Download Notes: Chapter Eight

Notes: Chapter Eight
Membrane Structure and Function
I.
Date:
Membrane Structure
a. Membranes contain ________________, __________________,
and _____________________ (which are all types of
macromolecules)
b. The lipids in the cell membrane are ______________________.
c. The current model of the cell membrane is called the ______________
____________________ model.
II.
Evolution of Cell Membrane Theories
a. 1895 the cell membrane was thought to be made of _____________ since substances
that dissolved in ___________ entered the cells faster than insoluble substances.
b. 1917 first artificial membrane formed from _______________________.
c. 1925 idea that the membrane was a ____________________ _______________.
d. 1935 the Sandwich model proposed a ________________ between two layers of globular
__________________.
e. 1972 ___________________ ______________ with membrane ______________
dispersed throughout the cell membrane (CURRENT AND ACCEPTED MODEL)
f. Fluidity of Membranes
i. Lipids move ___________________ in a membrane, but
___________-____________ is rare.
ii. ___________________ hydrocarbons have kinks that
keep the molecules from packing together and enhancing
membrane fluidity.
iii. Cholesterol ________________ membrane fluidity (at
moderate temps). At low temps it hinders
___________________ by disrupting the packing of the
phospholipids.
g. The Mosaic Structure of the Cell Membrane
i. Mosaic –
ii. Types of proteins in the membrane
1. Integral proteins
2. Peripheral proteins
iii. Functions of cell proteins
1.
2.
3.
4.
5.
6.
iv. Cell membranes have distinct ____________ and _______________ faces.
____________________ are found on the outer side of the membrane.
1. The carbohydrates on the surface of the cell membrane function to
_________________ one cell from another.
h. THE CELL MEMBRANE IS _______________ _____________________!!!
III.
Traffic Across Membranes
a. Permeability of the lipid bilayer
i. Hydrophobic molecules can dissolve across the lipid bilayer
1. ex:
ii. Ions and polar molecules can not dissolve across the membrane
1. ex:
iii. Transport proteins 1. Channel proteins –
2. Pump proteins –
3. The proteins are ______________. They will only allow specific molecules
to pass through.
b. Passive Transport across the membrane
i. Diffusion –
ii. Concentration gradient iii. Passive Transport –
c. Osmosis –
i. hypertonic –
ii. hypotonic –
iii. isotonic –
d. Why is water balance important?
i. The control of water balance is ________________________ (animal cells).
ii. Ex: Fish in salt water
iii. Plant cells can be _____________ (normal state), __________________ (limp),
or ______________________ (lethal state).
e. Facilitated Diffusion
i. Facilitated diffusion requires the help of a ________________ or
________________ to move molecules or ions.
f. Active Transport
i. Active transport requires the use of ___________. Energy is required because
molecules are usually going against their ___________________
_______________.
ii. Ex: Sodium-potassium pump
g. Some ion pumps generate voltage across membranes
i. Ex: nerve cells
ii. An unequal distribution of charged ions across a membrane will cause a
_________________ _______________.
iii. A transport protein that generates voltage across a membrane is a
___________________ pump.
iv. Most common example of a electrogenic pump is the ____________ pump.
h. Cotransport
i. Some molecules are transported across the membrane at the same time, this is
________________________.
ii. Ex: H+ ions are transported out of a cell, and both the H+ ions and sucrose
molecules are transported into the same cell.
i.
Exocytosis and Endocytosis
i. When the cell secretes macromolecules by the fusion of vesicles with the plasma
membrane, this is ___________________. (think exit)
ii. When the cell takes in macromolecules and matter by forming new vesicles from
the plasma membrane this is ___________________ (think enter)
1. phagocytosis –
2. pinocytosis –
3. receptor-mediated endocytosis -