the cell membrane. what is the cell membrane? aka: plasma membrane the boundary between the cell and...
TRANSCRIPT
The Cell Membrane
What is the cell membrane?
• AKA: Plasma membrane• The boundary between the cell and the
environment• Does every cell have a cell membrane?– Yes, Each and every cell has a cell membrane.
How do cell membranes help to maintain homeostasis?
• The cell membrane allows nutrients to come into the cell
• Glucose, amino acids, lipids
• The cell membrane removes waste
Selective Permeability
• The cell membrane lets some molecules in and keeps others out
• EX. A cell is low on glucose so the membrane lets in some glucose, but does not overfill the cell with the monomer.
Structure of the cell membrane
• What does the cell membrane look like up close?
Lets look at one of these
structures up close
Structure of cell membrane
• Phospholipids– Phosphate head– Glycerol– 2 Fatty acid tails
Phospholipids
• 1.) Phosphate Head• Polar• Hydrophilic• Make up the outer borders of the
membrane
• 2.) Fatty Acid Tails• Nonpolar• Hydrophobic• Make up the inner part of the
membrane
Structure of cell membrane
• Phospholipid bilayer– 2 layers of phospholipids make up a cell
membrane
Phospholipid Bilayer
• Remember polar heads and nonpolar tails
The fluid Mosaic Model of the cell membrane
• Lipid bilayer is not strong & firm like a hard shell, but it is fluid like a soap bubble consistency
• So, it is called the Fluid Mosaic Model (fluid like, with many proteins stuck in it)
The fluid Mosaic Model of the cell membrane
• It is a flexible membrane, made fluid because of cholesterol molecules located in the phospholipid bilayer.
• Proteins in the membrane move around.
Other components of the cell membrane
• Cholesterol– Helps to stabilize
the phospholipids and keep them from sticking together
Other components of the cell membrane
• Carbohydrates- linked to lipids or proteins– Recognition of Cells – “Name tag of cell”– Ex. Is the cell a heart cell, liver cell, or brain cell?– Ex. Glycolipids & Glycoproteins (marker protein)
Other components of the cell membrane
• Proteins- make up 50 %- 70% of membrane– Regulate which molecules enter and which
molecules leave a cell.– Receive info & ID the cell
Types of proteins in the cell membrane
• Carrier Protein– Allow needed substances or waste materials
to move through the cell membrane
Types of proteins in the cell membrane
• Receptor Protein– These have binding sites for molecules such as
hormones or substrates to bind to
Types of proteins in the cell membrane
• Channel or Pore protein– Hydrophilic channel – allows lipid insoluble
substances to pass in and out of cell.
Types of proteins in the cell membrane
• Glycoproteins– Protein with what macromolecule attached
to it?• Carbohydrate
– Functions for cell to cell recognition
Where are proteins located in the cell membrane?
• Integral Proteins– Proteins inside the cell membrane
• Peripheral Proteins– Proteins outside the cell membrane