Lipid Advanced Metabolism Flashcards
(119 cards)
1
Q
Endogenous lipid comes from where?
A
Within the body
2
Q
Exogenous lipids come from where?
A
Outside the body through the diet e.g. burgers n pizz
3
Q
Define Lipid
A
A biological substance that is insoluble in water but soluble in organic solvents such as alcohol, chloroform, ether, and acetone. Some phospholipids are not soluble in acetone & some have limited solubility in H2O.
4
Q
What does the body use lipids for in terms of nutrition?
A
Primary source of fuel for the body
5
Q
What is the significance of lipids to structure of cells?
A
- Gives cell membrane stability and rigidity
*Allow for transmembrane transport of important molecules
6
Q
What kind of hormones have lipids
A
Steroid hormones such as… vitamin D, cortisol, and aldosterone.
7
Q
What kind of fat produces heat?
A
Brown. Fat
8
Q
What is the fat surrounding nerves and help conduct signals in the neuron?
A
Myelin sheet
9
Q
List major lipids
A
*Free fatty acids
*Phospholipids
*Cholesterol (free & esterified)
*Triglycerides
*Glycolipids
*Prostaglandins
10
Q
What are triglycerides made up of?
A
Glycerol esters combined with free fatty acids. Refer to Major lipid slide
11
Q
What kind of fatty acid has no double bonds?
A
Saturated fatty acids
12
Q
What kind of fatty acid has one double bond?
A
mono-unsaturated fatty acid
13
Q
What fatty acid has 2 or more double bonds?
A
Polyunsaturated fatty acid
14
Q
what’s the range of carbons for a short chain FA?
A
4 - 6 carbon atoms
15
Q
What’s the carbon range for a medium - chain FA?
A
8 - 12 carbon atoms
16
Q
What’s the carbon range for a long chain FA?
A
12 + carbon atoms
17
Q
Complete the phrase; _____ are essential component of cell membranes.
A
Phospholipids
18
Q
What acts as a detergent in clearing other fats out of the body?
A
Phospholipids
19
Q
What is the term to describe a molecule that has a hydrophilic and hydrophobic structure?
A
Amphiphilic structure
20
Q
Cis versus Trans fatty acids?
A
21
Q
Where are phospholipids synthesized?
A
Liver & intestinal epithelium
22
Q
What are three kinds of important phospholipids?
A
- Lecithin (phosphatidyl choline)
- Cephalins (phosphorylated ethanolamine, inositol, and serine)
- Spingomyelin (spingolipid)
23
Q
Cholesterol has a ______ ring with side chain of carbon atoms.
A
Perhydrocyclophenanthrone ring with side chain of carbon atoms
24
Q
Cholesterol (endogenous) is made from what?
A
Acetyl - CoA
25
What is the product of the enzyme aceto acetyl CoA synthetase?
Aceto acetyl CoA
26
What is the product of HMG - CoA Synthetase?
HMG - COA important for cholesterol or ketogenesis
27
What is the rate limiting enzyme in cholesterol synthesis?
HMG - CoA Reductase, a build up of HMG CoA will suggest a defect in HMG CoA reductase.
28
What are the important functions of cholesterol? (Name 4)
1. Manufacture & repair of cell membrane
2. Synthesis of Bile acids
3. Synthesis of Vitamin D (steroid hormone)
4. Precursor of five major classes of steroid hormone (Progestins, glucocorticoids, mineralocorticoids, androgen, and estrogen)
29
What are the five major classes of steroid hormones?
1. Progestins
2. glucocorticoids
3. mineralocorticoids
4. androgen
5. estrogen
30
Surplus cholesterol goes where?
Into the bile acid synthesis pathway to help digest fat (turns fat into droplets)
31
Where is endogenous cholesterol made in the body?
The liver
32
What is the purpose of LCAT, lecithin cholesterol acyltransferase?
Trasnfer FA from Carbon 2 of phosphatidylcholin to cholesterol
33
If there is a deficiency with LCAT, lecithin cholesterol acyltransferase, what will we see?
Elevated levels of cholesterol
34
LCAT, lecithin cholesterol acyltransferase is bound to what protein?
Lipoprotein (HDL)
35
Acyl - CoA : cholesterol acyltransferase (ACAT) does what?
Catalyzes the formation of CoA and cholesterol ester
36
A person with high cholesterol is at risk for what?
Cardiovascular disease
37
Where does esterification of cholesterol by LCAT take place?
Plasma
38
Hydrolysis of cholesterol takes place where?
Liver
39
What fat is considered majority of neutral fats?
Triglycerides
40
What is triglycerides made of?
A glycerol ester + 3 Fatty acids
41
Triglycerides are a main storage form of _____?
Fats
42
Stored triglycerides can be catabolized into what during fasting or between meals?
Free fatty acids
43
Where do plasma triglycerides come from?
Intestine and liver
44
Intestinal triglycerides come from where?
Dietary fat
45
What organ is the manufacturer of plasma triglycerides?
Liver
46
If a patient requires a lipid profile what do they need to do?
Fast for about 12 hours
47
Cerebroside contains what?
Ceramide with a sugar at the 1 - OH moiety.
48
Glycolipids include two other groups. What are they?
Gangliosides and membrane glycosphingolipids
49
This glycolipid lipid is important for cell recognition. What is it?
Membrane glycosphingolipids
50
What is the major membrane lipid of CNS called?
Gangliosides
51
Describe the prostaglandin structure.
Long chain polyunsaturated FA (eicosanoids) with C20, including a cyclopentane ring.
52
Prostaglandins are synthesized from what two things?
Arachidonic acid and other polyunsaturated fatty acids
53
A subscript means what on a prostaglandin?
It means the number of carbon double bonds.
54
Describe prostaglandin's influence on the body.
* Important in chemical cell communication (paracrine)
* Functions like a hormone but not a hormone
* Not stored but made as needed b/c of short half life.
55
What are the three phases of lipid metabolism?
*Digestive phase (intra luminal phase)
*Absorptive phase (cellular phase)
* Transport phase
56
What must happen before fats interact with pancreatic enzymes?
They must be emulsified by bile salts
57
What are the two enzymes that processes fat?
Lipase and cholesterol esterase
58
Lipase converts triglycerides into what?
diglycerides and monoglycerides.
59
Cholesterol esters will be converted by lipase and cholesterol esterase into what?
Free cholesterol & free fatty acids
60
What enzyme converts phospholipids into derivatives (lyso-derivatives)?
Phospholipase
61
After enzyme action on triglycerides, what is formed?
mixed micelles (emulsified lipids)
62
Micelles are made of what?
Monoglyceride, Diglyceride, Free fatty acid, free cholesterol, phospholipids, and bile acids
63
Describe how micelles get absorbed into the intestines (absorptive phase).
1. Micelles come in contact with mucosal cell
2. Monoglyceride and fatty acids enter the ER of cell (via diffusion)
3. Smaller Free fatty acids (10 or lower carbons) go directly into portal circulation & attach to albumin.
4. Within intestinal cells the free fatty acids (10C +) are re-esterified to form Triglyceride and cholesterol esters.
5. Lipids packaged into chylomicrons for transport (circulation)
64
Describe the transport phase for the chylomicrons.
1. Mucosal cells release chylomicron into abdominal lymphatics (several hrs after meal). This is considered reverse pinocytosis
2. Chylomicrons enter the systemic circulation
3. Chylomicrons are carried to the liver (via the bloodstream) and other tissue for use / metabolism.
65
What is the apolipoprotein specific for chylomicron transport?
APO B48
66
What is the percentage make up of a chylomicron?
* 82% triglyceride
* 9% cholesterol
* 7% phospholipids
67
What is the destination for chylomicrons?
All tissue; adipose tissue is the principle site of uptake
68
A chylomicron has offloaded triglycerides with the help of triglyceride lipase. What is the new protein carrier called?
LPL
69
What is the fate of TG remnant remains?
Removed by the liver
70
What is TG remnant remains made of?
Triglyceride poor, cholesterol rich, highly antherogenic lipoprotein
71
What are the uses of lipid?
1. Metabolic fuel
2. Synthesis into other material
3. Complexed into specific lipoprotein carriers by liver for transport
4. Excess TG stored in adipose tissue
5. Excess cholesterol excreted as bile salt
72
Lipid synthesis is what kind of feedback?
Negative feedback
73
What are the site of lipid synthesis?
Liver, intestines, and other tissue
74
What tissue / organ is the primary site of endogenous lipid production?
Liver
75
What are newly packed chylomicron called?
VLDL
76
Describe fatty acid synthesis
Successive addition of two carbon units derived from malonyl CoA which allow four carbon intermediates.
77
What is the rate limiting step in fatty acid synthesis?
Acetyl CoA carboxylase + Biotin
78
What inhibits acetyl CoA carboxylase?
Long chain acyl CoA.
79
What activates Acetyl CoA Carboxylase?
Citrate
80
Fatty acid synthesis not only provides fatty acid but also ____
NADPH for other chemical pathways
81
How many molecules of what is required to make one molecule of palmitate?
8 Acetyl CoA; Yields 8 NADPH via malic enzyme rxn
82
14 molecules of NADPH is required to make one molecule of palmitate. Where do the 7 molecules of NADPH if fatty acid synthesis makes 8 NADPH?
The additional NADPH come from Pentose Phosphate Pathway
83
List short term regulation of Acetyl CoA carboxylase (FA synthesis)
Allosteric activation - Citrate,
Allosteric inhibition - Long chain acyl CoAs,
Enhancement: Insulin, Dephosphorylation,
Inhibition: Glucagon, phosphorylation of cAMP
84
List long term regulation of acetyl CoA carboxylase (FA synthesis)
Enhance enzyme synthesis: High carb diet, Fat free diet,
Decrease Enzyme synthesis: High fat diet, Fasting, Glucagon
85
List long term regulation of fatty acyl CoA synthase
Enhanced Enzyme synth: High carb or Fat free diet
decreased Enzyme synth: High fat diet, fasting, glucagon
86
What is the most commonly occuring fatty acid that is natural?
Palmitic Acid
87
What is the purpose of the carnitine cycle?
To transport long fatty acid chains
88
Describe beta oxidation
Removal of 2 carbons at the beta carbon (2nd carbon). The product is ATP and acetyl CoA
89
Between alpha or beta oxidation, which yields more energy?
Beta oxidation. Alpha oxidation does not yield a lot (2 ATP less / double bond) however NADP + is made.
90
The lack of alpha oxidation in a person leads to what? Describe the genetics aspect of it too.
Deficiency of alpha oxidation leads to Refsum's disease. Its an autosomal recessive neurological disease.
91
What is the fate of uneven carbon fatty acids?
They get oxidized to propionyl CoA and bicarbonate. They are then converted into succinyl CoA (a precursor of oxaloacetate).
92
List apolipoprotein functions
1. Maintain structural integrity of complex and ensure solubility of complex
2. Activate important enzymes in lipoprotein metabolic pathways
3. Facilitate uptake of lipoprotein into cells through their recognition by specific cell surface receptor.
Note: Different Apo proteins require their own specific receptors
93
Describe APO A - 1
1. Major APO of HDL
2. Structure protein activates LCAT
3. Ligand for HDL binding
94
Describe APO A-II
1. Structural protein in HDL
2. Activates LCAT
3. Enhances hepatic TG lipase activity
95
Describe APO B
1. Large major structural protein in VLDL & LDL forms
2. APO B 100 synthesized in liver found on VLDL, IDL, and LDL
3. APO B-48 in intestine - Found on chylomicrons
96
Describe APO E
1. Binds to LDL receptor & chylomicron remnant receptor
2. Several isoforms
97
Describe APO (a)
1. Strucural protein for Lp(a)
2. Highly glycosylated apo
3. May inhibit plasminogen binding
98
What method would be use to separate lipoproteins?
*Ultracentrifugation based on density; VLDL, LDL, HDL, etc.
*Electrophoresis results in separation based on electrical charge of the
protein
99
What would be needed for electrophoresis for lipoprotein separation?
1.Agarose or cellulose acetate
2. Barbital buffer or stain with fat stain
Bands that may appear are beta band (cholesterol and LDL), pre - beta band (TG and VLDL) , and alpha band (HDL)
100
How would the layers look like after lipoprotein has been ultracentrifuged?
* Chylomicrons
* VLDL-Very Low Density Lipoproteins
* IDL-Intermediate Density Lipoproteins
* LDL-Low Density Lipoproteins
* HDL-High Density Lipoproteins
101
What are the units used to represent densities of lipoprotein?
Svedberg units (Sf); Low density = high Sf ; High density = low Sf units
102
Describe how lipids are transported if they go through the endogenous pathway.
Hepatic lipids transported by VLDL and LDL to peripheral tissue.
103
Describe how lipids are transported if they go through the reverse cholesterol pathway.
Transports cholesterol via HDL from peripheral tissues back to the liver for excretion or reuse.
104
List the steps of reverse cholesterol pathway
1. HDL produced mostly in liver
2. In intestine, HDL binds free cholesterol from peripheral cells (macrophages)
3.Cholesterol esterified by LCAT
4. Cholesterol ester delivered to liver for eventual excretion
***Direct uptake of HDL by liver via Apo A
***Apo E containing HDL binds LDL receptor or remnant receptor
*** HDL exchanges cholesteryl ester to VLDL / LDL for TG
105
What is the protein that facilitates transfers of cholesterol ester?
CETP, cholesteryl ester transfer protein slide 53
106
Where does the HDL assembly take place?
In the blood circulation
107
Describe LDL rececptors
▪ APO B-100 and APO E
▪ Cell binding
▪ Uptake and degradation of LDL
▪ Synthesis inhibited by high cholesterol level
▪ Defective receptors stimulates intracellular cholesterol synthesis
108
Describe remnant receptors
▪ APO E
▪ Clearance of chylomicron and β-VLDL remnants from blood circulation
109
Describe scavenger receptors
▪ Surface of macrophage and muscle cells
▪ Mediate removal of modified LDL from blood circulation
▪ Macrophage with high cholesterol accumulation: Foam cells
110
How does cardiovascular disease happen?
From lipids being deposited into vessels over time. This leads to an occlusion.
111
A high fat diet will lead to what?
Increase in endogenous production which may result in arterial plaque formation
112
A disease or condition where plaque forms in the heart.
Coronary heart disease or coronary artery disease
113
A disease where plaque forms in the arms and or legs is what?
Peripheral vascular disease
114
A disease where plaque forms in the brain is what?
Cerebrovascular disease
115
What kind of information is gained from a lipid profile?
1. Total and HDL cholesterol
2. Measured or calculated LDL cholesterol
3. Triglyceride determination
3. Lipoprotein electrophoresis
116
List the formula for VLDL
TG / 5
117
What is the formula for LDL?
LDL = total cholesterol - VLDL - HDL
118
_______ relationship between HDL cholesterol & coronary risk
Inverse relationship
119
What would invalidate LDL / HDL cholesterol risk ratio?
Chylomicron present ( sign of patient did not fast) and serum triglyceride greater than 400 mg/dL
