- Glycolysis
- Krebs Cycle
- Electron Transport Chain and Oxidative Phosphorylation
ATP is produced by two different types of processes - Substate level phosphorylation
- Oxidative phosphorylation
Glycolysis takes place in the Cytoplasm.
Kreb cycle and the Electron Transport Chain and Oxidati...
- Glycolysis
- Krebs Cycle
- Electron Transport Chain
and Oxidative
Phosphorylation
ATP is produced by two
different types of processes
- Substate level
phosphorylation
- Oxidative phosphorylation
Glycolysis takes place in the
Cytoplasm.
Kreb cycle and the Electron
Transport Chain and
Oxidative Phosphorylation
take place in the
Mitochondrion.
How do organisms get energy
Autotrophs - They make their
own carbon compounds, they
make what is required to make
ATP, they don’t make the ATP
directly… they make the
carbon compound that would
be broken down to get the
ATP. Usually that carbon compound is glucose.
Photoautotrophs (eg. plants)
- Through the sun
Plants do photosynthesis: they make their glucose, the glucose then undergoes cellular respiration to get the ATP.
Chemoautotrophs (e.g. archaebacteria)
- Make organic compounds without sun’s energy
They don't use the sun's energy, they use energy from chemical compounds
Heterotrophs (e.g. animal, fungi, most protists/bacteria)
- Through plants
- Glucose is the ultimate source of energy
- glucose stores energy in its bonds and cellular respiration is a way to acquire this energy
They have to ingest or take in their carbon compounds, ultimately the carbon and the glucose came from plants when they did photosynthesis, but these organisms
have to take it in. Fungi would be decomposing the material taking in glucose that way. Humans would be eating a plant or something that ate a plant so glucose is
the ultimate source of energy.
Why glucose, why not some other compounds?
- Many weak bonds with high free energy potential. (bonds hold energy, its chemical potential energy so when you break bonds energy can be released).
- It is stable (won’t break down on its own)
- Easy to store as starch or glycogen.
- Water-soluble (Important for cells in aqueous environment must be water soluble)
- Easy to transport in solution and can pass through membranes.
Cellular Respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (Glucose + Oxygen -> Carbon dioxide + water + ATP).
As the bonds within this glucose molecule break down that is where energy is released. Glucose stores the energy, cellular respiration is the way to get that energy out
of the glucose molecule.
Cellular respiration has many steps and each step is catalyzed (sped up by enzymes) by a different reaction (type of reactions involved are exergonic = net release of
energy and there can be redox reactions, redox reactions are the reduction oxidation reactions which really involve passing of electrons.
Bonds are broken through exergonic oxidation reactions. So the glucose molecule is oxidized (broken down) and in the process it’s being oxidized it’s going to become
CO2. So all the carbon in the glucose will eventually be released as CO2. AND the oxygen molecule is reduced to water (gained electrons).
So you can see the carbon being converted to CO2 and the hydrogen that’s within the glucose molecule will eventually be put into water molecules.
, Left side picture:
If you took a sample of glucose in a test tube and burnt it
on a bunsen burner: the slope going up the maximum Y is
the activation energy required to break the glucose bonds.
At the maximum Y is the transition state where all the
molecules would be free. Then the products are formed.
You can see that the products are lower than the reactants
and there has been a net release of energy of Gibbs free
energy.
Right side picture (cellular respiration): That is not what
happens in the cell because there is no way you could
have that massive release of energy all at once within a
cell nor can the activation energy be overcome. Therefore
its a series of steps, each catalyzed by an enzyme that will
eventually get the products produced
In cellular respiration energy is released from combustion
of glucose. 34% of this energy goes to ATP; 66% goes to
heat (Byproduct of cellular respiration is heat which can
be beneficial to organisms. Basically just living is
providing enough energy to keep the body temperature at what it needs to be for all the enzymes to work.
Each reaction requires enzymes:
Kinases – attach phosphates
Dehydrogenases – remove H
Isomerases – change structure (does not add or remove anything)
Phosphatases – remove phosphates
Aerobic (requires oxygen) vs Anaerobic (does not require oxygen) Respiration:
C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy
- In the above equation oxygen is the electron acceptor in the oxidation of glucose
- Most organisms are obligate aerobes – they Most organisms are obligate aerobes – they require oxygen and cannot survive without it
- Obligate anaerobes (some species of bacteria) use other molecules as the final electron acceptor and must live in environments that has no oxygen
- Facultative anaerobes can tolerate aerobic and anaerobic conditions
Mitochondria
- Double membrane (outer and inner) and the inner one is
folded and where the folds happen is called Cristae. The folds increase
the surface area of the inner membrane = the electron transport chains
are embedded along the inner membrane so if you can have more folds
you can have more electron transport chains.
- Within the inner membrane there is the matrix which is fluid
filled and has a lot of proteins and enzymes.
- The space between the two membranes is called the
intermembrane space.
Energy transfer terminology:
Substrate Level Phosphorylation: ATP forms directly in an enzyme catalyzed reaction
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