Chapter 12 Respiration

External Respiration – Process by which organisms exchange gases with their environment. Takes place in the lungs of mammals gills of fish through stomata & lenticels in plants.

Internal Respiration – Controlled release of energy from food (usually glucose).It is controlled by enzymes. The energy released is trapped in ATP (adenosine triphosphate. Two types of Internal Respiration: Aerobic and Anaerobic.

Aerobic Respiration – The controlled release of energy from food using oxygen.

Aerobic respiration is relatively efficient and approx 40% of the energy in glucose is conterted to ATP. Glucose is completely broken down in aerobic respiration. The energy not converted to ATP is lost as heat.

Aerobic respiration is a two stage process.

Stage 1:

Is an anerobic process (does not require oxygen to take place)

Releases only a small amount of energy – it is inefficient as an energy release system.

Takes place in the cytosol (cytoplasm minus the cell organelles) of the cell.

Involves splitting glucose (six carbon sugar) into 2 three carbon sugars. A small amount of energy is released and used to produce a small number of ATP molecules.

In stage 1 glucose is incompletely or partially broken down. Stage 1 only produces a low yield of energy.

Micro-Organisms Used in Bioprocessing

Detailed Study of Respiration1. Aerobic Respiration

Stage 2• A series of complex reactions some of which require

oxygen.• If oxygen is present pyruvic acid enters a

mitochondrian and loses a carbon dioxide molecule to form acetyl co enzyme A.

• Pyruvic acid also loses two high energy electrons and a proton H+.

• The two high energy electrons and the proton combine with NAD+ to form NADH.

• Each NADH enters an electron transport system.

Krebs Cycle• Acetyl Co A enters a series of reactions known as Krebs Cycle• Acetyl Co A is broken down to carbon dioxide and protons H+ in a

number of reactions• The energy from Acetyl Co A is relased in a number of steps to form

high energy electrons.• These high energy electrons along with protons H+ are picked up by

NAD+ to form NADH.• The NADH molecules enter an electron transport system

Electron Transport System (Chain)• Located on the inner membrane of the the mitochondrion• Infolding on the inner membrane of the mitochondrion increase its surface area.• ETS consists of a number of molecules• High energy electrons are passed from NADH to the • first of these molecules.• As the electrons are passed from molecule to moleculewithin each system they lose some of their energy.• Some of the energy lost from the electrons is used to form ATP and the rest of the energy is lost as heat.• At the end of the system the low energy electrons combine with

oxygen and hydrogen H+ to form water

2. Anaerobic Respiration