ATP and Water Flashcards
What does ATP stand for?
Adenosine triphosphate
What is ATP?
A molecule made of a ribose sugar, an adenine base and 3 phosphate groups.
Draw the structure of an ATP molecule.
From left to right…
Rectangle —>
Adenine base
Pentagon (pentose) —>
Ribose sugar
3 Circles —>
Phosphates
What does ADP stand for?
Adenosine diphosphate
What is ADP?
A molecule made of a ribose sugar, an adenine base and 2 phosphate groups.
What is the reaction involving ATP and ADP?
ATP + H2O ⇌ ADP + Pi
What are the enzymes involved? Name the exo and endo directions.
ATP hydrolase (forward reaction exothermic)
and
ATP synthase (backward reaction endothermic)
What is Pi?
Inorganic phosphate group that is produced.
P = phosphorus
i = Inorganic
What does ATP hydrolysis do?
Releases energy.
The energy produced is used to drive an energy-requiring reaction.
What processes use the energy released from ATP?
Active transport
Cell division
Muscle contraction
Heat
Synthesis of organic molecules
Secretory activities (glands producing hormones)
What is organic and inorganic?
Organic =
Molecule containing carbon
Inorganic =
Molecule not containing carbon.
What is an exergonic reaction?
A reaction that releases energy.
Give examples of an exergonic reaction.
ATP hydrolysis
Respiration
What is an endergonic reaction?
A reaction that requires energy.
Give examples of an endergonic reaction.
Photosynthesis
Protein synthesis
What is the role of ATP?
1~ ATP hydrolysis is exergonic, so there’s a release of free energy.
2~ Enzymes help couple the energy to endergonic reactions (which absorbs energy)
3~ The molecules in the endergonic reaction are PHOSPHORYLATED and is more reactive than before.
4~ Molecules join together to form product, and Pi is produced (phosphate is removed).
5~ ATP is resynthesised as Pi joins to and ADP to form ATP.
What are the advantages of hydrolysing ATP instead of glucose directly?
+ Energy is released very rapidly - only single bond broken, whereas in glucose a number of bonds are broken (which takes more time) - energetically more favourable.
+ Provides energy in small and usable amounts - glucose releases too much energy.
What are the features of ATP?
A = amount of energy released is SMALL - can be coupled to energy-requiring reactions (endergonic) which don’t need too much energy - less energy wasted as heat.
T = ta da! Energy is released in a SINGLE reaction - very rapid, less time-consuming.
P = Pi (inorganic phosphate) released during ATP hydrolysis can be used to phosphorylate substances to make them MORE REACTIVE.
= Soluble =
Small & soluble so it can be easily transported around the cell.
= Cannot diffuse =
Can’t diffuse out of cell, meaning the cell will not run out of energy.
What does phosphorylation mean?
When a molecule gains a phosphate group.
What happens to the ‘Pi’ that’s released?
= Phosphorylation =
Joins to molecules to make them more reactive.
= DNA & RNA =
In the phosphate-sugar backbone of DNA & RNA.
= In Phospholipids =
Make up phospholipids.
What is the name of the reaction where ADP is produced?
Hydrolysis
ATP hydrolysis
What is the name of the reaction where ATP is produced?
Condensation
ATP synthesis
What is the formula for a phosphate ion?
PO₄³⁻
What is the water potential of pure water?
0
Water moves by…
diffusion & osmosis.
Which substances, out of glucose, glycogen, starch and cellulose can dissolve in water?
Glucose can dissolve in water.
Cellulose, starch and glycogen cannot dissolve in water.
What happens to the water potential if something dissolves in water?
It decreases to the negatives.
0 is the maximum it can go.
Why do water and oil not interact with each other?
Water is polar, and oil is non-polar, so they cannot form hydrogen bonds.
What does hydrophobic mean?
Will not mix/interact with water.
What does hydrophilic mean?
Will mix/interact with water.
What are the properties of water?
Strong cohesion =
H₂O has strong cohesion between water molecules due to H bonding - produces surface tension for small aquatic animals
Strong cohesion also supports columns of water in the transport cells of plants.
Metabolite =
H₂O is a metabolite in many metabolic reactions, including condensation & hydrolysis.
Solvent =
So metabolic reactions occur AND allows transport of substances.
High specific heat capacity =
So good at buffering changes in temperature.
High latent heat of vaporisation =
Provides a cooling effect through evaporation.
What is a metabolite?
A product or reactant involved in metabolism.
What is metabolism?
The sum of all chemical reactions that occur within living organisms.
What reactions use water as a metabolite?
Condensation / Hydrolysis
Photosynthesis / Respiration
Give 5 properties of water that are important in biology. Explain the importance of each property you identify. [4 marks]
1 = A metabolite IN condensation/hydrolysis/photosynthesis/respiration.
2 = A solvent SO metabolic reactions can occur and allows transport of substances.
3 = High specific heat capacity SO buffers changes in temperature.
4= Large latent heat of vaporisation SO provides a cooling effect (through evaporation).
5= Strong cohesion (between water molecules) SO provides surface tension supporting (small) organisms.
6 = Strong cohesion SO supports column of water (in plants)
Why is solid ice less dense than liquid water?
As water freezes, molecules have less energy - no longer break their H bonds - become locked into a lattice structure - H bonds keep molecules further apart - making it less dense.
What are the properties of ice?
Insulator =
Ability of ice to float means it acts as an insulator - prevents water below from freezing and allowing life to exist below the surface and preserves habitats.
