Lecture 1 Bacteriology Classification and Bacteria Structure

Cocci, bacilli/rods, spirochetes

3 shapes used to classify bacteria

Mycoplasm

What specific type of bacteria doesn’t have a cell wall?

Gram Stain

What type of staining uses crystal violet and red dye safranin?

Gram Positive and Gram Negative

Gram staining separates bacteria into these two groups based on the composition of the cell wall

Blue/purple, iodine, organic solvent, red dye

Gram stain procedure

• Crystal violet stains all cells ____/______

• ______ solution added (all cells remain blue)

• _______ _______ extracts blue dye from lipid-rich, thin-walled gram (-) bacteria > lipid poor, thick-walled gram (+)

• ____ ____ stains gram (-) cells red/pink and gram (+) remains blue

Acid-Fast stain

Which type of staining is specific for mycobacteria (Ex: M. tuberculosis) and results from high lipid content of the cell wall

Gram (+)

Bacteria with thicker peptidoglycan layer, + / - teichoic acid

Teichoic

________ acid is unique to gram (+) bacteria.

Gram (-)

bacteria with a complex outer layer

• lipopolysaccharide (endotoxin), lipoprotein, and phospholipid

Periplasmic Space

• location of beta-lactamases

beta-lactamases

What is sometimes located in the periplasmic space of gram (-) cells and degrades penicillin in some species?

Lipopolysaccharide (LPS)

• only on Gram-negative bacteria

• forms outer membrane

• Acts as endotoxin

  • responsible for fever and shock

Teichoic Acid

• only in cell wall of Gram-positive bacteria

• induces septic shock with infection of certain bacteria

• Mediates attachment of staphylococci to mucosal cells

Periplasmic Space

• Gram negative bacteria ONLY

• space between peptidoglycan layer and outer LPS membrane containing

  • components of transport systems for iron, proteins, sugars

  • enzymes involved in breakdown of macromolecules

  • lytic virulence factors including beta-lactamase

Peptidoglycan

• Present only in bacterial cell walls

• Provides rigid support and maintains shape of cell

• Thicker in Gram positive cells

• target of antimicrobials

  • because human cells don’t have this

Active, oxidative phosphorylation, cell wall, toxins

Importance of cytoplasmic membrane

• ______ transport of molecules into the cell

• Site of energy generation

  • _________ _______________

• Synthesis of ____ ____ precursors

• Secretion of enzymes and ______

Nucleoid

The region within a bacterial cell where the genetic material (DNA) is located

Introns

Bacterial DNA contains no _______

Haploid

Bacteria contain single circular DNA molecule per cell, making it _______.

Amorphous Matrix

• Ribosomes - 70s

  • Free in cytoplasm

Plasmids

Double-stranded circular DNA outside of nuceloid; transmissible or nontransmissible; carry genes for antibiotic resistance, resistance to heavy metals, UV light, Pili, and exotoxins

independently

Plasmids replicate ___________

Granules

Storage area for nutrients

Capsule

• Gelatinous Layer composed of polysaccharide

• Covers entire bacterium

virulence, serologic, vaccines, human

Importance of Capsule

• Determinant of _________

• Aids in identification of _________ type

• Utilized as antigens in ________

• Adherence to _____ tissue

Flagella

Whip-like appendages that aid in movement of certain bacteria towards nutrients/other attractants (Chemotaxis)

No

Are flagella present on all bacteria? (yes or no)

pathogenic, identification

Importance of flagella

• May play a role in __________ nature of bacteria

  • Ex: E. Coli ability to propel from urethra to bladder

• Flagella proteins used for bacteria _____________

Pili

Hairlike filaments found mainly on gram (-) bacteria

• shorter and straighter than flagella

attachment, sex pilus

Importance of Pili

• Mediate __________ of bacteria to receptors on human cell surface

• ____ _____ - forms attachment between cells during conjugation

Glycocalyx

Slime layer secreted by bacteria to allow adherence to many surfaces

• skin

• heart valves

• prosthetic joints

• catheters

• teeth

Spore formation

occurs in response to adverse conditions

Bacillus and Clostridium

Which bacteria produce spores?

no, dormant, heat, chemicals, autoclaving

Spores have __ metabolic activity, remain _____ for years, resistant to ____ and _________, and require ___________ to sterilize against them.

binary fission

bacteria reproduce by ______ _______

replication, growth, segregation, splitting

Division by Binary Fission

• __________ of DNA

• ______ of a cell

• __________ of DNA

• _________ of cells

Aerobic Bacteria (Aerobes)

Utilize oxygen in the final steps of energy production

superoxide dismutase

• one of two enzymes required to clear toxic molecules in aerobes

• reduces free radical superoxide (O2)

Catalase

• one of two enzymes required to clear toxic molecules in aerobes

• reduces hydrogen peroxide (H2O2)

obligate aerobes

require oxygen to grow, no exceptions

Facultative Anaerobes

• May grow with or without oxygen

  • respiration or fermentation

• Most bacteria fall into this category

• Grow faster in the presence of oxygen

obligate anaerobes

• cannot grow in the presence of oxygen

• lack catalase and / or superoxide dismutase

sugar, aerobic, oxygen, organic, identify/classify

Fermentation

• Breakdown of _____ to produce energy

• Less efficient than _______ metabolism

• Utilized by facultative and obligate anaerobes in the absence of ______

• Converts final pyruvate of glycolysis into other _______ molecules

• Utilized as a means to ________/________ bacteria based upon fermentation end products

Haploid

Bacteria are _______, containing only a single copy of their genome

Bi-directionally

DNA replication in bacteria occurs _______________

Conjugation, transduction, transposition

Mechanisms of transferring DNA between cells

Transformation

Utilized in laboratories for the manipulation of DNA

Conjugation

• Mating of two bacterial cells

• Controlled by fertility (F) plasmid

  • encodes protein (pilin) that forms sex pilus

  • May contain genes for antibiotic resistance or virulence

• F plasmid is transferred to donor cell and is now capable of instigating conjugation

high-frequency recombination

• Hfr

• F plasmid is integrated into bacterial DNA

Transduction

• DNA transfer by a bacterial virus - bacteriophage

• Piece of bacterial DNA incorporated in virion

• Divided into two types

  • General

  • Specialized

General Transduction

random pieces (segments) of DNA

Specialized Transduction

DNA adjacent to integration site

Transformation

• Transfer of DNA itself from one cell to another

• Mechanisms

  • Uptake of free DNA fragments by a cell

    • unlikely to play a big role naturally in disease

  • Utilized for the manipulation of DNA in the laboratory

within, DNA, inverted repeats, drug resistance, disrupt/mutate

Transposons

• Promotes transfer of DNA ______ bacterial cells

• Small pieces of ____ that can move freely in chromosomal DNA, plasmids, and bacteriophages

• Flanked by short sequence of ________ _______

• May contain genes for ____ __________, toxins

• may integrate and _______ / ______ genes

Recombination

Integration of DNA into host cell chromosome

Homologous recombination

exchange between similar sequences of DNA

Non-homologous recombination

• exchange between unrelated sequences

• produces insertions or deletions