Download Warm Up (5 minutes)

Catalyst: December
nd
2 ,
2014
 Prepare to complete your Discovery assessment B.
 Checklist:
 Answer sheet
 Test booklet
 Pencil
Agenda
 Catalyst: 5 minutes
 Discovery Exam set-up: 5 minutes
 Discovery Assessment B
 Reminders:
 Honors Projects due THURSDAY!
Announcements
 Updated grades
 Grade slips tomorrow
 Dojo rewards
Catalyst: December
rd
3 ,
2014
 Prepare to complete your Discovery assessment B.
 Checklist:
 Answer sheet
 Test booklet
 Pencil
When you finish your exam…
Read the “Just Add Urine” article and answer the reading
questions
Agenda
 Discovery Test B
 Unit 4 tracking (if time)
Announcements
 Unit 4 grades
Catalyst #2: December
th
4 ,
2014
 1. What is the major difference between
prokaryotic and eukaryotic cells?
 2. How would you classify your brain cells?
 Eukaryotic or Prokaryotic?
 Animal or Plant?
3. Draw the cell membrane (refer to
Assignment 4.1) and label the following
structures: Phospholipid bilayer, Fatty acid
tails, phosphate heads, peripheral protein
Agenda
 Catalyst: 5 minutes
 Intro to solutions and osmosis (15
minutes)
 Osmosis Gizmo Demos + Questions (
Remaining)
 Homework:
 None 
Announcements
 Unit “5.2”
 Begin preparing for semester exams
Unit 4.2 : Guiding Questions
 How does a cell make sure it has
enough water and nutrients?
 What happens to the cell in
different environments?
 How do cells take in the nutrients
they need and release the
substances they do not?
Today’s SPI & Objectives
 SPI 3210.1.7 Predict the movement of water
and other molecules across selectively
permeable membranes.
 SWBAT define solute and solvent in order to
understand the components of a solution
 SWBAT define osmosis
 SWBAT define hypotonic, hypertonic, and
isotonic solutions and predict the effect of
each solution on a cell
Solutions
 Cells are typically surrounded by water
and other substances that are dissolved in
water
 The term used for a liquid with at least
one substance dissolved in it is a
solution
 Example: Salt water
Solutions
 Every solution has two parts:
 A solvent is the liquid that dissolves the
other substances

Example: Water
 Solutes are the substances dissolved in
the liquid

Example: Salt
CFU 1
 Kool-Aid is made by
dissolving sugar in
water.
 What is the solvent?
 Water
 What is the solute?
 Sugar
Concentration
 Solvent concentration is a measure of
the relative amount of solvent in a
solution
 High solvent concentration= a lot of liquid
 Solute concentration is a measure of
the relative amount of solute in a solution
 High solute concentration= a lot of solute
The Cell Membrane
 Recall, the cell membrane is selectively
(semi) permeable
 It selects what enters and leaves the cell
 One substance that can move into and out
of the cell is water
Osmosis
 Osmosis is the movement of water across
a semi-permeable membrane from high
solvent concentration to low solvent
concentration
 Water always moves from where there is
relatively more water to relatively less water
 Therefore, it moves from lower solute
concentration  higher solute concentration
Osmosis
Dynamic Equilibrium
 When the concentration of water on each
side of the membrane becomes equal,
water continues to move but in equal
amounts
 This is known as dynamic equilibrium
 Dynamic=moving
 Equilibrium= equal
CFU 2
 Only water can pass
through the
membrane
 In which direction
will more water move
based on the diagram
to the right?
 Left (more water,
less solute) to right
(less water, more
solute)
Osmosis
Cells & Their Environment
 Cells are typically surrounded by water
(solvent) and substances that are dissolved in
water (solutes)
 In other words, they are located in solutions
 There are 3 types of solutions in which cells can
be located:
 Hypotonic
 Hypertonic
 Isotonic
Hypotonic Solutions
 Lower solute
concentration than the
cytoplasm of the cell
 Hypo=lower
 Less solute, more water
 More water moves into
the cell than out of the
cell
Hypotonic Solutions
 The cell swells in a hypotonic solution
 Water causes the cell to expand
Hypertonic Solutions
 Higher solute
concentration than the
cytoplasm of the cell
 Hyper=more
 More solute, less water
 More water moves out of
the cell than into the cell
Hypertonic Solutions
 The cell shrinks in a hypertonic
solution
Isotonic Solutions
 The same solute
concentration as the
cytoplasm of the cell
 Iso=same
 The same amount of water
moves into and out of the
cell
Isotonic Solutions
 The cell remains the same size in an
isotonic solution
Gizmo Review Questions
 We will look at 3 simulations of cells in
different solutions using Gizmos
 Answer the 4 questions for each
Example (1, 2 and 3)
 Answer additional questions 1 and 2
Exit Ticket
1. What happens when a cell is located in a
solution with a lower solute concentration
than the inside of the cell?
2. Why does a cell shrink in a hypertonic
solution?
3. In what type of solution are the cells
pictured below?