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, 12/9/11 Title: 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 Protein Channel 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, 12/12/11 Title: 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: New Vocabulary Objectives for Class:  Use scientific vocabulary to explain how a cell membrane controls what enters and leaves a cell

Homework: Read pages 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 12/15/11 Title: 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 & Conclusions RESULTS – 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 Membranes Writing 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 word 2. Make sure everyone has descriptions of two more words 3. Fill in the Connections part for each word by writing how it relates to at least one other word, or to the experiment 4. At the bottom of that page, brainstorm some topic sentences to start off your Background paragraph 5. 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 report Small groups will come to work w/ Dickson on the Do Now from earlier this week Work 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: Friday12/16/11 Title: 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!