What are the four parts of a cell that EVERY cell has ......Draw a Cell membrane that spans...
Transcript of What are the four parts of a cell that EVERY cell has ......Draw a Cell membrane that spans...
What are the four parts of a cell that EVERY cell
has? (Look waaay back to cell theory)
A. Plasma membranes form a boundary between
the inside and the outside environment
1. It is made by a two-layer structure called the
phospholipid bilayer
2. A phospholipid has 2 basic parts:
a. A head that “loves” water (hydrophilic)
b. A tail that “hates” water (hydrophobic)
3. The “head” is a polar molecule (attracted to water
molecules), the “tail” is non-polar (avoids water)
4. Membranes have “heads” on outside and “tails” on
inside so only the heads interact with water
The cell membrane is “semi-permeable”,
which means that it regulates the passage
of materials into and out of the cell
5. Other molecules are embedded within the membrane
a. Proteins form channels through membrane for transportation
b. Cholesterol molecules strengthen cell membrane
c. Carbohydrates attached to proteins act like “identification tags”
On a blank page
Draw a Cell membrane that spans horizontally
across the center of one page,
In this membrane Label the parts of the
phospholipid bilayer (Including charges)
Include An example of each molecule shown
above
Draw 5 water molecules on each side of the
membrane
We will be using this diagram for Cell transport
What are the major parts of a cell membrane?
What does selectively permeable mean?
Cells maintain a balance between
themselves and their environment
This balance is called equilibrium
Molecules are in constant motion.
As they move, they tend to go to areas that are
less crowded or “concentrated”.
Molecules always move from an area of high
concentration to an area of low concentration
Diffusion.swf
Two examples of diffusion & passive
transport (no energy required)
1. Perfume / scent around a room
2. Food coloring in water
Small Uncharged molecules, O2 CO2
Can move directly through Lipid bilayer
In diffusion and osmosis, the molecules move
“downhill” or with the concentration gradient.
Notice how no energy is required to move in
passive transport
High Concentration
Low Concentration
Isotonic Environment
The concentration of molecules is equal inside
and outside of the cell
Water enters and leaves equally
Hypotonic Environment
The concentration of molecules is lower outside of the
cell
More water enters than leaves
“hypo-” means “below” or “under”
What are some other words that start with “hypo-”?
Hypodermic, hypothermia, hypoallergenic, hypoxia,
hypoglycemic
Hypertonic Environment
The concentration of molecules is higher outside of the
cell
More water leaves than enters
“hyper-” means “above” or “higher”
What are some other words that start with “hyper-”?
Hyperactive, hyperextend, hypertension, hyperbaric, hyperbole,
hyperglycemic, hypersensitive, hypersonic, hyperventilate
Hypotonic?
Hypertonic?
Isotonic?
In facilitated diffusion, molecules are too big to
fit through the membrane directly
The molecules will instead pass through special
protein “channels” or “carrier proteins” in the
cell just for these molecules
Like diffusion, it does not require energy
Carrier Protein.swf
Water actually has a difficult time crossing the cell
membrane
Instead, it uses facilitated diffusion to cross the
membrane through protein channels called
“aquaporins”
Aquaporin.mpg
• When molecules move across a cell membrane
it is called diffusion
• When water moves across a cell membrane, it is
called osmosis
Osmosis.swf
Purpose to observe how salt water affects the
structure of a plant cell through the loss of water
due to osmosis
Hypothesize: What will happen to the Elodea
cells when they are exposed to salt water?
Procedure Grab a leaf of elodea out of the beaker, Make a
wet mount slide with H2O and observe at all
objectives
Draw the FOV for the 400x total magnification
and Label the Cell wall, Vacuole and
Chloroplasts in your Notebook
Clean your slide and prepare another wet mount
slide this time using Salt water, wait 10
minutes then Observe at all objectives and
Draw at 400x magnification.
Describe the differences you see between the
fresh water mount and the salt water mount.
Explain how the process of osmosis can be
attributed to the differences you see.
Why didn’t the cell wall keep the cell from
changing it’s water content?
Want to keep cookies fresh longer?
Describe the three cellular environments
What type of environment are these cells
exposed to?
Sometimes molecules
the cell needs are too
big to diffuse into or out
of the cell
The cell must use
energy to move these
molecules into or out of
the cell
When the cell must use
energy, it is called
active transport
High Concentration
Low Concentration
Active Transport moves molecules from an area of
LOW concentration to an area of HIGH
concentration
In other words, they are moving AGAINST the
concentration gradient
Notice how energy is required in active transport
• There are 4 types of active transport, all of which require energy
1. Endocytosis– Cell brings in material
2. Pinocytosis– Cell “drinking”
3. Phagocytosis– Cell “eating”
4. Exocytosis– Cell releases waste
• Each of these involves bringing materials into the cell except for exocytosis.
In molecular transport, small
molecules are carried or
“pumped” across the cell
membrane
In bulk transport, large
molecules or even solid
clumps of material can be
moved across the membrane
Phagocytosis.swf Active Transport & Facilitated Diffusion.swf