Text of Cellular Energy Photosynthesis & Respiration Part 2: Cellular Respiration
Cellular Energy Photosynthesis & Respiration Part 2:
How are photosynthesis and respiration linked?
Energy Why do living things need energy? Reproduction Repair
Growth and development Movement ATP Adenosine Triphosphate The most
usable form of chemical energy in the body. ATP is made during
cellular respiration. A molecule of ADP (adenosine diphosphate) is
joined with a phosphate group to make ATP (an anabolic reaction).
ATP has a great deal of energy in it because of the 3 phosphate
groups. These groups are all negative. It takes a lot of energy to
hold the 3 negative groups next to each other. When 1 phosphate is
separated from the group of 3, ATP is converted back into ADP and
energy that was in the bond is released (a catabolic
Cellular Respiration It is the process that converts the
chemical energy stored in the bonds of glucose into chemical energy
cells can use (ATP); produces 36-38 ATP Equation: Reactants: The 6
O 2 molecules come from the air. They were put there by
photosynthetic organisms. The C 6 H 12 O 6 comes from being
generated during photosynthesis. Autotrophs will use the food that
they made. Heterotrophs will consume the glucose. Products: The CO
2 and the H 2 O are released into the atmosphere. Most of the
energy in glucose is going to be lost as heat (~60%) while some
(~40%) is transformed into ATP for the organism to use. Occurs in
the CYTOPLASM and the MITOCHONDRIA First step occurs in the
cytoplasm (Glycolysis); 2 nd (Krebs Cycle) and 3 rd (Electron
Transport Chain) steps occur in the mitochondria (In eukaryotic)
Utilized by ALL aerobic eukaryotic organisms (plants, algea,
animals) If an organism is anaerobic, it will perform glycolysis
and then fermentation C 6 H 12 O 6 + 6O 2 ---> 6CO 2 + 6H 2 O +
energy (ATP + heat)
Glycolysis 4 ATP (Net gain 2 ATP) This is the first step in
cellular respiration. It does not require oxygen to occur
(anaerobic). This step occurs in the cytoplasm of cells. Here,
glucose will undergo a series of reactions that converts the
molecule into two 3-carbon molecules called pyruvic acid
(pyruvate). The process will require the use of 2 ATP molecules.
The process will make 4 ATP molecules. Therefore, the net gain from
glycolysis is 2 ATP molecules. The process also make 2 molecules of
NADH from 2 molecules of NAD +. Reactants: Glucose + 2 ATP + 2 NAD
+ Products: 2 Pyruvic Acids + 4 ATP + 2 NADH If an organism is
going to use oxygen, an aerobic organism, they will take the 2
molecules of pyruvic acid to the mitochondria for the Krebs cycle.
If an organism does not use oxygen, an anaerobic organism, they
will continue in the cytoplasm using fermentation.
Anaerobic Respiration: Fermentation 0 ATP Used by single-celled
organisms, such as yeast cells Glucose is broken down by
glycolysis, making 2 pyruvic acid molecules and 2 NADH molecules.
Through the use of the energy in NADH, pyruvate is broken down into
CO 2 and ethyl alcohol. The NADH is converted back into NAD + to be
used again in glycolysis. Occurs in your muscle cells when oxygen
is not available Glucose is broken down by glycolysis, making 2
pyruvic acid molecules and 2 NADH molecules. Through the use of the
energy in NADH, pyruvate is further broken down and produces the
waste product of lactic acid, which causes muscle soreness. The
NADH is converted back into NAD + to be used again in glycolysis.
Alcoholic FermentationLactic Acid Fermentation No ATP is made
during the process of fermentation. The entire purpose of
fermentation is regenerate NAD+ to perform glycolysis again.
Cellular Respiration Major Steps After glycolysis, aerobic
organisms that have access to oxygen, will use the Krebs cycle and
the electron transport chain. Prokaryotes: Happens in the cytoplasm
and the cell membrane Eukaryotes: Happens in the mitochondria Krebs
Cycle: The oxidation of glucose that began in glycolysis is
completed. Electron Transport Chain (ETC): NADH and FADH 2 (energy
carriers) are used to make ATP. Oxygen is used at this step.
Mitochondrion Organelle where aerobic respiration occurs
(oxygen is needed). The Krebs cycle happens in the matrix (fluid)
of the mitochondria. The ETC happens in the inner membrane of the
mitochondria. The inner membrane is highly folded. It is called the
cristae. The cristae allow for more electron transport chains to be
in the mitochondria in a smaller space.
Krebs Cycle (Citric Acid Cycle) 2 ATP Happens in the matrix of
the mitochondria. Pyruvic acid diffuses through the double membrane
into the matrix. Here, the 2 pyruvic acid molecules will undergo a
series of reactions. The end result is that the pyruvic acid is
broken down into 6 CO 2. Reactants: 2 Pyruvic Acid + 8 NAD + + 2
FAD + 2 ADP Products: 6 CO 2 + 8 NADH + 2 FADH 2 + 2 ATP Only
produced 2 ATP in this step. Most of the energy of glucose is now
trapped in the energy carriers FADH 2 and NADH.
The Electron Transport Chain 34 ATP Embedded in the inner
membrane of the mitochondria. Electrons in the NADH and FADH 2 have
a lot of energy. The electrons transfer into the chain. As they
pass through the chain, they use their energy to pull H + out of
the matrix creating a concentration gradient. This drives
chemiosmosis to create ATP by using ATP synthase located in the
membrane. At the end, the electrons that were moving through the
chain are accepted by a molecule of O. They also combine with two
molecules of H + and makes water. The energy in NADH and FADH 2
make 34 ATP molecules in this step.
The Importance of Oxygen It is the final acceptor of the
electrons as they move through the chain. If the electrons had no
where to go, then they would build up in the chain, and the chain
could not work again.
The End At the end, 36-38 molecules of ATP have been made.
About 40% of the energy in glucose is converted into ATP by the end
of all 3 processes. (20x more efficient than glycolysis alone). The
remaining energy is being lost as heat. Cellular Respiration:
Photosynthesis C 6 H 12 O 6 + 6 O 2 --> 6 CO 2 + 6 H 2 O +
energy 6 CO 2 + 6 H 2 O + light energy ---> C 6 H 12 O 6 + 6 O