5.2 Signaling Lipids Flashcards
1
Q
What role do lipids play in ETC and glycosylation rxns?
A
- As coenzyme
2
Q
Other functions of lipids?
A
- hormones that transmit signals over long distances and as intracellular messengers responding to extracellular signals
- Certain special lipids with
conjugated double bonds absorb light, which is extremely important for vision; others act as pigments in plants and animals
3
Q
Terpenes
A
- are a class of lipids built from isoprene (C5H8) moieties
- produced mainly by plants and also by some insects. They are generally strongly scented
- also the primary components of much more pleasant smelling essential oils extracted from plants
- grouped according to the number of isoprene units
- a single terpene unit contains two isoprene units
4
Q
Monoterpenes (C10H16)
A
- contain two isoprene units
5
Q
Sesquiterpenes
A
- contain three isoprene units
6
Q
Diterpenes
A
- contain four isoprene units
- Vitamin A
7
Q
Carotenoids
A
- Tetraterpenes: have eight isoprene units
- β-carotene and lutein
8
Q
Terpenoids
A
- referred to as isoprenoids
- derivatives of terpenes that have undergone oxygenation or rearrangement of the carbon skeleton
- share similar characteristics with terpenes in terms of both biological precursor function and aromatic properties, contributing to steroid biosynthesis, as well as the scents of cinnamon, eucalyptus, camphor, turmeric, and numerous other compounds.
- Steroids are metabolic derivatives of terpenes
9
Q
Steroids
A
- characterized by having
four cycloalkane rings fused together: three cyclohexane and one cyclopentane - functionality is determined by the oxidation status of these rings and the functional groups they carry
- the large number of carbons and hydrogens make steroids
nonpolar, like the other lipids mentioned
10
Q
Cholesterol
A
- a steroid of primary importance
- major component of the phospholipid bilayer and is responsible for mediating membrane fluidity
- Interacts with both the hydrophobic tails and hydrophilic heads of phospholipids to maintain relatively constant fluidity in cell membranes
- At low temperatures, it keeps the cell membrane from solidifying
- at high temperatures, it holds the membrane intact and prevents it from becoming too permeable
- serves as a precursor to steroid hormones, bile acids, and vitamin D
11
Q
Prostaglandins
A
- 20-carbon molecules
- unsaturated carboxylic acids derived from arachidonic acid and contain one 5-carbon ring
- act as paracrine or autocrine signaling molecules
- regulate the synthesis of cyclic adenosine monophosphate (cAMP)
_cAMP mediates the actions of many other hormones - Downstream effects of prostaglandins include powerful effects on smooth muscle function, influence over the sleep–wake cycle, and the
elevation of body temperature associated with fever and pain - (NSAIDs) like aspirin inhibit the enzyme (COX), which aids in the production of prostaglandins.
12
Q
Vitamin A (carotene)
A
- an unsaturated hydrocarbon that is important in vision, growth and development, and immune function.
- The most significant metabolite of vitamin A is the aldehyde form, retinal
13
Q
Retinol
A
- the storage form of vitamin A
- oxidized to retinoic acid
14
Q
Vitamin D
A
- In the liver and kidneys, vitamin D is converted to calcitriol (1,25-(OH)2D3), the biologically active form of vitamin D
- Calcitriol increases Ca and phosphate uptake in the intestines, which promotes bone production.
15
Q
Mnemonic to remember what vitamin A and D do
A
One way to remember Carotene is to remember that carrots are high in vitamin A, which is why eating carrots is colloquially suggested to improve vision. To remember that vitamin D regulates calcium, remember that it is frequently added to milk in order to aid in the
absorption of calcium
