Download Cellular Respiration Powerpoint1

Chapter 8
Cellular Respiration
Chemical Pathways



One gram of the glucose, releases 3811
calories of heat energy when burned
aerobically
A calorie is the amount of energy needed to
raise the temperature of 1 gram of water 1
degree Celsius
Cells release the energy from glucose and
other food compounds
Cellular Respiration




Process that releases energy by breaking
down food molecules in the presence of
oxygen
Takes place in the mitochondria
C6H12O6 + 6 O2 ----> 6 CO2 + 6 H2O + ATP
Occurs in three main stages: glycolysis,
Krebs Cycle, and ETC
Glycolysis








Is the first step of cellular respiration
It is an anaerobic process which means that it does not require
oxygen to proceed
Requires an input of energy (ATP)
Occurs in the cytoplasm
Is the splitting of sugar (glucose)
Releases only a small amount of energy but the process is fast;
can produce thousands of ATP molecules in a few milliseconds
Produces two molecules of a 3 carbon compound, PGA
The net yield is 2 ATP, 2 NADH, and 2 molecules
of pyruvate



Fermentation
Anaerobic process
that follows
glycolysis when
oxygen is not
available to the cell.
Converts pyruvate
and NADH into NAD+
so that glycolysis can
continue
Alcoholic Fermentation





Is useful to the beer, wine and baking
industries
Another way in which NADH is converted
back to NAD+
Produces alcohol, NAD⁺ and CO2
The CO2 produced by yeast makes the
dough rise and bubbles appear in beer and
sparkling wines
Pyruvic acid + NADH–> Alcohol +CO2+
+
Lactic Acid Fermentation





Occurs in the muscle cells of animals
One way in which NADH is converted back to
NAD+
Lactic acid and NAD⁺ are produced
Occurs when we exercise, and our body has
used up all of the ATP. Our muscles start
burning and are sore after exercising. It also
causes muscle fatigue.
Pyruvic Acid + NADH—>Lactic Acid + NAD+
The CAC, Krebs Cycle, or TCA Cycle
(2nd Step of Cellular Respiration)
Follows glycolysis if oxygen is available to
the cell
Pyruvic acid travels from the cytoplasm to
the mitochondria and is broken down into
carbon dioxide in a series of energy
extracting reactions
Is an aerobic process (requires oxygen)
Steps of the CAC Cycle, Krebs Cycle, or the TCA Cycle
1.
2.
3.
Pyruvic acid is broken down into CO2 and
2C Acetyl groups which is bound briefly to
acetyl CoA
2 Carbons are passed into the Kreb Cycle
to combine with a 4 carbon compound,
(Oxaloacetate), to produce a 6C
compound, citric acid.
2 C atoms are removed (in 2 molecules of
CO2)
Steps Cont’d
4.
5.
6.
3 Molecules of NAD+ are converted to
NADH
1 Molecules of FAD converted to FADH2
1 Molecule of ADP converted to ATP or
GDP to GTP
Cycles through twice to breakdown down
both molecules of pyruvate
Electron Transport in the Mitochondria
(3rd Step of Cellular Respiration)




Is a series of molecules along which
electrons are transferred, releasing energy
Carrier molecules bring electrons from
glycolysis and the Krebs Cycle to the ETC
The molecules are located on the inner
membranes of the mitochondria
Is an aerobic process because oxygen is the
final electron acceptor
Electron Transport in the Mitochondria
(3rd Step of Cellular Respiration)



Carrier molecules NADH and FADH2 give up
electrons that pass through a series of
reactions
At least 15 carrier proteins are involved in the
ETC
At the top of the chain, the electrons have
high energy, as they pass through the ETC,
the energy given off is captured in molecules
of ATP
Electron Transport in the Mitochondria
(3rd Step of Cellular Respiration)



High Energy electrons from NADH and
FADH2 are passed along a series of E.T.
enzymes in the inner membrane of the
mitochondria
At the end of the chain, an enzyme combines
electrons from the ETC, H+, and O2 from H20
Produces 34 molecules of ATP
ATP formation



H+ ions are pumped from the inside of the IM
to the outside
The outside is more positively charged than
the inside
The difference in charge supplies energy to
make ATP from ADP
Adenine
Phosphate Groups
ATP Molecule
Ribose
Energy in Balance




Photosynthesis-deposits energy
Respiration-withdraws energy
The equation from photosynthesis and the
complete breakdown of glucose are the
reverse of each other
The products of photosynthesis are the
reactants of cellular respiration and vice
versa
Total ATP Production









Glycolysis-net gain of ATP
=2 ATP
2 NADH x 3 ATP
=6 ATP
Pyruvate into Acetyl CoA
1 NADH x 3 ATP x 2 cycles
=6 ATP
Krebs Cycle
=2 ATP
3 NADH x 3 ATP x 2 cycles =18 ATP
1 FADH2 x 2 ATP x 2 cycles
=4 ATP
Total
=38 ATP (prokaryotes)
Eukaryotes use 2 ATP traveling from the cytoplasm to the
mitochondria resulting in
36 ATP
Overview of Cellular Respiration





Begins with glycolysis
Krebs Cycle is 2nd stage
Electron Transport Chain is the 3rd stage;
transports eResults in the formation of 36-38 molecules
of ATP
C6H12O6 + 6O2 ------> 6CO2 + 6H2O + ATP