Chapter Nine Reading Journal

Questions:
What is the basic summary of respiration?

The first step is glycolysis, which breaks down glucose and produces NADH, ATP and Pyruvate. In the energy investment phase the cell uses ATP to break glucose in G3P. In the energy pay off phase NADH and are produced along with Pyruvate, which makes it possible to move into the Krebs cycle. Through active transport the Pyruvate is moved into the mitochondria, once Coenzyme A is added CO2 and NADH are released forming Acetyl CoA. Acetyl CoA combines with oxaloacetate to start the Krebs cycle forming NADH and FADH2. These molecules are used as the electron transport chain, which creates a concentration gradient powering ATP synthase, which produces ATP.

What are the different types of fermentation?

Alcohol fermentation: Ethanol is converted to Pyruvate first CO2 is released forming acetaldehyde then its reduced by NADH to ethanol this recycles the NAD+ so the glycolysis can continue. Many bacteria and yeast use this for energy production.

Lactic Fermentation: Pyruvate is reduced to NADH forming Lactate. This is also used in bacteria and fungi, but also used in animal cells when they are short of oxygen. In humans lactate is taken to the liver and converted back to Pyruvate.

How does ATP synthase work?
NADH and FADH2 release their H+ ions to proteins in the membrane that pump the H ions across the membrane to create a concentration gradient. The H ions move back across the membrane to reach equilibrium through the protein ATP synthase that by the energy provided attaches P to ADP forming ATP. This is called oxidative phosphorylation. About 36 ATP are made through this process for every NADH 3 ATP can be produced and for every FADH2 2 ATP can be produced.

Facts:
*Glycolysis is one of the most wide spread metabolic pathways and is therefore the oldest.
*Cells are able to trigger the production of more ATP or make the process slow because of feedback inhibition.
* O2 acts as the final acceptor in the electron transport chain
* The general equation for glycolysis is C6H12O6 + 6O2 → 6CO2+ H20 + energy hydrogen is oxidized and the Oxygen is Reduced
* The majority of ATP is produced during ATP synthase/ electron transport chain, but it is made other times during respiration






This shows the Krebs cycle also known as the citric acid cycle. Acetyl CoA combines with the oxaloacetate to form citrate. As the cycle continues NADH and FADH2 are released as NAD+ and FADH are reduced. This is also the step in respiration where Co2 is released and it is considered a cycle because the same products will be produced every time allowing it to occur again in other words oxaloacetate will be produced allowing acetyl CoA to combine with it theoretically allowing it to continue forever.


Summary:
All cells need energy and they undergo a process called respiration to produce this energy. Respiration involves glycolysis, which can also be used for anaerobic respiration (respiration without O2) if O2 is present glycolysis moves to the Krebs cycle and then to the electron transport chain performing oxidative phosphorylation thus completing aerobic respiration. Fermentation is used in organism that produce energy either without the presence of a mitochondria or when O2 levels are depleted. Since glucose is not always available cells must perform respiration using other molecules such as fats and proteins by breaking them into either G3P, Acetyl CoA or as the case is only in proteins moving directly into the citric acid cycle.