AIM: How is the structure of the plasma membrane related to its function? DO NOW: What are some other names for the cell membrane?

What does the cell membrane do?

Functions Helps to maintain balance or homeostasis within the cell Boundary between cell and its environment Selectively permeable: allows some to pass and others are kept out

How is the cell membrane constructed?

The cell membrane Plasma membrane Phospholipid bilayer 2 layers of phospholipids –Embedded with proteins and cholesterol molecule

Construction of the Cell MembraneConstruction of the Cell Membrane Wisconsin Online Construction of the Cell Membrane

Wednesday AIM: How is the cell membrane selectively permeable? DO NOW: Explain the difference between hydrophilic heads and hydrophobic tails. Homework: Textbook read pages Review figure 7.20 and explain what is happening. Define dynamic equilibrium

Structure of a phospholipid Hydrophilic heads: water loving –Made up of phosphate and glycerol Hydrophobic tails: do not like water –Built from long hydrocarbon fatty acid tail

Why is it important for the membrane to be partly hydrophobic and partly hydrophilic?

m/anim/Life/memb.htm m/anim/Life/memb.htm

How do membrane proteins and cholesterol create a fluid mosaic?

Cell Membrane - Video Cell Membrane - Video

Membrane proteins Peripheral: at the surface of cell membrane –Fibrous proteins: receptors –Glycoproteins: cell to cell recognition or identification Integral: occupy the length of the bilayer –Pore proteins: passive transport –Channel proteins: active transport –Ion pumps

Why does the membrane need cholesterol? Helps stabilize the membrane Cholesterol is lipid soluble

How does the structure of the membrane relate to its function?

Friday 12/7/12 AIM: how does the structure of the cell membrane relate to its function? DO NOW: What do you think would happen to a fresh water fish if you put it in salt water and explain why you think that HOMEWORK: Text page 183 questions 1- 3

Fluid Mosaic model Individual phospholipids are not bonded Fluid because phospholipids move At the same time, proteins in the membrane also move among the phospholipids Proteins, cholesterol and carbohydrates create a mosaic model

Explain the difference between an integral and a peripheral protein. Integral proteins are large enough to span both layers of the phospholipid bilayer Peripheral proteins only span one layer

How does the cell membrane maintain homeostasis? By regulating and helping molecules enter or leave the cell Membrane proteins and hydrophillic heads help molecules enter and/or leave the cell

Tuesday 12/11/12 AIM: How does the cell membrane maintain homeostasis? DO NOW: 1- The cell organelles crossword puzzle 2- does the cell membrane function the same in the plant and in the animal cell? If so what is its function. HOMEWORK: textbook page 169 and 170 questions 2,4,5,6,8,9,11

The structure of the cell membrane helps it regulate homeostasis HOW? By being selectively permeable This means it chooses certain molecules to cross NOT ALL MOLECULES CAN CROSS THE CELL MEMBRANE

Use your notes to design a well organized table using the parts and the functions that build the plasma membrane

Thursday 12/13/12 AIM:how do molecules move across the cell membrane? DO NOW: Explain why the plasma membrane is called a phospholipid bilayer. Explain why the plasma membrane is called a fluid mosaic HOMEWORK:Text page 191 questions 1- 5

Membrane proteins Integral –Carrier protiens –Channel proteins Peripheral –Glycoproteins: part carbohydrate part protein

What are the functions of the Cell Membrane? Selective Permeability Maintain homeostasis Create a barrier Structural support

The cell membrane Regulates homeostasis by controlling which molecules can enter and/or leave the cell

Does the cell membrane let ALL molecules across? How does the cell membrane choose which molecules to cross?

Factors which effect permeability Size of molecule Solubility of molecule –Does it dissolve in water –Does it dissolve in lipid Charge on molecule Concentration gradient: amount or quantity of molecules on either side of the membrane

Transport Passive: molecules move from a high to low concentration Active: molecules move from low to high concentration

Assessment Explain how concentration gradient is a driving force of transport

Tuesday 12/18/12 pd 7 AIM: How do molecules move down the concentration gradient? DO NOW: 1- Draw the picture below\ 2-which direction will molecules move and why? HOMEWORK: Reading Comprehension handout

Essential Biochemistry - Membrane Transport Essential Biochemistry - Membrane Transport Slides 1-6

Transport across the membrane Cytoplasm has different molecules and ions. Some easily pass through the plasma membrane into the cell. These include water, oxygen, carbon dioxide, glucose and sodium and chloride ions.

Passive Transport Small lipid soluble molecules move from a crowded area to a less crowded area Down the concentration gradient No energy is required Simple Diffusion Facilitated Diffusion Osmosis These include water, oxygen, carbon dioxide, glucose and sodium and chloride ions.

Passive transport

How do molecules know when to stop moving? Dynamic equilibrium: same amount of molecules on each side of the membrane

Essential Biochemistry - Membrane Transport Essential Biochemistry - Membrane Transport7-8

Simple Diffusion Movement is driven by concentration gradient Molecules move from an area of high concentration to low concentration Solute concentration is equal

Facilitated diffusion Some molecules are too big to simply diffuse So they need the help of carrier proteins Transport is still driven by a concentration gradient

AIM: Why is osmosis simple diffusion? DO NOW: Explain why energy is not needed to move glucose down the concentration gradient of the cell. Read pages answer questions 1-5 on pages Questions 1-3 on Pages Homework: Reading Comprehension handout Cell transport: Read pages answer questions 1-5 on pages Questions 1-3 on Pages

Period 2 Tuesday 12/18/12 How do water molecules move across the cell membrane? AIM: How do water molecules move across the cell membrane? DO NOW: The cell transport handout page 111 Reading toolbox: create a concept map connecting the following terms: the cell membrane, concentration gradient, cell transport, the plasma membrane, passive transport, active transport, down, against, molecules, move, high, low, ATP, ion pump, the phospholipid bilayer, energy, simple diffusion, facilitated diffusion, osmosis, equilibrium, carrier proteins HOMEWORK: The cell transport handout page 116 questions 4-6

How is simple diffusion similar from facilitated diffusion? Both are examples of Passive transport So they both move molecules from high to low concentration We call that moving down the concentration gradient

How is simple diffusion similar from facilitated diffusion? Both are types of passive transport So they move molecules down the concentration gradient Which means molecules move from high concentration (a lot) to low concentration ( a little)

How is simple diffusion different from facilitated diffusion? Facilitated diffusion uses a membrane carrier protein WHY? Because some molecules are too big to cross the membrane by itself

Wednesday 12/19/12 AIM: How does solute concentration regulate osmosis? DO NOW: 1- Take out your handout 2- explain the similarities between osmosis and simple diffusion. HOMEWORK: Read page 180. Explain what happens to Red blood cells in hypertonic, hypotonic and isotonic environments

Simple diffusion and osmosis Both move molecules from high to low concentrations DO NOT NEED ENERGY Types of passive transport

Differences between simple diffusion and osmosis Osmosis is the simple diffusion of water molecules ONLY Simple diffusion moves small molecules like oxygen and ions

The cell membrane is selectively permeable That means it picks and chooses which molecules can cross

Osmosis Simple diffusion of water Water molecules move from a concentrated area to a less concentrated area Solute; dissolved molecule –Glucose, salt, ions

Activity On a clean sheet of loose leaf, list and briefly describe the similarities and differences of each type of passive transport.

Osmosis.mp4 - YouTube Osmosis.mp4 - YouTube

Tonicity Refers to the solute concentration on either side of the cell membrane Measures how many solute molecules are dissolved inside of the cell and out side of the cell

Isotonic: equal movement of water into and out of cell

Hypotonic solution: net water movement into the cell

Hypertonic: net movement of water out of the cell

Assessment In your own words, explain why you feel dehydrated after eating a large bag of salty potato chips

Osmosis in the kitchen - YouTube Osmosis in the kitchen - YouTube

Osmosis in plant cells

Plasmolysis in Elodea - YouTube Plasmolysis in Elodea - YouTube

Plasmolysis hypertonic environment: cell loses water Cell membrane separates from cell wall

Friday 1/4/13 AIM: How does the cell membrane regulate osmosis? DO NOW: Why do you feel dehydrated after eating a large salty popcorn and drinking a sugary soda? HOMEWORK: Textbook read pages: 1- DEFINE active transport 2- List and describe the different types of active transport

KScience - Animations KScience - Animations

Osmosis in plants (Red Onion) - YouTube Osmosis in plants (Red Onion) - YouTube

Add salt solution (hypertonic)

If I add fresh water to Cell A and let it sit for an hour what will happen? Complete the drawing of picture B and explain what has happened.

Hypotonic environment Water rushes into the cell and the cell swells Lysis: the cell bursts –Cannot stop water from entering What happens to single celled organisms like the ameba?

Contractile vacuole

Monday 1/7/13 AIM: How does the cell use energy to transport molecules across the plasma membrane? DO NOW: Use the picture displayed to explain how the molecules will move:

How does the concentration gradient determine the direction of molecule movement across the cell membrane?

Active transport Movement of substances against a concentration gradient From low to high Needs energy Membrane proteins use energy to move individual molecules

How does active transport differ from facilitated diffusion?

What happens to a plant cell when I place it in salt water?

How is active transport different from passive transport? Passive transport does not need energy to move molecules from high to low concentration Active Transport uses energy to move molecules against the concentration gradient

Differences between Active transport and facilitated diffusion Active Transport –Uses energy –Moves molecules from low to high concentration –Moves molecules against the concentration gradient Facilitated diffusion –Does not use energy –Moves molecules from high to low concentration –Moves molecules down the concentration gradient

Why is active transport necessary for homeostasis? Certain molecules need to enter or leave the cell against their concentration gradient

Ion Transport

Cotransport movement of 2 solutes together often moves 1 solute passively & other actively often moves 1 solute passively & other actively

Assessment In your notebooks draw the picture depicted below and explain how molecules move in the direction of the arrows