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Lipids
Homework
Read p. 62-64, “Lipids”
Questions to Ponder
Why do grocery store owners constantly
spray their fruits and vegetables with water?
We have “reduced salt areas” on our
highways to preserve the plants that grow
along the highway. Why would salted roads
be bad for them?
Why would shipmen and pirates have died if
they’d drunk ocean water while sailing at
sea?
Objectives
Understand what a fat is, the different
kinds of fats, which ones are less
healthy to consume and why?
Check out a
nutrition panel…
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–
–
–
–
–
Saturated fat?
Unsaturated fat?
Polyunsaturated fat?
Monounsaturated fat?
Trans fats?
Hydrogenated fat?
What do you know about…
Why are we told that saturated fats are
bad for us and hydrogenated fats are
REALLY bad for us, while unsaturated
fats aren’t so bad?
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Macromolecules
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All matter is made of atoms, so
understanding living things =
understanding basic chemistry.
A molecule is a unit of atoms bonded
together.
A macromolecule is a very large and
complex molecule.
Biochemistry!
An organic compound = in at least one
place, two carbons are bonded to each
other. (think organic = organism)
– Organic compounds are the chemical basis
of living things.
Macromolecules
Lipids
Nucleic acids
Amino acids
Carbohydrates
We’ll learn about them one by one over
the semester.
Lipids
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There are many types of lipids,
including steroids, cholesterols,
sphingolipids, prenol lipids, and
saccharolipids. We’re going to focus on
just two types:
– Fatty acids and triglycerides
– Phospholipids
Lipids
Easy to recognize!
They’re made of
long chains of
carbon atoms (C)
with hydrogen
atoms (H) attached.
Here’s one
example (three
different ways of
representing the
same chemical):
Palmitic acid
Lipids
Scientists often abbreviate that
chemical diagram to something like this:
Saturated vs Unsaturated
Saturated means “full of something.”
Saturated fats are completely full of
hydrogens.
Saturated vs Unsaturated
Unsaturated means “not full.”
Unsaturated Fats = carbons aren’t
totally surrounded by hydrogens.
Saturated vs Unsaturated
The difference between saturated and
unsaturated is being full of hydrogens.
Saturated= a straight line. Unsaturated
= has a kink.
“Good” vs “Bad” fats
Saturated = straight chains pack
together to make it solid.
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Unsaturated = crooked chains can’t
pack together, it stays a liquid.
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“Good” vs “Bad” Fats
(By the way, a “hydrogenated fat” is a
man-made saturated fat, and a “trans
fat” is an especially harmful kind of
hydrogenated fat.)
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Good vs. Bad fats
– Saturated fats, because they’re solid, can
clog up an artery like a traffic jam,
preventing blood from flowing through.
– Saturated fats in their rigid regular
structures are also harder to break down
for energy and easier to store.
Phospholipids
Phospholipids
– Make up cell membranes.
Polarity
 Water is polar, like a magnet.
 When it meets other compounds that are
also polar, just like magnets, they tend to
attract each other and stick together.
 We call compounds like that hydrophilic.
 Latin/Greek: Phil = Love <3
Polarity
 If a molecule isn’t polar, it tends to be
hydrophobic. Water and a hydrophobic
compound move away from each other.
 Latin/Greek: Phobia = Fear
Polarity
 The phosphorus end is polar, so it’s
hydrophilic. The two lipid chains are
hydrophobic, they separate from water
just like oil.
 Phosphorus head = hydrophilic
 Fatty acid tails = hydrophobic
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Polarity
 If you get more than one phospholipid in the
same place, they act in a predictable way
because of the attraction and repulsion from
the water they’re in.
 Simulation
 http://telstar.ote.cmu.edu/biology/Membra
nePage/index2.html
Et voila…
The inevitable chemical result is a
membrane!
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We call these layers of two lipids a
phospholipid bilayer. (Latin/Greek table: Bi =
two.)
The cell membrane of every living thing is a
phospholipid bilayer.
Et voila…
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Fluid Mosaic Model
Proteins are embedded in a cell
membrane.
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Fluid Mosaic Model
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The membrane = a fluid mosaic model,
because the mixed parts can flow
around each other.
Macromolecule Table
S hape
Carbohydrate
Amino acid
Nucleic acid
Lipid
Name
Biochemistry
Types
Key Locations
Functions/Uses
Other
Check for Understanding
Time to bestow some stickers!
– Put your notes away and keep just a blank
piece of paper. I will ask 9 questions about
lipids. Confer with your tablemate and
decide on the correct answer.
– The table or tables that get the most
questions correct, get one sticker per
person.
Check for Understanding
1. Which of these is not a lipid?
– A. Triglyceride
– B. Carbohydrate
– C. Phospholipid
2. Which kind has a kink in it, saturated
or unsaturated fats?
3. What are saturated fats saturated
with?
Check for Understanding
4. Having a kink in it makes a fat a…
– A. Solid.
– B. Liquid.
– C. Gas
5. Which part of a phospholipid is
hydrophilic?
– A. The phosphorus head
– B. The pholi body
– C. The lipid tails
6. What is the shape or identifying feature of
a lipid?
Check for Understanding
7. What kind of lipid makes up a cell
membrane?
8. In a phospholipid bilayer, why are the
tails on the inside and the heads on the
outside?
9. Which cell organelle is a described
by the fluid mosaic model?
Plasma Membrane
Selectively permeable membrane = a
membrane that some things can cross
and others can’t.
– The cell membrane is selectively
permeable, because of its phospholipid
fluid mosaic structure.
Cell Membrane
There are four ways that things can
move in or out of a cell: Simple
Diffusion, Facilitated Diffusion,
Osmosis, and Active Transport.
We begin with Passive Diffusion.
Observe!
Diffusion
Dye in water
Move out, troops. In a quiet and orderly
fashion listening to all directions.
Diffusion
Diffusion = The movement of particles from a
place where they are highly concentrated to a
place where they are not highly concentrated.
– It happens because molecules are in
constant motion.
Diffusion
http://highered.mcgrawhill.com/sites/0072495855/student_view
0/chapter2/animation__how_diffusion_w
orks.html
Simple Diffusion
One way for things to get in and out of a
cell…
Simple Diffusion = The diffusion of small
molecules across the cell membrane.
– Simple diffusion diffusion happens to it
automatically.
Simple Diffusion
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Facilitated Diffusion
If a molecule is too big for simple
diffusion, the cell membrane has some
protein channels (like windows).
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Facilitated Diffusion
Facilitated Diffusion = Diffusion helped
by proteins in the cell membrane.
– Just like Simple Diffusion, Facilitated
Diffusion doesn’t cost the cell any energy.
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Facilitated Diffusion
http://highered.mcgrawhill.com/sites/0072495855/student_view
0/chapter2/animation__how_facilitated_
diffusion_works.html
Vocab Review
Macromolecule
Lipid
Phospholipid
Phospholipid Bilayer
Fluid Mosaic Model
Hydrophilic
Hydrophobic
Diffusion
Simple Diffusion
Facilitated Diffusion
Selectively Permeable Membrane