Cell (plasma) Membrane Lipid bilayer: hydrophobic fatty acid tails, hydrophilic phosphate heads Peripheral proteins; loosely bound, easily removed with salt treatment Integral proteins; buried in the bilayer, membrane must be destroyed to free -may span the membrane, can have receptor or signaling attachment, cell -cell

Membranes are “Mosaic” and fluid Protein positions in the membrane are NOT static. Proteins float about in the lipid bilayer Artistic – representation of how the membrane arrangement varies with time (shift caused by a cellular event?)

Organelles Nucleus Nuclear envelope- double membrane enclosure Nucleolus – a darken area where ribosomes are synthesized Nuclear pore – large holes in the membranes that allow the exit of macromolecules (RNAs) Chromatin –DNA in its functioning state – being read, directing cellular acts

In the cytoplasm Ribosomes – 2 types – site of protein synthesis Complex of RNA and protein 1st type – free floating in the cytoplasm, and make free floating proteins 2nd type – membrane bound (endoplasmic reticulum) synthesizes membrane bound proteins (integral proteins)