BB451 exam 1 - Biosynthesis of Membrane Lipids Flashcards
phosphatidic acid
glycerol backbone with 2 fatty acids and phosphate
precursor of glycerophospholipids and fats
to create a fat…
replace phosphate of phosphatidic acid with fatty acid
phosphatidate –> DAG –> triglycerol
to make a glycerophospholipid…
add something to phosphate of phosphatidic acid –> phosphatidal compound
phosphatidate –> CDP-diacylglycerol–> glycerophospholipid
CDP - diacylglycerol
activated intermediate
donates phosphatidate part to something else (ex: serine –> phasphatidalserine)
activated intermediate
high energy to donate part of itself to something else
cells that contain fat
lipocytes
synthesis of DNA requires
energy, nucleotides, and other molecules made with them (proteins, glycogen, glycerophospholipids)
measure of nucleotides gives good measure of…
measure of nucleotides gives cells good measure of energy assessment, ability to use energy going forward
2 ways to make glycerophospholipids
activate diacylglycerol
activate thing that gets put onto diacylglycerol (ex: activate ethanolamine, add to CDP-diacylglycerol –> phosphatidylethanolamine
*both use activated intermediate and produce CMP
3 classes of sphingolipids
ceramides, cerebrosides, gangliosides
ceramide
collection of sphingolipids with fatty acid on them (addition of fatty acid to the amine group)
sphingolipids made from
palmitoyl CoA + serine manipulated to a ceramide
cerebroside or ganglioside formed by
addition of sugar to ceramide
sphingomyelin formed by
addition of phosphate group from phosphatidyl choline to ceramide
activated sugar has ..
nucleotide attached ex: UDP
deficiencies in enzymes that degrade sphingolipids lined to
neural disorders
ex: Tay-Sachs disease
cholesterol made from
Acetyl CoA
acetoacetyl CoA
2 acetyl CoA put together
HMG-CoA
3rd acetyl CoA added to acetoacetyl CoA
branch point for synthesis of ketone bodies or cholesterol
mevalonate
from HMG-CoA, path towards cholesterol
uses HMG CoA reductase
primary regulated enzyme in synthesis of cholesterol
HMG CoA reductase
regulated by feedback inhibition by cholesterol
statins
drugs to reduce cholesterol
target HMG CoA reductase
competitive inhibitors of enzyme (resemble HMG CoA, the substrate)
pathway of cholesterol synthesis
HMG CoA (6C) –> mevalonate (6C) –>isoprenes (5C) –> geranyl pyrophosphate (10C) –> farnesyl pyrophosphate (15C) —> squalene (30C) –> lanosterol –> 19 more steps to get to cholesterol
isoprenes
isopentenyl pyrophosphate and dimethylallyl pyrophosphate precursors to cholesterol can go back and forth between 2 each have 5 carbons come together --> geranyl pyrophosphate
farnesyl pyrophosphate formed by
addition of 5C isopentenyl pyrophostate to 10C geranyl pyrophosphate
squalene formation
2 farnesyl pyrophosphates
last linear intermediate
lanosterol
cyclic intermediate
look like cholesterol but still 19 mores steps
___ ATPs to get to squalene
18 ATPs to get to squalene
cholesterol important for synthesis of
steroid hormones (and vit. D) bile acids/salts
isoprenoid
made from isoprenes
ex: cholesterol, steroids, vit A and vit E
steroids
all compounds synthesized from cholesterol
ex: steroid hormones, vit D, bile acids
SREBP
plays role in controlling whether or not HMG-CoA reductase is made
3 components of SREBP
R = regulatory M = membrane portion D = DNA binding portion (bind to SRE)
when normal cholesterol levels, SREBP…
SREBP - ER
not need to make cholesterol
when cholesterol levels fall, SREBP…
moves to Golgi = SREBP-G
SREBP-G
serine protease cleaves to release MD regions
MD regions move to metaloprotease, cleaves D fro M
D enters nucleus, binds to promoter region (SRE) and HMG-CoA reductase is synthesized
