The Cell Membrane

Warm-up Complete the warmup sheet on your desk on your own. – List 3 things about the cell membrane Keep this on your desk until the end of the period

Introduction to Cell Membrane Paste this page at the TOP of C8 As you read, underline the STRUCTURE(S) of the cell membrane in one color and the FUNCTION(S) of the cell membrane in another

Cell Membranes Introduction Structure Function Each cell of your body is encased in a tiny bubble of membrane, one which has approximately the consistency of salad oil. This might seem like an awfully fragile boundary to place between a cell and the rest of the world, but the plasma membrane is actually very well-suited to its job. It not only defines the borders of the cell, but also allows it to interact with its environment in a controlled way. Cells must exclude some substances, take in others, and excrete still others, all in specific amounts; and they also must be able to communicate with other cells, identifying themselves and sharing information. To perform these roles, the plasma membrane needs lipids, which make a semi-permeable barrier between the cell and its environment. It also needs proteins, which are involved in cross-membrane transport and cell communication, and carbohydrates, which decorate both the proteins and lipids and help cells recognize each other. Here, we’ll take a closer look at the different components of the plasma membrane, examining their roles, their diversity, and how they work together to make a flexible, sensitive, and secure boundary around the cell.

Jigsaw Each person in your group has been assigned a different reading. – As you read, underline the structure and function (like we did in the introduction)

Membrane drawing Once everyone has finished reading, discuss as a group what you think the cell membrane looks like. Draw your cell membrane on your whiteboard! – Include functions! Draw final version in notebook on bottom of C8

Exit Ticket On the BACK of your warmup sheet, list 3 NEW things about the cell membrane

Warm-up Set your Notebook up to look like the pages below Cell Membrane Intro Reading Cell Membrane Image Labeled Components of the Cell Membrane Chart C8 C8b Cell Membrane Drawing Labeled

Let’s Compare… Working with your groups, compare your picture that you drew on Tuesday to the provided picture… – Were you close? You have 2 minutes

Components of the Plasma Membrane ComponentLocation PhospholipidsMain fabric of the membrane Cholesterol Tucked between the hydrophobic tails of the membrane phospholipids Integral proteins Embedded in the phospholipid bilayer; may or may not extend through both layers Peripheral proteins On the inner or outer surface of the phospholipid bilayer, but not embedded in its hydrophobic core Carbohydrates Attached to proteins or lipids on the extracellular side of the membrane (forming glycoproteins and glycolipids)

Cell Membrane Aka the plasma membrane Regulates what enters and leaves the cell and also provides protection and support – Lipid bilayer structure gives cell membrane its flexible structures Proteins and Carbohydrates are embedded in membrane – Fluid Mosaic Model

Bubble Lab Follow the provided instructions and complete the four bubble activities. – Turn in your worksheet when you have completed the provided activities!

Quick Write At the top of C9, answer the question: – What do you know about diffusion and/or osmosis?

Diffusion through Cell Boundaries Diffusion: Particles tend to move from an area where they are more concentrated to an area where they are less concentrated (high -> low) – When the conc. of the solute is the same throughout a system, the system has reached equilibrium – Only small, non-polar molecules can pass through – Diffusion does NOT require any energy use Simple Diffusion Animation

Osmosis Diffusion of water through a selectively permeable membrane – Water moves from an area of high water concentration to low water concentration – Does NOT require energy

How Osmosis Works Water will move across the membrane until equilibrium is reached – Meaning, the concentration of water and solute will be the same on both sides of the membrane Isotonic

How Osmosis Works Hypertonic: solution outside the cell has a higher solute concentration than inside the cell. – Water moves OUT of the cell and the cell SHRINKS

How Osmosis Works Hypotonic: solution outside the cell has a lower solute concentration than inside the cell. – Water moves INTO the cell and the cell SWELLS

How Osmosis Works

Osmosis Practice What type of solution are the cells below in? What direction will water move? – Draw this in your notebook at the top of C9b and answer the questions A B C

Facilitated Diffusion Molecules that cannot diffuse across the cell membrane’s lipid bilayer on their own move through protein channels – Protein channels act like carriers Move things from high -> low concentration – Does NOT require energy – Glucose

Active Transportation Used primarily when materials must move materials AGAINST a concentration gradient – Requires energy – Generally carried out by pumps found in the membrane

Crash Course In da Club – Membranes & Transport ~12 min In da Club – Membranes & Transport

DIFFUSION OSMOSIS ACTIVE TRANSPORT Place these features in the correct part of the Venn Diagram Involves water only Requires energy Is passive Movement of particles Needs a semi-permeable membrane High to low concentration Against a concentration gradient Occurs in nature How minerals get into root hair cells How oxygen leaves a leaf How water keeps plant cells turgid Involves transport of solutes Draw this in your NB

DIFFUSION OSMOSIS ACTIVE TRANSPORT Involves water only Requires energy Is passive Movement of particles Needs a semi- permeable membrane High to low concentration Against a concentration gradient Occurs in nature How minerals get into root hair cells How oxygen leaves a leaf How water keeps plant cells turgid Involves transport of solutes

Optional Study Table Draw and complete this chart in your NB on page C9d