lecture 10 - lipid metabolism Flashcards
what are the different classifications of lipids?
simple (fatty acids), compound (triacylglycerols) and derived (steroids)
what is a fatty acid comprised of?
a long chain of carbon atoms
what is classified as a short chain fatty acid?
less than 8 carbons - found in milk fat
what is classified as a medium chain fatty acid?
8-14 carbons, found in milk fat and coconut
what is classified as a long chain fatty acid?
more than 14 carbons, makes up most of our diets
what is a saturated fatty acid?
no double carbon bonds
what does an unsaturated fatty acid have?
at least one double carbon bond - less tightly packed
what is a mono unsaturated fat (MUFA)?
one double carbon bond
what is a poly unsaturated fat (PUFA)?
more than one double carbon bond
where are lipids stored?
in adipose tissues as triglycerides
what is lipolysis?
break down of fat which takes place in fasting conditions
- takes place in adipose tissue
what hormone activates lipolysis at rest?
glucagon
what is the main hormone that activates lipolysis during exercise?
adrenaline
what is the primary regulator to how fast fatty acids are broken down?
HSL
what regulates the num of transport proteins?
high fat diet
what is beta oxidation?
generates energy, cuts off carbon atoms from the chain and changes it into acetyl coA - happens in the aerobic energy system
what needs to happen to a fatty acid before it is used for beta oxidation?
transported across the membrane
what does it mean relating to beta oxidation if the fatty acid is longer?
the more cycles it has to undergo
during beta oxidation what is removed at every step?
an acetyl coA
what is decreased during exercise to allow beta oxidation to occur?
malonyl coA
what is the amount of acetyl coa dependent on?
carb availability
is fatty acid synthesis reversible?
no - fatty acids can’t be converted to glucose but glucose can be converted to fatty acids
during fatty acid synthesis what happens?
more acetyl coa is transported so that they can combine to create 4 carbon molecules
is a fatty acid synthesis allosteric regulation?
no - there is a high degree of hormonal control which happens at a much slower rate
what is this reaction activated by?
insulin
what is this reaction inhibited by?
glucagon
what does ACC do?
dictates the speed of fatty acid synthesis
what is a ketone body?
3 diff molecules which are classified – they are only produced in small quantities, useful when glucose is low – can be used as an alternative fuel source
what is a ketogenic diet?
low protein, high fat – ketosis – produce so many ketone bodies to act as an alternative fuel source to glucose so that we rely less on glucose – can produce weight loss
The longer the fast goes on for the higher the number of ketone bodies
Can be dangerous conditions e.g. diabetes – excessively high num of ketone bodies
