Movement Across cell Membranes

MOVEMENT ACROSS CELL MEMBRANES

Moretti and Dickson

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)1. Which molecule is bigger, starch or

glucose? Explain with a diagram in your notebook.

2. Do you want to share a slide or paragraph from your digestion story with the class? If so, write down exactly which slide or paragraph you would like to share.

3. Take out the project rubric and the project if it’s printed.

Bio 9D: Thursday, 12.2.10Title: Movement Across Cell Membranes – Day 1

Today’s Agenda & Objectives

Update on Class Contract: We are still going strong to get Round 2 of

cookies on Monday One strike earned on Tuesday No strikes earned yesterday No Class Contract violations

Let’s make today great so we can stay on track!

Objective: Moving on to a new unit SWBAT design an experiment to test which

molecules can pass through a cell membrane (drawing on knowledge of glucose, starch, and chemical indicators)

Today’s Agenda & Objectives

Objective: Moving on to a new unit SWBAT design an experiment to test

which molecules can pass through a cell membrane (drawing on knowledge of glucose, starch, and chemical indicators)

Agenda: Quick sharing of Digestion Projects (10

min max) Review Do Now (5 min max) Experiment Design (30 min)

Planning the Experiment: Individual:

Read Overview Small Groups:

Planning the Experiment How do we test for Starch and

Glucose?

Whole Class Discussion Small Group:

Experimental Set-Up Whole Class Review:

Experimental Set-Up

Designing a 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

No Homework!

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?

Bio 9D: Friday, 12.3.10Title: Movement Across Cell Membranes – Day 2

Check-In from Yesterday

We didn’t get to a contract violation, BUT… It was clear that someone was saying

inappropriate things (maybe more than one person?)

This gets in the way of our progress towards having an excellent class

On the small piece of paper, write: The inappropriate things that were said in class

yesterday Which person or people said them Any other thoughts you have about this.Everyone must write something down.

Today’s Objectives & Agenda

Describe and explain the following terms: Lipid Bilayer Selective Permeability Concentration Diffusion

Use this vocabulary to: Explain how a cell membrane controls what enters and leaves

a cell Design an experiment to test whether glucose and/or starch

can pass through the cell membrane

Agenda: Notes/Discussion/Quick Animation Cell Membrane Experiment:

Purpose & Hypothesis (discuss as class) Set up – Demo, then do it in your group Summarize procedure & make data table Collect data

Lipid Bilayer Two layers of lipids that form

the outer membrane of a cell. Flexible Strong Do not Dissolve in water

Cell Membrane Vocabulary

Objectives for Class: Use scientific vocabulary to explain how a cell membrane controls what

enters and leaves a cell

Image to the right shows the lipid bilayer of a cell. Notice how it has other components like protein channels & “pumps” built into it.

zoom out

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




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 Movement of molecules from a

high concentration (more stuff) to low concentration (less stuff)




Diffusion

Osmosis

Diffusion, Osmosis and Selective Permeability In Action:

http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm






Purpose of the Experiment:

To figure out whether the cell membrane will allow glucose, starch, or both to pass through the membrane?

Hypothesis: (write your prediction on the lab handout)




Review Experiment Set-Up: 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




Procedure Overview: Part I:

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 Part II: Wait 30 min to allow for substances to

move across the membrane


Water and Iodine




Owen

TraeMiguel Rayoni

Loveng

Nick

Davnys

Samantha

Joas Dyani

Hannah

Courtney

CarlhebDevon

Marcelo

Nekeyla

Christine

Lorreno

Kayla

Jackson

Homework: Type up all sections of lab report except for Background Information

Silent Do Now (in notebook w/ title & date) Take out your Diffusion Lab packet Look at your data table w/ your results 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?

Bio 9D: Monday, 12.6.10Title: Movement Across Cell Membranes – Day 3


Discuss and analyze the results of the diffusion experiment in order to…

Draw conclusions about which substances diffused across the membrane

Agenda: Quick Class Discussion & Revisit the

Animation Typing Time

Color Change?

Diffusion Across Cell Membranes:Presenting the Data/ Results



Water and Iodine


Bag Turned Purple/ Black

No Color Change to the Water

Glucose Test Strip changed color

Remember:Selective Permeability In Action: http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/Osmosis_Animation.htm



Lab Report Typing

Step 1: Set up the Title of your lab report with all required info

Step 2: Set up section headings in order for all sections of your lab report

Step 3: Skip Background Info for now.Step 4: Start typing whichever other section is

easiest for you to start on right now. All sections except Background Info should be typed by tomorrow.

Work quietly, talking with your lab partner only.

No internet use allowed until last 5 minutes of class (for emailing work).

Homework: Write the Background Info section of your lab report

Silent Do Now (not in notebook!)1. Take a napkin and a brownie!

2. For the next round of treats we will raise the expectations even higher! Do you think we should do this by…(answer on index card)

a) Making the standards for class behavior higher (fewer strikes, more anti-strikes for focused behavior required)

b) Making the length of time longer (two weeks without breaking contract)

3. On the handout: Read, evaluate, and write strengths & weaknesses for Example 1 and Example 2

Bio 9D: Tuesday, 12.7.10Title: Movement Across Cell Membranes – Day 3


Write an excellent Background Info section of a lab report Use the lab report rubric to identify mediocre

versus excellent examples of Background Info sections

Write explanations and connections for all important terms and concepts for the Diffusion Lab background info

Agenda: Evaluate examples of Background Info Class discussion Organize info for Diffusion Lab Background Info

Sample Background Info sections

Strengths:good knowledge of vocab words; made sure the reader understood the key terms

Things to improve: using the key terms to connect to the lab; more like a list of definitions; opening sentence could be more engaging; take out words like : “here’s what you need to know”

Overall grade:15/20…. C rass

Strengths: They explained things well, they gave examples of chemical equations, they have proper formatting, the diagrams are a good explanation for a bunch of vocab words. They connect the key terms to the lab. more _______

Things to improve: explain monosaccharide and polysaccarides better.

Overall grade: 18 out of 20 8] B]

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 You have 7 minutes to complete the

explanations for each term listed, plus at least 2 others

Do this by referring to your notes Work quietly, stay focused on the task,

and be productive!

Connections between words…

Homework: Complete lab report due tomorrow – typed, printed, stapled, ready to hand in w/ rubric @ start of class.

Silent Do Now (in NB w/ title and date)1. Write down what you understand about

diffusion and concentration (check your notes for reminders). What are they and how to they relate to each other?

2. What is an example of diffusion that you have seen in everyday life?

Bio 9D: Wednesday, 12.8.10Title: Cell Membranes Wrap-Up


SWBAT… Define and illustrate 4 ways that substances can move

across cell membranes Diffusion, osmosis, facilitated diffusion, and active transport

Explain when each process would be used for materials entering a cell

Agenda: Notes/Discussion on Vocabulary

We are going to hold “tangent” questions until the end today! Review Questions (Worksheet)Remember: Earn treat-points for sustained productive

class.Strikes for side conversations that interrupt class (3 per class starts the treat-cycle over)

Concentration How much “stuff” is in a given amount

of liquid 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 concentrationNote: For osmosis to occur, the membrane only allows water to pass across and not the solute

Cell Membrane Vocab Review



Diffusion

Osmosis

Facilitated Diffusion When a substance diffuses

through a membrane by going through a protein channel

Regular diffusion goes through the lipid bilayer




Prot

ein

Cha

nnel

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!





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

Documents

Movement Across cell Membranes