ATP, Water And Inorganic Ions Flashcards
Why is ATP useful?
Releases energy in small amounts
Broken down in a single reaction so releases energy rapidly
Adds phosphate to other molecules so makes them more reactive
Easily resynthesised
What is the structure of ATP
- nucleotide base adenine
- a ribose sugar
- 3 phosphate groups
What happens when energy is needed by a cell?
ATP is broken down into ADP (adenosine diphosphate) and Pi (inorganic phosphate). This is a hydrolysis reaction. A phosphate bond is broken and energy is released. The reaction is catalysed by the enzyme ATP hydrolase.
What does it mean by ATP hydrolysis can be coupled to energy requiring reactions within a cell?
The energy released can be used directly to make the coupled reactions happen, rather than being lost as heat.
What is phosphorylation?
Inorganic phosphate released in the hydrolysis reaction can be added to another compound making it more reactive
How can ATP be re-synthesised?
in a condensation reaction between ADP and Pi. This happens during respiration and photosynthesis and is catalysed by the enzyme ATP synthase
What is the structure of water?
2 Hydrogen atoms and 1 oxygen atom joined by shared electrons
Water is a polar molecule
It has a positive end and a negative end
The poles are attracted to each other
This forms hydrogen bonds between all molecules of water
Describe what is meant by the polarity of water
Because the shared negative hydrogen electrons are pulled towards the oxygen atom, the other side of each hydrogen atom is left with a slight positive charge. The unshared negative electrons on the oxygen atom give it a slight negative charge. Polar molecule- has a slight negative charge on one side and a slight positive charge on the other
Large latent heat of vaporisation
Effective cooling mechanism with little loss of water through evaporation e.g. sweating or panting
High specific heat capacity
Water requires a lot of energy to change temperature, temp changes are buffered. E.g stable environment for aquatic organisms
Metabolite
In condensation and hydrolysis reactions e.g. photosynthesis and respiration
Solvent
Good medium for metabolic reaction and transport of solutes e.g. reactions in cytoplasm and ions in transpiration
Cohesion and surface tension
Supports columns of water e.g. cohesion tension theory
Provides a habitat for small organisms e.g pond skaters
Ice is less dense than liquid water
So water beneath ice is insulated and remains liquid e.g. aquatic organisms don’t freeze
Provides a habitat for organisms e.g. polar bears
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So photosynthesis can take place under water e.g. kelp can photosynthesis
