BELL WORK:
Answer the following questions on
your bell work page:
1. Name two major differences between
prokaryotic and eukaryotic cells.
2. Draw a picture to illustrate the Endosymbiotic
Theory.
**I will collect ALL your bell work tomorrow!!**
CO: I will investigate cellular
processes such as homeostasis
and molecule transport.
LO: I will begin a lab and take
notes on osmosis and diffusion.
The Egg Demo
Potato Lab Day 1
• Each station has 3 cups of solution and 3
pieces of potato.
• Choose one person from your group to record
your data on the chart – you will keep this
chart until tomorrow, so don’t lose it!
• Weigh each piece of potato, write down the
weight, and put the potato into one of the
cups. DO NOT MIX UP THE PIECES!
• One person from your group will bring the
cups to me when you are finished.
All cells are surrounded by a thin, flexible
barrier known as a cell membrane.
What is the cell membrane’s
function (job)?
(2 things)
The two main functions are:
1) to regulate what enters and leaves the
cell
2) to provide protection and support.
What is the cell membrane made
(composed) of?
(3 types of molecules)
• The composition of cell membranes is a
double-layered sheet called a lipid
bilayer.
Bi- means 2
Also called the
phospholipid bilayer
Proteins are embedded in the lipid bilayer.
• Proteins form channels or pumps that help move
large materials across the cell membrane.
• Carbohydrates are
attached to many
proteins
embedded on the
outside of the
bilayer.
• The carbohydrates
allow individual
cells to identify
one another.
How do substances move into/out
of the cell membrane?
(4 ways)
Why does food coloring spread out in water?
• In a solution,
particles are
constantly
moving.
• They collide with
one another and
spread out
randomly.
• Particles move from an area of high
concentration to an area of low
concentration.
• This is known as diffusion.
• The concentration is the amount of a
substance dissolved into water.
• A concentration
gradient is a
difference
between two
concentrations.
• Diffusion is the
movement of
particles down the
concentration
gradient.
High
Concentration
Low
Concentration
• When the
concentration of a
solute is the same
throughout a
system, the system
has reached
equilibrium.
• When equilibrium is
reached, particles do
continue to move
across the
membrane.
• Substances
that diffuse
across a
membrane do
not require
the cell to use
energy.
• If a substance is able
to diffuse across a
membrane, it is
permeable.
• If a substance
cannot diffuse across
a membrane, it is
impermeable.
• Selectively
permeable means
that some substances
can pass across while
others cannot.
• Biological
membranes are
selectively
permeable.
• Diffusion of water through a selectively
permeable membrane is called osmosis.
• Remember: SALT SUCKS
HOMEWORK TONIGHT!
• If you are watching
tonight’s video on your
PHONE, you will need
to search for the video
directly on YouTube…
• If you STILL need to complete
Tuesday’s homework and you
will be using your PHONE, you
will need to search for the
video directly on YouTube…
• Search 2.4.4
• Search
Defining Diffusion
and Osmosis (by
Stephanie Castle)
Compartmentalization
(by Bozeman Science)
BELL WORK:
Answer the following question on your
bell work page:
What three molecules make up a cell
membrane? (hint: look at
yesterday’s notes!)
Take out your homework (for me to
check) and ALL your bell work (for me
to collect).
The Egg Demo
HYPOTONIC SOLUTIONS
Hypotonic means “below strength”
Water (outside the cell) = HIGH
Solute (outside the cell) = LOW
REMEMBER… “Hypo means
LOW, makes the cell GROW!”
Like the egg in
distilled water…
HYPERTONIC SOLUTIONS
Hypertonic means “above strength”
Water (outside the cell) = LOW
Solute (outside the cell) = HIGH
REMEMBER… “Hyper means
HIGH, makes the cell DRY!”
or….SALT SUCKS!
Like the egg in
syrup…
ISOTONIC SOLUTIONS
Isotonic means “same strength”
Water (outside the cell) = SAME
Solute (outside the cell) = SAME
REMEMBER… in ISOTONIC
solutions, water is still
moving, you just can’t see it!
Like the egg in
vinegar…
What would happen if
you put a freshwater fish
into the ocean? Why?
What would happen if
you put a saltwater fish
into fresh water? Why?
Potato Lab Day 2
• Send ONE person from your group to collect
your potatoes.
• Take each potato out of the solution, pat it
dry, and weigh it again. Write TODAY’S weight
in the “After soaking” column.
• Calculate the difference (if any) in weight.
• Based on today’s notes, label the three
solutions as hypertonic, hypotonic, or isotonic.
• With your group, answer the lab questions. Be
sure to turn in your papers before you leave!!