L1 - Intro to Biochemistry

objectives

Understandings:

• The diverse functions of biological molecules depend on their structures and shapes.
• Metabolic reactions take place in highly controlled aqueous environments.
• Reactions of breakdown are called catabolism and reactions of synthesis are called anabolism.
• Biopolymers form by condensation reactions and are broken down by hydrolysis reactions.
• Photosynthesis is the synthesis of energy-rich molecules from carbon dioxide and water using light energy.
• Respiration is a complex set of metabolic processes providing energy for cells.

Applications and skills:

• Explanation of the difference between condensation and hydrolysis reactions.
• The use of summary equations of photosynthesis and respiration to explain the potential balancing of oxygen and carbon dioxide in the atmosphere.

Guidance:

• Intermediates of aerobic respiration and photosynthesis are not required.

Metabolism

• The chemical reactions that take place in the cells of the body are collectively known as Metabolism.
• These reactions are:
  • Enzyme Catalysed
  • Occur in highly controlled aqueous environments
• And function for organisms to:
  • Grow
  • Reproduce
  • Maintain their Structure
  • Respond to their Environment

Catabolism

• Reactions that involve the breakdown of matter to produce energy are called Catabolism.
  • An example is Respiration

Anabolism

• Reactions that use energy to synthesise larger organic molecules are called Anabolism.
  • An example is Photosynthesis

• Biological molecules are incredibly diverse and their function depends on their:
  • Structure
  • Shape

Condensation Reactions

• Condensation reactions involve the reaction between two smaller molecules to form one larger molecule where water is made as a bi-product
• An example is when amino acids bond together to form proteins
• In these examples a bond forms between a Carboxyl group (-COOH) and an amine group (-NH2)
• When they join together water is released
• These can polymerise when they repeatedly react with each other to form biopolymers
• To make a biopolymer each reactant must contain at least two reactive functional groups.
• Examples are:
  • The formation of Polypeptides from amino acids and Carbohydrates from Sugars. When 2 amino acids join together we call this a dipeptide. They would only have one peptide bond.
• Condensation reactions are examples of Anabolic reactions.

Hydrolysis Reactions

• These are the reverse of the Condensation reactions
• They involve the reaction of water (usually in the presence of an acid/alkali) with a larger molecule to decompose it into smaller molecules.
• Example: The hydrolysis of proteins into amino acids and polysaccharides into simple sugars
• Hydrolysis reactions are Catabolic Reactions.

Photosynthesis

• Photosynthesis describes the process where plants and other organisms synthesise organic molecules, such as carbohydrates, from Carbon Dioxide, Water and light energy.
• During this process Oxygen gas is released
• This can explain the origin of Oxygen in the Earth's atmosphere
• Photosynthesis is a complex process that requires the presence of chlorophyll - but we can simplify it in the following equation:

• Photosynthesis is Endothermic
• The energy required for the process, which comes from the sun, is stored in the energy rich products.
• It is an example of an Anabolic Reaction.

Respiration

• Respiration is the reverse of photosynthesis
• It is a Catabolic Process
• Aerobic Respiration, which requires the presence of oxygen, consists of a series of complex redox reactions whereby energy rich molecules, such as carbohydrates, are broken down in cells to release energy.
• The Products are Carbon Dioxide and Water.
• The overall equation can be simplified to:

• Anaerobic Respiration can occur when there is insufficient oxygen available.
• In anaerobic respiration - glucose is converted to lactic acid but less energy is evolved per molecule than during anaerobic respiration.