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Cellular Level of Life
Ch. 7
22
Biology
Undergraduate 1
02/23/2011

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Term
Neuron
Definition
involved in every thought, movement, or sensation in animals
Term
Dendrites
Definition
Collect incoming electrical signals; they listen
Term
Neuron fires...
Definition
when Na+ ions cross cell membrane
Term
Na+
Definition
Sodium ions
Term
Why don't Na+ ions cross the membrane all the time?
Definition
Lipid bilayer forms barrier to most molecules
Term
Saturated Fatty Acids
Definition

-straight lines

-saturated with hydrogens

-2 H on 1 C

Term
Unsaturated Fatty Acids
Definition

-double bonds

-one H on one C

Term
characteristics of phospholipid bilayers
Definition

-constantly moving 

-membrane fluidity (fluid/viscous)

-cholesterol 

Term
How does cholesterol affect membrane fluidity?
Definition
reduces membrane fluidity/creates regions of vicousity
Term
What drives formation of membranes?
Definition
need for water to form Hydrogen bonds
Term
Amphipathic
Definition
a molecule having hydrophobic and hydrophillic regions
Term
Hydrophilic
Definition
polar regions of some molecules soluble in water
Term
Hydrophobic
Definition
non-polar, non-ionic substances
Term
Is cholesterol amphipathic?
Definition
Yes
Term
phospholipid
Definition
main structural component of biological membrane
Term
a membrane is ________ on it's surface and _________ in its center
Definition
polar; non-polar
Term
Diffusion
Definition
random movement of molecules; high to low concentration
Term
Why do things move across the membranes in a particular direction?
Definition
a concentration gradient is too ordered; equilibrium can be reached
Term
What can get across the lipid bilayer?
Definition

-non-polar

-very small polar things (eg-water)

Term
Osmosis
Definition
diffusion of water through a membrane
Term
[image]
Definition
phospholipid
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