Lipids (general) Flashcards
5 types of lipids
Fatty acids, neutral glycerides, phospholipids, sphingolipids, cholesterol and derivatives
Five functions of lipids
Energy storage, membranes, messenger, hormone building blocks, covalent modification of proteins
What type of lipids do we eat?
Neutral glycerides (e.g. triglycerides)
Fatty acids come in three forms:
Saturated, unsaturated, and unusual (branched/plants)
What does saturated mean in terms of a FA?
No double bonds
What are the functional components of a FA?
Hydrocarbon chain and a carboxylic acid group
Fatty acids in humans have the following characteristics?
Even numbered (made by 2 carbons at a time), 12-24 carbons long, saturated or unsaturated, all double bonds are in cis configuration, DB in FA are separated by at least one CH2 group, unbranched.
T or F: Natural human FA can be trans and odd numbered
False to both counts
How do we notate FAs?
Number of carbons:Number of double bonds
If unsaturated: Delta(number of first atom from carboxyl group):N of Carbons: Number of bonds
What are alpha, beta…omega carbons?
1 Carbon is in the carboxyl group, alpha is first carbon attached to that an so on. Omega is always the last carbon
Beta oxidation happens on what carbon?
Beta carbon (second from the carboxyl carbon)
What is an omega-3 FA?
Double bond is on the third to last C (between 3 and 4) i.e. double bond starts on the 3rd carbon from the end (same nomenclature for omega-6)
For a human FA, what are the only possibilities for an additional double bond on a unsaturated FA?
+/- 3 from the first one e.g. 12 and 9 or 12 and 15 and so on
Longer the chain, the ________ the melting point and is more ________
higher, solid
The more cis double bonds, the __________ the melting point and more _________ property
Lower, more fluid
Unsaturated bonds lead to _________ increased rate of oxidation
Increased
What is the basic structure of neutral glycerides?
Glycerol that is esterified with FA up to three times
What determines the property of neutral glyceride?
The FAs attached
What is the structure of a phospholipid?
Same as FA except one of the FA is replaced with a phosphate group attached to an alcohol group (determines name)
What is the structure of a phospholipid?
2 fatty acids, glycerol, phosphate, and alcohol group
Where is cardiolipin found?
In inner mitochondrial membrane
What hydrophobicity do phospholipids have?
Amphipathic
What is the heiracrhcy of sphingolipids?
Sphingosine to ceramide to sphingomyelin and glycosphingolipids
Sphingosine is made into?
Ceramide
Ceramide is made into?
Sphingomyelin and glycoshingolipids
Where are glycosphingolipids found?
Blood cell antigens
What is the structural difference between sphingosine and ceramide?
FA added to sphingosine to make ceraminde
Sphingosine is a type of?
Long chain amino alcohol
Adding phosphotidylcholine to ceramide gives oyu?
Sphingomyelin
T or F: Glycosphingolipids are important for cell cell contact
T
What are the four general functions of cholesterol?
Essential membrane component, bile salts, steroid hormones, vitamin D
What is an apolipoprotein?
Lipoproteins on the outside of miscelles that direct the internal contents
How are triacylglycerols and cholesteryl esters transferred in the blood?
In phospholipid enclosed micelles
What are the four major types of lipoprotein carriers?
Chylomicrons, LDL, VLDL, and HDL
What is the size order largest to smallest of lipoprotein carriers?
Chylomicrons, VLDL, LDL, HDL
What do chylomicrons primarily transport?
Triglycerides
What do VLDLs mainly carry?
Triglycerides
What do LDL mainly transport?
Cholesterol
What do HDLs mainly transfer?
Protein
T or F: High LDL is bad prognosis for heart disease
T
LDL has only one type of apoprotein:
B-100
Mutation of B-100 leads to issues with what?
LDL
Mutation in B-48 apoprotein leads to issues with potentially?
Chylomicron
Triglycerides in the diet are primarily transported by?
Chylomicrons
VLDL carry fat from where?
The liver to tissue
What tissues primarily need FA?
Adipose, lung, muscle
What is the percentage composition of triglycerides from highest to lowest for lipoproteins?
Chylomicron, VLDL, LDL, HDL
What is the percentage composition of cholesterol from highest to lowest for lipoproteins?
LDL, HDL, VLDL, CM
Liver AND intestine make this type of Lipoprotein
HDL, deliver from tissues to liver for elimination
VLDL generates?
LDL to deliver cholesterol to tissues and liver
Liver generates?
VLDL to deliver endogenous FA to peripheral tissue
Intestine generates?
CM to deliver dietary FA to peripheral tissues
Endogenous FA is transported by? Exogenous FA?
VLDL, CM
What is the function of bile salts?
Emulsification of lipid droplets in small gut
Bile salts are made in?
The liver
Bile salts are stored in?
Gall bladder
How much bile salt is used each day? Lost?
15-30 g and 0.5 g/day
What is bile made from?
Cholesterol
What is PTL?
Panceratic triglyceride lipase. Released from pancreas to hydrolyze a TAG into a monoacylglyceride and 2 free FA salts
What happens to the FA salts and monoacylglyceride from PTL?
Rejoined in the intestinal mucosal cells and pushed into lymphatic vessel and to the blood stream
What transporter is responsible for bringing fat derivatives from the intestinal lumen into the enterocytes in the mucosa?
FATP4 transporters
What apoproteins cover chylomicrons?
B-48, C, and E
CM carry what in addition to TAGS?
Fat soluble vitamins
What is the function of LPL?
In all tissue, cleaves FA off and makes 3 FA and glycerol. Glycerol is water soluble and FA is used by tissue
What is steatorrhea?
Fat in stool due to absorption issues
What is abetalipoproteinamia?
B-100 defect causing no FA or ADEK vitamin absorption
What are the five main functions of adipose?
Energy storage, protection of organs, insulation, soluble fat vitamin storage (ADEK), synthesis of adipokines (hormones from fat, usually peptide hormones)
Two body shapes, two types of fat, worse for disease?
Apple, Pear. Subcutaneous, Visceral. Visceral is worse.
T or F: Adipose cells grow in volume not in number
T (generally)
When does adipose number typically stabilize?
Early 20s
What happens in the fed state in regards to fat?
High insulin. Glucose taken to glycerol-P for TAG. Glucose to Acetyl-CoA to FA to TAG. CM and VLDL deliver to FA which is taken to TAG
What happens in the fasting state for adipose?
TAG acted upon by Hormone Sensitive Lipase (HSL, only in adipose) and made into FA and glycerol. FA is carried by albumin in serum to where needed
What is HSL?
Hormone sensitive lipase which breaks down TAG in adipose during fasting state (only in adipose)
In adipose, what happens when glucagon/epinephrine is conjugated to receptor?
cAMP to PKA activation. Phosphorylates HSL to make it active.
In adipose, what happens when insulin is conjugated to receptor?
Activates PDE (phosphodiesterase) to take cAMP to AMP which causes HSL to become dephosphorylated to become inactive
What is leptin?
An adipokine that inhibits hunger and increases metabolic rate
Where is leptin made? Effects? Long or short?
Adipose, dec. appetite, inc. caloric expenditure, long term effect
What is ghrelin? Where is it made? Effects?
Produced by stomach, increases appetite, short and long effects.
T or F: Bile salts decrease weight gain
T (by increasing energy expenditure via brown fat)
What are beige/brown fat cells?
Adipose cells that undergo thermogenesis to waste energy
What are phospholipases?
Break down phospholipids.
What bond in phospholipids is important to know?
C site (between the glycerol and phosphate group). Important for signal transduction
Where does Degredation of sphinosines occur?
In the lysosome
What is sphingolipodosis?
Failure to break down sphigosines leading normally to CNS issues
What is Tay-Sachs diesease?
Failure to break down ganglioside GM2 which is a glycosphingolipid due to an enzyme deficiency in the lysosome
What can cross the lipid bilayer?
Small uncharged polar molecules, gases, and urea. Ions, large molecules, water, charged molecules cannot
What is endocytosis?
Eating of external particles. Autophagy is a special type of endocytosis
What are coated pits usually rich in?
Receptors in order to endocytose molecules specifically
T or F: Endosomes are low in pH?
True to release contents from receptors
What is transferrin?
An important receptor for ion. Apo-transferrin is attached to two irons and brought in in receptors. Acidified to release from receptor the iron
T or F: LDL is taken up by cells
T (all other lipoproteins are not taken up, LDL has a receptor)
Name the four functions of cholesterol
Essential membrane component, bile salts, steroid hormones, vitamin D
T or F: Plasma levels of cholesterol are linked to death rate
T
T or F: Dietary cholesterol has a major effect on plasma cholesterol levels
F
How is cholesterol degraded?
Trick question. There is no degradation pathway. It is excreted as bile salts
What precursor molecule is cholesterol synthesized from?
Acetyl CoA
What is the cholesterol production/intake rate for body?
0.5 g/d from diet and 0.5 g/d from synthesis
What is the rate limiting step for cholesterol synthesis?
HMG-CoA Reductase
What do statins do?
Block HMG-CoA reductase step in synthesis
LDL-Receptors are rich in what apoprotein?
B-100
What is familial hypercholesteremia?
Disorder of high plasma cholesterol, typically a mutation in apoB100, autosomal dominant
When is cholesterol made de novo?
When there is no LDL in the blood serum
What is SRE?
Sterol Receptor Element in nucleus
How is cholesterol synthesis controlled on cellular level?
SREBP is activated (SRE-binding protein) which activates BOTH LDL receptor synthesis and HMG CoA reductase synthesis
T or F: LDLR and HMGCR are co-regulated? By what?
T (Sterol Receptor elements)
How does high LDL lead to plaque in bloodstream?
LDL gets oxidized and is consumed by macrophage which becomes a foam cell if too many are eaten. Builds up plaque on the endothelial cells.
