Molecules of Life

Topics: Protein, Amino acid, Cell wall Pages: 10 (1984 words) Published: July 31, 2013
Inorganic ions
➢ Inorganic ions are important for the structures and metabolism of all living organism ➢ An ion is an atom or a group of atom which has overall electric charge. ➢ Inorganic ion are water soluble

|Ions |Roles/Functions | |Calcium (Ca2+) |Make teeth and bones | | |Make calcium pectate to hold the cell walls of neighbouring | | |plant cells together | |Magnesium (Mg2+) |Make teeth and bones | | |Make chlorophyll | |Nitrate (NO3-) |Make amino acids and nucleotides | |Iron(II) (Fe2+) |Part of haemoglobin which transport oxygen |

Water provides an environment that
• Has a fairly stable temperatures
• Is transparent so that light can penetrate for plant

Polar substances which can dissolves in water are called hydrophilic while non-polar substances which do not interact with water are called hydrophobic

Water as an universal solvent
Ions and polar molecules are charged. They are attracted to water molecules because of the weak positive and negative poles and are therefore dispersed easily in water forming solution

Water is an universal solvent (due to its high polarity) for numerous of biochemical molecules, giving solution and enabling • Transport of nutrients
• Secretion of substances

Water in metabolic reactions
Essential metabolic reactions take place in solution in water. • Hydrolysis involves the addition of water in the breakdown of large biological molecules into their monomers. • Water is a metabolic product of respiration is essential for organisms, especially those living in dry habitats • Water is needed (as a reactant) for photosynthesis

Water in support
Water is incompressibility
• The uptake of water by plant cells provides turgidity which helps the non-woody plant to remain upright. • Water provides buoyancy for aquatic organisms
• These properties allow aquatic organism to walk on the water surface and water to be pulled through the xylem in plants

Water in temperature regulation
Water has a high specific heat capacity means it absorbs a lot of heat for its temperature to rise and loses a lot to cool. The helps to: • Regulate temperature fluctuation in organisms
• Minimize the increase in temperature in cells as a result of biochemical reactions; reduce fluctuation in temperature in aquatic habitats

Water has a high latent heat of vaporization
• To increase the cooling effect in mammals through sweating in in plants through transpiration

• Water has a relative low viscosity
• Water molecules can slide over each other and flow with less friction through the blood vessel. Blood vessel and watery solutions for example can act as lubricants to allow food to move more easily down the alimentary cannal.

Freezing properties of water
At 4(C water is at its maximum density and becomes less dense as it freezes • Water is denser as a liquid than as a solid
• Cold water forms ice on the upper surface, insulating the aquatic organisms below • Water must lose a relative large amount of heat energy to freeze, making the formation of ice crystals in cells less likely.

Water as a lubricant
The viscosity of water makes it a useful lubricant
• Mucus: this is used in externally in animals e.g snail and internally in the...
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