Lec 14: Intro To Lipids Flashcards
- heterogenous group of compounds relatively insoluble in water and freely soluble in nonpolar organic solvents.
- not true polymers
Lipids
Lipids are _____ related to nonpolar organic solvents in terms of solubility.
(chemically, physically)
Physically related
Functions of Lipids
- important constituent of diet
- storage form of energy
- serves as electrical insulators of myelinated nerves
- Lipids are composed of ___.
- It is the group accountable for the nonpolar nature of fat.
- Majority of plasma fatty acids are found as _____.
- Fatty acids
- R group
- A part of triglycerides or phospholipids
Classifications of fatty acids depend on ____.
- chain length
- presence of double bonds
- number of double bonds
FATTY ACID CHAIN LENGTH
- short chain: ___
- medium chain: ___
- long chain: ___
- very long chain: ___
- short chain: C2–C6
- medium chain: C8–V14
- long chain: at least C16
- very long chain: at least C22
- produced by bacterial fermentation of dietary carbohydrates.
- absorbed directly into blood.
- important source of energy for colonic mucosa
Short Chain Fatty acids
- benefits patients with inadequate bile acid pools.
- absorbed directly into blood.
- has NO effect on atherosclerosis.
Medium Chain Fatty acid
- A fatty acid that has NO double bond.
- A fatty acid that has at least one double bond.
- A fatty acid with ONLY ONE double bond.
- A fatty acid having MORE THAN ONE double bonds.
- Saturated fatty acid
- Unsaturated fatty acid
- Monounsaturated fatty acid
- Polyunsaturated fatty acid
Examples of PUFA (polyunsaturated fatty acids)
- w–3 series: ___
- w–6 series: ___
- w–9 series: ___
w–3 series:
- Cervonic acid
- a-Linolenic acid
- Timnodonic acid
w–6 series:
- Arachidonic acid
- Linoleic acid
w–9 series:
- Elaidic acid
- Oleic acid
Significance of Omega-3 fatty acids (w-3 FA)
• decreases serum triglycerides
—> decreased risk of cardiovascular disease.
• lowers thromboxane production
—> decreased tendency for platelet aggregation
• for infant’s development of neurologic system.
GEOMETRIC ISOMERISM OF FA
- A fatty acid when H atoms are found on the same side.
- A fatty acid when H atoms are found on opposite sides.
- Cis-form fatty acid
- mostly liquid in RT
- Transform fatty acid
- stable structure
- solid at RT
Main storage for of lipids
Triglycerides
- Very hydrophobic and usually water insoluble.
- classified as neutral lipid.
Triglyceride
Contains 3 saturated fatty acid molecules that are attached to one molecule of glycerol by ester bonds.
Triglycerides
- amphipathic
- synthesized in the cytosolic compartment of all organs of the body (esp. Liver)
- acts as a barrier to protect the cell against various environmental insults.
Phospholipids
PHOSPHOLIPIDS
- Most abundant phospholipids.
- Hydrophilic head is composed of ___.
- Hydrophobic tail is composed of ___.
- What does amphipathic mean?
- Phosphatidylcholine, Phosphatidylethanolamine
- A phosphate group
- Two fatty acid tails
- Both hydrophobic and hydrophilic.
- an amphipathic lipid found on the surface of lipid layers along phospholipids.
- in the liver, converted to primary bile acids that promote fat absorption.
- useful for synthesis of steroid hormones
Cholesterol
- a 27-carbon compound
- has four fused hydrocarbon rings
Cholesterol
- Composed of both lipids and proteins.
- there are amphipathic cholesterol and phospholipid molecules on its surface.
Lipoprotein
- primarily located on the surface of lipoprotein particles
- a protein which attaches to the lipid
- maintains the structural integrity of lipoproteins
Apolipoproteins
The most important lipoproteins in the body.
APO A-1
major lipoprotein located in HDL
APO B-100
major lipoprotein located in LDL & VDL
APO B-48
major lipoprotein located on the chylos or chylomicrons
Cite the 4 forms of lipoproteins. (Give their source & remarks)
Chylomicron
Source: intestine
Remarks: lowest density, highest TAG content
VLDL
Source: Liver
Remarks: N/A
LDL
Source: VLDL
Remarks: highest cholesterol content
HDL
Source: liver, intestine
Remarks: highest protein content
- The lightest lipoprotein with a density of less than 0.95 kg/L
- A very light lipoprotein with a density of 0.95 to 1.006 kg/L
- Chylomicrons
- VLDL
Matching Type
1. Alpha region
2. Beta region
3. Pre-beta region
choices:
a. LDL
b. IDL
c. VLDL
d. HDL
- d. HDL
- a. LDL & b. IDL
- c. VLDL
- General term for the imbalance of cholesterol, LDL cholesterol, triglycerides, and HDL in the blood.
- Possible causes.
- Dyslipidemia
- Diet, tobacco exposure, genetics
CHD Positive Risk Factors (more likely to develop CHD)
Age
• Men: more than 45 years old
• Women: more than 55 years old, premature menopause
LDL concentration
• more than 160 with one risk factor
• more than 130 with two risk factors
• more than 100 with CHD equivalent
HDL concentration
• less than 40
Others
• cigarette smoking
• hypertension
• diabetes mellitus
• metabolic syndrome
CHD Negative Risk Factors (less likely to develop CHD)
• increased HDL of more than 60
• LDL concentration of less than 100
• Elevated concentrations of ApoB-containing lipoproteins
• Abnormally high levels of cholesterol within the arterial wall.
Atherosclerosis
• defect in the gene ABCA1 transport
• fat is deposited into the tissues where it shouldn’t be, leading to Foam cells.
• telltale sign of enlarged yellow orange tonsils.
Tangier disease
- Function of ABCA1 transporter.
- Effects of the presence of foam cells.
- Cause of enlarged yellow orange tonsils.
- Allows HDL to enter the cell membrane.
- Hepatosplenomegaly, Peripheral neuropathy (excess fat in nerves), premature coronary disease.
- Cholesterol deposition in the tonsils.
- A common genetic disease caused by mutation by one or more of the genes critical for LDL cholesterol catabolism.
- In #1’s answer, the disease has a defect of ____.
- In #1’s answer, it is characterized by ___ and leads to ___.
- Familial Hypercholesterolemia
- Defect of LDL-C receptor
- Characterized by extremely elevated levels of LDL-C, and leads to early onset atherosclerotic cardiovascular disease.
FAMILIAL HYPERCHOLESTEROLEMIA
• elevated chylomicrons
• significant increase in triglycerides
• inherited deficiency of LPL or ApoC-II
Type 1 Hyperchylomicronemia
FAMILIAL HYPERCHOLESTEROLEMIA
• increase cholesterol
• elevated LDL
• genetic defect
Type 2 Hypercholesterolemia
FAMILIAL
HYPERCHOLESTEROLEMIA
• elevated beta-lipoproteins
• rare
Type 3 Dysbetalipoproteinemia
FAMILIAL HYPERCHOLESTEROLEMIA
• increased triglycerides
• elevated VLDL
• causes: ___
Type 4 Hypertriglyceridemia
causes:
• diabetes
• obesity
• alcoholism
• poor dietary habits
