Transcript Chemistry, Lipids, and Cell Membranes

III. Chemistry, Lipid structure, and Cell Boundaries
Chemistry – study of the composition,
properties, & changes of substances.
Inorganic Chemistry – study of all
compounds that don’t contain carbon.
-Inorganic compounds don’t contain
carbon, ex : H2O, NaCl, etc.
-2 exceptions : CO2 & CaCO3 (in
rocks)
Organic Chemistry – study of all
compounds that contain carbon.
-Organic compounds contain
carbon, ex : CH4.
A. The Chemistry of Carbon
1. Carbon has 4 valence
electrons for bonding.
2. Carbon can bond with
other carbon atoms to
form carbon chains.
3. Carbon can form large,
complex molecules,
ex : Chains form rings.
B. Macromolecules : “Giant molecules”
-Living cells contain large
molecules known as
macromolecules or giant
molecules.
-Are formed by polymerization
– process of building large
compounds by joining smaller
ones together.
Monomer – small units that can
join together to form polymers.
Polymer – large compound
formed from combinations of
monomers.
C. Lipid structure
Recall : Lipids – macromolecules
made mainly from carbon
& hydrogen atoms &
glycerol; includes fats, oils,
waxes, phospholipids, &
steroids.
Body Use of Lipids

The body uses lipids to :

Get extra fuel 9 kcal/gram.

Build cell membrane parts.

Provide insulation for the winter
or cold environments.

Give padding to organs.

Waterproof the skin, ears, etc.

Make hormones.
-Can be found in : meats, oils,
milk, nuts, and egg yolks.
Saturated vs. Unsaturated Fats
*Lipids include 2 types of fats : Saturated vs. Unsatured.
Saturated – having all single carbon
to carbon bonds in the fatty acid
(C – C). Is bad fat that is solid at
room temperature and tends to be
stored in animals, ex : butter. *These
build up in our bodies & are solids
that increase cholesterol.*
Unsaturated – having 1 or more pairs
of carbon to carbon double or triple
bonds in the fatty acid. This is healthier
fat that tends to by liquid at room
temperature, ex : olive oil.
Polyunsaturated Fats
Polyunsaturated – having more
than 1 double or triple bond in
the fatty acid.
-Lipids also include cholesterol,
which is made by the liver and
can accumulate,
leading to heart attacks if over
200.
What is the correct amount of
lipids that the body needs?
Answer : 30% of diet.
D. Cell Boundaries
*Cell borders separate the cell
from its environment. May be :
Cell membrane – a thin, flexible
barrier found around all cells.
Cell wall – a strong supporting
layer around cell membranes in
plant cells.
1. The Cell Membrane
-Cell membranes regulate what enters
& leaves the cell (selectively permeable).
It also provides protection/support.
-Is made up of a double-layered
sheet called a lipid bilayer (2 layers
of flexible lipids). Mostly lipids &
proteins.
Structure of the Cell Membrane
-Proteins are found embedded in the lipid bilayer, some
with carbohydrate chains attached.
-The bilayer contains phospholipids, molecules with a
phosphate head & a lipid tail.
-The phosphate head is hydrophilic (water-loving) & the
lipid tail is hydrophobic (water fearing).
Cell Membrane : Fluid Mosaic Model
-Cell membranes are fluid : proteins & lipids are
constantly in motion.
-Because cell membranes are fluid & have patterns
(mosaics) of proteins & other molecules in them,
scientists refer to the structure of the cell membrane
as the Fluid mosaic model.
2. Cell Walls
Main function : to provide
support & protection for
the cell.
-Found in plants, algae,
fungi, & some prokaryotes.
-Are made mostly of
cellulose, a tough
carbohydrate fiber.