Transcript Cell Transport - Solon City Schools

Cell Transport
What can cross the cell membrane
easily?
• 1) Hydrophobic molecules- like
lipids, carbon dioxide, and oxygen
can dissolve in membrane and cross
it w/ ease
• 2) Water- although it is polar it’s tiny
enough to pass b/w the fatty acid tails
of the membrane (osmosis)
• *These molecules use passive
transport (diffusion & osmosis) (no
energy used) to cross the membrane
Cell Membrane
What molecules have trouble
crossing the cell membrane?
• 1) Sugars and amino acids (large
molecules)
• 2) ions (polar) (ex. Na+ , K+)
• *These molecules use facilitated
diffusion (w/ help from transport
proteins like channel or carrier
proteins) (no energy used) to cross
the membrane or they use active
transport (requires energy)
Crazy Cell Transport Vocab Words
We Need to Know
• Equilibrium- concentration of a substance
is the same throughout a space
• Solute- substance that dissolves in
another
Ex. Sugars, salt, amino acids, & ions
• Solvent- substance that dissolves the
solute
Ex. In cells, solvent is water
• Solution- mixture of solutes and solvent
Passive Transport
• Passive Transport- movement of a
substance through a cell’s membrane
WITHOUT USING ENERGY
• *PARTICLES MOVE FROM AN
AREA OF HIGHER
CONCENTRATION (LARGE
AMOUNT) TO AN AREA OF
LOWER CONCENTRATION (SMALL
AMOUNT).
Concentration Gradient
HIGH
LOW
Types of Passive Transport
• Osmosis- movement of water
through a membrane from an area of
high conc. to low conc.
• *water always moves across cell
membranes to maintain equilibrium
Types of Osmosis
• Isotonic Solution- solute conc. in the
solution outside of the cell is the same as
it is inside the cell
• -Likewise, conc. of water in the solution
outside the cell is the same as the conc. of
water inside the cell
• ex. Equal amounts of water will move into
and out of the cell, cell volume/shape is
maintained
• ex. IV’s at the hospital are isotonic to your
cells.
Isotonic Solution
• Isotonic Animation
• *Red dots = solute
• *Black dots = water
Types of Osmosis
• Hypotonic Solution- solute conc. in
the solution outside the cell is lower
than inside the cell
• -Therefore, more water is present
outside the cell than inside
• ex. Water moves into the cell and
may cause it to burst
• ex. Why grocery stores spray fruits
and veggies
Hypotonic Solution
• Hypotonic Solution Animation
• *Red dots = solute
• *Black dots = water
Types of Osmosis
• Hypertonic Solution- solute conc. in
the solution outside the cell is higher
than inside the cell
• -Therefore, more water is present
inside the cell than outside
• ex. Water moves out of the cell and
causes it to shrivel
Hypertonic Solution
• hypertonic solution animation
• *Red dots = solute
• *Black dots = water
Review of Isotonic, Hypertonic, and
Hypotonic Solutions
• Isotonic, Hypertonic, and Hypotonic
Solutions' Animations
Types of Passive Transport (continued)
• Diffusion- movement of particles
directly through a membrane from an
area of high concentration to low
conc. (ex. Oxygen, carbon dioxide,
water, lipids all use this process)
• Ex. Oxygen diffuses into the blood
stream b/c there is a higher conc. of
oxygen in the lung’s air sacs than
there is in the blood
• Animation: How Diffusion Works
Types of Passive Transport (cont.)
• Facilitated diffusion- transport of
large particles through a membrane
by a channel or carrier protein
• Ex. Glucose, amino acids, ions
• *particles move from a high conc. to
a low conc.
• *no energy used
• Facilitated Diffusion animation
Active Transport
• Active Transport- transport of
specific particles through a
membrane by a channel or carrier
protein
• ex. Ions, etc.
• *particles move from a low conc. to a
high conc.
• *REQUIRES ENERGY
Active Transport
• Active Transport Video
Types of Active Transport
• *Sometimes some food molecules are too large
to move into the cell by transport proteins
• 1. Endocytosis- process by which large
food particles and extracellular particles
are engulfed by a portion of the cell’s
membrane
• ex. Phagocytosis (cell eating)- white
blood cells engulf bacteria
• ex. Pinocytosis (cell drinking)- uptake of
extracellular fluid
• ENTER THE CELL
• Animation: Phagocytosis
Types of Active Transport (cont.)
• Exocytosis- reverse of
endocytosis- dumping of waste
materials outside a cell by
discharging them from waste
vesicles that fuse w/ the plasma
membrane
• EXIT CELL
Exocytosis Animation
Overall Idea of Cell Transport
• cell is able to function b/c it is able to
control what enters or leaves
• -like a home, a cell membrane has “doors
with locks” that only allow certain particles
to pass through
• -plasma membrane is selectively
permeable b/c it allows the passage of
some solutes but not others