Download Chapter 4 Cells and Their Environment

Chapter 4 Cells and Their Environment
Section 1 Passive Transport
I. Diffusion
1. Cells maintain ___________ by controlling the movement of substances
across their cell membrane.
2. Cells use __________ to transport some substances across the cell
membrane. Other substances move across the ___________
_____________ without any use of energy by the cell.
A. Random Motion and Concentration
1. _____________ ____________ movement across the cell membrane that
does not require energy. Ex. __________ (see figure 1)
2. _____________ ___________ - a difference in the concentration of a
substance across a space. Ex. ________________________________
_______________________________________________
Illustrate
3. Equilibrium – ________________________________________
______________________________________________________
Ex. __________________________________________.
Illustrate
B. Movement of Substances
1. ________________ of a substance in a solution also move around
randomly.
2. If there is a concentration gradient in the solution, the ________
_____________________________________________________
_____________________________________________________.
3._________________ - is the movement of a substance from an area of high
concentration to an area of lower concentration caused by the random motion
of particles of the substance.
Illustrate
4. Many substances, such as molecules and ions dissolved in the _________
and in the fluid outside cells, _____________________________________
______________________________________.
Illustrate
5. Substances must be able to pass across the ___________________ for
diffusion to take place.
6. The cell membrane is _________________________ to substances.
7. Why can certain substances move across the cell membrane and others
can’t?______________________________________________________
____________________________________________________________
____________________________________________________________
II. Osmosis
1.
__________________________ are small and can diffuse through the
cell membrane.
2.____________ - is the diffusion of water through a selectively permeable
membrane.
Illustrate
3. Like other forms of ________________, osmosis involves the movement of
a ________________________________________________________.
4. If the solutions on either side of the cell membrane have different
concentrations of dissolved particles, they will also have ________________
______________________________________________________________.
5. Osmosis will occur as free water molecules move into the solution with the
______________________________________________________________.
6. The direction of water movement across the cell membrane depends on the
relative concentration of free water molecules in the ____________________
________________________________.
7. There are 3 possibilities for the direction of water movement.
a. Hypertonic Solution – when the fluid outside the cell has a _________
__________________________________________________________
__________________________________________________________
The cell _______________.
Illustrate
b. Hypotonic Solution – if the fluid outside the cell cell has a _________
__________________________________________________________
__________________________________________________________
The cell _________________.
Illustrate
c. Isotonic Solution- if the cytoplasm and the fluid outside the cell _____
__________________________________________________________
__________________________________________________________
This results in no net movement of water across the cell
membrane and the cell stays the same size – a ________________
There is no change in ________ ____________.
Illustrate
8. If left unchecked, the swelling caused by a hypotonic solution could cause a
______________________________.
9. What do plant cells have that prevent the cell from expanding too much?
___________________________________
III. Crossing the Cell Membrane
1. __________________________________ can pass across
the cell membrane when aided by transport proteins.
2. Transport proteins called ____________ for ions and polar
molecules.
3. Each channel allows only a _________________________
__________________________________________________
Illustrate
A. Diffusion Through Ion Channels
1. Ions such as ___________________________ are involved in
many important ___________________. Ex. _________________
_____________________________________________________
2_______________________________ – a transport protein
through which ions can pass. This is a type of _______________
___________________. No use of _____________is required
because ions move down their concentration gradient.
B. Electrical Charge and Ion Transport
1.The movement of a _____________________________, such
as an ion, across the cell membrane is influenced by the particles
______________________________________________ charge.
2. The inside of a typical cell is _________________________
with respect to the outside of the cell. Opposite charges attract and
like charges ___________________.
Illustrate
3. A more _____________________ charged ion outside the cell
is more likely to diffuse into the cell.
C. Facilitated Diffusion
1. ______________________________ – a transport protein that
can bind to a specific substance on one side of the cell membrane,
carry the substance across the cell membrane, and _____________
_____________________________________________________.
2. Facilitated diffusion – _______________________________
__________________________, such as amino acids and sugars –
down their concentration gradient. This is a type of passive
transport. Draw figure 4 page 80.