Cellular Respiration


Fermentation-

Leads to partial degradation of sugars in the absence of oxygen
Cellular Respiration uses oxygen to break down organic molecules, and is more efficient than fermentation.

Overall Process:

Organic compounds + O2 ---> CO2 + H2O + Energy
Carbohydrates, fats and protiens are all able to be used as fuel.

Glucose:
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + Energy (ATP + heat)



Redox Reaction


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Catabolic pathways relocate electrons stored in food molecules, releasing the energy that is used in synthesizing ATP.

Redox reactions are thise that result in the transfer of one or more electrons from one or more reactant to another.

Redox reactions are more formally known as Oxidation-Reduction Reactants.

Oxidation-
The loss of electrons.
Reduction- The gain of electrons.





In cellular respiration Glucose is oxidized, Oxygen is reduced, and Electrons loose potential energy.
Molecules with an abundance of hydrogen are good fuels because their bonds are a source of "hilltop" electrons that "fall" closer to oxygen.

Respiration involves three metabolic stages:
  1. Glycolysis
  • Occurs in the Cytoplasm.
  • Begins by breaking Glucose into two molecules of PYRUVATE.
  • Can accept a wide range of carbohydrates.
  • Polysaccharides are hydrolozyed to glucose to enter glycolysis.


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2. Krebs Cycle
  • Occurs in the Mitchondrial Matrix.
  • Degrades Pyruvate to CARBON DIOXIDE.
  • Cycle begins when acetate from Acetal CoA combines with Oxaloacetate to form Citrate.
  • The oxaloacetate is reycled and the acetate is broken down into CO2.
  • Each cycle produces ONE ATP by substrate phophorylation, 3 NADH, and 1 FADH2 per acetyl CoA.


3. Electron Transport Chain
  • NADH passes electrons to the chain.
  • Electrons move from molecule to molecule until combining with Oxygen and Hydrogen ions, forming Water.
  • While being passed along the chain, the energy that is carried by these eletrons is stored in the mitochondrion in a form that can be used to synthesize the ATP by OXIDATIVE PHOSPHOYLATION.
  • Oxidative Phosphorylation produces 90% of the ATP generated by respiration.






PHOTOSYNTHESIS


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Photosynthesis nourishes almost all of the world either directly or indirectly.

Photosynthesis provides the organic compounds that are needed by the organisms for energy and carbon skeletons.

Autotrophs

Produce their organic molecules from CO2 and other organic raw materials obtained from the environment.
  • Can be seperated different groups by the source of energy that drives their metabolism.
  1. Photoautotrophs- Use the light as the energy source.
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    Plants use the light to begin the stages of Photosynthesis.

2. Chemoautotrophs- Harvest energy from oxidizing inorganic substances.

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Chemoautotrophy is unique to bacteria.




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Any green part of a plant has chloroplasts.

The leaves, however, are the most important site for photosynthesis.

The green color in a leaf comes from Chlorophyll.

  • Chlorophyll is the green pigment found in the chloroplast.
  • It also plays an important part in the absorption of light energy during photosynthesis.
Chloroplasts are found in the MESOPHYLL cells, forming the tissues on the inside of the leaf.
O2 exits and CO2 enters through the STOMATA.
Veins deliver water and the roots carry off sugar to the needing areas.
A normal mesophyll has 30 to 40 chloroplasts.

Each chloroplasts has 2 membranes around a central Aqueous space.
This space is called the STROMA.
The stroma also have an internal aqueous space called the THYKALOID SPACE.
Thykaloids are stacked into columns called GRANA.


Photosynthesis is a redox reaction.
It reverses the direction of the electron floe in respiration, causing water to split and electrons are transferred with the H+ from water to CO2, which then reduces it to sugar.

LIGHT

Travels in rhythmic waves.
Many of its properties are those of a discrete particel, the PHOTON.
The amount of energy packaged in a photon is inversely related to its wavelength; Photons with SHORTER wavelengths pack MORE energy.

When light meets matter, it can be reflected, transmitted or absorbed.
If the light looks green, it is because the chlorphyll is aborsbing red and blue light, and is transmitting and reflecting green light.
  • Chlorophyll a- Dominant pigment. Absorbs best in the red and blue wave lengths and the least in green.
  • Chlorophyll b- Has a slightly different absoption spectrum and funnels the energy from these wavelengths to Chlorophyll a.
  • Caroteniods- Can funnel the energy from other wavelengths to chlorophyll a and also participates in PHOTOPROTECTION again excessive light.

http://www.science.smith.edu/departments/Biology/Bio231/calvin.html

The Calvin Cycle is able to regenerate its starting material after molecules enter and leave the cycle.

CO2 enters and leaves as sugar.

The actual sugar product isn't glucose, but a 3-carbon sugar (G3P)

For a net synthesis of one G3P, the Calvin recycle consumes 9 ATP & 6 NADPH.