Biological Molecules - Water, ATP + Ions Flashcards
What does ATP stand for?
Adenosine Triphosphate
What type of molecule is ATP?
a phosphorylated macromolecule
What are the 3 parts of ATP?
Adenine
Ribose
Chain of 3 phosphates
Why is ATP the immediate energy source?
because a cell is incapable of releasing energy directly from glucose
Give an example of endosymbiotic theory
Mitochondria are unicellular organisms that live inside of eukaryotic cells -> they even have their own DNA and a plasma membrane separate from the cell
Which organelles can produce ATP?
Mitochondria and Chloroplasts
What happens to ATP once produced by mitochondria?
it diffuses out to the rest of the cell to power other cellular processes
Where is the available energy in ATP stored?
In the bonds between the phosphate groups
these bonds are unstable and so have low activation energy
when they break they release a substantial amount of energy
How many phosphates are removed during the breakdown of ATP?
1
What is the symbol equation for the breakdown of ATP?
ATP + H20 -> ADP + Pi + E
What is the word equation for the breakdown of ATP?
Adenoside Triphosphate + Water -> Adenoside Diphosphate + inorganic phosphate + energy
What type of reaction is the breakdown of ATP?
As a water molecule is used, it is a hydrolysis reaction
What enzyme catalyses the breakdown of ATP?
Hydrolase
How can the hydrolysis of ATP be ‘coupled’ with another reaction?
It can be coupled with an endothermic reaction, as the hydrolysis is exothermic
Instead of the energy being lost as heat, it is instead used to power the coupled reaction
The released phosphate molecule can also be used to phosphorylate another molecule in order to make it more reactive
What is the % of water in a cell’s mass?
70%
What are the 4 main properties of water?
Dipolar due to bent shape
Strong surface tension and cohesive
High specific heat capacity
Good solvent
What is a use of the high specific heat capacity of water?
It acts as a buffer against rapid temperature changes, making aqueous environments relatively stable
Why is water a good solvent?
The dipolarity means that ionic compounds can dissolve as the positive ions are attracted to the O- and the negative ions are attracted to the H+
Explain why water has surface tension and is cohesive
Due to the dipolarity, water molecules have strong intermolecular bonds as O- attracts H+
This causes the molecules to stick together
The hydrogen bonds allows water to be drawn up through tubes, forming a miniscus
Describe the function of iron ions in haemoglobin
each of the 4 polypeptide chains making up haemoglobin has an Fe2+ ion in the centre
this is the part of haemoglobin that bonds to oxygen
whilst oxygen is bonded to the ion, it temporarily becomes Fe3+
Describe a use of hydrogen ions
H+ ions are sometimes concentrated to facilitate certain enzyme reactions eg there are more hydrogen ions in the stomach
Describe a use of sodium ions
sodium ions can travel relatively easily through, taking larger molecules such as glucose or amino acids with them that need to be transported too
this is called co-transport
What is the food test for non-reducing sugars?
Place a tube in boiling water and add HCl in a 1:1 ratio
Boil for 5 mins
Use sodium hydrocarbonate to neutralise the solution
test with benedict’s solution
What is the food test for starch?
Add iodine
orange turns blue/black
What is the test for proteins?
Biuret test:
crush solid food, add deionised water and decant the liquid
add equal amounts of sample liquid and NaOH solution
gently mix in a few drops of copper sulphate solution
positive result -> blue to purple
