metabolism and bioenergetics Flashcards
why do cells need metabolism?
cells need fuels and the ability to convert fuels into potential chemical energy in the form of ATP, which can be used for mechanical work
what is a calorie?
the amount of heat required to raise 1g of H2O by 1 degree from 14.5 to 15.5
what are the 3 metabolic phases?
digestive phase
interdigestive phase
fasting phase
what are the main substrates for energy at rest?
50% carbohydrates, 50% fats
what are the main substrates for energy in short exercise?
carbohydrates
what are the substrates for energy in long exercise?
carbohydrate and fat
why are erythrocytes completely dependent on glucose?
they contain little or no mitochondria
why does the brain have an absolute requirement for glucose as a fuel?
the brain has zero capacity for FFA oxidative, very little capacity for the use of lactate, ketone bodies and amino acids
what are the three pathways for ATP synthesis?
ATP-PCr (anaerobic)
glycolysis (anarobic)
Oxidative phosphorylation (aerobic)
what are the roles of the ATP-phosphocreatine system?
- recycling of ATP during exercise (3-5s) until all used up
- replenishing ATP
how is the ATP-phosphocreatine system regulated?
by a series of feedback loops
phosphocreatine is Pi + energy -ATP
pos feedback: high [ADP] stimulates creatine kinase = greater ATP
neg: ATP inhibits creatine kinase
where in the body is carbohydrate stored?
in the liver (110g) and in the muscle (500g)
what are the regulatory steps in glycolysis?
- hexokinase
- PFK1
- pyruvate kinase
what is the net yield of glycolysis from one molecule of glucose?
2ATP, 2NADH, 2 pyruvate
in OXPHOS, how many ATP are produced per: NADH? FADH?
NADH - 2.5
FADH - 1.5
what is the net ATP production from oxphos?
31-38
how is glycogen broken down?
as it is already phosphorylated, it can be broken down with a-glucosidase/glycolyltransferase to produce glucose-1-phosphate, which is then converted to glucose-6-phosphate by phosphoglucomutase
how is glycogen breakdown more efficient than glycolysis?
produces 3ATP rather than 2
what is the net ATP yield from metabolism of one molecule of palmitate?
128
what are the uses of lactate?
can be used as a substrate in the heart, or recycled in the liver
what does oxidative capacity of muscles depend on?
- presence of mitochondria
- enzyme activity
- fibre composition
- endurance training
- O2 availability
what are type type I, IIa and IIb muscle fibres responsible for?
I - used for everyday activities
IIa - short, high intensity endurance exercise
IIb - extremely short, high intensity
what is anaerobic training?
training at 90-100% max HR
interval training most appropriate
what is aerobic training?
70-90% of max HR
interval training and continuous training appropriate
