Bioenergetics part 2 Flashcards
What is energy released from macronutrients harnessed by our bodies to do?
Synthesise ATP
So ATP is carrier of energy from macronutrients
What is Adenosine triphophate made up of?
Adenine
Ribose
Phophate chain
How does ATP produce energy basically?
When you break phosphate bond lots of energy released
It’s the only compound that transfers chemical energy to energy requiring processes
Why do we use ATP?
Phosphate bonds trap large portion of potential energy from food
Easily transfers to other compounds to fuel endergonic reactions or raise compounds to higher activation levels (means that eventually energy release will be greater)
Example of this is storing glucose as glycogen
Explain how ATP is the energy currency, and reasons which it isn’t aswell?
Simplifies the coupling of energy producing reactions to energy requiring reactions (ATP can be used by all)
However, ATP cannot be accumulated, or transferred from cell to cell
Once the ATP has been used and no more can be generated, the cell dies (can’t go in debt)
What mechanisms do cells have to prevent death when run out of ATP?
Fatigue in ,muscle arrests ATP utilisation during physical activity
Maintenance of the ATP to ADP concentration ratio
This take precedence over cell function
Features about the ATP-ADP ratio?
Not equillibrium, 50/1 in favour of ATP
A system that is far from equilibrium is capable of doing work
Breakdown of ATP increases ADP concentration, but ATP is rapidly reformed
What are luxury reactions?
Physiological functions of the cells, that aren’t essential for that cell to survive (body may die)
What type of reaction is the breakdown of ATP?
Hydrolysis reaction, a Phosphate bond (terminal) is broken down when joined with water
ATP + H2O = ADP + Pi (inorganic Phosphate)
-(delta)G7.3kcal.mol^-1 amount of energy released
What enzyme catalyses ATP breakdown?
Adenosine triphosphatase (ATPase)
What can happen to ADP to release more energy?
A further phosphate group can be cleaved releasing more energy
Catalyzed by adenosine diphosphatase
This leaves adenosine monophosphate - AMP
Is a rare occurrencre as turnover of ATP (hydrolysis-re synthesis) is so effective
So only used in exhaustive situations
What does the enzyme adenylate kinase do?
Catalyse ATP regeneration from ADP
2ADP = ATP + AMP
Most important at beginning of exercise
Does ATP hydrolysis require oxygen?
No, Oxygen would take too lung too get to cells
Why haven’t human evolved to store more ATP instead of relying on re synthesis?
It would be too heavy, and therefore inefficient
How much ATP stored in the body at any given time?
80-100g
3mmol of ATP per kg wet weight muscle tissue
How is instant replenisment of ATP achieved?
PCr - phosphate phosphocreatine
Provides Phosphate group
Formula for ATP being used for biological work?
ATP = ADP + Pi + Energy
Catalysed by ATPase
Formula for ADP being turned into ATP?
PCr + ADP = Cr + ATP
Catalysed by creatine kinase
Where is Creatine Kinase found in abundance?
Locations of ATP hydrolysis and regeneration
How long does it take for PCr to theoretically deplete?
8-12 sec
What does PCr creating a buffer mean?
Gives time for other energy pathways to get going
What is the stimulus for Creatine Kinase activity?
Increase in ADP concentration (thus ATP Hydrolysis)
Describe the PCR shuttle?
Made in centre of Mitochondria
ATP leaves inner mitochondrial membrane, and binds to MiCK (mitochondrial creatine Kinase) in the inter membrane space
Then outside the mitochondrial membrane MMCK (muscle machinery Creatine Kinase) gives a Cr to MiCK, then PCr goes to MMCK,
Which then goes to ATPase and then the myofibril for contraction
The ATP has turned into ADP and returned inside the mitochondrial membrane to be re-synthesised into ATP
This reduces the distance ADP and ATP have to travel as they are very heavy, and Cr and PCr are lighter
What are the 3 macronutrients?
Carbs
Protein
Fat