The Cell Membrane
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Transcript The Cell Membrane
Unit 2: Cells
Chapter 7-3
Cell Biology standard 1a
Students know cells are enclosed within semipermeable
membranes that regulate their interaction with their
surroundings.
Learning Goals:
•1. Describe the job/function of the cell membrane
•2. Explain what semi-permeable means.
•3. Describe the structure of the cell membrane.
•4. Describe the 3 types of movement across the cell
membrane. Include whether energy is required and which
direction the molecules move.
Cell Membranes surround ALL cells!
It controls what enters/leaves the cell
SEMIPERMEABLE – means it allows some
things through but not others
Made up of a Phospholipid bilayer
Polar heads “love” water (hydrophilic)
Nonpolar tails “fear” water (hydrophobic)
“Fluid mosaic model”
– describes the
structure of the cell
membrane.
Proteins float around
in the membrane like
icebergs in the ocean
Which of the following is NOT true
about the cell membrane:
A.
B.
C.
D.
Surrounds all cells
Controls what enters and leaves the cell
Surrounds the nucleus
Is a phospholipid bilayer
The cell membrane is
semipermeable. This means:
A. All things can pass through
B. Some things are let in or out but not
everything
C. Everything is blocked
D. Only small molecules may pass through
Keeps things in or out
Molecules can enter/leave the cell 3 ways
1. Diffusion
2. Carrier-Facilitated (“helped”) diffusion
3. Active transport
ATP
No energy required
Molecules move from area of high
concentration to area of low concentration
Concentration = # of molecules in an area
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Diffusion of water is called “osmosis”
No energy required
ATP
Molecules “helped” across by proteins from
high to low concentration
Energy required!
ATP
◦ ATP – the “battery” of the cell
◦ Breaking a bond in ATP releases energy
◦ Can “pump” molecules from low to high
concentration building them up in the cell
The diffusion of water is called:
A Osmosis
B. Transfusion
C. Water transport
D. Active transport
In diffusion molecules move:
A. From low to high’ no energy
B. From low to high; needs energy
C. From high to low; no energy
D. From high to low; needs energy
In carrier facilitated diffusion
molecules move:
A. From low to high’ no energy
B. From low to high; needs energy
C. From high to low with the help of a
protein; no energy
D. From high to low; needs energy
In active transport molecules
move:
A. From low to high’ no energy
B. From low to high; needs energy
C. From high to low; no energy
D. From high to low; needs energy
Learning Goals:
•1. Describe the job/function of the cell membrane
•2. Explain what semi-permeable means.
•3. Draw and label the structure of the cell membrane.
•4. Describe the 3 types of movement across the cell
membrane. Include whether energy is required and which
direction the molecules move.