Download Cells - Mrs. GM Biology 200

Unit 4: The Cell & Its Environment
Ch. 2:1 (pg. 31) Cell Theory
Ch. 2:3 (pgs. 38-40) Special Cell Processes (Diffusion & Osmosis)
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Cells
• Who first
observed
cells?
• What was he
looking at?
• Did he see live
cells?
–No, just cell
walls.
Robert Hooke
Further Discoveries Lead to the Cell Theory
1. All organisms are made of one or more cells.
(Schleiden & Schwann)
Cell Theory Rap
2. The cell is the basic unit of structure and
function in organisms. (Schleiden & Schwann)
3. Cells are produced from other cells (Virchow)
Properties of the Plasma Membrane
• What are the functions (jobs)
of the cell membrane?
1. Boundary between cell & its
environment
2. “Gatekeeper”
• Lets certain
materials in/out
(“selectively
permeable”)
A Model of the Plasma Membrane
• In general, what does the plasma
(cell) membrane look like?
–phospholipid bilayer
A Model of the Plasma Membrane
• What does the plasma (cell)
membrane look like in more detail?
–“Fluid Mosaic Model”
• Molecules (like proteins) embedded in
phospholipid bilayer & in constant motion
Membrane Movement Animation
Movement of Materials
Across the Cell Membrane:
Passive Transport
• What is passive transport?
– Does passive transport require energy?
• Why/why not?
– Ex. of passive transport?
Concentration gradient =
differences in concentration
Movement of Materials Across the
Cell Membrane: Passive Transport
• Ex. Diffusion
–How do
molecules of
solute move?
• Do they ever
completely
stop?
Movement of Materials Across the
Cell Membrane: Passive Transport
• What is the
special name
for the diffusion
of water?
– osmosis
Effects of Water Concentrations
on Cells
• What is an
isotonic
solution?
–concentration of
solutes (& water)
same on both
sides of the
membrane
• Which way would
water move?
How osmosis works animation
Effects of Water Concentrations
on Cells
• What is a hypotonic
solution?
–lower concentration
of solutes outside cell
• higher concentration
of water outside cell
• Which way would
water move?
How osmosis works animation
Effects of Water Concentrations
on Cells
• What is a
hypertonic
solution?
–higher concentration
of solutes outside cell
• lower concentration of
water outside cell
• Which way would
water move?
How osmosis works animation
Effects of Water Concentrations on
Cells: Cytolysis & Plasmolysis
plasmolysis
cytolysis
What adaptation prevents the plant cell from bursting?
What happens to cells in
different types of solutions?
Which cells were in salt water?
How can you tell?
Elodea in salt water
Membrane Function
Passive Transport: Facilitated Diffusion
• Even though they’re going w/ the concentration
gradient (high  low) some substances:
– can not dissolve in lipid bilayer
– are too large to squeeze through
carrier
Membrane Function
Passive Transport: Facilitated Diffusion
• So how can these materials permeate
the membrane???
– Facilitated diffusion
• With the help of:
– Channel proteins (pores)
– Carrier proteins
– Gate proteins
carrier
– Does facilitated diffusion require energy?
Why/why not?
• No, b/c going from high  low
carrier (transport)
protein
channel protein
(pores)
Channel & Gate
Protein
Animations
gat e
protein
Signal molecule not combined
w/ gate (gate closed)
Signal molecule
combines w/ gate
Once ions pass through,
signal molecules unbind &
gate closes
Gate opens & ions
can pass through
Movement of Materials Across the
Cell Membrane: Active Transport
• What is active
transport?
– Does active transport
require energy?
• Why/why not?
– Ex. of active transport?
Concentration gradient =
differences in
concentration
Movement of Materials Across the Cell
Membrane: Active Transport
• How can materials be moved
against the concentration
gradient (low  high)?
– transport proteins (pumps) that
use energy (ATP)
Passive & Active Transport Animation
Protein/Transport Pumps Animation
Active Transport Animation
Active Transport:
Endocytosis & Exocytosis
• Not all materials can pass through
membrane…
– So, how do they get into/out of the cell?
•
Membrane encloses the material  pinches off 
releases the material on the other side
– endocytosis
– exocytosis
Exocytosis & Endocytosis Animation 1
Endocytosis & Exocytosis Animations 2
Exocytosis & Endocytosis
Animation 1
Endocytosis & Exocytosis
Animations 2
Active Transport:
Endocytosis & Exocytosis
• Which way do substances
move during endocytosis?
– What are 2 types of endocytosis?
• phagocytosis
• pinocytosis
– What types of materials are
moved by phagocytosis &
pinocytosis?
– Do they require energy?
Liquid droplets
Exocytosis & Endocytosis
Animation 1
Endocytosis & Exocytosis
Animations 2
Active Transport:
Endocytosis & Exocytosis
• Which way do
substances move during
exocytosis?
– What types of materials
are moved by exocytosis?
• Does exocytosis
require energy?
The Cell Wall
•
•
•
•
•
•
What is the cell wall?
Where is it located in the cell?
What is it made of?
What type of organisms have cell walls?
What does the cell wall do for the cell?
Does it affect the cell’s permeability?