Respiration

Respiration

By Naomi Keddy

Respiration is the enzyme controlled release of energy from food within all living cells.

There are two Types of respiration:

1.       Aerobic Respiration – Which is the controlled release of energy from cells that requires the presence of oxygen.

Balanced equation:

C6H12O6+6O2→6CO2+6H2O+2820kJ

Glucose + Oxygen → Carbon Dioxide + Water + Energy

Aerobic respiration:

 -It uses oxygen.

-It releases carbon dioxide and water.

-It releases a large amount of energy.

2. Anaerobic Respiration – Which is the controlled release of energy from cells that thrive in the absence of oxygen.

Anaerobic Respiration:

-It doesn’t require oxygen

-It releases a small amount of energy

There are two types of Anaerobic Respiration:

1. Alcohol fermentation in yeast

Equation:

Glucose → Alcohol + Carbon Dioxide + Small amount of energy

2. Lactic acid fermentation

Equation:

Glucose → Lactic acid + small amount of energy

The Use of Micro-Organisms in Industrial Fermentation:

Biotechnology is the use of living things or their components (cells and enzymes) to make useful products.

Bioreactors: This is the vessel in which the biological reactions take place.

Examples of Bioprocessing

Micro-organism Product Use

Bacteria Yoghurt Food

Antibiotics Kills Bacteria

Hormones Maintains health (e.g. insulin)

Yeast Ethanol Beer and Wine

Carbon Dioxide Rises Dough

.

 Stages of Aerobic Respiration:

There are three stages to be considered.

1. Glycolysis

2. Krebs Cycle

3. Electron Transport System

Stage 1: Glycolysis

- Glycolysis occurs in the absence of oxygen.

-During glycolysis, glucose is broken down into two molecules of a 3-Carbon compound called pyruvic acid

Stage 2: Kreb’s Cycle

- Pyruvic acid from glycolysis enters the lumen of the mitochondrion where it loses carbon dioxide to become acetyl co-enzyme A (C2)

- Acetyl Co-Enzyme A enters the Kreb’s cycle.

- The Kreb’s cycle is a series of chemical reactions which result in the loss of carbon dioxide and pairs of hydrogen atoms (electrons and protons).

- The carbon dioxide is excreted.

- The pairs of hydrogen atoms Two high energy electrons and H+ are picked up by NAD+ to form NADH which enters the membranes of the cristae of the mitochondrion where oxidative phosphorylation takes place.

Stage 3: Electron transport system:

- The pairs if hydrogen atoms picked up by the NAD+ from glycolysis and the Kreb’s cycle are carried into the membranes of the cristae of the mitochondrion.

- Pairs of electrons are passed down the carrier system (electron transport system) releasing energy used in phosphorylation.

- Here they are passed along a system of electron carriers.

- As electrons are transferred from one carrier to another enough energy is released to phosphorylate ADP to ATP three times.

- At the end of the chain, the electrons and H+ are combined with oxygen to form water. 

 Glycolysis

- It takes place in the cytoplasm.

-Oxygen is not used.

- It takes place in aerobic and anaerobic respiration.

 Kreb’s Cycle

- It takes place in the lumen of the mitochondrion.

- It only occurs in aerobic respiration.

Electron transport system:

- It takes place on the cristae of the mitochondrion.

- It only occurs in the presence of oxygen.

- Vitamins of the B group are required to make carriers 1 and 2

.