1Lipids are what type of compounds chemically?
A heterogeneous group of compounds of biochemical importance
2What is the solubility property of lipids?
Insoluble in water but soluble in nonpolar solvents
3What are the four main classifications of lipids?
Simple lipids, compound lipids, derived lipids, and lipids complexed to other compounds
4What are simple lipids?
Esters of fatty acids with glycerol or other higher alcohols
5What are the two main types of simple lipids?
Fats and waxes
6What are fats composed of?
Fatty acids + glycerol
7What is another name for triglycerides?
Triacylglycerols or neutral fats
8What is an oil?
Fat in the liquid state
9What are waxes composed of?
Fatty acids, usually long-chain, esterified with alcohols other than glycerol
10What are compound lipids?
Fatty acids esterified with alcohol and containing other groups
11What groups can compound lipids contain?
Phosphate, nitrogenous base, carbohydrate, protein, etc.
12What are the two subclasses of compound lipids?
Phospholipids and non-phosphorylated lipids
13What are examples of phospholipids?
Lecithin, cephalin, phosphatidylserine, phosphatidylinositol, sphingomyelin
14What are examples of non-phosphorylated lipids?
Glycosphingolipids and sulpholipids/sulfatides
15What are derived lipids?
Compounds derived from lipids or precursors of lipids
16What are examples of derived lipids?
Steroids, fatty acids, prostaglandins, leukotrienes, terpenes, and dolichols
17What are lipoproteins?
Macromolecular complexes of lipids with proteins
18Why are lipoproteins important?
They transport lipids through the bloodstream
19What is a triacylglycerol (TAG)?
An ester formed from glycerol and three fatty acid groups
20How is TAG formed?
By esterification of fatty acids with glycerol
21Why is TAG called a neutral lipid?
It is electrically neutral
22What is the main function of TAG?
Highly concentrated energy reserve
23Where are excess fatty acids stored as TAG?
In adipose cells
24What can excess dietary fatty acids be converted into?
Triacylglycerols
25What can carbohydrates be converted into for energy storage?
Triacylglycerols
26What are phospholipids?
Compound lipids that are major components of cell membranes
27What alcohols can be present in phospholipids?
Choline or inositol
28What bond attaches the alcohol to the lipid portion?
Phosphodiester bond
29What can phospholipids contain besides diacylglycerol?
Sphingosine
30What are the main functions of membrane phospholipids?
They are predominant lipids of cell membranes
31What are examples of non-membrane phospholipid functions?
Lung surfactant and essential components of bile
32What does amphipathic mean?
Having both hydrophobic and hydrophilic components
33What are the two main parts of a phospholipid?
A hydrophilic phosphate head and hydrophobic fatty acid tails
34Why is the phospholipid head hydrophilic?
The phosphate group is negatively charged and polar
35Why are phospholipid tails hydrophobic?
They are uncharged and nonpolar
36What are the two classes of phospholipids?
Glycerophospholipids and sphingophospholipids
37What is the backbone of glycerophospholipids?
Glycerol
38What is the backbone of sphingophospholipids?
Sphingosine
39What is sphingomyelin?
A sphingophospholipid containing sphingosine
40What is the major class of phospholipids in membranes?
Glycerophospholipids
41What is phosphatidic acid (PA)?
The simplest phospholipid and precursor of other glycerophospholipids
42What is the structure of phosphatidic acid?
Diacylglycerol with a phosphate group on carbon 3
43What is one major function of phosphatidic acid?
Precursor for biosynthesis of many other lipids
44What role does phosphatidic acid play in cell signalling?
It acts as a second messenger with direct biological function
45How does phosphatidic acid affect membranes?
Its physical properties influence membrane curvature
46What can phosphatidic acid regulate directly?
Lipid-gated ion channels
47What is phosphatidylcholine also called?
Lecithin
48What is DPPC?
Dipalmitoylphosphatidylcholine or dipalmitoyl lecithin
49Why is DPPC important?
It is a major component of lung surfactant
50Which cells secrete DPPC?
Type II pneumocytes
51Where is lung surfactant found?
In the extracellular fluid layer lining the alveoli
52What does lung surfactant do?
Decreases surface tension and helps prevent alveolar collapse
53What is respiratory distress syndrome also called?
Hyaline membrane disease
54What is a major cause of respiratory distress syndrome in preterm infants?
Surfactant deficiency
55Which cells are associated with surfactant deficiency in respiratory distress syndrome?
Type II pneumocytes
56What happens to lung compliance in respiratory distress syndrome?
It decreases
57What is phosphatidylinositol (PI) involved in?
Mediation of hormone action on biomembranes
58What cellular processes are regulated by PI?
Growth, proliferation, differentiation, motility, survival, and intracellular trafficking
59What role does PI have in immune function?
It helps regulate immune responses
60What is PI-3K?
Phosphatidylinositol 3-kinase
61What is the role of PI-3K in insulin signalling?
It promotes glucose uptake into cells
62What happens after insulin activates its receptor?
Intracellular signalling is activated
63What cellular process is involved in insulin signalling according to the lecture?
GLUT4 trafficking
64What does GLUT4 do?
Acts as a glucose transporter
65What type of phospholipid is sphingomyelin?
A sphingophospholipid
66What is unique about sphingomyelin?
It contains phosphate but no sugar moiety
67What is the backbone of sphingomyelin?
Sphingosine
68What is attached to carbon 1 of sphingosine in sphingomyelin?
Phosphorylcholine
69What is an important function of sphingomyelin in the CNS?
It is an important constituent of the myelin sheath
70How does sphingomyelin contribute to skin function?
It helps maintain skin water permeability
71What is formed when sphingomyelin combines with fatty acid?
Ceramide
72What are sphingolipids derived from?
Ceramide
73How is ceramide formed?
By esterification of a fatty acid with the amino group of sphingosine
74What is a glycosphingolipid?
A molecule containing both carbohydrate and lipid components
75What is the precursor of phosphorylated and glycosylated sphingolipids?
Ceramide
76Where are glycosphingolipids found in greatest amounts?
Nerve tissue
77Where are glycosphingolipids located in the plasma membrane?
The outer leaflet
78What is a major role of glycosphingolipids?
Regulating cellular interactions and communication
79What are cerebrosides?
The simplest neutral glycosphingolipids
80What are cerebrosides composed of?
Ceramide and one monosaccharide
81Which sugars occur in cerebrosides?
Glucose or galactose
82What type of bond links the sugar in cerebrosides?
β-glycosidic bond
83Where are cerebrosides mainly found?
Brain white matter and peripheral nervous tissue
84What is the function of cerebrosides in nerve tissue?
Protection, insulation, and nerve conduction
85What is the most common cerebroside in myelin?
Galactocerebroside
86What is glucocerebroside mainly involved in?
Synthesis and degradation of more complex glycosphingolipids
87What are globosides formed by?
Attaching additional monosaccharides to glucocerebroside
88What is an example of a globoside?
Lactosylceramide
89What are acidic glycosphingolipids?
Glycosphingolipids that are negatively charged at physiological pH
90What provides the negative charge in gangliosides?
N-acetylneuraminic acid (NANA)
91What provides the negative charge in sulfatides?
Sulfate groups
92What are gangliosides?
The most complex glycosphingolipids
93Where are gangliosides mainly found?
Ganglion cells of the CNS, particularly nerve endings
94What do gangliosides contain?
Ceramide, oligosaccharides, and one or more NANA molecules
95What do the letters M, D, T, and Q in ganglioside notation indicate?
One, two, three, or four NANA molecules
96What are sulfatides?
Sulfated galactocerebrosides
97Why are sulfatides negatively charged?
Due to their sulfate group
98Where are sulfatides predominantly found?
Brain and kidneys
99What is the function of sulfatides?
Structural maintenance of myelin
100Where are sulfatides degraded?
In lysosomes
101What disorder results from accumulation of sulfatides?
Metachromatic leukodystrophy
102What enzyme deficiency causes metachromatic leukodystrophy?
Lysosomal sulfatase (arylsulfatase A) deficiency