ATP +water +ions Flashcards
biological molecules
what are the uses of energy?
- active transport (any named process) : glucose absorption, ion uptake at roots etc.
- muscle contraction : for movement
- protein synthesis : for growth and repair
- phosphorylation : making molecules more reactive by lowering their activation energy
what is ATP?
the energy from respiration takes the form of a nucleotide called adenosine triphosphate (ATP)
Describe the structure of ATP
● Ribose bound to a molecule of adenine
(base) and 3 phosphate groups
● Nucleotide derivative (modified nucleotide)
how is energy released?
-the bonds between the outer phosphate groups in ATP are unstable, so have a low activation energy
-a single hydrolysis reaction can remove a phosphate. The phosphate can form bonds with other molecules which releases energy (phosphorylation)
Describe how ATP is broken down
● ATP (+ water) → ADP (adenosine diphosphate) + Pi (inorganic phosphate) + energy
● Hydrolysis reaction, using a water molecule
● Catalysed by ATP hydrolase (enzyme ATPase)
Give two ways in which the hydrolysis of ATP is used in cells
● Coupled to energy requiring reactions within cells (releases energy)
○ eg. active transport, protein synthesis
● Inorganic phosphate released can be used to phosphorylate
(add phosphate to) other compounds, making them more reactive
Describe how ATP is resynthesised in cells
● ADP + Pi → ATP (+ water)
● Condensation reaction, removing a water molecule
● Catalysed by ATP synthase (enzyme)
● During respiration and photosynthesis
Suggest how the properties of ATP make it a suitable immediate source of energy for cells
- Releases energy in (relatively) small, manageable amounts / little energy lost as heat
- broken down in a single reaction / one bond hydrolysed to release energy (so immediate release)
-phosphorylation lowers the activation energy needed for biological molecules to react - rapidly formed
-solution - most biological reactions take place in solution; cytoplasm
-Cannot pass out of cell
where does the energy come from?
1.light - results in photophosphorylation
2.respiration - oxidation phosphorylation
3. doner molecule - substrate level phosphorylation
what are the disadvantages of ATP?
- ATP cannot be moved from cell to cell/ stored because it is so reactive
true or false “ATP has 3 phosphorus groups.”
false
ATP has 3 phosphate groups
true or false “ATP hydrolysis creates energy.”
false
Energy cannot be created - only transferred / released.
true or false “ATP can be stored.”
false
ATP is too unstable to be stored within cells.
true or false “The only use of ATP is energy release.”
false
The inorganic phosphate can be used to phosphorylate other
compounds, making them more reactive.
what are the differences between the nucleotide in ATP (nucleotide derivative) and the nucleotides in DNA
- ATP has 3 phosphates DNA 1 phosphate group per nucleotide
- ATP has ribose, DNA deoxyribose
- ATP - base always adenine, DNA it varies
Why is glucose not a good immediate energy source for a cell?
-Stable so energy is released slowly.
-Large amount of energy released - difficult to manage.
-Many reactions required to release energy.
compare ATP and carbs
Explain how hydrogen bonds occur between water molecules
● Water is polar molecule (electrons have uneven distribution)
● Slightly negatively charged oxygen atoms attract slightly positively
charged hydrogen atoms of other water molecules
- 2 hydrogen atoms covalently bonded to 1 oxygen atom
describe the H bonds in water molecules
- form between polar molecules containing hydrogen
- they do not result in a permanent structure, bonds break and reform as water molecules move around
how is the water property metabolite important?
Used in condensation / hydrolysis / photosynthesis / respiration
how is water property Solvent (can
dissolve solutes) important?
- Allows metabolic reactions to occur (faster in solution)
- Allows transport of substances eg. nitrates in xylem, urea in blood
how is the water property (Relatively) high
specific heat
capacity important?
● Buffers changes in temperature
● As can gain / lose a lot of heat / energy without changing temperature
1. Good habitat for aquatic organisms as temperature more stable than land
2. Helps organisms maintain a constant internal body temperature
how is the water property (Relatively) large
latent heat of
vaporisation important?
● Allows effective cooling via evaporation of a small volume (eg. sweat)
● So helps organisms maintain a constant internal body temperature
how is the water property Strong cohesion
between water
molecules important?
- Supports columns of water in tube-like transport cells of plants
eg. transpiration stream through xylem in plants - Produces surface tension where water meets air, supporting small
organisms (to walk on water)
name some properties of water
polar, solvent, reactive
Why is it useful to living organisms that water is polar?
can act as a universal solvent (chemical reaction happens faster in solutions)
why is it useful to living cells that water is reactive?
takes place in hydrolysis and condensation reactions
true or false “Water is cohesive which aids transpiration.”
Transpiration is the loss of water vapour from leaves. The transpiration stream is the constant movement of water through the plant. Cohesion aids the transpiration stream.
Where are inorganic ions found in the body?
In solution in cytoplasm and body fluid, some in high concentrations and others in very low concentrations
Describe the role of hydrogen ions
● Maintain pH levels in the body → high concentration = acidic / low pH
● Affects enzyme rate of reaction as can cause enzymes to denature
describe the role of iron ions
● Component of haem group of haemoglobin
● Allowing oxygen to bind / associate for transport as oxyhaemoglobin
describe the role of sodium ions
- Involved in co-transport of glucose / amino acids into cells
- Because sodium moved out by active transport
- Creates a sodium concentration/diffusion gradient;
- Involved in action potentials in neurons
describe the role of phosphate ions
- Component of nucleotides, allowing phosphodiester bonds to form in DNA / RNA
- Component of ATP, allowing energy release
- Phosphorylates other compounds making them more reactive
- Hydrophilic part of phospholipids, allowing a bilayer to form
how do water and ions enter cells?
they can move down a concentration gradient
both move through channel proteins
ions can move against a concentration gradient by active transport
