MOVEMENT ACROSS CELL MEMBRANES Biology 9B - Dickson.
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Transcript of MOVEMENT ACROSS CELL MEMBRANES Biology 9B - Dickson.
MOVEMENT ACROSS CELL MEMBRANES
Biology 9B - Dickson
Homework: None – have a great weekend!
Silent Do Now (in NB w/ date & title) What is the difference between “regular”
diffusion and facilitated diffusion? What do you think the cell membrane is made
of? What does it mean for the membrane to be
“selectively permeable? What is one thing you learned from doing the
StarLogo computer lab?
Bio 9B: Friday, 12/9/11Title: Movement Across Cell Membranes
Today’s Objectives
Describe how the structure of the membrane helps it to function
Describe and explain the following terms: Lipid Bilayer Selective Permeability Diffusion Osmosis Facilitated Diffusion Active Transport
Agenda: Notes/Discussion Exit Ticket and Hand Back Work / Grades
The cell membrane is made of…
Lipid Bilayer Two layers of lipids that form
the outer membrane of a cell. Flexible Strong Do not Dissolve in water
Proteins in the lipid bilayer Help transport molecules
across the membrane
Cell Membrane Structure
Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what
enters and leaves a cell
zoom
in
Selective Permeability When a membrane only
allows certain substances to pass across the membrane (and not others)
Based on the size, shape, and charge (+/-/neutral) of the substances
Cell Membrane Function
Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what
enters and leaves a cell
Diffusion Movement of molecules from a
high concentration (more stuff) to low concentration (less stuff)
Spreading out so all areas have an equal concentration
Osmosis Diffusion of water through a
selectively permeable membrane
Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what
enters and leaves a cell
Diffusion
Osmosis
Methods for Materials to Enter/Leave the Cell
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
Prot
ein
Cha
nnel
Methods for Materials to Enter/Leave the Cell
Active Transport When a substance is pumped across a
membrane from where there’s a low concentration to where there’s a high concentration (against the concentration gradient)
Opposite of diffusion 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
Methods for Materials to Enter/Leave the Cell
Homework:Complete pages 3 and 5 of the lab
packet. Silent Do Now:
Complete the worksheet. Today’s Goals: You will be able to:
Form a well-reasoned hypothesis about diffusion across membranes.
Test this hypothesis by following a lab procedure to perform an experiment
Create a data table in order to organize and record your results.
Bio 9B: Monday, 12/12/11Title: Diffusion Lab
Lab:Diffusion Across Cell Membranes
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.
Water
Model Cell w/ Dialysis Tubing Membrane
Starch & Glucose Solution
Set-up Dialysis Bag Moisten tube and tie one end Add the starch & glucose solution to the tube Tie the top of the tube
Rinse w/ tap water to wash excess solution from outside of bag
Set-up Beaker 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
and iodine
Diffusion Lab:Procedure Review – Part 1
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.
Starch & Glucose Solution
Starch How do we test for it?
Use Iodine How do we know starch has passed through membrane?
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
Diffusion Lab:Procedure Review – Part 3
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.
Expectations for Lab Work
Stay at your own table (no wandering) Talk quietly with members of your own
group Stay focused on the lab! Follow every step of the procedure Stay safe – use materials as instructed,
no messing around
Diffusion, Osmosis and Selective Permeability In Action:
http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm
New Vocabulary
Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what
enters and leaves a cell
Homework:Read pages 956-960. Answer questions on the back of the assignment sheet (write answers in notebook)
Silent Do Now (in notebook w/ title & date) Copy the table on the board into your notebook.
Make it huge (fill the whole page of your notebook). Fill in the first column (Results) by filling in each
box with… Was there a color change? If so, describe!
Take out your lab packet and check your data table on page 4 if you can’t remember the results.
Bio 9B: Thursday 12/15/11Title: Diffusion Lab – Analysis & Conclusions
Today’s Objectives & Agenda:You will be able to:
Explain the results of the diffusion experiment Use the lab report rubric to identify mediocre
versus excellent examples of Background Info sections
Write or improve your own Background Info, Analysis, and Conclusion sections of your lab report
Agenda: Class Discussion of Results, Analysis, and
Conclusions Evaluate examples of Background Info Class discussion & brainstorm for this lab’s
Background Info Time to type! And also to conference w/ Ms.
Dickson about past assignments.
Color Change?
Diffusion Across Cell Membranes:Presenting the Data/ Results
Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what
enters and leaves a cell
Water and Iodine
Starch & Glucose Solution
Bag Turned Purple/ Black
No Color Change to the Water
Glucose Test Strip changed color
Diffusion Lab: Analysis & ConclusionsRESULTS – Was there a color change? Describe!
ANALYSIS – What does this mean?
CONCLUSIONS Why did this happen? Does it support our hypothesis?
Dialysis Bag
Turned from white to purple
Water in Beaker
No change (stayed orange)
Glucose Test Strip
Turned from green to brown-green
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 MembranesWriting Better Background Information Sections
Objectives for Class:
Use the lab report rubric to identify mediocre versus excellent examples of Background Info 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
Sample Background Info sections
Strengths:
Contains scientific terms and definitions
Things to improve:
Unclear definitions
Missing connections
Awkward wording
Topic sentence
Overall grade: Fair
Strengths:
State purpose
Explains all terms
Good connections & examples
“Because…”
“However…”
Things to improve:
Add more vocabulary
Overall grade: Excellent
Example 1 Example 2
Objectives for Class: Use the lab report rubric to identify mediocre versus excellent examples of Background Info sections
Diffusion Lab Background Info
Turn your lab packet to page 5 Your Tasks in A Small Group:1. Make sure everyone has descriptions of each word2. Make sure everyone has descriptions of two more words3. Fill in the Connections part for each word by writing how
it relates to at least one other word, or to the experiment4. At the bottom of that page, brainstorm some topic
sentences to start off your Background paragraph5. Number each term in the chart based on the order you
think you should introduce it in your Background paragraph
Your goal as a group is to help EVERYONE be ready to write an excellent Background Info paragraph!
Quiet Independent Work Time
Tasks to Work On:Continue writing your lab report (it is due Monday)Do tonight’s HW (book reading & questions)Conference w/ Dickson about past assignments or
help on the lab reportSmall groups will come to work w/ Dickson on the Do
Now from earlier this weekWork quietly and professionally Stay focused
on biology.No internet – it slows down everyone’s laptop!
Homework:Typed & completed lab report due Monday.Silent Do Now – On an index card, not in your
notebook! Find the following definitions in your notebook and write
them on an index card (all definitions on same card): Diffusion Osmosis Facilitated Diffusion Active Transport
Today’s Objective: Apply these vocabulary words to various situations in living things – so that you can accurately identify examples and pictures of each process.
Bio 9B: Friday12/16/11Title: Cell Membrane Vocabulary Application
Instructions
Spend 3 minutes at each station Read the scenario, look at the pictures,
read the questions Mark your answers on the answer sheet
(do not write on the station handouts) Work with your assigned partner (next
slide), talk quietly on with them, and stay focused on the work.
Partners
Justin—Jarred Ritshly—Kira Jenna—Skyeler—Tia Ronica--Naidaliz Sequoia—Steven—
DJ
Cabinet Side of the Room Window Side of the Room
Noah—Priscilla Nicole—Zak—Sara Destinee—Emily Aaron—Emperor Tracey-Natalie-
Elizabeth
Exit Ticket
Work silently on your own to correct or finish your Do Now sheet from Monday
If you don’t get your Do Now sheet back, complete the AP Biology test questions!