Chapter 3 - Bacteria and Archaea

Detail the causes and mechanisms of sporogenesis and germination.

When spores of Clostridium sp. are embedded in a wound with dead tissue, they can germinate, grow, and release toxins.

Bergy's Manual of Determinative Bacteriology

for differentiating and identifying unknown micobial species

Bergy's Manual of Systematic Bacteriology

for studying prokaryotic relationships and origins (where you would do taxonomy classifying them where they belong in the phylogenetic tree)

Gracilicutes

gram-negative cell walls and thus are thick-skinned

Firmicutes

gram-positive cell walls are thick and strong

Flagella

prokaryotic propellers (like a boat propeller). Bacterial locomotion. Three distinct parts (Basal body (hook, rod, and rings) and filament). Comprised of many proteins. Moves in a 360 degree rotation.

Explain how a flagellum works in the presence of an attractant.

Bacterial movement: Bacteria move in response to chemical signals called chemotaxis. Receptors bind extracelluar molecules, which triggers flagellum to rotate. Runs: Smooth linear movement toward stimulus. Tumbles: Flagellar rotation reverses (the bacteria goes backwards) causing the cell to stop and change its course.

4 different types of bacterial appendages

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Identify five structures that may be contained in bacterial cytoplasm

1) bacterial DNA 2) Prokaryotic Ribosome 3) inclusion or granules: storage bodies 4) The Cytoskeleton 5) Bacterial Endospores

Describe 3 major shapes of bacteria

1) coccus - spherical shaped 2) bacillus/rod - rod shaped 3) spirillum - small, curving or spiral shaped

Eukaryotes

Chromosomes: multiple, linear Types of ribosomes: 80S

Bacteria

Chromosomes: single or few, circular. Types of ribosomes 70S

bacterial DNA

DNA of most bacteria exists in the form of a single circular bacterial chromosome, DNA is aggregated in a dense area of the cell called a nucleoid, many of these bacteria contain other, non-essential pieces of DNA called plasmids.

Provide at least 4 terms to describe bacterial arrangements

Diplococcus - two cells Streptococcus - variable number of coci in chains Tetrad - cocci in packets of four Sarcina - packet of 8-64 cells Staphylococci - number of cells varies

Bacterial Endospores

Dormant bodies inside of the cell, heat resistant due to calcium and dipicolinic acid content, Cortex-spore coats protect against radiation and chemicals, metabolically active vegetative cells can undergo sporulation, sporulation is not a reproductive function for most bacteria.

Identify three structures some but not all bacteria possess

Flagella, pili, and fimbriae An outer membrane plasmids inclusions endospores Intracellular membranes

Differentiate between the two main types of bacterial envelope structure.

Gram positive cell: Thick peptidoglycan. Teichoic acid, lipoteichoic acid (chemicals that help with binding of the stain). One Membrane. Gram negative cell: Thin peptidoglycan. Lipopolysaccharide (located on the outside of the peptidoglycan). Two membranes. Porins (helps things flow in and out of the cell)

Name a substance in the envelope structure of some bacteria that can cause severe symptoms in humans

Lipopolysaccharide: located in the outermost layer of the outer membrane (OM) in gram negative bacteria. Lipid A (endotoxin) stimulates fever and shock.

Inclusion or Granules: Storage Bodies

Non-membrane bound granules, usually for storage of nutrients inside the cell

The cytoskeleton

Peptidoglycan layer determines shape of many bacteria, others use protein fibers composed of actin and tubulin to alter cell shape (minature bones of the cell)

Archaea

Prokaryotic microorganisms, many are found in extreme environments, psychrophiles (can survive extremely cold temperatures), halophiles (can survive extremely salty environments), chromosomes are single and circular, types of ribosomes: 70S but structure is similar to 80S

Peptidoglycan cell wall

Repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments. Present in most bacteria. Provides strength to resist rupturing due to osmotic pressure.

Define a species in terms of bacteria

Theoretically, a collection of bacterial cells, all of which share an overall similar pattern of traits and 70-80% of their genes. Members of a given species can show variations: subspecies, strain, or type are terms used to designate bacteria of the same species that have differing characteristics. Serotype: refers to representatives of a species that stimulate a distinct pattern of antibody (serum) responses to their hosts.

Prokaryotic ribosome

Two subunits (30S and 50S), total size is 70S (versus 80S in eukaryotes), 60% rRNA, 40% protein, translates mRNA into proteins

List the structures all bacteria possess.

a cell membrane cytoplasm Ribosomes A cytoskeleton One (of a few) chromosome(s)

Mendosicutes

archaea with unusual cell walls

Capsule

bound more tightly to the cell, denser and thinker than a slime layer. Visible by negative staining. Produces a sticky (mucoid) character to colonies. Encapsulated bacterial cells generally have greater pathogenicity.

Tenericutes

lack a cell wall and thus are soft

Fimbriae

used for attachment (hair-like structures)

Pilus

used for attachment and genetic exchange during conjugation.