APK 2105C Lecture Notes - Lecture 5: Peripheral Membrane Protein, Fluid Mosaic Model, Endoplasmic Reticulum
23 May 2018
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Chapter 2, Part 3
The Cell: Structure & Function
• Basic cell structure (all cells have these 3 components)
o Plasma membrane = separate the intracellular from extracellular
▪ Fluid mosaic model
• Moveable structure
• Mosaic means there are proteins and lipids together
▪ Phospholipid bilayer
• Phosphate heads face inward and outward
• Tails face each other
• Barrier between ECF and ICF
• Gives fluidity of membrane
• Phospholipids can change places with neighbors and flip down to
other side of membrane
▪ Cholesterol molecules
• Some of it hangs out with phosphate heads—OH group allows for
this
• Contributes to structural integrity of membrane
▪ Proteins
• Peripheral membrane proteins = not embedded in either layer of
membrane
• Integral membrane proteins = embedded in at least one layer of
the membrane
• Transmembrane protein = embedded in both layers of membrane
o Most common
o Channels
o Acceptors
o May have carbohydrate chain attached facing ECF
▪ Functions in cellular recognition
• Glycoproteins
o Nucleus = brain of the cell
▪ Not all cells have a nucleus
▪ All cells started with a nucleus
▪ Usually near core of the cell
▪ Stains darkly (lots of proteins)
▪ Has nucleolus in the middle of the nucleus
• Makes ribosomal subunits
▪ Bilayer membrane = nuclear envelope
• Has pores that allow things to pass through
• Pores form when layers of the membrane fuse together
▪ Chromatin throughout the nucleus
o Cytoplasm = cytosol and organelles
▪ Cytosol = ICF stuff inside the cell
• Mostly water (needs to be solvent for many chemical rxns)
• Significant differences between ions in ICF and ECF (ex: high and
low Na concentrations)
▪ Organelles = mini organs with a specific function
• Endoplasmic reticulum
o Reticulum = network
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