Transcript Passive and Active Transport

Cell Membrane
 Phospholipid bilayer – two layers of
phospholipids back to back
 Phosphate Heads – polar – water
soluble - hydrophilic
 Lipid Tails – non-polar – water
insoluble – hydrophobic
Cell Membrane
Cell Membrane
Cell Membrane
 Cholesterol stabilizes the membrane by
preventing the lipid tails from sticking
together
 Proteins help regulate what enters and
exits the cell
 Carbs stick out from the membrane to
identify chemical signals
What is Cell Transport?
Discovering how molecules
travel across the cell membrane.
Maintains homeostasis for the
cell
There are 2 types of transport
Passive Transport
Passive Transport – moving
particles across the cell membrane
from high to low concentration
using no energy
There are 3 examples
Passive Transport
 Facilitated Diffusion – uses channel or carrier
proteins to move molecules from a high to low
concentration
 Channel proteins allow easier travel for
larger molecules
 Carrier proteins change shape to help
molecules to travel through
 Diffusion – moving any type of molecule
across the cell membrane from a high to low
concentration
Facilitated Diffusion
Diffusion
Osmosis
 Osmosis – diffusion of water across a
cell membrane
 Water travels from a high to low
concentration
 Concentration Gradient – unequal
distribution of particles that controls
osmosis
 3 different solutions
But First…
 Solute – a substance that is dissolved in
another substance
 Ex. Salt, Sugar
 Solvent – a substance that dissolves other
substances
 Ex. Water
Osmosis
 Isotonic Solution – the concentration of
the solute inside the cell is the same as
the concentration of the solute outside of
the cell
 Water moves in and out of the cell at
the same rate
Isotonic Solution
Osmosis
 Hypotonic Solution – The concentration
of solute outside the cell is smaller than
inside the cell
 There is more water outside the cell
than inside
 Water moves into the cell
 The Cell Swells
Hypotonic Solution
Hypertonic Solution
 Hypertonic Solution – The
concentration of solute outside the cell is
greater than inside the cell
 There is more water inside the cell
than outside
 Water moves out of the cell
 The Cell Shrinks
Hypertonic Solution
Active Transport
Active Transport – moving particles
across the cell membrane from low
to high concentration using energy
Uses carrier proteins
Uses 2 Processes
Active Transport
 Endocytosis – the cell membrane
encloses and forms around large particles
in order to let it pass through
 Exocytosis – the expulsion of materials,
waste, and hormones from the cell
Transport Protein
Protein embedded in the cell
membrane responsible for picking
up or passing molecules through the
cell membrane. This requires energy.
Endocytosis
Exocytosis
Why Is Active Transport
Important?
 Rid the cell of toxins
 Movement to avoid danger or to find
food, water, and or mates
 Synthesizing needed molecules