Lipid Review Flashcards
Characteristics of lipids? (hydrophilicity, solubility, polarity, components)
Hydrophobic, insoluble in water, non-polar, long hydrocarbon chains (many C-C and C-H bonds)
what are the two types of glycerolipids
Triacylglycerol and phospholipids
Both contain a glycerol backbone
Structure of a glycerol backbone
Types of fatty acids? Differences?
Saturated: no double/triple bonds
Unsaturated: has double/triple bonds
types of non-glycerolipids?
Sphingolipids, waxes, and sterols (example of sterol is cholesterol)
Types of lipid complexes?
Lipoproteins (extracellular)
lipid droplets (intracellular)
Characteristics of unsaturated and saturated fatty acids? (MP, state at room temp)
unsaturated (double bonds): Low MP, liquid at room temp
Saturated (no double bonds): higher MP, solid at room temp
What are the two things all fatty acids have?
All have a carboxyl carbon and a long carbon chain
Fatty acid nomenclature
1st number: how many carbons
2nd number: how many double bonds
3rd number: position of double bond/s
What are the following components of?
Phospholipids, triacylglycerol, cholesterol + fatty acids, proteins attached to certain fatty acids
Phospholipid: membrane structure, cell signaling
Triacylglycerol: Stored energy, source of ATP
Cholesterol + fatty acids: cholesterol ester
Proteins attached: membrane attachment
Sources of Fatty acids
Diet and synthesis
How are fatty acids synthesized
synthesized from acetyl CoA
Products of FA oxidation
Acetyl CoA, FADH2, NADH
How are phospholipids organized in a lipid bilayer
Polar head group point out,
non-polar tails point inwards
why does fatty acid composition of phospholipids regulate membrane fluidity
They are rigid enough to be a barrier and flexible enough to allow transports of proteins, lipids, other molecules
function of glycosylphosphatidylinositol (GPI) anchors? How many human proteins are GPI-anchored proteins?
Functions to tether proteins to outside of cell membrane, 150 human proteins are GPI-anchored
T/F Different cellular membranes have the same phospholipid compositions
false
how can lipid asymmetry regulate signals
Rearranging, certain types of phospholipids from inside to outside can activate enzymes that need that specific phospholipid to activate. exposure to PS to outer regions that are - charged can interact with proteins that are + charged
how does lipid asymmetry allow for membrane curvature
Different phospholipids have different shapes usually dictated by head group, a mixture of different phospholipids allows for necessary curvature and flexibility of a membrane.
What shape is phosphatidylcholine and phosphatidylethanolamine?
Phosphatidylcholine: cylindrical, flat sheets
Phosphatidylethanolamine: conical, curvature
How are fatty acids connected to glycerol
by an ester bond
Why do we store TG instead of fatty acids?
Fatty acids are toxic at high concentrations. (abnormal cell signaling, dissolve cellular membrane)
TG are chemically inert and we can store lots of TG for energy
T/F TG have a mixed FA composition in different tissues
True
Kennedy pathway of lipid synthesis
What tissue is responsible for TG storage
Adipose tissue, TG also found in liver, small intestine, and mammary gland
Describe the catabolism of stored fat in adipose tissue?
When blood glucose is low, lipases will break down TG, the fatty acids will then undergo B-oxidation to create CO2 and ATP in muscle
Functions of cholesterol
Makes bile acids (important for absorption of nutrients)
Important for membrane structure (30-50% of lipids in membrane are cholesterol)
Precursor of steroids
what is atherosclerosis? Causes?
Build-up of plaque in arteries that can lead to blood clots
Caused by increased cholesterol
Review sources of cholesterol slide
Functions of chylomicrons, VLDL, LDL, and HDL
Chylomicrons and VLDL: transport TG (still carry some cholesterol)
LDL and HDL: Transport Cholesterol (still carries a little TG)
Rank chylomicrons, VLDL, LDL, and HDL in terms of size
Largest
Chylomicrons
VLDL
LDL
HDL (most dense, heavier)
Smallest
Which cholesterol is bad and which is good
LDL = bad
Most of the body’s cholesterol is bad, increases risk of heart disease and stroke
HDL = good
Carries cholesterol from tissues to the liver
excreted from the body in bile
lowers risk for heart disease and stroke
What are the uses of phosphatidylcholine and phosphatidylethanolamine
Uncharged,
PC: structural
PE: structural/protein tether
What is the use of phosphatidylinositol and phosphatidylserine
Net negative charge
PI: signaling, protein tether
PS: apoptosis, blood clotting
Kennedy pathway of lipid synthesis
Starts with glycerol 3-Phosphate which is acted on by acyl transferase twice to attach two fatty acids one to C1 and one to C2, resulting in phosphatidic acid. Phosphate is then removed from phosphatidic acid by phosphatidic acid phosphatase to become 1,2 diacylglycerol. Where it is then acted upon by acyl transferase gain another fatty acid onto C3 to become triacyl glycerol
Describe cholesterol synthesis (main enzyme)
Starts with 3 acetyl CoA which then undergoes multiple reactions until it comes to a reaction catalyzed by HMG- CoA reductase. HMG CoA reductase regulates cholesterol metabolism. After that reaction, it will eventually become cholesterol which in turns provides feedback onto HMG CoA reductase to reduce synthesis
Four types of lipids
Fatty acids
GLycerolipids
Non-glycerolipids
Lipid complexes
