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Lecture 9

BIOL 1F90 Lecture Notes - Lecture 9: Lipid Bilayer, Hydroxy Group, Amphiphile


Department
Biological Sciences
Course Code
BIOL 1F90
Professor
Fiona Hunter
Lecture
9

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Lecture 9 Biology- Chapter 3: Continuation September 28,2015
Phospholipids:
Another class of lipids, similar in structure to triglycerides but the
third hydroxyl group of glycerol is linked to a phosphate group
instead of a fatty acid
The third carbon is attached to a phosphate with a change and
another head group with a charge nature
In most phospholipids, a small polar or charged nitrogen-
containing molecule is attached to this phosphate (crutial)
These groups constitute a polar hydrophilic (water-loving)
region at one end of the phospholipid
At the opposite end is the nonpolar, hydrophobic (water-
fearing) fatty acid chains
Phospholipids are amphipathic (both polar and non-polar)
In water, the amphipathic nature of phospholipids allow them to
organize into bilayers:
With their polar ends facing out, interacting with water,
and their nonpolar ends facing one other in the interior
*lawyer example, whith the phospholipid bilayer, non-polar fatty acid
tails in middle, polar heards sticking out
*inside of plasmamembrane containes you, all de%ned by a barries
between the world and you(living) that barrier is a memebrane allows
interior of a cell to be di&erent from the outside(natural and organic
matterial) di&erence in pH, etc
polar and non-polar covalent bonds create amphipathic if not no
membrane is made
Steroids:
Four fused rings of carbon atoms form the skeleton of all steroids
A few polar hydroxyl groups may be attached to the ring
structure, but they are not numerous enough to make a steroid
highly water soluble
Steroids with a hydroxyl group are known as sterols
tiny di&erences in chemical structure can lead to profoundly
di&erent biological properties
Hormones estrogen vs. testosterone
*Cholesterol is similar to other hormones such as estrogen and
testosterone, don’t look very di&erent but this settle di&erence makes
a di&erence
Testosterone: has a methyl group and a double bonded oxygen
(carbonyl group)
Estrogen: Hydroxyl group
-These enzymes bond to estrogen not testosterone
Waxes:
All waxes contain one or more hydrocarbons and long structures:
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