Warm-Up Turn in Microscope Lab and vocabulary. 1. Have a clean sheet of notebook paper for the warm-up. 1.Define the word homeostasis in your own words. 2. Based on how you defined the word homeostasis, why is the cell membrane so important for maintaining homeostasis? 3.You went out running on a hot day. After you run, you sit down and feel very warm. How will your body respond in order to maintain homeostasis? 4.You are outside on a very cold day. You feel very cold. How will your body respond in order to maintain homeostasis?

Important for homeostasis - the process of maintaining a constant internal environment; cell membranes are crucial to homeostasis Cell membrane = plasma membrane

Cell Membranes Functions: 1. Regulates what enters and leaves the cell = SEMI- PERMEABLE 2. Separates the inside of the cell from the outside 3. Recognizes/responds to outside signals

Membrane: Prokaryotic Cell

Membrane: Eukaryotic Cell

Cell Wall Location: Layer outside of the cell membrane in some organisms Function: Provide structure and support

Plants Cell Wall

Bacteria Cell Wall

Fungus

Phospholipid: Structure Phosphate Head Two Fatty Acid Tails Hydrophilic: LOVES water Hydrophobic: HATES water

Phospholipid bilayer Membrane is made up of two layers of phospholipids. With this arrangement in mind, where is the “water” in the diagram? WATER Hydrophilic Hydrophobic

Location: Surrounds the cell and organelles

Function of Phospholipids Controls what comes in and out of cells; the gatekeeper

Cholesterol Location: Found in between the phospholipids in the bilayer. Function: Helps keep the phospholipid bilayer from sticking together; contributing to the fluidity of the membrane

Proteins

1. Transport or Integral Proteins A protein that spans the entire membrane helps transport larger molecules across the membrane

2. Peripheral Proteins A protein that spans the surface of the membrane helps in signaling other cells

Carbohydrate Location: 1)On top of peripheral proteins = glycoprotein 2)Or directly on membrane = glycolipids Function: Help recognized similar cells to form tissues OR to recognize foreign substances in the cell

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Make your own cell membrane. 1.Make you sure you have these parts labeled: phospholipid bilayer, a single phospholipid boxed, transport protein, cholesterol, carbohydrate, a nucleus, label the inside and outside of the cell. 2.On the inside write the function of these words: cell membrane, homeostasis, carbohydrate chain, transport protein, and cholesterol.