MicroBiology-Draft/Sample

Summary of Cell Structures

Cell Structure Prokaryotes

Bacteria Archaea

Eukaryotes

Genome

characteristics

• Single
  chromosome


• Circular


• Haploid


• Lacks histones
  
  
  • Single chromosome
  
  
  • Circular
  
  
  • Haploid
  
  
  • Contains histones
    
    
    • Multiple chromosomes
    
    
    • Linear
    
    
    • Haploid or diploid
    
    
    • Contains histones
    
    
    
    
  
  
  
  

Cell division Binary fission Binary fission Mitosis, meiosis

Membrane lipid

composition

• Ester-linked


• Straight-chain
  fatty acids


• Bilayer
  
  
  • Ether-linked
  
  
  • Branched isoprenoids
  
  
  • Bilayer or monolayer
    
    
    • Ester-linked
    
    
    • Straight-chain fatty acids
    
    
    • Sterols
    
    
    • Bilayer
    
    
    
    
  
  
  
  

Cell wall

composition

• Peptidoglycan,
  or


• None
  
  
  • Pseudopeptidoglycan,
    or
  
  
  • Glycopeptide, or
  
  
  • Polysaccharide, or
  
  
  • Protein (S-layer), or
  
  
  • None
    
    
    • Cellulose (plants, some
      algae)
    
    
    • Chitin (molluscs, insects,
      crustaceans, and fungi)
    
    
    • Silica (some algae)
    
    
    • Most others lack cell walls
    
    
    
    
  
  
  
  

Motility

structures

Rigid spiral flagella

composed of flagellin

Rigid spiral flagella

composed of archaeal

flagellins

Flexible flagella and cilia

composed of microtubules

Membrane-

bound

organelles

No No Yes

Endomembrane

system

No No Yes (ER, Golgi, lysosomes)

Ribosomes 70S 70S • 80S in cytoplasm and

rough ER

• 70S in mitochondria,
  chloroplasts

Table 3.2

Cell Morphologies

Eukaryotic cells display a wide variety of different cell morphologies. Possible shapes include spheroid, ovoid,
cuboidal, cylindrical, flat, lenticular, fusiform, discoidal, crescent, ring stellate, and polygonal (Figure 3.37). Some
eukaryotic cells are irregular in shape, and some are capable of changing shape. The shape of a particular type of
eukaryotic cell may be influenced by factors such as its primary function, the organization of its cytoskeleton, the

Chapter 3 | The Cell 115