Lipids Flashcards
Different types of lipids are carachterized by a variety of structures and functional groups, but they all have what same defining characteristic?
Low solubility in water and high solubility in nonpolar organic solvents
What are the main functions of lipids? What structural components are associated with each function?
- Energy Storage; Long carbon chains
- Cellular organization and structure (particularly in the membrane); Barriers separate aqueous environments because they are hydrophobic
- Provision of precursor molecules for vitamins and hormones; Useful as precursors for signalling molecules because they can pass through cellular membranes
Triacylglycerols
Glycerol backbone attached to 3 fatty acid chains. Main function is to store energy; can also provide thermal insulation and padding
Sometimes referred to as a fatty acid
(Also called triglycerides, or simply fats and oils)
Phospholipids
Of particular importance are Phosphoglycerides:
Glycerol backbone, 2 fatty acid tails, and a polar phosphate group; Amphipathic, and is therefore well suited as the major component of biological membranes
Sometimes referred to as a fatty acid
Amphipathic
Molecules with both polar and nonpolar groups
Amphoteric
A molecule able to act both as an acid and a base
Aliphatic
Relating to or denoting organic compounds in which carbon atoms form open chains (as in the alkanes), not aromatic rings
Phosphatids
Glycerol backbone with phosphate attached;
A part of most phosphoglycerides
Glycolipids
Similar to phosphoglycerides, except that glycolipids have one or more carbohydrates attached to the three-carbon glycerol backbone instead of the phosphate group.
Found in abundance in the membranes of myelinated cells in the nervous system
Sphingolipids
Has a long chain fatty acid and a polar head group; Backbone molecule is an amino alcohol called a sphingosine
Make up part of the cell membrane
Sphingomyelin
A type of sphingolipid: has a phosphate group attached to the sphingosine backbone
What types of lipids make up part of the cell membrane?
Phospholipids/phosphatids
Glycolipids
Steroids
Sphingolipids
Steroids
Four ringed structures
Includes some hormones, vitamin D, and cholesterol
Terpenes and terpenoids function
Precursor molecules that feed into various biosynthesis pathways that produce important products - ex. Steroids and vitamin A
Cholesterol
- major component of phospholipid bilayer
- at low temps prevents cell membrane from solidifying
- at high temps holds membrane together/prevents it from becoming too permeable
- precursor for steroid hormones, bile acids, and Vitamin D
Prostaglandins
Autocrine and paracrine hormones that regulate cAMP levels. Have powerful effects on muscle contraction, body temp, the sleep-wake cycle, and pain.
Fat-soluble vitamins
Vitamin A (Carotene) Vitamin D (Cholecalciferol) Vitamin E (Tocopherols) Vitamin K (phylloquinone and menaquinone)
What does Vitamin A metabolize into?
Retinal for vision and retinoic acid for gene expression in epithelial development
What does Vitamin D metabolize into?
Calcitrol in the kidneys - regulates calcium and phosphorous homeostasis in the intestines promoting bone formation.
Deficiency in Vitamin D causes rickets
What does Vitamin E act as in the body?
It acts as a biological antioxidant. Its aromatic ring destroy free radicals, preventing oxidative damage.
What is Vitamin K involved in?
It’s important for formation of prothrombin, a clotting factor. It performs posttranslational modifications on a number of proteins, creating calcium-binding sites.
Saponification
The ester hydrolysis of Triacylglycerols using a strong base like potassium hydroxide
Surfactant and how it acts like a soap
Lowers the surface tension at the surface of a liquid
Soaps acts as surfactants and form micelles.
