Download Plasma Membrane

Also known as the cell membrane – It
is so fun! 

To regulate/control what enters and exits the
cell.
What types of things can get in and out of the cell
from passing through the lipid bilayer (without
using a protein)?
- Tiny non polar molecules (carbon dioxide and
oxygen)
-water goes through aquaporins

Through proteins (integral or transmembrane
proteins)
*Know the diagram of a plasma membrane
- Phospholipid
Phosphate head is hydrophilic (likes polar molecules
like water)
- Lipid tail is hydrophobic (prevents molecules like
water from crossing the membrane)
-
-
Proteins – channel for molecules like water to
cross the plasma membrane


How does the plasma membrane regulate what
crosses the cell membrane?
What can cross the cell membrane without
using a protein?
1.
2.
3.
4.
What types of molecules can cross the cell
membrane without using a protein?
What types of molecules must use a protein to
cross the cell?
Draw a phospholipid and name the part that is
hydrophilic. Which part is hydrophobic?
Explain how the plasma membrane regulates
what enters and exits the cell.

Direction the molecules want to go


Solutes move from a high concentration gradient
to a low concentration gradient.
Passive transport/Diffusion: Molecules that cross
the cell membrane without using a protein
Carbon dioxide
 Oxygen



Facilitated Transport: molecules move through a
protein
Active transport: molecules move against the
concentration gradient (low to high)

Must use energy (ATP)


When water crosses the membrane
Water crosses the membrane so that the solute :
water ratio will be in equilibrium

Explain what concentration gradient and
equilibrium have to do with homeostasis

Must use the following vocabulary words:
concentration gradient, diffusion, homeostasis,
protein, membrane, equilibrium

Size: Surface Area and volume


Concentration Gradient


The relationship between surface area and volume
controls cell size. As a cell gets larger, its volume
increases faster than its surface area if the cell
maintains the same shape.
More solutes allow for more transport
Energy Use

ATP is needed for Active Transport
Take a look at
http://programs.northlandcollege.edu/biology/b
iology1111/animations/flagellum.html