Transcript Cellular Respiration Harvesting Chemical Energy

Cellular Respiration
Harvesting Energy From Food
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Obtaining Food
All organisms need food for energy and building materials. Biologists
classify organisms according to how they obtain food.
Autotrophs are organisms such as a
plant that makes its own food. For
example, during photosynthesis plants
use the sun's energy to convert water
and carbon dioxide into sugars.
Autotrophs are also called producers.
Heterotrophs are organisms that
cannot make their own food, such as
humans, meaning "other eaters."
Heterotrophs are also called
consumers.
Principles of Energy Harvest
Energy flow occurs through
the ecosystem
The products of photosynthesis
are the chemical ingredients for
cellular respiration, while the
products of cellular respiration are
the chemical ingredients for
photosynthesis.
ATP provides the energy for cellular work
ATP: (adenosine triphosphate) main energy source that cells use for most
of their work
An ATP molecule contains potential energy, much like a compressed
spring. When a phosphate group is pulled away during a chemical
reaction, energy is released.
The ATP Cycle
ATP is constantly recycled in your cells. A working muscle cell recycles all
of its ATP molecules about once each minute. That's 10 million ATP
molecules spent and regenerated per second!
ATP powers cellular work by coupling energy releasing to energy
using reactions
ATP + H2O  ADP + P
ATP and Cellular Work
Cells perform three main types of work: chemical work, mechanical work,
and transport work.
The transfer of the phosphates from ATP forming ADP provides the energy.
Overall Equation for Cellular Respiration
In cellular respiration, the atoms in glucose and oxygen are rearranged,
forming carbon dioxide and water. The cell uses the energy released to
produce ATP.
"Falling" Electrons as an Energy Source
Food represents a source of high energy electrons similar to the potential
energy of being on top of a slide.
When the electrons pass from the high potential state of food to oxygen,
released energy is converted to other forms of energy.
How does burning compare
to cellular respiration?
When sugar is burned,
oxygen atoms pull electrons
from carbon and hydrogen,
forming new chemical bonds.
Burning releases energy in
the form of heat and light.
Burning Compared to Cell Respiration: The energy release is controlled by
enzymes and carrier molecules in a series of steps.
Electron Transport Chains
Compared with burning, cellular respiration is a more controlled. Energy is
released from glucose in small amounts that cells can put to productive
use—the formation of ATP molecules.
In Eukaryotic Cells, the reaction of Aerobic Respiration occur
Inside MITOCHONDRIA.
Structure of Mitochondria
Mitochondria are found in almost all eukaryotic cells. Its structure is key to its
role in cellular respiration.
Its complex folding pattern of membranes and spaces allows for many sites
where reactions can occur.
Respiration involves glycolysis, the Krebs cycle, and
electron transport
Stage I: Glycolysis
The first stage in breaking down a glucose molecule, called glycolysis (splitting
sugar), takes place outside the mitochondria in the cytoplasm of the cell.
Glycolysis oxidizes glucose to pyruvate
The energy input and
output of glycolysis.
Concentrate on the
totals, not the details!
Glycolysis movie
Stage 2: The Krebs Cycle
The Krebs cycle finishes the breakdown of pyruvic acid to carbon dioxide,
releasing more energy. The enzymes for the Krebs cycle are in the fluid matrix
within a mitchondrion.
Stage 3: Electron Transport Chain and ATP Synthase Action
The final stage occurs in the inner membranes of mitochondria. This stage has
two parts: an electron transport chain and ATP production by ATP synthase
Chemiosmosis: The Energy-Coupling Mechanism
ATP synthase protein complex
functions as a mill, powered by
the flow of hydrogen ions.
This complex resides in
mitochondrial and chloroplast
membranes of eukaryotes and
in the plasma membranes of
prokaryotes..
The gradient of hydrogen ions
“pushes” the ATP synthesis.
Animation of ATP synthesis in Mitochondria
Copyright 1997. Thomas M.
Terry, The University of
Connecticut
Cellular respiration generates many ATP molecules for each sugar
molecule it oxidizes
During respiration, most energy flows in this sequence:
Glucose NADH  electron transport chain  protonmotive force  ATP
Harvesting Energy without Oxygen
Fermentation in Human Muscle Cells
When your lungs and bloodstream can't supply oxygen fast enough to meet
your muscles' need for ATP. Your muscle cells use fermentation to make ATP
without using oxygen.
How does the energy production of Lactic Acid fermentation compare to
aerobic respiration?
Lactic Acid fermentation occurs in animal cells deficient in oxygen
Lactic Acid Fermentation movie
Fermentation in Microorganisms
Yeast (a microscopic fungus) is capable of both cellular respiration and
fermentation.
Fermentation in yeast produces ethyl alcohol. The carbon dioxide that is
released during fermentation creates bubbles and pockets that make bread
rise. The alcohol evaporates during baking.
Fermentation enables some cells to produce ATP without the
help of oxygen. Alcoholic fermentation occurs in yeast.
Alcoholic Fermentation movie
The catabolism of various
food molecules.
Carbohydrates, fats, and
proteins can all be used as
fuel for cellular respiration.