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