Biochemistry

Definition:

It is the science that describes the structure, organization, and functions of living matter in molecular terms.

History:

1828 - Friedrich Wohler successful synthesis of urea from ammonium.

1897 - Hans Buchmer and Eduard Buchner discovery of in vitro fermetation quiet by accident. Sucrose was rapidly fermented into alcohol by the yeast juice.

Characteristics of living organisms

Living organisms are composed of lifeless molecules, which conform to all the physical and chemical laws that describe the behavior of inanimate matter.

1. Degree of complexity: Thousands of different molecules make up a complete cell.

2. Energy: Living organism extract, transform, and use energy from their environment. Inanimate matter does not absorb energy to do work.

3. Living organisms are open system: Living things are not in equilibrium with our surroundings. Living organisms exchange both energy and material with its surroundings.

• They take up chemical fuels from the environment and extract energy by oxidizing them.
• They absorb energy from sunlight.

Bioenergetics

Definition: It is the study of energy transformations and exchange.

Metabolism: It is the process through which living things acquire and use free energy to carry out functions.

• Catabolism: It is the degradation pathways to obtain components and energy from biomolecules such as nucleotides, proteins, lipids and polysaccharides. The process generates energy.
• Anabolism: It is synthesis of biomolecules such as nucleotides, proteins, lipids, and polysaccharides from single molecules. The process requires energy.

Autotrophs ·    Self-feeding organisms. ·    They are prokaryotes that can produce all their cellular components from simple molecules such as H2O, CO2, NH3 and H2S. ·    Cells use CO2 from the atmosphere as the carbon source.

Heterotrophs ·    Feeds on other organisms. ·    They obtain energy by oxidation of organic compounds as carbohydrates, lipids, or proteins. ·    Cells obtain carbon from glucose, proteins, and lipids.

Biomolecules are composed predominantly of: C H O N.

Obtention of Oxygen:

• Aerobics: Organisms that live in the presence of oxygen. Oxygen is used to oxidize.
• Anaerobics: Organisms that live in the absence of oxygen 

Obtention of Nitrogen:

  Plants and bacteria: Plants obtain nitrogen from ammonia or nitrates.

• Nitrifying bacteria: Oxidize ammonia into nitrates.
• Denitrifying bacteria: Reduce nitrates into ammonia.

  Animals: Animals and humans obtain nitrogen from aminoacids.