LIPIDS Flashcards
week 3 lect 2 Ioannis
biological lipid?
generally insoluble in water but soluble in organic solvents, they’re hydrophobic
Biological functions of lipids?
storage of energy
insulation from environment
protection of organs
water repellent
buoyancy control and acoustics in marine mammals
membrane structure
cofactors for enzymes
signalling molecules
pigments
antioxidants
inflammation
digestion
when a fatty acid is not a component, what is it referred to as?
a free fatty acid (FFA) or an un-esterified fatty acid
what is the fatty part of a fatty acid?
the hydrocarbon chain (H and C atoms) - it is the hydrophobic portion
what is the acid part of a fatty acid?
the carboxyl group - it is the hydrophilic portion
What are monounsaturated fatty acids?
have a single double bond between two carbons in the chain - usually results in a kink
What are polyunsaturated fatty acids?
have multiple double bonds between different carbons
the more double bonds in an unsaturated fatty acid?
the more fluid the fatty acid and the lower the melting point
MUFA?
monounsaturated fatty acids
PUFA?
polyunsaturated fatty acid
Why do reindeer’s have a high proportion of PUFA’s in the cell membranes of a reindeer’s leg near the hoof?
always in contact with cold snow - always cold and we need to maintain the fluidity of the membrane
Multiples PUFA’s - not stacked due to the kinks, so it is not tightly packed, if too rigid there are issues with ion channels and transport over the membranes
alpha carbon?
carbon number 2 on a fatty acid
what are omega-3 FAs considered as?
anti-inflammatory
what are omega-6 FAs considered as?
pro-inflammmatory (arachidonic acid)
Name three arachidonic acid derivatives?
Prostaglandins, Thromboxanes, Leukotrienes
What does NSAIDs block?
inflammation pain and fever (bad stuff)
BUT ALSO
mucosal protection, renal blood flow and haemostasis (GOOD STUFF)
Triacylglycerols (triglcerides / TAGS)
thre fatty acids linked to a glycerol
ester bonds can be hydrolysed by?
enzymes called lipases or esterases –> secreted by pancreas
where does the ester bond form in a triglyceride?
between the three OH groups in glycerol forms an ester bond with the carboxyl group of a fatty acid
FAs are converted into TGAs within the cell and exported in the blood as part of the?
Lipoprotein pathway (and/or chylomicrons)
why does cholesterol go in and out of the liver again and again?
so it can be re-packaged and can be sent to the tissues that need it
where are triglycerides stored?
in the ‘fat tissue’
(adipose tissue formed of adipocytes)
Lipogenesis?
synthesis of fatty acids/TAG
Process of lipogenesis?
acetyl coA (from glycolysis/pyruvate)
NADPH is required for each additional acetyl coA
Plus glycerol (from glucose) to form TAGS
Happens mainly in the liver
Main pathway for getting rid of excess glucose
TAGS are exported from the liver cells as VLDL to other tissues
Beta oxidation, where does it happen?
mitochondria
fatty acids cannot cross the?
double membrane of the mitochondria
why can the brain not utilise the FAs as energy?
as the FAs cannot cross the blood brain barrier
what transports fatty acids into the mitochondria?
the carnitine shuttle
4 stages of the carnitine shuttle?
- fatty acid bound to CoA –> fatty acyl CoA
- CoA exchanged for carnitine –> acyl carnitine
- Acyl carnitine translocated by facilitated diffusion with unbound carnitine
- Carnitine on acyl carnitine exchanged for CoA
excess acetyl CoA is converted into?
ketones
what types of ketones is acetyl coA converted into?
acetoacetate
B-hydroxybutyrate
Acetone (spontaneous)
What are the four components of glycerophospholipids?
Two fatty acids
Glycerol
Phosphate
Polar head group (variable choline demonstrated)
What are sphingolipids?
similar to phospholipids –> hydrophilic and hydrophobic component
ONLY ONE FATTY ACID
Sphingomyelin consists of?
phosphocholine head group
sphingosine
a fatty acid
ceramide?
a fatty acid and sphingosine
cholesterol?
a sterol (AKA steroid nucleus)
name 5 steroid hormones?
sex hormones
cortisol
aldosterone
steroid drugs
brassinolide
what does detergent do?
it solubilises lipids and makes them water-soluble
bile acids act as?
biological detergents
what breaks fats up and what into?
into smaller droplets ( or micelles) to aid digestion and this is done by bile acids (biological detergents)
sigmoidal?
S-shaped curve
at lower temperatures, adding cholesterol does what to fluidity of the cell membrane?
increases the fluiditiy
at higher temperatures the addition of cholesterol does what to the fluidity of the membrane?
reduces fluidity
why fluidity important?
for faciliated diffusion, too rigid, the diffusion won’t happen
what are the fat soluble vitamins?
A,D,E,K
what are the water soluble vitamins?
B,C
what is vitamin D necessary for?
calcium absorption from the small intestine
is vitamin A hydrophobic/philic?
hydrophobic
vitamin A is aka?
retinol
what can retinol be produced from?
b carotene
what can retinol be converted into?
11-cis-retinal
what can 11-cis-retinal be converted into?
retinoic acid
is vitamin hydrophobic/hydrophilic?
hydrophobic
what prevents blood from clotting?
warfarin-based rodenticides as it makes vitamin k not in reduced form anymore
vitamin a involved in what activity?
both osteoclastic and osteoblastic activity –> high liver diet led to inappropriate bone formation
why is excess vitamin A toxic but excess vitamin C is not?
because vitamin C is water soluble and we can excrete via urine whereas vitamin A is not water soluble so we cannot excrete
