5.1 Structural Lipids

Question 1

Lipids

Answer 1

• serving vital structural, signaling, and energy storage roles
• can be an important part of
  processes like cell recognition and signaling

Question 2

Amphipathic

Answer 2

• has both hydrophilic and hydrophobic regions
• fatty acid tails are the hydrophobic region

Question 3

Phospholipids

Answer 3

• contain: a phosphate and alcohol that comprise the polar head group, joined to a hydrophobic fatty acid tail by phosphodiester linkages
• One or more fatty acids are attached to a backbone to form the hydrophobic tail region

Question 4

How’re lipid properties determined?

Answer 4

• by the degree of saturation in fatty acid chains and the functional groups to which the fatty acid chains are bonded

Question 5

What 2 properties determine how the molecule will behave?

Answer 5

• Saturation and length

Question 6

Why’re saturated fatty acids more stable?

Answer 6

• Have greater van der Waals forces

Question 7

Glycerophospholipids
(or phosphoglycerides)

Answer 7

• phospholipids that contain a
  glycerol backbone bonded by ester linkages to two fatty acids and by a phosphodiester linkage to a highly polar head group

Question 8

Why are head groups on lipids important?

Answer 8

• the head group determines the membrane surface properties
• glycerophospholipids are named according to their head group
• can be positively charged, negatively charged, or neutral
• very important to cell recognition, signaling, and binding

Question 9

Sphingolipids

Answer 9

• have a sphingosine or sphingoid (sphingosine-like) backbone
• have long-chain, nonpolar fatty acid tails and polar head groups
• sites of biological recognition at the cell surface and can be bonded to various head groups and fatty acids
• Most contain contain a phosphodiester linkage, others contain glycosidic linkages to sugars
• Ex: cell surface antigens of RBCS

Question 10

What’re the 4 major subclasses of Sphingolipids?

Answer 10

• Simplest sphingolipid is ceramide (has a single hydrogen atom as its head group)
• Sphingomyelins are the major class of sphingolipids and are also phospholipids
  _major components in the plasma membranes of cells producing myelin
  _have no net charge
• glycosphingolipids are found mainly on the outer surface of the plasma membrane and can be further classified as cerebrosides (have single sugar) or globosides (have two or more sugars)
• Gangliosides are glycolipids that have polar head groups composed of oligosaccharides with one or more N acetylneuraminic acid (NANA; also called sialic acid) molecules at the terminus and a negative charge
  _play a major role in cell interaction, recognition, and signal transduction.

Question 11

Waxes

Answer 11

• esters of long-chain fatty acids with long-chain alcohols
• they form pliable solids at room temperature (wax)