Transcript with the concentration gradient.

Cellular
Transport
Cell Membrane
• Job: Controls what enters and leaves the
cell.
• Selectively permeable – picks and
chooses what crosses the membrane.
Cell Membrane Structure
1. Phospholipids bilayer –
• has a hydrophilic “ Water- loving” head
and a hydrophobic “water-fearing” tail.
• Phospholipids are arranged tail to tail.
Cell Membrane Structure
2. 3 types of proteins
a. Channel Proteins – provides a passageway for
molecules to enter and leaved the cell.
b. Receptor Proteins – Receive chemical signals from
the other cells.
c. Marker Proteins – Identifies the cell – lets the body
know where the cell is supposed to be.
Movement Across the Membrane
• Terms:
– Concentration – the
amount of something in
a certain area
– Concentration gradient –
there is a difference in
concentration of a
specific substance in two
different areas.
Movement Across the Membrane
• There are two types of transport.
– Passive Transport – does not require energy
– Active Transport – requires energy
Passive Transport
• All passive transport moves from an area
of high concentration to an area of low
concentration.
– This is called moving with the concentration
gradient.
• 3 types
1. Diffusion
2. Facilitated Diffusion
3. Osmosis
Passive Transport
• 1. Diffusion – the movement of particles
from an area of high concentration to an
area of low concentration.
– Requires no energy
– Occurs with small particles and nonpolar
particles that can easily move through the
phospholipids bilayer of the membrane
Passive Transport
– Diffusion
continued…
– Diffusion is the
random movement
of particles until all
particles are
equally spread out
or mixed together.
Passive Transport
• 2. Facilitated Diffusion
– Movement of particles from an area of high
concentration to an area of low concentration
with the help of channel proteins
– Moves with the concentration gradient
– Requires no energy
– Facilitate means to “help”
Passive Transport
• 3. Osmosis – the movement of WATER across
a semi-permeable membrane from an area of
high concentration to an area of low
concentration.
– Things to remember about osmosis:
• We are always talking about WATER
movement
• Solute (the stuff dissolved in the water)
cannot cross the membrane.
Passive Transport
• Osmosis Continued …
– Osmosis requires no energy
– When there is a high concentration (more)
solute dissolved in the water, there is less
water.
– When there is a low concentration (less) of
solute dissolved in the water, there is more
water
• Osmosis continued…
– Water will move from where there is more
water to where there is less water. (high to
low)
– HINT: Water always goes to the area with
more SOLUTE.
Which Way Will The Water Move?
Isotonic – solute is equal on both sides of
the cell. Water moves equally in and out of
the cell. The cell will remain the same.
Which Way Will The Water Move?
Hypertonic – there is more solute
outside of the cell than inside. Water
will leave the cell. The cell will shrink.
Which Way Will The Water Move?
Hypotonic – there is less solute outside of the
cell than inside. Water will enter the cell. The
cell will swell.
•OSMOSIS ANIMATION
Osmotic pressure – pressure against the
inside cell membrane
Active Transport
• Materials always move from an area of low
concentration to an area of high
concentration.
– This is called moving against the
concentration gradient.
– Active Transport requires the use of the
cell’s energy.
Active Transport
•
3 Types:
1. Ion Pumps
2. Endocytosis
3. Exocytosis
Active Transport
• 1. Ion Pumps –
– Ions are pumped across the membrane with
the help of channel proteins.
– Ions are pumped against the concentration
gradient. (low to high)
– Requires energy
Active Transport
• 2. Endocytosis –
– Large particles are taken into the cell.
– The cell extends its membrane, engulfs
(surrounds) the particle and takes it in.
– 2 types
• Pinocytosis “Cell drinking”
• Phagocytosis “Cell eating”
Active transport
• 3. Exocytosis
– Particles are released from the cell.
– A vesicle joins with the cell membrane to
release unnecessary material.
Two Major Types of Cells
• Eukaryotic Cells
• Have a nucleus and
membrane bound
organelles
• Has a lot of ‘stuff’ in
the cell
• Ex: animal cells, plant
cells, blood cells
• Prokaryotic Cells
• Has no nucleus or
major membrane
bound organelles
• They do have
ribosomes and loose
DNA
• Ex: bacteria