H.W -1What are the difference between Cellular respiration
and Fermentation ?
There are two important ways a cell can harvest energy
from food: fermentation and cellular respiration. Both start with
the same first step: the process of glycolysis which is the
breakdown or splitting of glucose (6 carbons) into two 3-carbon
molecules called pyruvic acid. The energy from other sugars,
such as fructose, is also harvested using this process.
Cellular Respiration
Fermentation
Cellular respiration, unlike
fermentation, is an aerobic
process. In cellular respiration
glucose is completely
degradated and the chemical
energy released is captured
and used to convert ADP to
ATP, and ultimately results in
the production of 36 to 38 ATP
molecules / glucose molecule.
The energy produced in this
manner is much greater than
that produced in fermentation.
The overall equation for this
process is:
C6H12O6 + 6O2 ------------>
6CO2 + 6 H2O + 36-38 ATP
Alcoholic fermentation as
carried out by yeasts, is an
anaerobic process
Some organisms, such as lactic
acid bacteria, carry out lactate
fermentation that results in the
production of lactate instead of
the alcohol, ethanol. This
process is used in the
production of yogurt, cheese,
and chocolate. The overall
equation for this process is:
C6H12O6 + Lactic Acid Bacteria
------> 2 CO2 + C3H6O3 + 2
ATP
H.W -2What is le Chatelier's Principle ?And give pratical
illustration of this generalization in the use of
sunglasses ?
In chemistry, Le Chatelier's Principle, also called the Le
Chatelier-Braun principle, can be used to predict the effect of a
change in conditions on a chemical equilibrium. The principle is
named after Henry Louis Le Chatelier and Karl Ferdinand Braun
who discovered it independently
H.W -3What is Resonance?
In physics, resonance is the tendency of a system to oscillate
at its maximum amplitude, associated with specific frequencies
known as the system's resonance frequencies (or resonant
frequencies). At these frequencies, even small periodic driving
forces can produce large amplitude vibrations, because the
system stores vibrational energy. When damping is small, the
resonance frequency is approximately equal to the natural
frequency of the system, which is the frequency of free
vibrations. Resonant phenomena occur with all types of
vibrations or waves: there is mechanical resonance, acoustic
resonance, electromagnetic resonance, NMR, ESR and
resonance of quantum wave functions. Resonant systems can
be used to generate vibrations of a specific frequency, or pick
out specific frequencies from a complex vibration containing
many frequencies.
H.W -4would you expected the free energy of hydrolysis of
acetyl coenzyme A to be equal to or greater than that of
acetoacetyl coenzyme A ?
CH3- C- CH3- C~S- COA
(Acetoacetyl COA)
CH3- C~S- COA
(Acetyl COA)
The free energy of acetoacetyl CoA is greater than that
of acetyl CoA.
The important factor in acetyl CoA is the diminished resonance
interaction between the pi electrons of the sulfur atom and the
carbonyl group is less than that of acetoacetyl CoA (acetoacetyl
is less stable).
Acetoacetyl CoA gives 2 molecule of acetyl CoA which enter the
TCA cycle give more energy than one molecule of acetyl CoA.
H.W -5write a full report on ATP molecule:
1- how it was discovered ?
ATP was discovered in 1929 by Karl Lohman and was
proposed to be the main energy-transfer molecule in the cell by
Fritz Albert Lipmann in 1941
2- how is determined quantity ?
A method for measuring ATP based on the firefly luciferinluciferase reaction is described. The method involves a 30
second integration of the light produced following mixing of the
sample and enzyme. The relationship between light measured
and quantity of ATP present is linear over at least a
thousandfold concentration range, with less than a 2% relative
standard deviation.The method of light measurement includes
the peak intensity of the initial flash and a portion of the signal
which follows. Therefore, the peak intensity of the initial flash
alone is not necessarily the most reliable basis for
measurement of ATP.The method uses a commercially
available luciferin-luciferase preparation without further
purification. The level of sensitivity is equal to that reported for
purified luciferin-luciferase preparations.The method of
constant addition for quantitation of ATP in plant extracts is
described. The lack of specificity associated with the luciferinluciferase reaction is controlled by this method.
3- function ?
It is the medium used for transferring energy from one
place to an other inside the cells.
4- on what from it is present inside the cell ?
Coenzyme
5- how much of it in a typical cell ?
The ATP concentration inside the cell is typically 1-10 m M
H.W -6What is the difference in structure between ATP and
GTP ?
ATP
GTP
Compared with ATP , would you expect GTP to carry
more, less or about the same amount of energy?
ATP carry more energy than GTP
H.W -7NAD has two ribose units in its structure .FAD has
a ribose and ribitol . what is the is the
relationship between these molecules ?
Enzymes relay the electrons released by substrate
oxidation to special molecules we call electron acceptors.
Electron acceptors may be organic or inorganic, and the most
common examples thereof are NAD+ and FAD. Each of these
molecules ca accept two electrons, yielding NADH+H+ and
FADH2, respectively. Since cellular amounts of NAD+ and FAD
are very small, special mechanisms are needed in order to
convert NADH+H+ and FADH2 back into NAD+ and FAD. This
is performed through electron transfer from NADH+H+ and
FADH2 to other molecules, which may occur through either
fermentation or respiration. Contrary to general belief, the
distinction between these two processes does not lie on a
requirement for O2!
H.W -8Why do mitochondria have their own genome ?
Because, a long time ago, a mitochondrion was an
organism in it's own right. Another single celled organism
formed what is called a symbiotic relationship with the
mitochondrion. This single celled organism is what gave rise to
all
modern
organisms
with
mitochondria.
So, it has its own DNA because it used to be a separate
organism entirely
This is because all the mitochondria in the developing human
embryo come from the egg. There are no mitochondria in the
sperm head, which carries the paternal half of the nuclear
genome.
H.W -9Explain why fever is accompanies the toxic overdoses
of Aspirin drug ?
Because we have a lot of opinions we have different
answers
I took the akin and true answers:
1-Dealt with heavy doses of aspirin lead to reduced blood
haemoglobin causing anaemia and a lack of , and coming out
like fever...
2- Working through the enzymes necessary to discourage
Tnsnie Albroostjlandin article is the main reason for the sense
of pain or through their impact on central pain and heat in the
brain, increase the minimum dose Alaspirin cause stomach
disorders or decline in the functions of the liver which can lead
to the accumulation of toxic substances in the blood hold The
show symptoms of these disorders usually in the form of
internal or fever, nausea and other symptoms.
3-your body is simply fighting the toxins. the internal body
temp raises. to fight and kill of foreign toxins
The heat in the body is mainly managed by the liver. it is the
function of the liver to detoxify the toxic substances by
metabolism. hence during the process of this conversion the
metabolic heat is produced. this resemblances the fever
situation.
H.W -10Name a poison that can keep ADP from exchanging
with ATP
1) What happens to that the energy change in the cell
when this poison is working ?
2) dose electron flow speed up stay the same on What?
There are several well-known drugs and toxins that inhibit
oxidative phosphorylation. Although any one of these toxins
inhibits only one enzyme in the electron transport chain,
inhibition of any step in this process will halt the rest of the
process.
For example, if oligomycin inhibits ATP synthase, protons
cannot pass back into the mitochondrion. As a result, the
proton pumps are unable to operate, as the gradient becomes
too strong for them to overcome. NADH is then no longer
oxidized and the citric acid cycle ceases to operate because the
concentration of NAD+ falls below the concentration that these
enzymes
can
use.
some
compounds
that
effect
oxidative
phosphorylation:
Cyanide Carbon monoxide Poisons Inhibit the electron
transport chain by binding more strongly than oxygen to the
Fe–Cu center in cytochrome c oxidase, preventing the
reduction
of
oxygen.
Oligomycin is an Antibiotic that Inhibits ATP synthase by
blocking the flow of protons through the Fo subunit.
CCCP2,4-Dinitrophenon is a poison containing Ionophores that
disrupt the proton gradient by carrying protons across a
membrane. This ionophore uncouples proton pumping from
ATP synthesis because it carries protons across the inner
mitochondrial
membrane.
Rotenone is a pesticide that prevents the transfer of electrons
from complex I to ubiquinone by blocking to the ubiquinonebinding
site.
Not all inhibitors of oxidative phosphorylation are toxins. In
brown adipose tissue, regulated proton channels called
uncoupling proteins can uncouple respiration from ATP
synthesis. This rapid respiration produces heat, and is
particularly important as a way of maintaining body
temperature for hibernating animals, although these proteins
may also have a more general function in cells' responses to
stress.
H.W -11The C subunits of the Fo component of Fo F1 ATP
synthase form an ion channel across the inner
mitochondrial membrane. When certain glutamate
aspartate residues of a C subunit react eith
dicyclohexylcarbodiimide (DCCD) the subunit is unable
to participitate in proton transport.
a) What is the effect of DCCD on electron transport and
respiration in suspentions of intact mitochondria?
The catalytic a and b subunits of the F1-complex are
responsible for synthesizing ATP. The Fo complex consists of 3
proteins a, b and c. Fo forms a proton channel through the
membrane. Protein c is very hydrophobic (a "proteolipid") and
probably acts as the channel. DCCD (dicyclohexyl carbodiimide)
binds covalently to protein c and blocks the proton channel.
Thus, inhibits the process.
b) What happens when dinitrophenol is subsequently
added to DCCD treated mitochondria?
2,4-dinitrophenol is uncoupler .Uncouplers block oxidative
phosphorylation by dissipating the H+ electrochemical gradient.
These agents cause maximum respiratory rates but the
electron transport
What phosphate/oxygen ratio for FADH2?
ATP‫ <ـــــــــــــــــــــــــ‬4H+
FADH2 enter ETC And give 6H+ so:
ATP‫ <ـــــــــــــــــــــــــ‬4H+
??‫<ــــــــــــــــــــــــ‬6H+
P/O = 6/4= 1.5
(2molecule of ATP)
What P/O ratio for NADH2?
1ATP‫<ـــــــــــــــــــــــــ‬4H+
NADH2 enter ETC and give 10H+ so:
1ATP‫<ـــــــــــــــــــــــ‬4H+
??‫<ــــــــــــــــــــــــ‬10H+
P/O= 10/4 = 2.5 (3molecule of ATP)
How many ATP per glucose are synthesized?
 Glycolysis :
substrate level phosphorylation=2ATP
cytosotic NADH2=2 NADH2 are transport tomitochondria by
aspartate_malate shuttle and enter oxidative phosphorylation to give
4ATP(some energy loss from transport)
6ATP× Grooming phase= 2 NADH2
 Citric acid cycle :
3= 18ATP × Mitochondria NADH2= 6 NADH2
2 =4ATP× Mitochondria FADH2= 2 FADH2
-substrate level phosphrylation = 2GTP =2ATP
-sum of ATP= 2+4+6+18+4+2= 36 ATP
a- What is the effect of
chain and respiration?
DCCD on electron transport
The catalytic a and b subunits of the F1-complex are
responsible for synthesizing ATP. The Fo complex consists of 3
proteins a, b and c. Fo forms a proton channel through the
membrane. Protein c is very hydrophobic (a "proteolipid") and
probably acts as the channel. DCCD (dicyclohexyl carbodiimide)
binds covalently to protein c and blocks the proton channel.
Thus, inhibits the process.
b- What happened when DNP is added to DCCD treated
mitochondria?
2,4-dinitrophenol is uncoupler .Uncouplers block oxidative
phosphorylation by dissipating the H+ electrochemical gradient.
These agents cause maximum respiratory rates but the
electron transport generates no ATP, since the translocated
protons do not return to the interior through ATP synthase.
If both inhibitor and an uncoupler are added then the ETC
runs but no ATP synthesis occurs.