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
How is there a pH difference between the lysosome and cytosol created
- have ATPase, hydrolysis ATP and this releases energy
- energy used to pump hydrogen ions into lysosome
- makes lysosomes more acidic/ drop in pH
- can be found in Golgi apparatus as well
- uses ATP to pump hydrogen ions inside the lysosome rather than pumped hydrogen ions making ATP
How do you create energy using glycolysis
- Glycolysis takes place in cytoplasm and takes place in anaerobic conditions - does not require oxygen
- Glucose is converted to pyruvate
- If no oxygen is present then lactic acid is produced
- Pyruvate from glycolysis is used to generate either acetyl CoA for the citric acid cycle or lactic acid
- ATP generated by substrate level phosphorylation – transfer of phosphate group from triose sugar to ADP
- Produces 2 pyruvate molecules
describe the process of glycolysis
- Coverts glucose to fructose-1,6-bisphoshate, this requires two molecules of ATP, these are converted to ADP
- Fructose -1,6 – bisphosphate is made and this is an unstable 6 carbon compound which is converted to DHAP and GALP
- All the DHAP is converted to GALP
- Therefore, there are 2 molecules of GALP
- GALP is converted to 2 molecules of pyruvate this makes 4 molecules of ATP and produces 2 molecules of reduced NAD
describe the process of the links reaction
- Take place in the matrix of mitochondria and requires aerobic conditions
- Produces acetyl CoA x2
- 2 NADH
- And 2 carbon dioxides
describe the process of the TCA (the citric acid cycle)
- The citric acid cycle occurs in the matrix of the mitochondrion in aerobic conditions
- couples reactions between - electron donor (NADH) and electron acceptor (Oxygen) and transfer of hydrogen ions across the membrane
- primary active transport - uses energy from redox reactions directly to transfer hydrogen ions
- only functions when oxygen is present
- 2 GTP/ATP
- 6 NADH
- 2 FADH2
- 4 CO2
describe the process of electron transport chain
- Four protein complexes in the mitochondrial membrane as electrons are transported from one complex to another hydrogen ions are pumped across the membrane
- This generates a proton motive force/gradient
- This only happens when oxygen is present as the electrons are placed on oxygen at the end of the process
- The electrons come from NADH and reduced FAD produced from glycolysis/ TCA – these are electron carriers
- Uses energy from redox reactions directly to transfer hydrogen ions
- And it only functions when oxygen is present
describe the process of oxidative phosphorylation
- Cells use enzymes to oxidise nutrients, they release energy which is sued to produce ATP
- NADH is oxidised to unload electrons to the electron transport carrier
- Proton pumps – use this energy to pump protons against the concentration gradient from the matrix to the intermembrane space
- Protons diffuse across through ATP synthase – they use energy that the protons release to produce ATP
what do you use energy for
- Making larger biological molecules requires energy
- Usually from ATP
- Anabolism – protein synthesis, DNA replication, Hormone/steroid synthesis
what is a coupling reaction
this is a reaction that links two reactions together
give an example of a coupling reaction
- Reaction breaks down ATP to and uses energy directly to do something else
- Examples in translation (GTP) and human fat synthesis
what do you use energy for
- glucose transporters
- transporters in sodium and potassium pumps
- co transport coupling energy
- motility
- heat
describe the use of energy in a glucose transporter
- Active transport – transports proteins within the membrane must use energy ATP to move substances either to the inside or to the outside of the membrane, breaks down ATP into ADP and Pi
- In this case the transport of glucose against its concentration gradient
- Can thing of coupling- transporter that transport things more than once
- Can have an electrical charge as well that drives transport, this is linked to PMF
- Passive and active as well
describe the use of energy in a sodium and potassium pump
- The sodium potassium pump must break ATP down into ADP in order to pump three sodium ions outside the cell
- Two potassium ions are then transported into the cell
- Both are transported against a gradient
describe the use of energy in cotransport (coupling energy)
- In co-transport, one process, is coupled with movement of a molecule of sugar into the cell while allowing sodium to enter through the protein
describe the use of energy In motility
Muscle cells contain tubular myofibrils
- These are composed of repeating sections of sacromeretes which appear under the microscope as dark and light bands
- Sacromeres are composed of actin and myosin that slide past each other when the muscles contract and relax
1. Myosin heads hydrolyse ATP into ADP and Pi and become reoriented and enlarged
2. Myosin heads bind to actin and form cross bridges
3. Myosin heads rotate towards the centre of the sarcomere (power stroke)
4. As myosin heads bind ATP the cross bridges detach from actin
describe the use of energy in heat
- Turning PMF into heat- uncoupling
- Thermogenin in babies
- Mitochondria – brown adipose tissue
what are the sources of energy
catabolism - breaking down substances
what are the uses of energy
- Anabolism
- Transport – passive/active, uniport/coupling, charge drivern or not, primary/secondary active transport
- Molility
- Heat
what are the stores of energy
- ATP
- Phosphatecreatine
- other nucleotides such as GTP and UTP - these convert them into ATP before being used
- medium storage: carbohydrates/glycogen - in liver and muscles, can be broken down rapidly into glucose when needed in aerobic respiration, controlled by mechanisms
- fats stores
products of glycolysis
- 1 glucose (6C) goes to 2 pyruvate (3C)
- 2 NET ATP
- 2 NADH
what are the function of TCA
- metabolic pathway for aerobic respiration
- conversion of fats to acetyl CoA
- provide precursor for many compounds
- conversion of proteins
products of TCA
- 2 GTP/ATP
- 6 NADH
- 2 FADH2
- 4 CO2
describe the process of NAD
- acetyl CoA
- get rid of CoA which goes back into the links reaction
combines with acetyl CoA and citrate (6C) - citrate turns to a 5C compounds carbon dioxide is removed, reduced NADH is produced
- 5C turns to 4C produced NADH and Carbon dioxide
4 carbon goes to oxaloacetate and this produced GTP, FADH2 and NADH - oxaloacetate combines with acetyl group and the whole process starts again
How is ATP made
- made of adenine and ribose and 3 phosphates
- 250g in total
- formed by phosphorylation of ADP and AMP
- continuously recycled between catabolism and anabolism
- common to all living things
what did the ration of ATP sort
ADP/AMP
- tells the energy state of body
- high ratio and high energy in the cells
how does phosphocreatine
- synthesised by phosphorylation of creatine by ATP - CATALYSED BY CREATINE KINASE
- reversible reaction
- used to replenish ATP supply quickly (ATP buffer)
- creatine: excreted in urine as creatinine if not phosphorylated
describe fat stores
- mainly in adipose tissue
- high density of energy - occupy less volume and limitless storage
- fats can be converted into acetyl CoA for aerobic respiration but not glucose
what happens when ATP is far from the equilibrium
- usually high ATP: ADP ration maintained in cell
- pushes cell to return to equilibrium
- leads to more ATP breaking down easily
What are the examples of transport in biological energy
primary active transporter - Na/K pump
- glucose transporter
- sodium glucose linked transporter (SGLT1) - secondary active transporter
describe anabolism
- formation of larger complex substances from simple substances,
- converts glucose to glycogen
- converts amino acid to proteins
describe heat
- babies cannot shfver to generation their own heat
- have brown adipose tissues as a heat source
ETC H+ diffuse down Thermogenin (instead of ATP synthase) energy from chemiosmosis to be diffused as heat
