Lec 14: Intro To Lipids

Question 1

• heterogenous group of compounds relatively insoluble in water and freely soluble in nonpolar organic solvents.
• not true polymers

Answer 1

Lipids

Question 2

Lipids are _____ related to nonpolar organic solvents in terms of solubility.

(chemically, physically)

Answer 2

Physically related

Question 3

Functions of Lipids

Answer 3

• important constituent of diet
• storage form of energy
• serves as electrical insulators of myelinated nerves

Question 4

1. Lipids are composed of ___.
2. It is the group accountable for the nonpolar nature of fat.
3. Majority of plasma fatty acids are found as _____.

Answer 4

1. Fatty acids
2. R group
3. A part of triglycerides or phospholipids

Question 5

Classifications of fatty acids depend on ____.

Answer 5

• chain length
• presence of double bonds
• number of double bonds

Question 6

FATTY ACID CHAIN LENGTH

• short chain: ___
• medium chain: ___
• long chain: ___
• very long chain: ___

Answer 6

• short chain: C2–C6
• medium chain: C8–V14
• long chain: at least C16
• very long chain: at least C22

Question 7

• produced by bacterial fermentation of dietary carbohydrates.
• absorbed directly into blood.
• important source of energy for colonic mucosa

Answer 7

Short Chain Fatty acids

Question 8

• benefits patients with inadequate bile acid pools.
• absorbed directly into blood.
• has NO effect on atherosclerosis.

Answer 8

Medium Chain Fatty acid

Question 9

1. A fatty acid that has NO double bond.
2. A fatty acid that has at least one double bond.
3. A fatty acid with ONLY ONE double bond.
4. A fatty acid having MORE THAN ONE double bonds.

Answer 9

1. Saturated fatty acid
2. Unsaturated fatty acid
3. Monounsaturated fatty acid
4. Polyunsaturated fatty acid

Question 10

Examples of PUFA (polyunsaturated fatty acids)

• w–3 series: ___
• w–6 series: ___
• w–9 series: ___

Answer 10

w–3 series:
- Cervonic acid
- a-Linolenic acid
- Timnodonic acid

w–6 series:
- Arachidonic acid
- Linoleic acid

w–9 series:
- Elaidic acid
- Oleic acid

Question 11

Significance of Omega-3 fatty acids (w-3 FA)

Answer 11

• decreases serum triglycerides
—> decreased risk of cardiovascular disease.

• lowers thromboxane production
—> decreased tendency for platelet aggregation

• for infant’s development of neurologic system.

Question 12

GEOMETRIC ISOMERISM OF FA

1. A fatty acid when H atoms are found on the same side.
2. A fatty acid when H atoms are found on opposite sides.

Answer 12

1. Cis-form fatty acid
   
   • mostly liquid in RT
2. Transform fatty acid
   
   • stable structure
   • solid at RT

Question 13

Main storage for of lipids

Answer 13

Triglycerides

Question 14

• Very hydrophobic and usually water insoluble.
• classified as neutral lipid.

Answer 14

Triglyceride

Question 15

Contains 3 saturated fatty acid molecules that are attached to one molecule of glycerol by ester bonds.

Answer 15

Triglycerides

Question 16

• 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.

Answer 16

Phospholipids

Question 17

PHOSPHOLIPIDS

1. Most abundant phospholipids.
2. Hydrophilic head is composed of ___.
3. Hydrophobic tail is composed of ___.
4. What does amphipathic mean?

Answer 17

1. Phosphatidylcholine, Phosphatidylethanolamine
2. A phosphate group
3. Two fatty acid tails
4. Both hydrophobic and hydrophilic.

Question 18

• 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

Answer 18

Cholesterol

Question 19

• a 27-carbon compound
• has four fused hydrocarbon rings

Answer 19

Cholesterol

Question 20

• Composed of both lipids and proteins.
• there are amphipathic cholesterol and phospholipid molecules on its surface.

Answer 20

Lipoprotein

Question 21

• primarily located on the surface of lipoprotein particles
• a protein which attaches to the lipid
• maintains the structural integrity of lipoproteins

Answer 21

Apolipoproteins

Question 22

The most important lipoproteins in the body.

Answer 22

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

Question 23

Cite the 4 forms of lipoproteins. (Give their source & remarks)

Answer 23

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

Question 24

1. The lightest lipoprotein with a density of less than 0.95 kg/L
2. A very light lipoprotein with a density of 0.95 to 1.006 kg/L

Answer 24

1. Chylomicrons
2. VLDL

Question 25

**Matching Type** 1. Alpha region 2. Beta region 3. Pre-beta region choices: a. LDL b. IDL c. VLDL d. HDL

Answer 25

1. _d. HDL_ 2. _a. LDL & b. IDL_ 3. _c. VLDL_

Question 26

1. General term for the *imbalance of cholesterol, LDL cholesterol, triglycerides, and HDL in the blood.* 2. Possible causes.

Answer 26

1. Dyslipidemia 2. Diet, tobacco exposure, genetics

Question 27

CHD Positive Risk Factors (more likely to develop CHD)

Answer 27

**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

Question 28

CHD Negative Risk Factors (less likely to develop CHD)

Answer 28

• increased HDL of more than 60 • LDL concentration of less than 100

Question 29

• Elevated concentrations of ApoB-containing lipoproteins • Abnormally high levels of cholesterol within the arterial wall.

Answer 29

Atherosclerosis

Question 30

• 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._

Answer 30

Tangier disease

Question 31

1. Function of ABCA1 transporter. 2. Effects of the presence of foam cells. 3. Cause of enlarged yellow orange tonsils.

Answer 31

1. Allows HDL to enter the cell membrane. 2. Hepatosplenomegaly, Peripheral neuropathy (excess fat in nerves), premature coronary disease. 3. Cholesterol deposition in the tonsils.

Question 32

1. A common genetic disease caused by *mutation by one or more of the genes critical for LDL cholesterol catabolism.* 2. In #1's answer, the disease has a defect of ____. 3. In #1's answer, it is characterized by ___ and leads to ___.

Answer 32

1. Familial Hypercholesterolemia 2. Defect of LDL-C receptor 3. Characterized by *extremely elevated levels of LDL-C*, and leads to *early onset atherosclerotic cardiovascular disease.*

Question 33

**FAMILIAL HYPERCHOLESTEROLEMIA** • elevated chylomicrons • significant increase in triglycerides • inherited deficiency of *LPL* or *ApoC-II*

Answer 33

Type 1 Hyperchylomicronemia

Question 34

**FAMILIAL HYPERCHOLESTEROLEMIA** • increase cholesterol • elevated LDL • genetic defect

Answer 34

Type 2 Hypercholesterolemia

Question 35

**FAMILIAL HYPERCHOLESTEROLEMIA** • elevated beta-lipoproteins • rare

Answer 35

Type 3 Dysbetalipoproteinemia

Question 36

**FAMILIAL HYPERCHOLESTEROLEMIA** • increased triglycerides • elevated VLDL • causes: ___

Answer 36

Type 4 Hypertriglyceridemia **causes:** • diabetes • obesity • alcoholism • poor dietary habits