially
dangerous or even beneficial for some people.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• On one side of the issue it is claimed that
ketones are formed due to the result of a
restricted or low intake of carbohydrates.
• This occurs during times of starvation, fasting,
severe dieting or when glucose is not fully
utilized as in diabetes. Due to such a restricted
carbohydrate intake, the body converts to the
oxidation of more fats for energy.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• This shift occurs mainly because the entry of
acetyl-coA into the Krebs cycle depends on
the availabilityof oxaloacetic acid (1st step in
Krebs cycle), which becomes deficient in a low
carbohydrate diet.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• This scenario of low oxaloacetic acid levels
will in turn cause fatty acid oxidation to be
incomplete thereby causing an excess of
acetyl-coA to accumulate in the cells. The
excess acetyl-coA is transported to the
• liver where it is converted to ketones via a
process called ketogenesis
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• Since most ketones are acidic, in certain
people ketosis can lead to metabolic acidosis
or ketoacidosis which is an increase in blood
and tissue acidity which can be dangerous.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• The body eliminates most ketones (i.e.
acetone) by excreting them through the urine
as well as the breath. Ketones excreted
through the breath give a person’s breath a
sweet, fruity smell that has been likened to the
smell of nail varnish.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• The physiological significance of these ketone
bodies takes the form of ATP production.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• There is limited transport of fatty acids across
the blood-brain barrier, which explains why
fatty acids are not a significant fuel source for
the brain. Ketone bodies, however, can cross
the blood brain barrier and can therefore be an
alternative source of energy for the brain.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• Unlike glucose, the uptake of ketone bodies
occurs via the family of monocarboxylate
transporters (MCTs), which are not insulin
mediated.”
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• MCT proteins enable ketones to pass readily
through the blood-brain barrier. Many types of
peripheral cells, including brain cells, not only
use glucose, but also use ketones to produce
acetyl-CoA.”
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• ATP is produced by ketones when the ketone
bodies – beta-hydroxybutyrate (BHB) and
acetoacetate (AcAc) enter the mitochondria
and are acted upon by several enzymes.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• Ketolysis – the splitting up of ketones – takes
place first when 3-oxoacid-CoA transferace
(OCT) adds coenzymeA to AcAc, which is then
split into two molecules of acetyl-CoA by
acetoacetyl-CoA thiolase (ACT). The acetyl-
CoA molecules then enter into the Krebs/TCA
cycle
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• In the liver, much of the acetyl CoA generated
from beta-oxidation of fatty acids is used for
synthesis of the ketone bodies acetoacetate
and beta-hydroxybutyrate, which enter the
blood.
ATP Production: Ketogenisis
• Ketogenesis & Ketosis
• In skeletal muscles and other tissues, these
ketone bodies are converted back to acetyl-
CoA, which is oxidized in the TCA cycle to
produce ATP.
• ketones are basically water soluble fats
which dissolve in blood. And are a source
of energy for many tissues including the
muscles, brain and heart.
• Though ketones can’t totally replace all the
sugar required by the brain, they can
replace a good chunk of it.
ATP Production: Protein/Amino Acid
Catabolism
• The first step in protein catabolism is to
digest protein molecules into individual
amino acids. Once this is done the removal
of the amino group (NH2) is required and
takes place in the liver via a process called
deamination. The removed amino group is
converted to ammonia (NH3).
ATP Production: Protein/Amino Acid
Catabolism
• Ammonia is highly toxic and is further
converted in the liver to urea and then
excreted from the body via the kidneys.
ATP Production: Protein/Amino Acid
Catabolism
• Once the amino group is removed the
remaining carbon skeleton – a keto acid -
can enter the cellular respiration cycle
either as pyruvic acid (50%), acetyl CoA
(25%) or enter directly into the Krebs/citric
acid cycle (25%) to generate ATP (different
amino acids go through different pathways).
ATP Production: Protein/Amino Acid
Catabolism
• Catabolism of amino acids is not a practical
source of quick energy and is typically only
used in starvation situations.
•
ATP Production: Protein/Amino Acid
Catabolism
• Proteins are harder to break apart than
carbohydrates or lipids, their catabolism
generates toxic waste products (ammonia),
and they are the structural and functional
parts of every cell, and thus tend to only be
used when no other energy source is
available.
ATP Production: ATP Turnover
• Regardless of the source of ATP –
glycolysis, beta-oxidation, Krebs cycle,
oxidative phosphorylation –ATP needs to
be “turned over” so that it is re-used over
and over. This is to supply the body with
the huge amounts of ATP it demands, of
which cannot be produced in such volumes
from scratch by normal metabolic
pathways.
ATP Production: ATP Turnover
• The turnover process takes place naturally
by means of a protein called adenine
nucleotide translocator (ANT) or ATP-ADP
translocase.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• The production of ATP, via ATP synthase,
occurs on the inside of the mitochondrial
inner membrane – in the matrix. But most
of the cellular ATP usage is required
outside the mitochondria - in the cytosol.
• Therefore ATP needs to be transported
from the mitochondria’s matrix to the cell’s
cytosol.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• This is accomplished through a special
protein called adenine nucleotide translocator
(ANT) or sometimes referred to as the ATP-
ADP translocase which is located on the
inner membrane of the mitochondria.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• ANT is the most abundant protein of the inner
mitochondrial membrane and is the most
active enzyme in animal (human) cells.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• Once transported into the cytosol, ATP
undergoes hydrolysis via the enzyme
• ATPase. ATPase breaks the phosphate bonds
and thereby releasing energy to be used for the
cells many biochemical functions.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• This process also results in the formation of a
new molecule -adenosine di-phosphate (ADP)
and a phosphate molecule. ANT will now be
used to transport the ADP molecule back into
the matrix for reprocessing.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• ANT simultaneously transports both ATP and
ADP. For each ATP molecule transported out of
the matrix, one molecule of ADP is transported
into the matrix.
Adenine Nucleotide Translocator
(ANT)/ATP-ADP Translocase
• Once in the matrix ADP and phosphate are re-
synthesized via ATP synthase to produce a new
molecule of ATP starting the cycle all over.
ATP Production: The ATP–CP System
• The ATP-CP System. Unlike the normal
metabolic pathways this pathway or system
is exclusive to muscle (includes cardiac),
brain and eye cells only. The ATP-CP system
is a non-lactic acid producing, anaerobic
(without oxygen) system whose primary use
is for quick short-acting bursts of energy.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• When the body is at rest energy needs are
fulfilled by aerobic catabolism because the
low demand for oxygen can easily be met
by oxygen exchange in the lungs and by
the oxygen carried to the muscle by the
cardiovascular system.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• If physical activity is initiated, the energy
requirements of contracting muscle are met
by existing ATP.
• However, stores of ATP in muscle are limited,
providing enough energy for only a few
seconds. If the physical activity continues
ATP levels diminish as it is converted to ADP.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• Luckily, the body has a small reservoir of
creatine phosphate(CP)/phosphocreatine
(PCr) which can be used to quickly
regenerate ADP into ATP. Creatine
phosphate is nothing more than a molecule
of creatine with a phosphate molecule
bonded to it.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• This process is catalyzed by the enzyme
creatine kinase (CK), and the reaction is
reversible. The enzyme can either add a
phosphate to creatine to make creatine
phosphate, or remove one to make creatine,
depending on the needs of the cell
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• This process is catalyzed by the enzyme
creatine kinase (CK), and the reaction is
reversible. The enzyme can either add a
phosphate to creatine to make creatine
phosphate, or remove one to make creatine,
depending on the needs of the cell
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• Creatine phosphate is found in muscle, brain
and eye cells in the amount of 4 to 6 times
greater than that of ATP. Thus most energy is
stored at these sites in creatine phosphate
pools.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• Because only one enzymatic reaction is
involved in this energy transfer, ATP can be
formed rapidly (within a fraction of a second)
by using creatine phosphate.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• At rest, muscle fibers produce more ATP than
is required by the body. This excess ATP is
used to synthesize creatine phosphate.
• The enzyme creatine kinase catalyzes
muscles fibers to break down excess ATP
and transfer a phosphate group to creatine,
forming creatine phosphate and ADP.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• During contraction, muscle fibers transfer the
phosphate group from creatine phosphate to
ADP, forming ATP.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• All though the ATP-CP system creates ATP
almost instantly, it does have its limits.
• In that in can only produce about 15
seconds worth of physical activity. Although
this may seem like a very limited amount of
time, creatine phosphate provides the
muscles with ATP before aerobic respiration
can take over.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• The ATP-CP system is active at the
beginning of all forms of activities but is
especially important in high intensity
exercises that require short bursts of energy.
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• All though the ATP-CP system creates ATP
almost instantly, it does have its limits. In that
in can only produce about 15 seconds worth
of physical activity. Although this may seem
like a very limited amount of time, creatine
phosphate provides the muscles with ATP
before aerobic respiration can take over
The ATP–Creatine Phosphate
(CP)/ATP–Phosphocreatine (PCr)
System
• The ATP-CP system is active at the
beginning of all forms of activities but is
especially important in high intensity
exercises that require short bursts of energy.
The Methylation Connection
• Methylation is one of the most common
metabolic functions of the body, occurring in
the order of a billion times per second. It is the
process by which a methyl group (CH3) is
transferred from one molecule (a methyl
donor) to another (which becomes
'methylated').
The Methylation Connection
• over 100 different biochemical reactions in the
body, which are catalyzed by
methlytransferase enzymes, influencing such things as:
- Energy (co-q10, carnitine, creatine)
- Cell membrane growth & repair (myelin,
phospholipids)
- Neurotransmitters (adrenaline, nor-
adrenaline, dopamine, serotonin, histamine)
The Methylation Connection
• over 100 different biochemical reactions in the
body, which are catalyzed by
methlytransferase enzymes, influencing such things as:
- Hormones (thyroid, adrenal, melatonin)
- Immunity (T-cells, autoimmunity, histamine,
TH1/TH2 balance, viral DNA, NK cell function)
- DNA & RNA
- Detoxification (sulfur metabolism, glutathione,
redox)
The Methylation Connection
• The main methyl donor in the body is called
S-adenosylmethionine (SAMe). Levels of
SAMe are maintained by a basic cellular
biochemical cycle, called the methylation
cycle. Whereby SAMe is synthesized from the
amino acid methionine.
Methylation & Coenzyme Q10
Synthesis
• Coenzyme Q10 (CoQ10) is a vital component
of the electron transport chain where it is
responsible for the transfer of electrons
between complex I, II & III.
• Without out CoQ10 there would be no ATP
production.
Methylation & Coenzyme Q10
Synthesis
• CoQ10 is a non-essential nutrient which is
naturally produced in the human body and
is synthesized from the amino acid tyrosine
and precursor molecules. Two of the final
steps in the biosynthesis of CoQ10 involve
methylation by SAMe
Methylation & Carnitine Synthesis
• Carnitine is responsible for the shuttling of
long chain fatty acids across the
mitochondrial membrane so they may be
used in the beta-oxidation system.
Methylation & Carnitine Synthesis
• Carnitine is a non-essential nutrient which is
naturally produced in the human body from -
the synthesis which begins with the
methylation of the amino acid lysine by
SAMe.
Methylation & Carnitine Synthesis
• After several more steps requiring
consecutive methylations and the interaction
of several enzymes, vitamins and minerals –
carnitine is produced in the body.
Methylation & Creatine Synthesis
• The ATP–creatine phosphate system is the
body’s energy reserve tank. Supplying
energy for quick short
• acting burst of energy.
Methylation & Creatine Synthesis
• Creatine is a non-essential nutrient which is
naturally produced in the human body from
the amino acids glycine, aginine and
methionine. The synthesis of creatine occurs
primarily in the kidneys and liver.
Methylation & Creatine Synthesis
• Once synthesized, creatine is transported in
the blood for use by muscle tissue, brain and
the eyes.
• Approximately 95% of the human body's total
creatine is located in muscle tissue.
Methylation & Creatine Synthesis
• The synthesis of creatine, via methylation, is
the single greatest drain of the body’s methyl
reserves, consuming over 70% of the body’s
entire supply.
• Furthermore, given that the body’s methyl
reserves are limited in size, creatine
synthesis alone could potentially create a
state of methyl-deficiency.
Methylation Cycle & Adenosine
• Adenosine is a molecule, made up of
ribose and adenine, which form the back
bone to the all-important molecule this
report has centered on – adenosine tri-
phosphate (ATP), adenosine di-phoshpate,
(ADP), and adenosine mono-phosphate
(AMP)
Methylation Cycle & Adenosine
• Adenosine can be synthesized in the body
through a couple of pathways, but a key
pathway is through the methylation cycle. In
the methylation cycle SAMe is enzymatically
converted into an intermediate molecule
called S-adenosylhomocysteine (SAH). And
via a series of enzymatic activities SAH can
be converted to adenosine or any one of its
by products →AMP →ADP→ATP.