(M) Lec 4: Lipids and Lipoproteins (Part 1) Flashcards
- referred to as “fats”
- is composed of C and H (hydrocarbons)
- is soluble to ORGANIC acids but insoluble in water
- functions as metabolic fuel, membrane stabilizers, and has many uses in different metabolic pathways (precursor for steroid hormones)
Lipids
Familiarize with the 5 major lipids
- Phospholipids (most abundant)
- Cholesterol
- Triglycerides
- Fatty Acids
- Fat-Soluble Vitamins (A, D, E, K)
Lipids provide how many times more energy than carbohydrates and proteins?
Twice as much
Match the ff. functions to the right fat-sloluble vitamin:
- For the eyes to avoid blindness
- For coagulation factors
- Prevents bone disorders and rickettsia
- An antioxidant
A, D, E, or K (provide all 4)
Sorry I’m trying to compress the cards as much as possible so just answer it altogether
- A
- K
- D
- E
Classification of Lipids
What are the 2 glycerol esters?
- Triglycerides
- Phosphoglycerides
Classification of Lipids
What are the 2 sterol derivatives?
- Cholesterol
- Phytosterol
Note: Sterols have RINGS (thank you beyonce)
What is the 1 sphingosine derivative/sphingolipid?
Ceramide
Note: The derivatives have 2 fatty acids attached to sphingosine
Classification of Lipids
This accounts for the 4 fat-soluble vitamins (A, D, E, K)
Terpenes
- a long chain of C-H bonds that terminate with a carboxyl group (RCOOH)
- the building blocks of lipids
- is mostly bound with albumin
- product of TAG hydrolysis and adipose tissue
- e.g. palmitic, stearic, oleic, linoleic, and arachidonic acid
Fatty Acids
Classification of Fatty Acids
As to length, choose among the ff.:
1. Short chain
2. Medium chain
3. Very long chain
4. Long chain
A. > 12 C atoms
B. 4-6 C atoms
C. 8-12 C atoms
D. > 20 C atoms
- B
- C
- D
- A
The no. of atoms of a fatty acid should be (odd/even)?
Even
Classification of Fatty Acids
As to no. of C=C bonds, choose among the ff.:
1. has one double bond
2. w/o double bonds
3. has 2 or more double bonds
4. w/ double bonds
A. Saturated
B. Unsaturated
C. Monounsaturated
D. Polyunsaturated
- C
- A
- D
- B
Classification of Fatty Acids
As to no. of C=C bonds and their structures, choose among the ff.:
1. is bent, liquid at RT, and not stable
2. is liquid at RT because the Cs are on the same side producing a kink
3. is solid at RT as it behaves like a saturated fatty acid
4. is linear, compact, solid at RT and harder to break
A. Saturated
B. Unsaturated
C. Cis configuration
D. Trans configuration
- B
- C
- D
- A
Fatty Acids (additional)
- This is the major dietary fatty acid
- These are not synthesized from carbohydrate precursors unlike most fatty acids but are instead supplied by the diet as they are essential fatty acids (2)
- These are precursors for the synthesis of eicosanoids (prostaglandins, thromboxanes, prostacyclins, and leukotrienes)
A. Elaidic Acid
B. Linolenic Acid
C. Polyunsaturated Fatty Acids
D. Linoleic Acid
- A
- B & D
- C
These 2 eicosanoids are for inflammation and clotting factor development, respectively
- Inflammation - Prostaglandins
- Clotting Factors - Thromboxanes
- are aka phosphoglycerides
- most abundant lipid derived from phosphatidic acid
- has 2 fatty acids + phosphorylated glycerol (structure is similar to TAGs but instead of 3, they have 2 fatty acids)
- is amphipathic (has hydrophillic and hydrophobic parts)
- forms include lecithin/phosphatidyl choline, sphingomyelin, and cephalin
Phospholipids
Phospholipids
Match them according to prevalence in the cell structure:
1. Lecithin
2. Cephalin
3. Sphingomyelin
A. 20%
B. 10%
C. 70%
- C
- B
- A
Phospholipids
- This is essential for the membrane and for diagnosing neonatal distress syndrome
- Acts as a reference material for the 3rd trimester of pregnancy which correlates to lung maturity of the baby
- Acts as a surfactant for effective gas exchange
Sphingomyelin
- this contains 3 molecules of fatty acid + 1 molecule of glycerol by ester bonds
- is very HYDROPHOBIC and water insoluble (it has no charge)
- forms adipose tissue
- when metabolized, it releases the fatty acids as its energy source (used when in a fasting state)
- additional info: lipoprotein lipase (LPL), epinephrine, and cortisol
Triglycerides (TAGs)
- this enzyme breaks the TAG and releases fatty acid and glycerol (lipemia clearing factor)
- removes entities that cause turbidity (TAG-rich lipoproteins) to plasma and serum
- a deficiency of this enzyme reduces clearance therefore there will be accumulation of TAGs
Lipoprotein Lipase (LPL)
- this evaluates suspected atherosclerosis and measures the body’s ability to metabolize fat
- requires a 12-14 hour fasting period to clear the chylomicrons
- serum or plasma can be used
- postural changes can decrease this analyte by 50% when laying down
Triglycerides (TAGs)
Triglycerides
If the sample is lipemic or will be delayed in processing, how do you preserve it?
Freeze at -20ºC
Make sure to warm and mix it before testing
Note: Frozen samples produce a different reading so it’s better to analyze immediately
Triglycerides
Bilirubin is considered an interference because as we age (around 45-65 years old), it (increases/decreases) by 2ml/dL every year
Increases
- nucleus is made out of cyclopentanoperhydrophenanthrene
- an unsaturated steroid alcohol with 4 rings and a single C-H side chain
- is synthesized in the liver and found on the surface of lipoproteins
Cholesterol
- its A ring and OH group are amphipathic
- not catabolized by most cells (not an energy source) but synthesized by animals
- a source of primary and secondary bile acids, steroid hormones, and vitamin D
- e.g. progestins, glucocorticoids, mineralocorticoids, androgens, and estrogens
Note: Bile acids are emulsifying agents
Cholesterol
Forms of Cholesterol
- makes up 70% of the cholesterol
- can be found in plasma or serum (at the CORE)
- is bound to fatty acid (hydrophobic form)
- undergoes esterification by the Lecithin Cholesterol Acyl Transferase enzyme (LCAT); is activated by APO A1
Cholesterol Ester
Forms of Cholesterol
- makes up 30% of the cholesterol
- this can be found in plasma, serum, and RBCs (at the SURFACE)
- the OH group attached to a ring is amphipathic
Free Cholesterol
This function of the LCAT enzyme transfers fatty acid from lecithin to a cholesterol ring
For esterification
Sources of Cholesterol
- This makes up 15% of the cholesterol in our body
- This makes up 85% of the cholesterol in our body and is the precursor for steroid hormones
Which is EXOGENOUS and which is ENDOGENOUS?
- Exogenous
- Endogenous
- one 18-carbon or longer fatty acid is bound to an amino group of sphingosine
- is important for cell membrane structure and the CNS
- has the ff. forms: sphingomyelin, galactosylceramide, and glucosylceramide
Ceramide
- has 5 branched chain units
- are intermediates in the metabolic production of cholesterol
- a precursor for the fat-soluble vitamins
Terpenes
What are the 3 major lipid components in plasma?
- Triglycerides (TAGs)
- Cholesterol
- Phospholipids
- these are a complex of lipids with specialized proteins
- transports TAG and cholesterol to sites of energy storage and utilization
Lipoproteins
- known as the protein portion of lipoproteins
- is an “amphipathic helix”
Apolipoproteins
- this helps keep lipids in the solution during bloodstream circulation
- it directs lipids to the correct target organs and tissues in the body
- it maintains structural integrity of the complex
- these serve as ligands for cell receptors
- are activators/inhibitors of various enzymes that modify lipoprotein particles
Apolipoproteins
Alauporic Nomenclature (apolipoproteins)
- Helps activate the LCAT enzyme
- An arginine-rich apolipoprotein
- The thin-line lipoprotein which activates the LCAT reaction
- Is produced by the liver and intestine
- Causes high LDL levels; higher risk for developing CAD and Alzheimer’s
A. Apo A1
B. Apo E
C. Apo D
D. Apo E4
Yes, there are 4 choices for 5 questions, one answer will be doubled
- A
- B
- C
- A
- D
Alauporic Nomenclature (apolipoproteins)
What are Apo B-100 and Apo B-48 made out of? (2 separate answers)
- Apo B-100: VLDL and LDL
- Apo B-48: Chylomicrons