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.
Section 2 Active Transport
I. Movement Against a Concentration Gradient
1. Cells have a way to move some substances against their
concentration gradient- _______________________________
__________________________________________________.
2. _________________________ – the transport of a substance
across the cell membrane against its concentration gradient.
3. Active transport requires the cell to use _________________.
4. Most often the energy required is supplied by ____________.
A. Sodium-Potassium Pump
1. Sodium-Potassium Pump- transports ___________________
______________ out of a cell and _______________________,
into the cell.
2. Sodium ions are usually more concentrated
___________________ the cell than inside and _____________
are more concentrated inside than outside.
3. These substances are being transported __________________
their concentration gradient.
The two main reasons why the sodium-potassium pump is
important:
a. The sodium-potassium pump is needed to _____________
___________________________________________________
The increased concentration of sodium ions would cause water
to enter the cell by _____________________, causing the cell
to _______________________________.
b. The Na+ /K+ helps maintain the _____________________
__________________________ of both of these ions.
II. Movement in Vesicles
1. Many substances, such as ___________________________,
are too large to be transported by carrier proteins. These
substances move across the cell membrane by
__________________.
2. ______________________ – the movement of substances
into a cell by a vesicle.
a. The cell membrane forms a _________________
around a substance.
b. The pouch then closes up and pinches off from the
membrane to form a _________________.
3. ________________________ – the movement of substance
by a vesicle to the outside of a cell.
a. Vesicles in the cell ____________________________,
releasing their contents.
b. Cells use _________________________ to export
proteins that are modified by the Golgi apparatus.
c. Ex. ________________________________________.
III. Membrane Receptor Proteins
1. Body cells must _________________________ with each
other to coordinate ______________________________,
and other activities.
2. Some cells release __________________________ that
carry information to nearby cells and throughout the body.
Ex. __________________________
3. Hormones are made in one part of the body and carried in the
_______________________________________, where they
have their effects.
4. _________________________ – is a protein that binds to a
specific signal molecule, enabling the cell to respond to the
signal molecule.
Ex. ________________________________________________
______________________ that tell the muscles when to
contract and when to relax.
A. Functions of Receptor Proteins
1. a signal molecule is bound by a ______________________
that fits that molecule.
2. Receptor proteins are embedded in the _________________
of the cell membrane.