Transcript Ch. 8 Cells & Their Environment

Ch. 8 Cells & Their Environment
Section 8.1 – Cell Membrane
1. What is homeostasis, and what is the main way that the cell membrane helps
maintain homeostasis?
- the maintenance of stable internal conditions in a changing environment.
- by controlling the movement of substances across the cell membrane.
2. List three other functions of the cell membrane.
-Provides structural support to the cytoplasm, recognizes foreign
-material, communicates with other cells.
3. The _____ _____ is made of a double layer of phospholipids.
The double layer of phospholipids is called a(n) _____ _____.
- cell membrane
- lipid bilayer
4. The lipid bilayer forms because there
is _____ both inside and _____ of the cell.
- water
- outside
5. The phosphate _____ of a phospholipid
is polar. It is _____ _____ water.
- head
- attracted to
6. The long fatty acid _____ of a phospholipid are nonpolar.
They are _____ _____ water.
- tails
- repelled by
7. The lipid bilayer forms a barrier, preventing
most molecules from passing through it. Only
molecules that are _____ in size and _____
can pass through the lipid bilayer.
- small
- nonpolar
8. Ions, which are _____ particles, and _____ molecules
are repelled by the nonpolar interior of the lipid bilayer.
- charged
- polar
9. The cell membrane includes various kinds of _____. Some face the inside of the cell.
Some face the _____ of the cell. Others span the entire width of the _____ _____.
- proteins
- outside
- cell membrane
Pair-Share
Take 3 minutes to explain why water requires a
channel to get through the cell membrane.
Use the following terms in doing so:
1. Cell membrane
2. Lipid bilayer
3. Hydrophobic
4. Polar
5. Nonpolar
10. What are proteins made of?
- amino acids
11. Why do proteins stay within the lipid bilayer of the cell membrane?
Nonpolar parts of the protein are attracted to the interior of the lipid bilayer while
also repelled by water on either side of the membrane.
12. List the four types of proteins found in a cell membrane.
- cell-surface markers
- receptor proteins
- enzymes
- transport proteins
13. Cell Surface Marker
- identifies the cell type
Example: markers on red blood cells that denote blood type
14. Receptor protein
-
recognizes and binds to substances outside the cell, enabling the cell to
sense its environment
Example: HIV virus infecting human
white blood cells
15. Enzyme
- helps with chemical reactions inside the cell
16. Transport protein
- Helps substances move across the cell membrane
Use your notes to identify each of the following cell membrane proteins.
3.
1.
2.
4.
Section 8.2 – Cell Transport
1. What is the purpose of cell transport? What is
the difference between active transport and
passive transport?
- Cell transport is the movement of substances
across a cell membrane.
- Active transport requires energy to move a
substance while passive transport does not.
2. What is equilibrium?
- When a space is filled evenly with molecules
or particles.
3. What is diffusion? Why is diffusion an example
of passive transport?
- The movement of substances from an area of high
concentration to an area of low concentration,
down the concentration gradient.
4. simple diffusion
b. small, nonpolar molecules passing directly
through the cell membrane
5. facilitated diffusion with channel proteins
c. an ion, sugar, or amino acid moving through
a specific pore, based on the size and charge of
the moving substance
6. facilitated diffusion with carrier proteins
a. a substance binds to a protein, which changes
shape; both move together across the cell
membrane, where the substance is released
Osmosis
7. What is osmosis, and why is it important in cells?
- The movement of water across a membrane from an area of high concentration to an
area of low concentration.
8. Explain how water moves across a cell membrane.
- Water moves through specific channel proteins.
9. water moves into the cell
c. The solution a cell is in is hypotonic, meaning that it has a lower solute concentration
than the cytoplasm does.
10. a state of ongoing equilibrium occurs
b. The solution a cell is in is isotonic, meaning that it has the same solute. concentration
as the cytoplasm does
11. water moves out of the cell
a. The solution a cell is in is hypertonic,
meaning that it has a higher solute
concentration than the cytoplasm does
Active Transport
12. The transport of a substance across the cell membrane against its concentration
gradient is called _____ _____.
- active transport
13. The energy needed for active transport is usually supplied by _____.
- ATP
14. What is the sodium-potassium pump? Describe how it works.
Endocytosis
15. Explain why proteins and polysaccharides cannot be transported across a cell
membrane by carrier proteins. How do these substances cross the cell membrane?
- they are too large, they use vesicles
16. What is endocytosis? Describe how it works.
- The cell membrane forms a pouch around the substance to be imported which then
pinches off into a vesicle.
Exocytosis
17. What is exocytosis? Describe how it works.
- A vesicle containing large molecules fuses with the cell membrane and expels its
contents outside of the cell.
18. What are some circumstances in which cells use exocytosis?
- Export proteins, release waste, remove bacteria
Label each of the following types of movement
across a cell membrane.
A.
B.
C.
D.