6 Feb 2012


glycolysis · from the Greek glyk-, sweet, and lysis, splitting

Virtually every dwelling cell provides out there the catabolic method called glycolysis-the stepwise wreckage connected with blood sugar (and also other simple glucose ). Glycolysis is usually a paradigm connected with metabolic pathways. Accomplished in the cytosol of cellular material, it really is in essence the anaerobic practice; it is main actions happen with no desire for oxygen. Located issues first made an appearance within an environment missing O2, and glycolysis was an earlier in addition to important process pertaining to getting rid of vitality coming from nutrient molecules. The idea performed a new central role within anaerobic metabolic techniques over the first TWO billion years connected with natural development we know. Modern creatures still hire glycolysis to offer precursor substances pertaining to exercise catabolic walkways (such as the tricarboxylic p never-ending cycle ) so when some sort of short-term power source when oxygen is actually limiting.

Oxidation involving Pyruvate and the Krebs Cycle (citric p cycle, TCA circuit)

Aim: get pyruvate along with use it in to the Krebs cycle, creating NADH and also FADH2
Where: the mitochondria
You can find a couple methods
The Conversion regarding Pyruvate to Acetyl CoA
The actual Krebs Cycle proper
This Krebs cycle plus the change involving pyruvate to Acetyl CoA produce 2 ATP's, 8 NADH's, in addition to 2FADH2's per glucose molecule.

The particular Oxidation of Pyruvate to form Acetyl CoA intended for Entry In to the Krebs Cycle

2 NADH's are generated (1 per pyruvate)
2 CARBON DIOXIDE are generally released (1 per pyruvate).

Net Engergy Production from Aerobic Respiration

Glycolysis: 2 ATP
Krebs Cycle: 2 ATP
Electron Transport Phosphorylation: 32 ATP
Each NADH produced in Glycolysis is worth 2 ATP (2 x 2 = 4) - the NADH is worth 3 ATP, but it costs an ATP to transport the NADH into the mitochondria, so there is a net gain of 2 ATP for each NADH produced in gylcolysis
Each NADH produced in the conversion of pyruvate to acetyl COA and Krebs Cycle is worth 3 ATP (8 x 3 = 24)
Each FADH2 is worth 2 ATP (2 x 2 = 4)
4 + 24 + 4 = 32
Net Energy Production: 36 ATP!

Photosynthesis: 6 CO2 + 6 H2O >> C6H12O6 + 6 O2
Respiration: C6H12O6 + 6 O2 >> 6 CO2 + 6 H2O
Notice that these reactions are opposites - this is important since the earth is a closed system
All life has a set amount of natural materials to work with, so it is important that they all be cycled through effectively and evenly

Energy Yields:
Glucose: 686 kcal/mol
ATP: 7.5 kcal/mol
7.5 x 36 = 270 kcal/mol for all ATP's produced
270 / 686 = 39% energy recovered from aerobic respiration

Related Catabolic Processes - Beta Oxidation

Beta Oxidation
Fats consist of a glycerol backbone with two or three fatty acids connected to it
The body absorbs fats and then breaks off the fatty acids from the glycerol
Glycerol is converted to glyceraldehyde phosphate, an intermediate of glycolysis
The fatty acids are broken down into two-carbon units which are then converted to acetyl CoA.
An eight-carbon fatty acid can produce 4 acetyl CoA's
Each acetyl CoA is worth 12 ATP's (3 NADP, 1 FADH2, 1 ATP)
Therefore, this short fatty acid is worth 48 ATP's, a fat with three chains of this length would be worth 144 ATP's!
This is why fats are such a good source of energy, and are hard to lose if you want to lose weight

A comparison between Plants and Animals

Animal cells and Plant cells contain mitochondria!
However, animal cells contain many more mitochondria than plant cells
Animal cells get most of their ATP from mitochondria
Plant cells get most of their ATP from the chloroplast
The ATP generated from the mitochondria is only used when the plant cannot generate ATP directly from the light-dependent reactions

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