The Cell Membrane Page: EQ: What are the major components of the cell membrane, and how does its structure relate to its function?

What is it? The cell membrane (or plasma membrane) surrounds every single cell & creates a barrier between the internal cell environment & its surroundings

What is its function? The cell membrane allows the cell to maintain homeostasis (internal balance) by controlling what enters & exits the cell

Important Characteristics Fluid Mosaic Model: Membrane structures float in and around each other like boats on water Selectively Permeable: Some materials can pass through the membrane, but some cannot

Structure: Membrane Called the phospholipid bilayer – 2 layers of phospholipids Phospholipid – Phosphate group + glycerol + 2 fatty acid chains

Structure: Membrane Components OUTSIDE THE CELL Glycoprotein Glycoprotein Glycolipid Carbohydrate Protein Channel Cholesterol Transmembrane Protein Peripheral Protein Cytoskeleton INSIDE THE CELL

Membrane Components: Carbohydrates Carbs are found on the surface of every eukaryotic cell & allow for cell recognition (like an ID tag) Cell Recognition: Ability of a cell to distinguish one cell from another Important For: Cell signaling Immune System – how our WBCs recognize foreign pathogens Organ & Tissue growth & development

Membrane Components: Cholesterol Cell Membrane must be fluid & flexible – consistency is like olive oil Cholesterol helps maintain the fluidity, permeability, and strength of the membrane

Membrane Components: Proteins Many Functions for proteins! They include: transport proteins, enzymes (protein pumps), cell surface receptors, & more!

Membrane Components: Proteins

Membrane Components: Proteins

Artificial protein channel created with a carbon nanotube last year Artificial protein channel created with a carbon nanotube last year! The nanotube is the gray structure & the gold structure is DNA entering a cell