Biological energy Flashcards
How is energy created
- Glycolysis
- Link reaction
- Tricarboxylic (TCA) cycle
- Electron transport chain (ETC)
name the two ways of how biological energy is stored and transferred
- chemical bond formation
2. holding something far from the equilibrium
energy is released on…
bond formation
how does chemical bond formation take place
- ATP
- Phosphocreatine
- Other phosphate containing molecule
- Sugar stores
what does ATP stand for
adenosine-5’-triphosphate
describe the structure of ATP
- Adenosine made from sugar ribose attached to adenine
- Adenosine is attached to 3 phosphate molecules
How is ATP formed
- Formed by phosphorylation of ADP and AMP: the di- and mono- phosphates, add phosphate groups and ATP is formed
- Continuously re-cycled between catabolism (synthesis) and anabolism (utilisation of ATP)
breaking bonds…
requires energy
where does energy come from
- Charge density – 3 phosphates that contain oxygen
- oxygen is negatively charged
- bonds are broken between phosphates, these are easily broken due to repulsion between phosphates
- Resonance – in a free phosphate the electrons can move around the molecule, this free movement of electrons means the bond is stable and it gives out a lot of energy when made, this means that the products of the reaction have more resonance so release more energy into the system, so ADP and free phosphate has more energy
- ATP less stable than ADP therefore it wants to go back to ADP as it is more energetically stable
- this reaction is exothermic
- Reaction is held far from equilibrium – this is another reason why energy increases coming out of the reaction
describe differences between ATP and ADP
ATP
Less stable
Very far from the equilibrium – wants to be broken down to ADP
ADP
Has lone electron to rotate between phosphate
Makes ADP more energetically stable
how is phosphocreatine made
- Synthesised by the transfer of a phosphate group from ATP catalysed by creatine kinase during an anaerobic reaction
- Can make phosphocreatine from ATP and make ATP from phosphocreatine therefore acts as an ATP buffer
what is the function of phosphocreatine
- Phosphocreatine plays a particularly important role in tissues that have high fluctuating energy demands such as muscle and brain
what is present in blood when there is tissue damage
creatine kinase
does resonance play a role in phosphocreatine
- Less resonance structures in phosphocreatine then there are in creatine and phosphate, therefore it acts as an energy store and works in a similar way to ATP
what are the medium to long stores
carbohydrate - medium term
fat stores - long term
describe carbohydrate stores
- Medium term energy storage in liver and muscle
- Synthesis and breakdown allosterically and reciprocally controlled
describe fat stores
- Mainly in adipose tissue
- High energy density – virtually limitless storage
- Can be converted into acetyl CoA for aerobic respiration but not glucose
how does the proton motor force work
Keeping this from equilibrium – PMF
- Membrane impermeable to hydrogen ions
- An electrochemical gradient is a gradient of both electrical potential and chemical concentration across a membrane
- Both components are often due to ion gradients, particularly proton gradients and the result is a type of potential energy which is available for work in a cell
- Proton motive force is an electrochemical gradient due to protons
- The term coupling is used to describe the linking to ATP generation
How does it work
- Pump hydrogen ion against concentration gradient
- Let it flow back down the concentration gradient then this releases energy
- This is useful in the breakdown of sugars
How do you convert ion gradients into ATP in the F1FO mitochondrial matrix
1.
- Occurs in F1 F0 ATP synthase
- Converting one store to another (PMF to ATP)
- Membrane powered by flow of protons into rotation, turns rotation into chemical energy into ATP
- One in the cytosol powered rotation into ATP
how do you convert the F1F0 mitochondrial matrix to ATP in the membrane
- In the membrane there are two half channels
- Hydrogen ion comes in in one channel and then has to move sideways to get to the other channel
- The movement of the hydrogen ion sideways in the membrane causes the entire centre to rotate and this causes a rotation change in shape in the beta subunits this makes ATP by combining ADP and Pi