ATP, Inorganic Ions and water Flashcards
what are the three parts of ATP?
- adenine
- ribose
- phosphates
synthesis of ATP
the conversion of ATP to ADP is a reversible reaction and therefore energy can be used to add inorganic phosphate to ADP to re-from ATP (reverse equation). the synthesis of ATP from ADP includes the addition of a phosphate molecule to ADP.
It occurs in three ways:
- in chlorophyll - containing plant cells during photosynthesis (photo-phosphorylation)
- in plant and animal cells during respiration (oxidative phosphorylation)
- in plant and animal cells when phosphate groups are transferred from donner molecules to ADP (substrate level phosphorylation)
what are these three components made up of?
- adenine: a nitrogen-containing an organic base
- ribose: a sugar molecule with a 5-carbon ring structure (pentose sugar) that acts as the backbone to which the other parts are attached
- phosphates: a chain of three phosphate groups
how does ATP store energy?
adenosine triphosphate is a nucleotide and as the name suggests has three phosphate groups. These are key to how ATP stores energy. the bonds between these phosphate groups are unstable and so have low activation energy which means they are easily broken when they do break they release a considerable amount of energy. Usually in living cells it’s not only the terminal phosphate that is removed according to the equation:
ATP+H2O-> adenosine diphosphate+ inorganic phosphate+ energy
as water is used to convert ATP to ADP is known as a hydrolysis reaction. the reaction is catalysed by the enzyme ATP hydrolase (ATPase)
ATP is used in energy-requiring processes in cells including:
-metabolic processes: ATP produces energy needed to build up macromolecules from their basic units e.g. making starch from glucose or polypeptides from amino acids
-movement: ATP provides energy for muscle contractions. in muscle contractions ATP provides energy for the filaments of muscle to slide past one another and therefore shorten the overall length of the muscle fibre
-active transport: ATP provides energy to change shape of carrier proteins in plasma membranes. this allows molecules or ions to be moved against a concertation gradient
-secretion: ATP is needed to form lysosomes necessary for the secretion of cell products
-activation of molecules: the inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate after compounds in order to make them more reactive thus lowering the activation energy in enzyme-catalysed reactions
what are the roles of ATP?
ATP is a better immediate energy source than glucose for the following reasons:
-Each ATP molecule releases less energy than each glucose molecule. the energy for reactions is therefore released in smaller, more manageable quantities rather than the much greater and therefore less manageable release of energy from a glucose molecule
-The hydrolysis of ATP to ADP is a single reaction that releases immediate energy the break down of glucose is a long series of reactions and therefore the energy release takes longer
ATP CAN’T be stored and so has to be continuously made within the mitochondria
where are inorganic ions found?
in organisms where they occur in solution in the cytoplasm of cells and in body fluids as well as part of larger molecules they may be in concentrations that range from very high to very low
different ions and their uses:
- Fe2+: haemoglobin to bind with oxygen for transport for aerobic respiration
-PO4-: ATP, phospholipids bilayer, DNA, RNA
-Mg2+: production of chlorophyll
-H+: pH, optimal pH of enzymes, Bohr effect, active transport of sucrose in phloem
-Na+: co-transport of amino acids and glucose across epithelial cells of the villi
what is the main bond that contributes to the properties of water?
hydrogen bonds
why is water an excellent solvent?
dipolar nature of water break apart ionic bonds, ions are free to move, free to collide and free to have chemical reactions; free for other things like cotransport
why does water have a high surface tension and cohesion
oxygen has a higher electronegativity keeps the electrons around it more frequently, water is sticky due to its many hydrogen bonds. when water sticks to surfaces it’s called adhesion and when water sticks to itself it’s called cohesion
why does water have a high specific heat capacity and latent heat of vaporisation?
SHC, buffering changes in temperature - for optimal temperature
LEV - providing a cooling effect with little loss of water through evaporation, kinetic energy taken away with vapour
what are some other properties of water?
- is a metabolite in many metabolic reactions, including condensation and hydrolysis reactions
- water is less dense when it’s a solid
- it acts as regent
