Transport in the Cell
Active and Passive Transport
How can molecules move through
cells?
• Semi-permeable membrane: allows
certain molecules to move in or out
depending on their properties
– Ex: if they are too big, they can’t go in easily
• Membrane is made of (composition):
– Bi-lipid layer
• 2 layers of lipids
– Proteins that transport materials across
– Carbohydrates that act as identifiers
Fluid Mosaic Model-membrane is a fluid with a bunch of
different components
Before we begin you must
understand….
• Concentration-how much solute is
in a solvent
• Why must molecules move?
– To maintain homeostasis
– Homeostasis-state of balance in which
the internal body remains in a normal
range
– Molecules must move to maintain this
Biology 11/5
HW-Concept Map
1. Take out 7.3 wkst and 7.3 notes.
2. Pick up your binder in the back.
Put 7.3 reading guide in wkst
section.
2 types of transport in the cell
• Passive transport
– Molecules move down
the concentration
gradient
• Area where there is a
lot of molecules to
where there is very
little
– Energy involved: NO
• Active transport
– Molecules move up the
concentration gradient
• Area where there is a
few molecules to
where there is a lot
– Energy involved: YES
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Type of Passive Transport
Diffusion-movement of molecules
from an area of high concentration
to an area of low concentration until
equilibrium is reached
– Equilibrium-equal distribution
• Molecules will move equally after this is
reached.
– Simple molecules can move
• Carbon dioxide, oxygen
Passive transport
Osmosis-Type of passive
transport
• Water moves from an area of
high concentration to an area
of low concentration
– No energy involved
– AKA: diffusion of water
Hypertonic and Hypotonic
• Hypotonic-More water outside the cell than
inside
– Distilled water
– Water comes into the cell
– Why? To balance out the concentration of
solutes
• Hypertonic-More water inside the cell than
outside
– Salt water
– Water leaves the cell
– Why? to balance out the concentration of
solutes
Isotonic
• Molecules are equal inside and
outside the cell
– Molecules move evenly across the
membrane
Biology 11/14
HW-finish concept map
Agenda: Stations; finish notes
You should be:
1. Take out 7.3 notes
2. Take out paper with station
information.
Station Exploration
• You will visit different stations.
• At each station, there will be directions
telling you what conditions each item was
place in or what to do with each item.
• On your paper, you need to write down a
brief description of what you see and why.
– Examples of answers for why: hypertonic,
hypotonic, diffusion, osmosis, decrease in
turgor pressure, molecule movement
HW-finish reading guide for 7.4 by
reading 7.4 and answer questions;
experiment B on wkst; 7.3-7.4 test on
Friday
Agenda: Finish demo discussion, go
over concept map/review guide, finish
notes
1. Take out review sheet if you didn’t
turn it in on Friday.
2. Take out demo info and noteguide.
Balloon Station
• Box smelled like lemon.
• Odor from the lemon moved out of the
balloon.
• How to explain better?
• The odor molecules were able to
permeate or go through the pores of the
balloon.
• Since particles like to move from high to
low concentration, the odor moved from
the inside of the balloon to the outside
where there were no lemon odor
molecules.
Gummi Bear in water
• Gummi bear grew in size
• Why?
– It was placed in a hypotonic
environment.
– There were more solutes inside the
gummi bear than outside.
– So water moved into the gummi bear
to balance the solutes.
– The water moved from an area of high
concentration to low concentration
through osmosis.
Why is water so important
to a plant?
• Water fills the vacuole and the
contents of the cell are pushed
against the cell wall
• Produces turgor pressure
• Gives the plant rigidity and the
ability to stand erect
Grapes in water
• Grapes are cracked on the skin.
• Grapes are placed in hypotonic
environment.
• There are more solutes inside the
grape than outside.
• To balance the solutes, water flows
into the grape through diffusion.
• The vacuole is full of water
increasing the turgor pressure.
Carrots in salt water
• Carrot was flimsy and bendable.
• Salt water was a hypertonic env.
• The carrot had a lower solute
concentration than the outside of the
cell.
• There was more water inside the cell
than out.
• To balance the solutes, water left the
carrot and went into the salt water.
• The carrot’s vacuole shrunk and wasn’t
pushing against the cell wall, decreasing
the turgor pressure.
Food coloring in cup of
water
• Food coloring dissolved evenly in
the cup.
• The food coloring diffused
throughout the water until
equilibrium was reached.
Congo red vs Food coloring
• The congo red egg didn’t look as red
as the one in food coloring.
• Why?
– Congo red particles are too big to
permeate the membrane.
– Red food coloring particles are smaller
so they can move through the
membrane by diffusion.
Dialysis Tubing-has pores
• Tubing with starch in
it
– Iodine on the outside
– Inside the bag is
purple
– Outside is yellow with
iodine
– Starch is too big to go
through the bag, but
iodine moves through
diffusion.
Dialysis Tubing with
Glucose in it
• Glucose was found outside the bag.
• Glucose is smallest enough to move
through the bag by diffusion.
Facilitated Diffusion-3rd
type of passive transport
• Molecules move from an area of high
concentration to an area of low
concentration with the help of a carrier
protein
– Molecules attach to a specific protein
– The protein allows it to move through the
membrane
– Needed when molecules are too big or have
an electrical charge (ions!!)
• Glucose (large molecules), Na+, Ca+, K+, Cl-
Active Transport-A
reminder!
• Requires energy from the
cell
• Move molecules from an
area of low concentration
to high
Endocytosis
• Process for bringing things
into the cell
• Used for large particles
(bigger than molecules, still
microscopic)
• Requires energy
Phagocytosis
Pinocytosis
• “Cell Eating” • “Cell Drinking”
• Small bits of
• Very large
liquid or other
particles
substances
taken in by
taken in
cell (engulfed)
Exocytosis
• Process for moving large
amount of material out a cell
Movie Time
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Bio 11/13
HW-finish wkst; Lab due Friday; test and
flashcards Friday (25 from 7.3 and 10 from
7.4)
1. Turn in analysis questions. Put
transport review in wkst section. This is a
great study tool for the test. Put lab info in
lab section.
2. Take out 7.4 notes-we will finish this.
Movie time
• http://www.brainpop.com/science/
cellularlifeandgenetics/passivetrans
port/
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Section 7.4
• Unicellular-one celled
– Bacteria, algae, yeast
– One cell does all the work
• Multicellular-many celled
– Plants, humans
– Specialized cells do certain things
Specialization
• Cell develop differently to perform
different tasks
• All cells at one time in your body
are the same (stem cells)
– Then they differentiate in fetal
development
• Become different cells with different
functions
• Muscle cells-allow movement
• Red blood cells-carry oxygen
• Guard cells in plants open and close
stomata on a leaf.
Group of tissues
Smallest
level
Group of organs
that perform a
specific function
Group of
similar cells
Largest level