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Cellular Respiration or
WOW do I Need Energy
ATP
All cells need energy. The most common form of
cellular energy is ATP. Below is ATP
It is the negative phosphate groups that give this molecule
energy as it becomes unstable. When the phosphate is
transferred to other molecules, those molecules have energy
because they become unstable.
ATP___> ADP + P is an exergonic reaction that releases
energy.
Below is an example of a cell using ATP in the active
transport of material across the membrane.
This is the potassium/sodium pump that uses ATP to pump
across the ions.
This is a muscle fiber and it shows how ATP is needed to
cause the muscle to contract.
A cell must be able to put the phosphate back on the ADP in order to
keep living as all cells need energy. This is an endergonic reaction
and requires an energy input. The source of energy needed to put the
phosphate back on is food such as glucose. Just like a car uses
gasoline for energy, cells use glucose as energy source to put the
phosphate back on ADP.
Which of the following does not require ATP?
A) The working of the sodium-potassium pump.
B) The contraction of a muscle fiber.
C) The disassociation of salt (NaCl) into Na+ and Cl- ions.
D) The synthesis of triose from carbon dioxide and water
during the Calvin cycle.
C
Salt when dissolve into water will automatically disassociate
into Na+ and Cl- ions. All the other three examples
require ATP.
Just like the gasoline a car uses for fuel, the energy used by cells,
comes from stripping the hydrogens from the glucose molecule. The
difference that this must be on in step-wise fashion. This is an
oxidizing reaction. Quite often when a molecule has hydrogen, it has
increased energy.
This reaction is classified as
A) an ionic reaction
B) an endergonic reaction
C) an exergonic reactin
D) an exotherminc reaction
B
To put a phosphate onto ADP energy is required. That
classifies it as an endergonic reaction.
The energy produced from the "burning" of glucose is used to
make ATP. In chemistry this process is called the oxidation of
glucose.
The energy in glucose must be released in steps instead of releasing it
all at once. It would be like putting a match in gas can to release it
all at once. Cellular respiration has three major parts with many
steps in each part.
3 Part of Respiration
I. Glycolysis
II. Kreb's Cycle
III. Electron Transport Chain
Which of the following has the most energy?
A) ATP
B) C8H18
C) H2O
D) NaCl
B
C8H18 has more energy because it is a long hydrocarbon
chain without any oxygen. This is gasoline and has more
energy than ATP.
How How is this reaction like burning gasoline in a car?
A) This is an oxidizing reaction that releases energy.
B) This is a reducing reaction that requires an energy input
C) This is a reaction that happens all at once.
D) This is a reaction that is spontaneous.
A
When gasoline is “used” in an engine, it is an oxidizing
reaction that is very explosive. The hydrogens are
stripped off the carbon chain. The above reaction is not
explosive but has many steps to it. Both reactions require
oxygen and both release energy.
Where does glycoysis occur?
A) in the mitochondrion B) in the chloroplast
Golgi apparatus D) in the cytoplasm
C) in the
D
Glycolysis occurs in the cytoplasm.
Overview of Glycolysis
I. Glycolysis-cytoplasmGlucose----> 2 pyruvic acid
2NAD + 2H---->2NADH
2ATP---->2ADP + 2P
4ADP + 4P----> 4ATP
NET 2 ATP for cell use
Glycolysis is does not need oxygen. This process
occurs in the cytoplasm. Two net molecules of ATP
are made for cell use. It involves glucose being
converted to two molecules of pyruvic acid.
Glycolysis involves glucose being converted to two
molecules of pyruvic acid. This process is not very
efficient at converting the energy of glucose into
ATP as only 2 ADP are phosphorylated instead of
32 as in Krebs and chemiosmosis.
Glycolysis is does not need oxygen. This
process occurs in the cytoplasm. Two net
molecules of ATP are made for cell use.
It involves glucose being converted to
two molecules of pyruvic acid.
Glycolysis involves glucose being
converted to two molecules of pyruvic
acid. This process is not very efficient at
converting the energy of glucose into
ATP as only 2 ADP are phosphorylated
instead of 32 as in Krebs and
chemiosmosis.
The first four steps of glycolysis is called
the investment phase because energy is
put into the system instead being made.
2 ATP consumed rather than made.
Which of the following is true about glycolysis?
A) It makes 32 molecules of ATP
B) It produces carbon dioxide gas
C) Glucose is broken down to two moleucles of pyruvate
D) No ATP is used, it is only produced
C
Glucose at the end of glycolysis is turned into two
molecules of pyruvate. Four molecules of ATP are made but
two molecules of ATP are consumed so the process “nets”
two molecules of ATP. No carbon dioxide gas is produced.
Put the following molecules in order order of greatest
energy to least amount of energy- Glucose-6-phosphate,
ATP, Glucose, Fructose 1-6 biphosphate
A) Glucose->Glucose-6-phosphate->Fructose 1-6->biphosphate->ATP
B) Glucose-6-phosphate ->Glucose->ATP-> Fructose 1-6 biphosphate
C) Fructose 1-6->biphosphate ->Glucose-6-phosphate->Glucose->ATP
D) Fructose 1-6->biphosphate ->Glucose->Glucose-6-phosphate->ATP
C
Carbohydrates when oxidized can generate a number of
ATP molecules from ADP and P. So ATP will have the least
amount of energy. Glucose and fructose are isomers of one
another and contain about the same amount of energy BUT
as phosphates are added to a molecules, the molecules
becomes unstable. As molecules become unstable their
energy increases. All that being the case, C is the correct
order of sequence.
In the last 6
steps of
glycolysis
energy is
harvested. 4
ATP are made
and two NAD
are reduced to
form NADH. In
the end, the
glucose molecule
is converted to 2
molecules
of pyruvic acid or pyruvate. This will be shuttled to the
mitochondrion where the last hydrogens will be stripped off to
reduce more molecules of NAD and FAD.
Step 1 _____________
Glucose becomes
glucose-6-phosphate.
This requires the use of
ATP. Glucose-6phosphate is more
unstable and has more
energy than regular
glucose.
Energy is put into the
system
In this step
A) ATP transfers energy to glucose
B) ADP gains energy
C) Glucose loses energy
D) No net energy is gained or lost during this step
A
In this step ATP transfers energy to glucose. ATP becomes
more stable as it loses a phosphate, this reduces the
energy. Glucose becomes less stable as it bonds to a
phosphate. This causes glucose increase in energy.
Step 2________________
Glucose-6-phosphate is
turned into fructose-6phosphate. Both of these
molecules are hexose and
have the same molecular
formula. This is called
isomerization.
Step 3_______________
Fructose-6-phosphate
becomes 1,6 fructose
biphosphate. This
requires another ATP to
be used. This new
molecule is more
unstable and has more
energy than the old one.
Step 4_______________
This hexose is unstable,
and will split to produce
two trioses, dehydroxy
acetone and PGAL.
Dehydroxy acetone will
turn into PGAL. From
this point on, everything
is multiplied by two.
Step 5________________
The PGAL will be turned
into diphosphoglyceric
acid. The molecule will
lose hydrogen and gain
inorganic phosphate. The
hydrogen will be
transferred to NAD to
become NADH. NADH
has more energy than
NAD.
Step 6_________________
One of the phosphates from
the molecule is transferred to
ADP to make or
phosphorylate ATP. The new
molecule left is
phosphoglyceric acid.
Step 7
This is a step that involves
moving the phosphate
group from the end carbon
to the middle carbon. This
increases the energy of the
molecule. This makes it
more unstable.
Step 8
This is a step that
involves removing a
molecule of water
or dehydration.
Step 9_________________
This is a step that involves
removing a phosphate and
putting it on ADP or
phosphorylating ADP to make
another ATP. Now 4 molecules
of ATP been made.
Summary of Glycolysis
I. Glycolysis-cytoplasmGlucose----> 2 pyruvic acid
2NAD + 2H---->2NADH
2ATP---->2ADP + 2P
4ADP + 4P----> 4ATP
NET 2 ATP for cell use
After glycolysis, the pyruvic acid will go into the mitochondria, so
that the rest of energy stored in the hydrogen can be extracted. If
no there is no oxygen, then the Kreb's cycle can not completed. A
cell can continue doing glycolysis in the absence of oxygen BUT it
must regenerate NAD to keep going. This step of regenerating
NAD from NADH is called fermentation. Anaerobic respiration =
fermentation + glycolysis.
The next step in the absence of oxygen, pyruvate will form either
lactic acid (muscles) or ethanol (bacteria, yeast or plants). In
either case NAD is regenerated so that glycolysis can continue.
This is called anaerobic respiration. If oxygen is available, then
the pyruvic acid will be shuttled to the mitochondria so that Kreb's
cycle will take place.
The purpose of fermentation is to
a. regenerate ADP + P from ATP
b. make lactic acid
c. make CO2
d. regenerate NAD from NADH
D
The limiting factor in glycolysis is NAD. That being the
case, if there is no oxygen present and to continue with
the glycolysis pathway, NAD must be regenerated from
NADH. Fermentation (lactic acid or alcoholic) oxidizes
NADH to regenerate NAD and allows glycolysis to
continue.
After glycolysis, the pyruvic acid will go into the
mitochondria, so that the rest of energy stored in
the hydrogen can be extracted. If no there is no
oxygen, then the Kreb's cycle can not completed.
A cell can continue doing glycolysis in the absence
of oxygen BUT it must regenerate NAD to keep
going.