Micro. Chapter 3: The Cell (Prokaryotic)

General Characteristic

• 2-8µM in length

• 1-2µM in diameter

Shapes

• Coccus - round

• Bacillus - rod

• Coccobacillus - short rod

• Vibrio - cured

• Spirilla and spirochetes

Coccoid Arrangements

• Used as an identifying characteristic

- When observing a sample go with shape that is most present

• Caused by divisional planes of various organisms

• Pairs

• Tetrads

• Chains

• Clusters

Cell Wall

• Made of plasma membrane

• Maintains structure

• Functions just as in human cells

Cytosol

• Jelly on the inside of the cell

• Mostly water

Cytoplasm

• Cytosol plus other components

Nucleoid

• Where the DNA is

• Not organized and doesn’t have any histones

- Nucleoid-associated proteins act in the place of histones

DNA

• Single chromosome

• Located in a circle around the cell

• AGTC based with a sugar / phosphate backbone

• Aranged in genes

• Double stranded

Plasmids

• Small extrachromosomal DNA, hundreds

• Doesn’t have genes required for normal life

- House keeping genes only

• Holds specialty genes

- Antibiotic resistance

- Toxins

- Special nutrient processing

• Replicated in-depended of chromosome

Ribosomes

• The exact same as eukaryotes cells

Inclusions

• Pockets of excess nutrients and other components

• Some have a phospholipid monolayer and proteins but others don’t

Endospores

• Form when conditions are to hard for life

• Inert forms of bacteria

• Only formed by some Gram positive rods

Bacterial spore

• A released endospore

• Inert

Vegetative cell

• Active, metabolizing cell formed from a bacterial spore

Germination

• Bacteria going from a spore (inactive) back to vegetative state (active)

Sporulation

• Bacteria moving from a vegetative state (active) to a spore (inactive)

Peptidoglycan

• A peptide that is unique to bacteria

• Amount and arrangement are used to separate bacteria into groups

- Gram positive

- Gram negative

Gram positive cell wall

• Thick layer of peptidoglycan

• 2 layers of teichoic acid threaded in

Gram negative cell well

• Thin layer of peptidoglycan

• 3 layers of Lipopolysaccharide threaded in

Acid fast bacteria

• Gram positive

• Mycolic acid on the outer most layer

- Waxy

• Messes up our gram stinging process

Exterior of a bacteria cell

• Glycocalyx

- Subdivided into Capsule and Slime layer

• S layer

• Fimbriae

• Pili

• Flagella

Glycocalyces

• Part of the exterior of the cell

• Made of sugar and sometimes protein

• Makes the cell slippery or sticky

• Subdivided into capsule and slime layer

Capsule

• Subdivision of glycocalyces

• More organized and denser than slime layer

Slime layer

• Subdivision of glycocalyces

• Less organized and denser than capsule

S layer

• Made of proteins and glycoproteins

• May help in withstanding osmotic pressure

• May interact with the immune system with pathogens

Fimbriae

• Plentiful, hair like projections

• Functions in adhesion

- May have other functions to

Pili (F pilus)

• Often used interchangeably with fimbriae but that’s incorrect

• Hollow tube that extends from one cell and connects with another

- Plasmid transfer

M Protein

• Antigen displayed on the surface of some Streptococcus

  pyogenes (Group A Streptococcus)

• Works to prevent phagocytosis in infection

- Virulence factor

- Prevents certain opsonization

Flagella

• Hair like projections

• Used for motility

- Has sticky ends

• Made from the protein flagellin

- Structure is slightly different depending on gram reaction

Flagellar arrangements

• The identify characteristic of bacteria

• Depend on attachment point and amount of flagella