Transcript Movement Across cell Membranes

Bio 9C: Thursday, 12.2.10
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.
Do Now: (in your notebook)
 Which
molecule is bigger, starch or glucose? Explain with a
diagram in our notebook.

Today’s Objectives:

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.
MOVEMENT ACROSS CELL
MEMBRANES
Moretti and Dickson
Designing a Lab:
Diffusion Across Cell Membranes
Planning the Experiment:
 Individual:


Read Overview
Small Groups:
Model Cell
w/ Dialysis
Tubing
Membrane
 Planning
the
Experiment
 How
do we test for
Starch and Glucose?

Whole Class
Discussion
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.
Designing a Lab:
Diffusion Across Cell Membranes
Class Discussion:
 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.
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.
Demo


What is happening to the dye in the water?
Based on prior knowledge, what do you think this is
called?
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

Selective Permeability
 When
a cell membrane (or any
membrane for that matter) only
allows certain materials to pass
across the membrane and not others
 Substance 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
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
Bio 9C: Friday, 12.3.10
Title: Movement Across Cell Membranes – Day 2

Homework:
Type the following sections of the Diffusion Lab:
 Background
Info
 Purpose/Hypothesis
 Summary of Procedure

Do Now: (in your notebook)
 Take

out lab prep and get ready to review procedures
Today’s Objectives:

Design an experiment to test diffusion of starch and glucose across a membrane

Use scientific vocabulary to explain how a cell membrane controls what enters and
leaves a cell
Designing a Lab:
Diffusion Across Cell Membranes
Review Experimental Set-Up:
 Part I:

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-ish
Put dialysis bag into beaker with water and
iodine
Part II: Wait 30 min to allow for substances to
move across the membrane
Water 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.
Designing a Lab:
Diffusion Across Cell Membranes
Review Experimental Set-Up:
 Part III:

How do you know the following
substances have left the bag:



Starch?
Glucose?
What other substances might
move across the bag? How will
you know?
Water 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.
Implementing the Lab:
Diffusion Across Cell Membranes
Review Experimental Set-Up:



Part I:

Preparing Dialysis Bag

Soak the dialysis tube in water to soften

Tie one end into a knot

Fill the tube about half-way w/ starch/ glucose solution

Tie the other end of the tube into a knot to seal the bag

Rinse w/ tap water to wash excess solution from outside of bag

Preparing the Beaker

Label your beaker

Fill a 140 ml beaker ¾ of the way with water

Add 10-15 drops of Iodine to water and mix . Note the color of the water

Test water with glucose test strip and note any color change

Preparing the Model:

Put dialysis bag into beaker with water and iodine solution
Part II:

Wait 30 min to allow for substances to move across the membrane
Water and Iodine
Part III:

Data Collection
 Diagram the experimental set-up
 Create a data table to collect data

Collect data by recording any color change to the beaker,
dialysis bag, and/or glucose test strip.
New 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
Bio 9C: Monday, 12.6.10
Title: Movement Across Cell Membranes – Day 3

Homework:
Finish Typing the Following Section of the Lab:
Data/ Results
 Analysis
 Conclusion
Bring in a printed copy of your background information section to class on
Monday!!!


Do Now:


What is the purpose of the lab?
Today’s Objectives:


Use scientific vocabulary to explain how a cell membrane controls what enters and leaves
a cell
Make clear connections between various vocabulary words and concepts to each other
and to the purpose of the lab, so as to write a better Background Information Section.
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
Diffusion Across Cell Membranes:
Review Background Information
Background Information Brainstorm
•
Objectives for Class:
• Implement an experiment to test diffusion of starch and glucose across a membrane
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
Remember:
Selective Permeability In Action:
http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/
Osmosis_Animation.htm
Water and Iodine
Objectives for Class:
 Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
Diffusion Across Cell Membranes:
Data Analysis

Work in your groups to explain what
your results mean.
If there are color changes, state was this
means in terms of what substances are
present, but
 DO NOT explain why the substance is
where it is (this should go in the
conclusion section)

Water and Iodine
Objectives for Class:
• Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
• Make clear connections between various vocabulary words and concepts to each other and to the purpose of the
lab, so as to write a better Background Information Section.
Bio 9C: Tuesday, 12.7.10
Title: Movement Across Cell Membranes – Day 4

Homework:
Finish Typing/ Revising the Lab Report:
 Final

Copy Due Thursday w/ Rubric!
Do Now:
 Take
out the Typed Background Information Section of the
Denatured Enzymes Lab Report

Today’s Objectives:

Use scientific vocabulary to explain how a cell membrane controls what enters and
leaves a cell

Make clear connections between various vocabulary words and concepts to each
other and to the purpose of the lab, so as to write a better Background Information
Section.
Writing Better Background Information Sections

Task I:
Read the to example Background Information sections from
the Denatured Enzyme Lab and grade them according to
the rubric.
 Discuss the grading

Objectives for Class:
• Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
• Make clear connections between various vocabulary words and concepts to each other and to the purpose of the
lab, so as to write a better Background Information Section.
Writing Better Background Information Sections

Task II: Whole Class
 Create
a mind-map to connect the
vocabulary and concepts for the
Background Information Section. This
will help us outline this section for us as
well.
Objectives for Class:
• Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
• Make clear connections between various vocabulary words and concepts to each other and to the purpose of the lab,
so as to write a better Background Information Section.
Writing Better Background Information Sections

Task III:

Use mind-map/
outline to re-write
your background
information section
more effectively.
Objectives for Class:
• Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
• Make clear connections between various vocabulary words and concepts to each other and to the purpose of the lab,
so as to write a better Background Information Section.
Diffusion Across Cell Membranes:
Complete Lab Report


Revise Background Information Section
Complete all sections of the Lab
Report
Water and Iodine
Objectives for Class:
• Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell
• Make clear connections between various vocabulary words and concepts to each other and to the purpose of the
lab, so as to write a better Background Information Section.
Bio 9C: Wednesday, 12.8.10
Title: No Class – Half Day
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

Homework:
Do Now:
Today’s Objectives: