metabolic stores Flashcards
(37 cards)
where is glycogen stored in the body?
liver and skeletal muscles
how many hours of moderate exercise is the store of glycogen sufficient for?
3-5 hours
what is the main source of alternative fuel stores in the body?
triglycerides
what is the structure of one molecule of triglyceride?
one glycerol and three fatty acids joined by esterification reaction
what type of enzymes break down triglycerides into glycerol and fatty acids?
lipases
what happens to the glycerol that is released during this process?
it is used in glycolysis to produce pyruvate
what happens to the fatty acids that are released by the lipase enzymes from the triglycerides?
the fatty acids are linked to coenzyme A, they are then oxidised to remove 2 carbon acyl units from the fatty acids which are used as acetyl coA in the citric acid cycle
whereabouts in the body are fatty acids mainly metabolised?
in the liver
what happens to the electrons that are passed from the fatty acids when they are oxidised?
they are passed along the respiratory chain, indirectly reducing ATP
when no other fuels are available, why does the breakdown of fatty acids lead to the formation of ketone bodies?
because oxaloacetate levels are depleted and therefore cannot be combined with the acetyl coA from fatty acid breakdown. The acetyl coA is therefore converted to ketone bodies.
what are the three main ketone bodies?
acetoacetate, 3-hydroxybutyrate and acetone
why is oxaloacetate depleted when there are no other fuels available?
because the liver converts it to pyruvate to produce glucose.
what happens to amino acids in the diet that are not required for building new protein?
they are used as a metabolic fuel
what happens when an amino acid is DEAMINATED?
its amino group is removed to produce NH4 and a keto acid that can be used in the citric acid cycle or in glycolysis
what happens to amino acids that cannot release their amine group as NH4?
TRANSANIMATION: they pass their amino group to a keto acid which can then be deaminated, and they are covered to a veto acid which can be used in glycolysis or citric acid cycle
what happens to the NH4 which is produced during TRANSAMINATION?
it is broken down to form urea in the kidneys and excreted
what is GLUCONEOGENESIS?
the formation of glucose from non-carbohydrate sources
what substrates can be used for gluconeogenesis?
glycerol, amino acids (Alanine), lactate and pyruvate
where does glycerol come from for lipid synthesis?
glycerol can be made from glucose through GLYCOLYSIS
where do fatty acids come from for lipid synthesis?
two carbon acyl units from acetyl CoA (from pyruvate) are linked together to form fatty acids by fatty acid synthetase
where are triglycerides mainly stored in the body?
in adipose tissue
what is the type of fuel most efficient for the body to use?
carbohydrate
what is the largest source of MOBILISABLE proteins in the body?
muscle
what is the only fuel the brain can use?
glucose
