energy concepts Flashcards
what does energy represent?
the capacity to do work
name some of the different forms of energy?
chemical
heat
mechanical
what does work =
force x distance
what does power =
work / time
what is meant by the concept of turnover?
and an example?
molecules are constantly used (degraded) and restored (sythesised)
e.g energy anabolism (building up using ATP) and catabolism (breaking down)
what is protein turnover?
constant and concurrent processes of protein synthesis (from amino acids) and breakdown (into amino acids)
what is ATP and what is its role?
the energy currency of the cell/body
energy source for cellular processes
has a role of being a common chemical intermediate (passes energy on from energy yielding reactions)
what is ATP homeostasis?
maintenance of constant intracellular ATP levels
so that ATP degredation (catabolism)=ATP resynthesis (anabolism)
what are the 3 main systems skeletal muscles employ to maintain ATP homeostasis?
immediate - ATP supply in muscles e.g PCr breakdown and myokinase reaction (anaerobic)
nonoxidative - start of glycolysis (glycolytic) (anaerobic)
oxidative (aerobic)
what are the 3 fundamental types of athletic activites?
power, speed and endurance
what are ADPases?
enzymes that split ATP (combined with water) by hydrolysis
ATP + H2O to ADP + Pi
what are the 3 roles of creatine phosphate (PCr) in maintaining ATP homeostasis?
part of IMMEDIATE energy system
combines with ADP to form (catalysed by creatine kinase) ATP + creatine
high energy compound:
also breaks down to form creatine, pi and energy
energy reserve to regenerate ATP:
the pi and energy products when it breaks down can be combined with ADP to form ATP
what is ‘Pi’?
the inorganic phosphate released when ATP is hydrolised to ADP
which exercise uses the most amount of ATP and how much?
maximal isometric contraction
12 mmol ATP/kg dm/s
what is the role of myokinase in maintaining ATP homeostasis?
reaction only important during high intensity exercise
works closely with breakdown of PCr to maintain intracellular ATP levels so immediate energy system
2ADP to (catalysed by myokinase/adenylate kinase) ATP + AMP energy from ATP limited so importance is formation of AMP
what do changes in ATP and AMP indicate for control of metabolic rate?
changes in [ATP] (concentration) are poor signals for control of metabolic rate
changes in [AMP] are powerful signals for metabolic control (activates mechanism of ADP restoration to ATP)
what is energy charge and indicator of and how to work it out?
indicator of the capacity of a cell to do work (charge of 1 when all adenylate pool in form of ATP so maximal free energy)
normal charge = 0.9-0.95
energy charge (determined by relative changes in adenylates) = [ATP] + 0.5[ADP] / [ATP] + [ADP] + [AMP]
how is AMP prevented from accumulating after the myokinase reaction?
converted to IMP (2 pathways after by purine nucleotide cycle)
results in increased energy charge and continuing contraction
what was the “old concept” of relative contribution to ATP resythesis?
that sequential activation and contribution of energy pathways (when one stopped the next one started)
what is the “new concept” of relative contribution to ATP resynthesis?
overlap of contribution of energy pathways (different pathways working simultaneously)
can fuel sources and energy sources be depleted?
fuel sources such as PCr and CHO can be depleted
energy sources such as ATP, GTP and UTP are regulated and cannot be depleted
what are the 3 main adenylates in cells?
ATP
AMP
ADP
what happens if AMP increases too much during exercise/
formed through breakdown of 2ADP in myokinase reaction
too much = energy charge of cell falls and not enough energy to continue exercise
