MOVEMENT ACROSS CELL
MEMBRANES
Moretti and Dickson
Bio 9A: Wednesday, 12.1.10
Title: Movement Across Cell Membranes – Day 1


Homework:
Read pages 182-189 (Section 7-3): Take notes based on
the questions on the back of Assignment Sheet and write
your answers in your notebook.
Silent Do Now: (in your notebook w/ title & date)
Which molecule is bigger, starch or glucose? Explain with a
diagram in your notebook.
When you’re done, take out your Digestion Project and make sure
it is ready to hand in!
Today’s Agenda & Objectives

Objectives:


Design an experiment by drawing on your knowledge of
starch, glucose, cell membranes, and experimental
indicators that test for the presence of starch and glucose.
Agenda:
Quick sharing of Digestion Projects (10 min max)
 Review Do Now (5 min max)
 Experiment Design (30 min)

Designing a Lab:
Diffusion Across Cell Membranes
Planning the Experiment:
 Individual:


Read Overview
Small Groups:

Planning the Experiment



How do we test for Starch
and Glucose?
Whole Class Discussion
Small Group:


Model Cell
w/ Dialysis
Tubing
Membrane
Experimental Set-Up
Whole Class Review:

Experimental Set-Up
Water
Objectives for Class:
 Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and
experimental indicators that test for the presence of starch and glucose.
Lennin
Martin
Olivia
Naidaliz
Joelle
Daysia
Alerte
Jesse
Kenny
Cassandra
Yamile
Victor
Nathy
Lila
Joshua
Amrita
Emiliano
Beverly
Lorena
Imani
Javier
Erick
Bryan
Devin
Hajar
Martely
Bio 9A: Thursday, 12.2.10
Title: Movement Across Cell Membranes – Day 2

Homework:
Rough draft of Background Info and Purpose & Hypothesis sections
for a lab report on the membrane experiment (refer to the handout
from yesterday)
Type and print or bring a handwritten copy to class tomorrow!

Silent Do Now (in NB w/ title & date)
What is happening to the dye in the water?
 What vocabulary word from last night’s reading applies to this
situation? Why?
 What do you think will happen to the dye by the end of class?

Today’s Objectives

Describe and explain the following terms:




Lipid Bilayer
Selective Permeability
Diffusion
Osmosis
Use this vocabulary to explain how a cell membrane
controls what enters and leaves a cell
Agenda:
 Notes/Discussion/Quick Animation
 Ticket To Go
 Plan lab procedure w/ partner

Cell Membrane Vocabulary

Lipid Bilayer
 Two
layers of lipids that form the
outer membrane of a cell.
 Flexible
 Strong
 Do
not Dissolve in water
Image to the right shows the
lipid bilayer of a cell.
Notice how it has other
components like protein
channels & “pumps” built
into it.
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
New Vocabulary

Selective Permeability
 When
a membrane only allows
certain substances to pass across
the membrane (and not others)
 Substances usually pass across
based on the size, shape, and
charge (+/-/neutral) of the
molecules
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
New Vocabulary

Concentration

How much “stuff” is in a given amount of liquid
Mass of a solute (stuff in the liquid) per a given
volume of the total solution

i.e.: 12g of salt in 3L of water = 12g/3L = 4g/L


Diffusion


Diffusion
Movement of molecules from a
high concentration (more stuff) to low
concentration (less stuff)
Osmosis
Osmosis

Movement of water through a selectively
permeable membrane from a
high concentration to low concentration
Note: For osmosis to occur, the membrane only allows water
to pass across and not the solute
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
New Vocabulary
Diffusion, Osmosis and Selective Permeability In Action:
http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Ticket to Go
On your small piece of paper:
 Draw one picture that illustrates at least 3 of the words
we’ve talked about today
Lipid Bilayer
 Selective Permeability
 Concentration
 Diffusion
 Osmosis


Write the words on the picture so I know which ones
you’re drawing
If you’re done early: Take out the lab handout for
tomorrow and work w/ your partner to start planning
your procedure
Bio 9A: Friday, 12.3.10
Title: Movement Across Cell Membranes – Day 3


Homework:
None!
Do Now:
Take out the Diffusion Lab Handout.
With your partner from Wednesday, talk QUIETLY to discuss
and fill in the Procedure Overview (Parts 1-4) on the
back of this handout.
You have 10 minutes to complete this.
Today’s Objective: Design, conduct, and analyze data
from an experiment to determine which substances
(glucose and/or starch) can pass through a cell
membrane.
Lennin
Martin
Olivia
Naidaliz
Joelle
Daysia
Alerte
Jesse
Kenny
Cassandra
Yamile
Victor
Nathy
Lila
Joshua
Amrita
Emiliano
Beverly
Lorena
Imani
Javier
Erick
Bryan
Devin
Hajar
Martely
Do Now #2 – In your notebook
Title for Today: Diffusion Lab
1.
Summarize the purpose of this experiment:
2.
Write a specific prediction for this experiment:
Diffusion Lab:
Procedure Review – Part 1

Set-up Dialysis Bag





Rinse w/ tap water to wash excess
solution from outside of bag
Set-up Beaker



Moisten tube and tie one end
Add the starch & glucose solution to the
tube
Tie the top of the tube
Fill a 250 ml beaker ¾ of the way with
water
Add Iodine to water – mixture should be
orange
Put dialysis bag into beaker with water
Water and Iodine
and iodine
Objectives for Class:
 Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and
experimental indicators that test for the presence of starch and glucose.
Diffusion Lab:
Procedure Review – Part 3

Starch

How do we test for it?


How do we know starch has passed through
membrane?


Use Iodine
Iodine outside the dialysis bag turns from yellow-orange to
purplish- brown
Glucose

How do we test for it?


Boil it in Benedicts solution or use a glucose test strip
How do we know glucose has passed through the
membrane?

Glucose test strip will change color
Objectives for Class:
 Design an experiment by drawing from your knowledge of starch, glucose, cell membranes, and
experimental indicators that test for the presence of starch and glucose.
Do Now #3


In your notebook, create a data table for this
experiment!
Your table must include a place to record
beginning and ending colors of:
 The
water/iodine in the beaker
 The dialysis bag (“cell”)
 The glucose test strip
9A – Same seats as last week!
Amrita
Yamile
Martin
Jesse
Lennin Bryan
Lorena
Alerte
Imani
Joelle
Lila
Victor
Erick
Nathy
Joshua
Cassie
Kenny
Daysia Javier Devin
Beverly
Hajar
Olivia
Emiliano
Naidaliz
Martely
Bio 9A: Monday, 12.6.10
Title: Diffusion Lab – Day 2
Homework:
Revise Background Info if necessary; continue with other
sections of lab report (whole thing due Thursday)
 Silent Do Now (in notebook w/ title & date)

Find your Diffusion Lab data table
 Summarize your results in your notebook and try to explain
what each result means.

Was there a color change in the beaker? What does this tell us about
a substance that did or did not diffuse?
 Was there a color change in the bag? What does this tell us?
 Was there a color change in the glucose test strip? What does this
tell us?

Today’s Objectives & Agenda







Discuss and analyze the results of the diffusion
experiment
Use the lab report rubric to identify mediocre versus
excellent examples of Background Info sections
Identify the strengths and areas for improvement in
your own background info section
Agenda:
Quick Class Discussion of Results
Evaluate examples of Background Info
Class discussion & brainstorm
Diffusion Across Cell Membranes:
Presenting the Data/ Results

Color Change?
Glucose Test Strip
changed color
Bag Turned
Purple/ Black
No Color Change to the Water
Water and Iodine
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Today’s Objectives & Agenda








Discuss and analyze the results of the diffusion
experiment
Use the lab report rubric to identify mediocre versus
excellent examples of Background Info sections
Identify the strengths and areas for improvement in
your own background info section
Agenda:
Quick Class Discussion of Results
Evaluate examples of Background Info
Class discussion & brainstorm
Peer editing
Lab: Diffusion Across Cell Membranes
Writing Better Background Information Sections
Task 1 – Do this silently on your own:
• Read the two example Background Information
sections from the Denatured Enzyme Lab
• Grade them according to the rubric.
• Identify strengths and areas for improvement
Objectives for Class:
Use the lab report rubric to identify mediocre versus excellent
examples of Background Info sections
Sample Background Info sections
Example 1
Strengths: gives exact definitions,
defines all the words,
necessary for understanding
the lab
Things to improve: do not give
examples, not detailed, needs
a paragraph, flow, no
creativity, seems robotic,
definitions were not explained
well
Overall grade: ¾ or 15/20 or
C
Example 2
Strengths: it’s flows like a river
It gave examples, they avoided
phrases like “a word you need
to know is blahblblah” they
included every definition. They
included the concept/idea.
Things to improve: don’t use
technical words. It doesn’t
give a one sentence overview
of the lab
Overall grade: 4/4
A or A+
Objectives for Class:
Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections
Lab: Diffusion Across Cell Membranes
Writing Better Background Information Sections
Task 2 – Do this silently on your own:
• Trade Lab Reports with your partner
• (5 min) Read their Background Info and identify…
• Does it start with a logical and meaningful topic sentence?
• Does it make strong connections between sentences? Between
words?
• Does it explain many important terms and concepts necessary
for understanding the lab?
• Does it avoid phrases like “what you need to know is…”
• Write down the strengths and areas for improvement on your
partner’s background info section.
• Take 2 minutes per partner to explain and give feedback
Objectives for Class:
Identify the strengths and areas for improvement in your own background
info section
Bio 9A: Tuesday, 12.7.10
Title: Cell Membranes Wrap-Up

Homework:
 Finish
Cell Membrane worksheet if not finished in class
 Completed, typed, printed lab report due Thursday

Silent Do Now (in notebook w/ title & date)
Look back at your vocab notes from last week
1. Compare and contrast diffusion and osmosis


How are they similar? How are they different?
2. What do you understand about facilitated diffusion? How is
it different from regular diffusion?
3. What do you know about active transport?
Today’s Objectives & Agenda
SWBAT…
 Define and illustrate diffusion, osmosis, facilitated diffusion,
and active transport
 Explain when each process would be used for materials
entering a cell
Agenda:
 Notes/Discussion: Facilitated Diffusion & Active Transport
 Review Questions
Note: Thanks for your feedback at the end of class yesterday.
We will discuss this further in class on Thursday.
Vocabulary Review
Diffusion

Diffusion


Movement of molecules from a
high concentration (more stuff) to low
concentration (less stuff)
Osmosis

Movement of water through a selectively
permeable membrane from a
high concentration to low concentration
Osmosis
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
New Vocabulary

Facilitated Diffusion
 When
a substance diffuses through a
membrane by going through a protein
channel

Regular diffusion goes through the
lipid bilayer
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
New Vocabulary

Active Transport
When a substance is pumped across a
membrane from where there’s a low
concentration (less stuff) to where there’s a
high concentration (more stuff)
 Requires a pump (made of protein) and ATP
energy!

Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Today’s Objectives & Agenda
SWBAT…
 Define and illustrate diffusion, osmosis, facilitated
diffusion, and active transport
 Explain when each process would be used for materials
entering a cell
Agenda:
 Notes/Discussion: Facilitated Diffusion & Active Transport
 Review Questions
Work on your own
 Finish in class, otherwise for HW along w/ lab report
