Transcript Cellular Respiration or WOW do I Need Energy ATP All cells need

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.
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.
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
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.
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
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, dihydroxy
acetone and PGAL.
Dihydroxy 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.
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.