Lipids Flashcards
List five general functions of lipids, according to the lecturer
- Serve as hormones or hormone precursors
- Aid in digestion
- Provide energy storage and metabolic fuels
- Provide functional and structural components in
biomembranes - Form insulation to prevent heat loss or to allow nerve
conduction
Describe the basic structure and two functions of cholesterol
- A steroid alcohol with 27 carbon atoms arranged in a tetracyclical sterane ring system
- Organizes cell membranes and controls permeability
Sterol Derivatives
Class Functions (Remember this!!! per slides)
List Six (6) functions
- Cholesterol: helps organize cell membranes and controls permeability
- 18-carbon steroid hormones: estrogens
- 19-carbon steroid hormones: androgens
- 21-carbon steroid hormones: progesterone, cortisol, aldosterone
- Bile acids: digestion and excretion
- Vitamin D: calcium and phosphate homeostasis
Explain the importance of emulsification and esterification of cholesterol in intestinal absorption.
Emulsification is necessary to solubilize cholesterol – occurs via micelle formation mediated by conjugated bile acids
Esterification reduces the toxicity of cholesterol (converts hydroxyl group on carbon 3 into an ester) – mediated by ACAT intracellularly and LCAT extracellularly
List the function and specific different sites of action in the body for both lecithin-cholesterol acyltransferase (LCAT) and acylcholesterol acyltransferase (ACAT).
LCAT and ACAT catalyze the esterification reaction for cholesterol reducing its toxicity
LCAT is located in the plasma (extracellular)
ACAT is located in the cells (intracellular)
List five (5) functions of bile acids (not an objective)
- Facilitates dietary cholesterol absorption
- Facilitates intestinal absorption of fat-soluble vitamins
- Facilitates digestion of dietary triglycerides
- Elimination of excess cholesterol
- Prevents the precipitation of cholesterol in the gallbladder
Recognize the following aspects of fatty acids:
a. The empirical formula and three (3) sources
b. Four functions
c. Harmful effects of trans fatty acids
d. The catabolic process of beta-oxidation
a. R-COOH (Carboxyl group)
1. Diet (largest source)
2. Adipose tissue
3. BIosynthesis of all but the essential
fatty acids
b. 1. Produce energy via beta oxidation in
mitochondria
2. Production of necessary
phospholipids
3. Cell membrane maintenance
4. Manufacture of milk in females
c. 1. Not always recognized by enzymes
2. If incorporated into cell membrane,
membrane is more dense and
function is altered
3. Raises LDL and triglycerides
4. Lowers HDL
5. Increases risk of CVD
6. Has a detrimental effect on
brain/nervous system
d. The process works repetitively to shorten the fatty acid chain forming acetyl-CoA that eventually will enter Kreb’s cycle – yields more ATP than the glucose metabolism
Recognize the following aspects of triglycerides:
a. The basic structure and the major function
b. The process of dietary triglyceride metabolism
a. Three (3) fatty acids attached to a glycerol backbone
Major function: storage of fat in the
tissues
b. Digested and absorbed by the
duodenum and ileum, respectively –
lipase and bile acids helps with the
breakdown to permit absorption
Recognize the functions of phosphoglycerides and sphingolipids
Phosphoglyceride function:
1. Components of cell membranes
2. Enzyme activators
3. Metabolic fuels
4. Signaling molecules
5. Surfactant
6. Component of lipoproteins
Sphingolipid function:
1. Form the major lipids of cell
membranes (increase their rigidity)
2. Act as signal transducers in the CNS
List the three fat-soluble vitamins (terpenes)
- Vitamin A
- VItamin E
- Vitamin K
Draw and label the specific internal and external composition of lipoproteins
Review the slides (pg.19 – slide 78)
State the general function of lipoproteins
Transport water insoluble lipids to various body tissues, necessary or cell membranes and the life of the cell
List four functions of apolipoproteins.
- Facilitate direct cellular uptake and catabolism of lipoproteins
- Serve as astructural component
- Serve as cofactors to regulate enzymes
- Facilitate transfer of lipids between lipoproteins
Classify chylomicrons, LDL, VLDL, and HDL according to their electrophoretic mobilities
Chylomicrons: point of application
LDL: beta region
VLDL: pre-beta region
HDL: alpha1 region
List the apolipoproteins present on chylomicrons and LDL.
Chylomicrons: A-I, B-48, C-I, C-II, C-III, E
LDL: B-100
