Microbiology Chapter 3.3

What is a Spirllum (Plural spirilla)?

A curved rod long enough to form spirals.

What is Spirochete?

A long, helical cell with a flexible cell wall and a unique mechanism of motility.

Rod Shape Bacteria

A rod shape bacterium is sometimes called a bacillus (plural bacilli). This term should not be confused with Bacillus the name of a genusa although it has a rod shape. Escherichia coli also has a rod shape.

What is a Vibrio (Plural vibrios)?

A short curved rod.

What does plasma of a cell consist of?

A viscous fluid that has water, enzymes & other proteins, carbohydrates, lipids and different inorganic molecules. Structures within the cytoplasm includes ribosomes and various storage granules.

When water and nutrients are deleted...

Cells aggregate to form a structure called a fruiting body which is visible to the naked eye.

Bacteria live in their natural habitat called?

Bacteria live on surfaces in associations called Biofilms.

What is Pleomorphic?

Bacteria that characteristically vary in their shape.

Cocci Division

Cocci that divide in 2 or 2 planes perpendicular to one another form cubical packets. Members of Genus Sarcina forms cubical packets. Cocci that divide in several planes at random may form clusters. Staphylococcus forms grapelike clusters.

Cocci that occur in pairs are called?

Diplococci. An important clue in the indentificaiton of Neisseria Gonorrhoeae is its characteristic diplococci arrangement.

What is the nucleoid of the Prokaryotic cell?

It is the gel like area where the chromosomes are located. The nucleoid is not enclosed within a membrane like Eukaryotic cells.

What is a coccobacillus?

It's a rod shaped bacterium so short that it can easily be mistaken for a coccus.

A summary of Prokaryotic Cell Structure

Extracellular 1) Filamentous Appendages-Composed of protein subunits that form a helical chain. 2) Flagella- Provides motility 3) Pili- Different pili has different functions. Ex fimbriae (Common Type) enable cells to stick to surfaces while other types mediate twitching or gliding motility. Sex pili join cells as a prelude to DNA transfer. 4) Capsules & Slime layers- Layers outside of cell wall, made of polysaccharide. 5) Capsule- Distinct and gelatinous. Enables bacteria to stick to specific surfaces allows some organism to thwart innat defense systems and cause disease. 6) Slime Layer- Diffuse & Irregular. Enables bacteria to stick to specifi surfaces. 7) Cell wall-Peptidoglycan provides rigidity to bacterial cell walls, preventingthe cells from lysing. A) Gram-positive-thick layer of peptidoglycan that has teichoic adds and lipoteichoic acids. B) Gram-negative- thin layer of peptidoglycan surrounded by an outer membrane. The outer layer of the outer membrane is lipopolysaccharide. Cell Boundary 1) DNA- Contains the genetic information of the cell. 2) Chromosomal- Carries the genetic information essential to a cell, Typically a single, circular, double-stranded DNA molecule. 3) Plasmid- extrachromosomal DNA molecule.Carries genetic information. 4) Endospore- A type of dormant cell. Generally extraordinarily resistant to heat, desiccation, ultraviolet light, and toxic chemicals 5) Cytoskeleton- Involved in cell division and controls cell shape. 6) Gas Vesicles- Small, rigid structures that provides buoyancy to a cell. 7) Granules accumulations of high molecular weight polymers, synthesized from a nutrient available in relative excess. 8) Ribosomes-Intimately involved in protein synthesis. 30s and 50s join to form 70s ribosomes.

Shapes: Prokaryotic Cells

Most common bacteria are of 1 or 2 shapes: Spherical called coccus (plural cocci) & cylindrical called rod.

Groupings: Prokaryotes or Prokaryotic Cells

Most prokaryotes divide by binary fission, a process where cell divides into 2. Cells that stick together after a division form a characteristic arrangement that depends on the planes in which the organisms divide. Example can be seen in cocci because they divide in more than 1 plane. Cells that divide in on plane may form chains or different length. Some cocci form long plane except for some in Genus Streptococcus.

Multicellular Associations

Some bacteria live as multicellular associations. Ex members of bacteria myxobacteria glide over moist surfaces together, forming a swarm of cells that move as a pack. These cells release enzymes that allows the pack to degrade organic material, including other bacterial cells.

What contents make up the cell envelope?

The capsule (If present), cell wall and cytoplasmic membrane. The cell envelope has the content of the cell the cytoplasm & nucleoid.

Structure of the Prokaryotic Cell

The cytoplasmic membrane surrounds the cell and act as a barrier bt the external environment and the interior of th cell. The membrane only allow a certain molecules into and out of the cell. The cell wall surrounds the cytoplasmic membrane to keep the cell content from bursting out. The cell wall also has appendages making it useful in motility and the ability to adhere to certain surfaces.