Chapter 7 Guided Notes
Phospholipid Bilayer- __________________________ head, hydro____________
___________________________ tails, hydro___________
The bilayer serves as a cellular barrier or border:
heads are polar/ nonpolar & tails are polar/ nonpolar
Impermeable to _______________ molecules
The cell membrane is a thin barrier about ________ thick.
** Which substances can cross more easily than others? Hydrophobic (nonpolar) or
Hydrophilic polar?
Phospholipid bilayer becomes semi-permeable due to _________________ __________________ that
allow specific material across the cell membrane
The cell membrane is more than lipids!
** Which are proteins the perfect molecule to build structures in the cell membrane?
Within membrane: _______________________ amino acids, hydro________________
Anchors protein into membrane
On outer surface of membrane in fluid: ____________________ amino acids, hydro____________
extend into extracellular fluid and into cytosol
** What is an aquaporin?
Function through __________________________________ change – protein changes shape
Many functions of membrane proteins- 6 examples
1.
2.
3.
4.
5.
6.
Proteins determine membrane’s specific functions - unique collections of proteins
Classes of membrane proteins
_________________________________ proteins, loosely bound to surface of membrane
ex:
________________________________ proteins, penetrate lipid bilayer, usually across whole
membrane. Transmembrane protein. Ex:
Chapter 7 Guided Notes
In 1972, _____________________________ & ____________________________ proposed that membrane
proteins are inserted into the phospholipid bilayer.
The _______________________________ ______________________________ Model
** What other molecules are embedded in the fluid matrix of the lipid bilayer?
Membrane Carbohydrates- play a key role in ________________________________________________
Distinguish one cell from another. Ex:
Important in
& Basis for
MOVEMENT ACROSS THE CELL MEMBRANE
Diffusion- movement from
____________________________ transport, no energy needed
Diffusion through protein channels called ____________________________________________
Active transport- cells may need to move moelcules ___________________ the concentration
gradient. _________________________________________________________ transport solute from one side
of membrane to other. Ex:
Cost:
** Anitport vs. Symport
How about large molecules?
Movement into or out of the cell through ________________________ & ______________________
Endocytosis –
__________________________ = cellular eating
___________________________ = cellular drinking
Exoctosis –
Concentration of water – direction of osmosis is determined by comparing total solute
concentrations
Hyptertonic –
HypotonicIsotonicHypotonic – a cell in fresh water – high concetration of water around the cell
Problem:
Example:
Solution:
Plant cells -
Chapter 7 Guided Notes
Hypertonic- a cell in salt water- low concentration of water around the cell
Problem:
Example:
Solution:
Plant cellsIsotonic- animal cell immersed in mild salt solution. No difference in concentration of water
between cell and environment
Problem:
Example:
AquaporinsEvidence that there were water channels, protein channels allowing flow of water across
cell membrane.
Cell (compared to beaker)
Beaker (compared to cell)
Which way does the water flow?
Diffusion through phospholipid bilayer
What molecules can get through directly?
What molecules can NOT get through directly?
Membrane fat composition varies- Fat composition affects flexibility
_______________________ - unsaturated hydrocarbon tails with kinks
________________________ - saturated hydrocarbon tails