Microbial Diversity: Prokaryotic and Eukaryotic Microbes

Eukaryote

(eu = true; karyo = nut or nucleus) have a “true nucleus”, in that DNA is enclosed by a nuclear membrane. A true nucleus consists of nucleoplasm, chromosomes, and a nuclear membrane.

Prokaryote

(pro = before; karyo = nut or nucleus) do NOT contain a “true nucleus”. They are about 10 times smaller than eukaryotic cells yet they are able to perform the necessary processes of life. Do not contain membrane-bounded organelles. (Archaebacteria, Eubacteria, Cyanobacteria)

Cell Membrane

selective permeability; they allow only certain substances to pass through them.

Mesosomes

inward foldings of the cell membrane are where cellular respiration of bacteria takes place.

Cytoplasm

contains chromosome, ribosomes, and other cytoplasmic structures. Surrounded by a cell wall, cell membrane, and sometimes a capsule or slime layer.

Ribosomes

Synthesize proteins

Cytoskeleton

strengthen, support, and stiffen the cell, and give the cell its shape.

Cell Wall

Provide rigidity, shape, and protection.

Gram-Positive Cell Walls

Thick, multilayered peptidoglycan; Teichoic acids (wall and lipoteichoic) interwoven in peptidoglycan

Gram-Positive Cell Walls

Retains crystal violet stain

Gram-Negative Cell Walls

Thin peptidoglycan layer; Outer membrane composed of phospholipids and lipopolysaccharide (LPS)

Gram-Negative Cell Walls

Does not retain crystal violet

Flagella

Exhibit motility for locomotion.

Some Bacteria

Flagella and axial filament (NOTE

Some Protozoa

Flagella and Cilia

Peritrichous

flagella all over the surface

Lophotrichous

a tuft of flagella at one end

Amphitrichous

one or more flagella at each end

Monotrichous

one flagellum

Atrichous

without flagella

Chromosome

usually consists of a single, long, supercoiled, circular DNA; serves as the control center of the bacterial cell.

Plasmid

An extrachromosmal small, circular molecule of double-stranded DNA.

Pili (Fimbriae)

Conjugation and attachment among most Gram-negative bacteria.

Viruses

Acellular, Either DNA or RNA, None (Nucleus), Protein capsid and lipoprotein envelope (surface), none motility

Viruses

Method of Replication - Assembly

Bacteria

Unicellular, Both DNA and RNA, Prokaryotic, Rigid cell wall Containing peptidoglycan, Some Motility,

Bacteria

Method of Replication - Binary fission

Fungi

Yeast – Unicellular Mold – Multicellular, Both DNA and RNA, Eukaryotic, Rigid cell wall containing chitin, None-Motility

Fungi

Method of Replication – Yeast=Budding and Mold= Mitosis

Protozoa and Helminths

Protozoa – Unicellular Helminths – Multicellular, Both DNA and RNA, Eukaryotic, Flexible membrane, Motility – Most.

Protozoa and Helminths

Method of Replication - Mitosis