Biological Molecules: Water Flashcards
what are the properties of water?
- a metabolite in many metabolic reactions
- water acts as an important solvent so metabolic reactions occur
- relatively high specific heat capacity so buffers changes in temperature
- has strong cohesion between water so supports columns of water in tube-like transport cells of plants
- relatively large latent heat of vaporisation so provides a cooling effect
why is water an important metabolite?
- water is involved in many metabolic reactions such as hydrolysis and condensation reactions
what is a hydrolysis reaction?
- breaks the chemical bond between two molecules, involves the use of a water molecule
what is a condensation reaction?
- joins 2 molecules together to form a chemical bond, involves the elimination of a water molecules
what is an example of condensation reaction?
• amino acids are joined together by polypeptides
what is an example of a hydrolysis reaction?
energy from ATP is released
why is water a good solvent?
• because water is polar which means that the slightly positively charged end of water molecule is attracted to the negative ion
• the slightly negatively charged end of water molecule is attracted to the positive ion
how does the waters polarity make water a good solvent, examples?
• ions surround water molecules = they dissolve
• living organisms can take up useful substances dissolved in water and the dissolved substances can be transported around the organisms body
(e.g. mineral ions)
why does water have a relatively high specific heat capacity?
*a lot of energy is needed to break the hydrogen bonds between water molecules give water a high specific heat capacity
what happens (in terms of heat energy) when water is heated?
• a lot of heat energy is used to break hydrogen bonds between water molecules
• this means that there is less heat energy available to actually increase the temp of water
• so water has a high specific heat capacity as it takes a lot of energy to heat it up
why is water having a high specific heat capacity useful for living organisms?
• water doesn’t experience rapid temperature changes
• water is a good habitat as the temperature under water is likely to be more stable than on land
• water inside organisms remains at a fairly stable temperature helping them maintain a constant internal body temperature
why is strong cohesion between water molecules important?
supports columns of water in tube-like transport cells of plants and produces surface tension where water meets air
why is a relatively large latent heat of vaporisation good?
- provides a cooling effect with little loss of water through evaporation
