Nucleic acids

• inorganic ions

  Found in organisms where they occur in solution in the cytoplasm of cells and in body fluids. They maybe in concentrations taht range from very high to very low.
• Important features of water

  transparency allows for aquatic plants to photosynthesise, provides support as it is not easily compressed, evaporation allows for organisms to control their temperature
• Water as a solvent

  Water dissolves other substances:

  - gases such as oxygen and carbon dioxide

  - wastes such as ammonia and urea

  - inorganic ions and small hydrophilic molecules such as amino acids, monosaccharides and ATP

  - enzymes, whose reactions take place in solution
• Water in metabolism

  Water produced as a by-product of metabolism
• Importance of water to living organisms

  Water's unique properties, which are related to the structure of a water molecule, are important for living things.
• Cohesion and surface tension in water

  • Molecules tend to stick together - cohesion

  • W/ hydrogen bonding, water has large cohesive forces allowing it to be pulled up a tube (e.g. xylem vessel)

  • When water molecules meet air, they tend to be pulled back into the body of water rather than escape (surface tension)

  • Water surface can act like a skin, strong enough to support small organisms
• Latent heat of vaporisation of water

  The energy required to completely convert one kilogram of water to steam without an increase in temperature. Requires a lot on energy.
• Water and hydrogen bonding

  -forms between the oxygen and hydrogen in separate water molecules

  -weaker than covalent and ionic bonds, but play an important role in water and other polar molecules
• Dipolar water molecule

  2 atoms of hydrogen and an atom of oxygen. oxygen has slight negative charge and hydrogen has a slight positive charge.
• Roles of ATP

  metabolic processes

  movement

  active transport

  secretion

  activation of molecules
• Synthesis of ATP

  ADP + Pi --> ATP
• How does ATP store energy?

  When 3rd phosphate adds to ADP
• Structure of ATP

  adenine, ribose, 3 phosphate groups
• Semi-conservative replication


  Each half of an original DNA molecule serves as a template for a new strand, and the two new DNA molecules each have one old and one new strand.
• Cytokinesis


  It follows nuclear division and is the process where the whole cell divides
• Nuclear division


  The division of a cell's nucleus, as in mitosis and meiosis
• What stabilises DNA?

  Phosphodiester backbone and hydrogen bonds
• Fuction of DNA


  Is the hereditary material responsible for passing genetic information from cell to cell and generation to generation.
• What base pairs with guanine?

  Cytosine
• What base pairs with adenine?

  Thymine or Uracil
• DNA structure


  DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine
• Ribonucleic Acid (RNA) structure


  single-stranded nucleic acid that contains the sugar ribose
• Name all of the nitrogenous bases

  adenine, guanine, cytosine, thymine (DNA), uracil (RNA)
• Nucleotide structure

  5 carbon sugar, phosphate group, nitrogenous base