Cell Structure & Function
Organizing Principles
Supramolecular Structures: All found in prokaryotic cells & eukaryotic cells, not membrane bound
Cell Membrane or Plasma Membrane• Selective permeability• Communication with the external
environment• Recognition of self vs. non-self
Ribosomes• Site of protein synthesis• Formed from two sub-units (large & small)• Free in cytosol or bound to endoplasmic
reticulum
Cell Wall• Found in all organisms except animals & a
few protista• Made of different macromolecules in
different kingdoms• Protects cell, maintains cell shape, &
prevents excessive water uptake• Allows turgor pressure to develop
Double Membrane Bound Organelles
• These are all prokaryotic in origin.• They have their own DNA and ribosomes• Reproduce by binary fission• Are killed by antibiotics• All easily seen in the light microscope
Mitochondria• Site of cellular respiration
Chloroplast• Site of photosynthesis
Nucleus• Holds DNA• Makes ribosomes in a specialized region
called the nucleolus• Transcribes DNA• Replicates DNA
Endomembrane System
• These structures work together to make, process and transport all macromolecules in a region separate from the cytosol
• Only seen with TEM
Rough Endoplasmic Reticulum• Endoplasmic (within the cytoplasm)• Reticulum (little net)• Makes, sequesters and folds proteins for
export or transport• Packages proteins in vesicles to send to the
Golgi Apparatus• Attaches carbohydrates to proteins
Smooth Endoplasmic Reticulum• Makes and packages
polysaccharides and lipids (with enzymes)
• Packages polysaccharides and lipids in vesicles
• Detoxifies many poisons
Golgi Apparatus
•Receives proteins from the RER and adds oligosaccharides to proteins
•Tags vesicles for proper delivery and sends them out for shipment
Lysosomes•Specialized vesicles made from the golgi that break down old organelles, foreign materials, bacteria and viruses
Cytoskeleton (Broad Category)•Creates internal structure and allows for movement internally and externally
Microtubules•Big tubes•Move chromosomes & vesicles•Provide internal support
Microfilaments
• Small tubes• Move vesicles• Create muscle contractions (actin & myosin)
Centrioles
•Barrel shaped•Anchor spindle fibers•Made of a collection of microtubules
Basal Bodies
•Barrel shaped•Anchor cilia and flagella
•Made of a collection of microtubules
Cilia
•Shorter versions of flagella•Move cells or beat to create currents
•Made of a collection of microtubules
Flagella
•Longer than cilia•Used for the movement of one cell
•Made of a collection of microtubules