Transcript Cell Transport and Response

9/20 BELL WORK
Which verb past tense does not belong with the
others? Why?
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bring
fight
buy
seek
catch
teach
draw
think
9/20 SCHEDULE
• Notes Ch 8.1 “Cell Membrane”
• Dir Rdg Ch 8 “Transport” or finish Test
Assignments:
1. Dir Rdg Ch 8 packet - TBA
Objectives:
1. Describe different kinds of cell transport.
2. Compare and contrast active and passive transport.
UNIT : CELL TRANSPORT
AND RESPONSE
MOVING IN, OUT, AND UPWARD
CH 8
CH 8.1 “CELL MEMBRANE”
Objective
• Describe how the cell membrane helps maintain
homeostasis.
• Explain the functions of membrane proteins.
INTRODUCTION
1. What happens soon after you eat a lot of salty
foods? What happens a few hours later?
2. Why do you think this happens?
HOMEOSTASIS
All living things respond to their environments.
• Homeostasis = maintenance of stable internal
conditions.
• Cells maintain homeostasis by controlling the
movement of substances across the cell membrane.
HOMEOSTASIS
Cells are suspended in fluid.
• The membrane…
• is gatekeeper/border patrol.
• provides structural support to the cytoplasm
• recognizes foreign material
• communicates with other cells
LIPID BILAYER
The cell membrane is a phospholipid
“sandwich”.
• Phospholipid = specialized fat with
a phosphate “head” and two
fatty acid “tails.”
LIPID BILAYER
Structure
• There is water inside and outside the cell, the
phospholipids form a lipid bilayer.
• The nonpolar tails make up the interior.
• The polar heads point toward the surfaces.
LIPID BILAYER, CONTINUED
Barrier
• Only certain substances can
pass through.
• Small, nonpolar substances pass
easily.
• Ions and most polar molecules
are repelled.
MEMBRANE PROTEINS
There are proteins throughout the membrane.
• The attraction and repulsion of parts of the protein to
water help hold the protein in place.
MEMBRANE PROTEINS, CONTINUED
Types of Proteins
• Cell-surface markers act like a name tag. A unique
chain of sugars identify each type of cell.
MEMBRANE PROTEINS, CONTINUED
These sugars are attached to the cell by
glycoproteins. They help cells work together.
MEMBRANE PROTEINS, CONTINUED
Types of Proteins
• Receptor proteins let cells sense their surroundings
by binding to certain substances outside the cell.
• When this happens, it causes changes inside the
cell.
9/21 BELL WORK
Shadow was examining a 14 ½ degree angle using his
magnifying glass that makes things 2 times bigger.
Under the glass, how large would the angle measure?
9/21 SCHEDULE
• Notes Ch 8.1 “Cell Membrane”- 8.2 “Cell Trasnport”
• Dir Rdg Ch 8 “Transport” or finish Test
Assignments:
1. Dir Rdg Ch 8 packet - FRIDAY
MEMBRANE PROTEINS, CONTINUED
Types of Proteins
• Enzymes in the cell membrane help with important
reactions inside the cell.
• Transport proteins carry materials that can’t pass
through the bilayer.
CH 8.2 “CELL TRANSPORT”
• Compare and contrast active and passive
transport.
• Explain why osmosis is important.
PASSIVE TRANSPORT
• Molecules move randomly in liquids and gases to fill
a space.
• Equilibrium: substances spread out evenly.
Brownian motion: Molecules are
moving and bounce off each other.
PASSIVE TRANSPORT
The amount of a substance in a given volume is
called the concentration.
In two containers…
• Same: equilibrium
• Different: a concentration gradient exists substances move.
• The movement of substances DOWN a concentration
gradient is called diffusion.
PASSIVE TRANSPORT, CONTINUED
Simple Diffusion - Some
things diffuse through the
lipid bilayer
• Examples: 02, CO2, and
steroids
PASSIVE TRANSPORT
Facilitated Diffusion
• Channel Proteins – tunnels in the membrane, let
things of right charge and size pass.
• Example materials: ions, water, sugars, and amino acids
PASSIVE TRANSPORT
Facilitated Diffusion
• Carrier proteins transport substances that fit within
their binding site. They change shape and release it
on the other side.
OSMOSIS
Facilitated Diffusion
• Water can diffuse across a selectively permeable
membrane during osmosis.
• There are channel proteins that only water molecules
can pass.
• Osmosis allows cells to maintain water balance as the
environment changes.
OSMOSIS, CONTINUED
Charged particles catch and hold water. The
remaining water is free to move.
• If a concentration gradient exists for solutes, there is
also a gradient for free water.
• Osmosis occurs as free water molecules move down
their concentration gradient to the solution that has
the lower concentration of free water molecules.
OSMOSIS, CONTINUED
The direction of water movement depends on the
cell’s environment.
Three situations:
• Hypertonic: a higher solute concentration than the
cytoplasm, water moves out of the cell. The cell
loses water/shrinks.
Hypertonic
onion cells.
OSMOSIS, CONTINUED
Three situations:
• Isotonic: same concentration, water diffuses in and
out of the cell at equal rates. The cell stays the
same size.
OSMOSIS, CONTINUED
Three Situations
• Hypotonic: lower concentration than the
cytoplasm, water moves in. The cell gains water
and expands.
Hypotonic onion cell
STOP NOTES
CONTROLLING OSMOSIS
Hypotonic swelling can cause a cell to burst.
Solution #1
• The rigid cell walls of plants and fungi prevent the
cells from expanding too much.
OSMOSIS, CONTINUED
Solution #2
• Some unicellular eukaryotes have contractile
vacuoles to force the water out of the cell.
OSMOSIS, CONTINUED
Solution #3
• Animal cells use energy to move ions, and the
water follows.
Water plays follow-the-leader.
OSMOSIS: ONION SKIN LAB
Notes
1. Use purple part of the onion's skin.
2. Avoid Contamination.
• Wash your equipment before and after using it.
3. Wash glassware ,dry it, and return.
ACTIVE TRANSPORT
Cells can use energy to actively move things
AGAINST their concentration gradient.
Pumps
• Some carrier proteins require energy to “pump”
substances.
ACTIVE TRANSPORT, CONTINUED
The sodium-potassium pump: actively transports
three sodium ions out and two potassium ions in.
• VERY important in animal cells, prevents too much osmosis
into cells
• Indirectly helps move glucose into cells.
SODIUM POTASSIUM PUMP VIDEOMP
ACTIVE TRANSPORT, CONTINUED
Vesicles
• Many substances are too large to use carrier
proteins, so cells use vesicles.
• proteins and polysaccharides
• Vesicles are a lipid bilayer, like the cell membrane,
so it can bud off or fuse with it.
ACTIVE TRANSPORT, CONTINUED
Vesicles
• The movement of a large substance into a cell using a
vesicle is endocytosis.
• The cell membrane forms a pouch around the
substance.
• The pouch then closes and pinches off from the
membrane to form a vesicle.
ACTIVE TRANSPORT, CONTINUED
Vesicles
• The movement of material out of a cell by means of
a vesicle is called exocytosis.
• Vesicles inside the cell fuse with the cell membrane.
Then the contents are released outside.
ACTIVE TRANSPORT, CONTINUED
Vesicles
Cells use exocytosis…
• to export proteins modified by the Golgi body.
• release their waste products.
• to remove bacteria or other microbes.
Exocytosis = cell bathroom break.
10/5 BELL WORK
Read’em and Reap wants to give away coloring
books. They’ve created a puzzle, so they don’t have
to give away too many.
• The first week of a month without an A in it.
• On a day of the week with a U in it.
• The month has no E, but the day does.
When will they give away the coloring books?
10/5 SCHEDULE
• 7 minutes to study, then ask specific questions on
material
• Ch 8 “Transport” test
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Use paper notes.
Keep electronics facedown and hands off. Music only!
Quiet until all tests are in.
ALL missing assignments MUST be in by 3:30
Assignments:
1. Dir Rdg “Membrane” and Transport” LATE
2. Letter Home – LATE
3. Osmosis Review - TODAY
STOP NOTES
EGG-SELLENT OSMOSIS DEMO
• Describe the eggs. (color, shape, size, texture)
• Are the following situations hypertonic, hypotonic,
or isotonic? How do you know?
• Egg 1 is in salt water.
• Egg 2 is in distilled water.
CH 8.3 KEY IDEAS
• Signal molecules
• Receiving Signals
• Signal Response
SENDING SIGNALS
• Communicating shares information.
• Cells in both multicellular and unicellular organisms
need to communicate in order to coordinate
activities.
• Cells use various methods of communication
depending on…
• whether the target is specific or general.
• whether the target is nearby or far away.
SENDING SIGNALS, CONTINUED
• Cells communicate and coordinate activity by
sending chemical signals that carry information to
other cells.
• A signaling cell produces a signal, often a molecule,
that is detected by the target cell.
• Target cells have specific proteins that recognize and
respond to the signal.
Nitrous oxide: anesthetic, opens blood
vessel, “laughing gas”
SENDING SIGNALS, CONTINUED
• Types of signals
• Neighboring cells communicate through direct
contact between their membranes.
• Short-distance signals act within a few cells of the
originating cell.
Direct
Contact
Short-distance
SENDING SIGNALS, CONTINUED
• Types of signals Cont’d
• Long-distance signals are carried by
hormones and nerve cells.
• Hormones are signal molecules
that are made in one part of the
body, and used in another.
• Hormones travel through the
bloodstream, but affect only
specific cells.
Negative effects of
growth hormone.
SENDING SIGNALS, CONTINUED
• Types of signals Cont’d
• Nerve cells also signal to distant parts
in the body, but their signals are not
widely distributed.
Ouch!!
SENDING SIGNALS, CONTINUED
• Types of signals Cont’d
• Some signals also come from outside the body.
• Gravity determines which way plant roots and stems
grow.
• Light
• affects plant growth and when some plants
flower.
• regulates peoples’ moods and sleep cycles
RECEIVING SIGNALS
• A target cell is bombarded by
hundreds of signals. But it
recognizes and responds to only a
few signals important for its
function.
• This response to some signals, but
not to others, is made possible by
receptor proteins in the cell’s
membrane.
G-protein involved in smell. It
triggers a neurotransmitter.
RECEIVING SIGNALS, CONTINUED
• The outer part of the receptor protein is folded into
a unique shape, called the binding site.
• Receptor proteins bind only to signals that match the
shape of its binding site.
• Only the “right” shape can fit while the “wrong”
shape have no effect on that particular receptor.
• A cell may also have receptor proteins that bind to
molecules in its environment.
BINDING SITE OF RECEPTOR PROTEINS
RECEIVING SIGNALS, CONTINUED
• Receptor proteins enable a cell to respond to its
environment.
• Once it binds the signal molecule, the receptor
protein changes its shape in the membrane.
• This shape change sends information into the
cytoplasm of the target cell.
RESPONDING TO SIGNALS
• The cell may respond by changing its membrane
permeability, activating enzymes, or forming a
second messenger.
• Transport proteins may open or close in response to
a signal.
Nicotine acts on receptors in the brain
increases dopamine
production…resulting in euphoria and
relaxation
RESPONDING TO SIGNALS, CONTINUED
• Some receptor proteins are enzymes or activate
enzymes in the cell membrane that trigger
chemical reactions.
• A signal molecule may also cause a second
messenger to form. The second messenger acts as
a signal molecule within the cell and causes
changes in the cytoplasm and nucleus.
SECOND MESSENGERS OF RECEPTOR
PROTEINS