energy concepts

Question 1

what does energy represent?

Answer 1

the capacity to do work

Question 2

name some of the different forms of energy?

Answer 2

chemical
heat
mechanical

Question 3

what does work =

Answer 3

force x distance

Question 4

what does power =

Answer 4

work / time

Question 5

what is meant by the concept of turnover?

and an example?

Answer 5

molecules are constantly used (degraded) and restored (sythesised)
e.g energy anabolism (building up using ATP) and catabolism (breaking down)

Question 6

what is protein turnover?

Answer 6

constant and concurrent processes of protein synthesis (from amino acids) and breakdown (into amino acids)

Question 7

what is ATP and what is its role?

Answer 7

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)

Question 8

what is ATP homeostasis?

Answer 8

maintenance of constant intracellular ATP levels

so that ATP degredation (catabolism)=ATP resynthesis (anabolism)

Question 9

what are the 3 main systems skeletal muscles employ to maintain ATP homeostasis?

Answer 9

immediate - ATP supply in muscles e.g PCr breakdown and myokinase reaction (anaerobic)

nonoxidative - start of glycolysis (glycolytic) (anaerobic)

oxidative (aerobic)

Question 10

what are the 3 fundamental types of athletic activites?

Answer 10

power, speed and endurance

Question 11

what are ADPases?

Answer 11

enzymes that split ATP (combined with water) by hydrolysis

ATP + H2O to ADP + Pi

Question 12

what are the 3 roles of creatine phosphate (PCr) in maintaining ATP homeostasis?

Answer 12

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

Question 13

what is ‘Pi’?

Answer 13

the inorganic phosphate released when ATP is hydrolised to ADP

Question 14

which exercise uses the most amount of ATP and how much?

Answer 14

maximal isometric contraction

12 mmol ATP/kg dm/s

Question 15

what is the role of myokinase in maintaining ATP homeostasis?

Answer 15

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

Question 16

what do changes in ATP and AMP indicate for control of metabolic rate?

Answer 16

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)

Question 17

what is energy charge and indicator of and how to work it out?

Answer 17

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]

Question 18

how is AMP prevented from accumulating after the myokinase reaction?

Answer 18

converted to IMP (2 pathways after by purine nucleotide cycle)
results in increased energy charge and continuing contraction

Question 19

what was the “old concept” of relative contribution to ATP resythesis?

Answer 19

that sequential activation and contribution of energy pathways (when one stopped the next one started)

Question 20

what is the “new concept” of relative contribution to ATP resynthesis?

Answer 20

overlap of contribution of energy pathways (different pathways working simultaneously)

Question 21

can fuel sources and energy sources be depleted?

Answer 21

fuel sources such as PCr and CHO can be depleted

energy sources such as ATP, GTP and UTP are regulated and cannot be depleted

Question 22

what are the 3 main adenylates in cells?

Answer 22

ATP
AMP
ADP

Question 23

what happens if AMP increases too much during exercise/

Answer 23

formed through breakdown of 2ADP in myokinase reaction

too much = energy charge of cell falls and not enough energy to continue exercise