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What is the single most abundant
compound in living organisms?
 A.
fat
 B.
water
 C.
carbon
 D.
sugar
 Answer: B


#1-5
› Food
› Light
› Middle
› Self
› Up, throughout, again

#6-10
› Carbohydrates
› Nucleic Acids
› Phospholipid bilayer
› Proteins
› Sugar, phosphate, nitrogenous base
Complete the following:
 The cell membrane is composed of the
__________________. The heads are
______________ and the tails
are_____________.

• What is energy?
o
Energy is the ability to do work.
• What is potential energy?
o
Stored energy
• What is kinetic energy?
o
Energy of motion
Composed of the phospholipid bilayer
 Allows movement of certain substances
into and out of the cell.
 Because the cell membrane is nonpolar,
polar molecules, such as water, are
unable to go through the cell membrane
without going through a protein channel.

• Passive Transport-substance crosses the cell
membrane without any input of energy by the
cell
• Diffusion-takes place from an area of high
concentration to an area of low concentration.
• As a result of diffusion, the concentration of
many types of substances eventually
becomes balanced on both sides of a
membrane.
• Ex. the dispersal of ink in a beaker of water

List all of the properties that make a reed
diffuser (shown below) work.
• Equilibrium-the concentration of molecules will be
the same throughout the space the molecules
occupy.
• Concentration gradient-the difference in
concentration of molecules across a distance.
• High Concentration  Low Concentration = Down (Passive)
• Low Concentration  High Concentration = Up (Active)
• Simple diffusion-diffusion across the membrane
• Osmosis-the process by which water passes
into or out of a cell
• Aqueous solution-a solution in which water is
the solvent.
• Osmosis
• Hypotonic- the concentration of solute outside
the cell is lower than the concentration inside
the cytosol.
• Hypertonic-the concentration of solute outside
the cell is higher than the concentration in the
cytosol.
• Isotonic-the concentration of solutes outside
and inside the cell are equal.
• Osmosis Animation
• Osmosis

In 3 lines, explain what happens when a
human drinks salt water.

It is dangerous for humans to drink salt
water because when you drink salt
water, you put your cells into a
hypertonic solution, so there is more salt
on the outside of your cells than the
inside. Water then leaves your cells &
causes your cells to shrivel up, you go
crazy and then you die.
• When the solute concentration outside the cell is
higher than that in the cytosol, the solution outside is
hypertonic to the cytosol, and water will diffuse out of
the cell.
• When the solute concentration outside the cell is lower
than the concentration in the cytosol, the solution
outside is hypotonic to the cytosol, and water will
diffuse into the cell.
• When the solute concentrations outside and inside the
cell are equal, the solution outside is isotonic, and
there will be no net movement of water.
• To remain alive, cells must compensate for the
water that enters the cell in hypotonic
environments and leaves the cell in hypertonic
environments.
• Contractile vacuoles are organelles that
regulate water levels in paramecia.
o
o
Is NOT a form of passive transport because it
requires the cell to expend energy.
Contractile vacuole
• Turgor Pressure-the pressure that water
molecules exert against the cell wall.
• Plasmolysis-the cells shrink away from the
cell walls, and turgor pressure is lost.
• Cytolysis-the bursting of cells.
• Egg Osmosis

What characteristic of life means that
you maintain a constant internal
environment?


Homeostasis-the maintenance of
constant internal conditions
Ex. Temperature, water content, uptake
of nutrients by the cell

Filtration-a type of passive transport
involves the movement of water and
solute molecules due to hydrostatic
pressure
Complete the following sentence:
 In a hypertonic solution, water will move
___________ a cell & in a hypotonic
solution, water will move __________ a
cell.


In 3 lines, explain the difference between
passive and active transport.
• Facilitated Diffusion-the movement of large
molecules across the cell membrane is
assisted by specific proteins in the
membrane.
• Characteristics of facilitated diffusion:
o
o
o
It requires a carrier protein.
It requires no energy input.
It involves a change in the shape of its carrier.
• Ex. Sugar molecules enter cells
• Facilitated Diffusion
• Carrier Proteins-the proteins that assist
molecules across the cell membrane
• Ion Channel-transport ions through the
membrane
• Ion Channel
• Active Transport-materials move from an
area of lower concentration, to an area of
higher concentration.
• Active transport systems are a form of
cell transport that requires energy from
molecules of ATP.
• Active Transport
• Allows a cell to stockpile substances in far
greater concentrations than they occur
outside the cell.
• Some types of active transport are performed
by carrier proteins called cell membrane
pumps.
• Ex. A calcium ion channel will allow only
calcium ions to pass through it.
• Sodium-Potassium Pump-transports Na+ &
K+ ions up their concentration gradients
• Usually pumps potassium into the cell.
• Conduction of nerve impulses.
• ATP supplies the energy that drives the pump
• Sodium Potassium Pump
• Pump
• Some substances are too large to pass
through the cell membrane by transport
processes, so they must undergo endocytosis
or exocytosis.
• Molecules that are too large to be moved
through the membrane can be transported
into the cell by endocytosis.
• Pinocytosis-“cellular drinking”
• Phagocytosis-“cellular eating”
o
o
Ex. Amoeba
Amoeba Eating
• Ridding the cell of material by discharging it
from sacs at the cell surface.
• Molecules that are too large to be moved
across a cell membrane can be removed from
the cell by exocytosis.
• Exocytosis
• Crash Course-Transport
• Why is it dangerous for humans to drink
ocean water?

Cell Membrane

Gummy Bear Labhttps://www.youtube.com/watch?v=HNT
ymLy03gY