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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. Cell membranes help maintain homeostasis, what is that?. Cells breathing

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Presentation Transcript
what is 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.
cell membranes help maintain homeostasis what is that
Cell membranes help maintain homeostasis, what is that?
  • Cells breathing
  • Cells getting blood to them
  • Cells maintaining internal conditions
  • Cells reproducing
how do cell membranes help to maintain homeostasis
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
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 macromolecule.
structure of the cell membrane
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
Structure of cell membrane
  • Phospholipids
    • Phosphate head
    • Glycerol
    • 2 Fatty acid tails (lipids=fats, oils, etc)
phospholipids
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
polar vs nonpolar
Polar vs. Nonpolar

Polar- positive and negative ends (b/c electrons are not shared equally)

Ex. Water

Nonpolar- does not have oppositely charged ends (atoms share electrons equally)

why are the phospholipids arranged tail to tail
Why are the phospholipids arranged tail to tail?

-b/c water is inside and outside the cell

phosphate group is hydrophilic (polar) end

-attracts water

fatty acid tail end is hydrophobic (nonpolar)

-repels water

structure of cell membrane12
Structure of cell membrane
  • Phospholipid bilayer
    • 2 layers of phospholipids make up a cell membrane
phospholipid bilayer
Phospholipid Bilayer
  • Remember polar heads and nonpolar tails
when something is hydrophilic it
When something is hydrophilic, it…
  • Has a chemical makeup that likes to be around water
  • Has a chemical makeup that does not like to be around water
other components of the cell membrane
Other components of the cell membrane
  • Cholesterol
    • Helps to stabilize the phospholipids and keep them from sticking together
other components of the cell membrane19
Other components of the cell membrane
  • Proteins
    • Regulate which molecules enter and which molecules leave a cell.
types of proteins in the cell membrane
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 membrane21
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 membrane22
Types of proteins in the cell membrane
  • Glycoproteins
    • Protein with what macromolecule attached to it?
      • Carbohydrate
    • Functions for cell to cell recognition
types of proteins in the cell membrane23
Types of proteins in the cell membrane
  • Receptor Protein
    • These have binding sites for molecules such as hormones or substrates to bind to
fluid mosaic model of cell membrane
Fluid Mosaic Model of Cell Membrane

-lipid bilayer is not strong & firm like a hard shell, but it is fluid like a soap bubble (often called a fluid mosaic model)

-individual phospholipids, arranged side by side, float within the bilayer (cholesterol prevents phospholipids from sticking together)

structure of cell membrane25
Structure of Cell Membrane

-nonpolar interior zone- true barrier that separates the cell from its surroundings

many polar particles like sugars, proteins, ions, & most cell wastes cannot cross this zone b/c they are repelled by the nonpolar region

lets build a cell membrane together
Lets build a cell membrane together
  • http://www.wisc-online.com/objects/index_tj.asp?objid=AP1101
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