Download Cell Membrane Notes - Ms. Stevens` Class

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
Glycoprotein
Glycoprotein
OUTSIDE THE
CELL
Carbohydrate
Glycolipid
Protein Channel
Cholesterol
Peripheral
Protein
Transmembrane
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!
The nanotube is the gray
structure & the gold
structure is DNA entering a
cell