MLT 107: Ch.1 Bacterial Cell structure, physiology, metabolism, and genetics

Type of stain: Stains nucleic acid of both GP and GN bacteria Used to locate bacteria in blood cultures and other specimens where background material obscures gram stains

Acridine Orange

Atmospheric Requirements: organism that grow better in the absence of oxygen

Aerotolerant anaerobes

Term for an organism that grows in high temperatures 50-60 C

Thermophiles

Types of Eukaryotes

fungi, algae, protozoa, animal cells, plant cells

when using gram stain, cell stains pink

gram negative

when using gram stain, cell stains purple

gram positive

Plasmid

• Extra piece of DNA • Code for antibiotic resistance and other virulence factors are often found on plasmids • Sometimes passed from one bacterial species to another. This is how resistance is acquired.

Respiration (Oxidation)

• More efficient energy-generating process • Molecular oxygen is the final electron acceptor • Aerobic process in obligate aerobes and facultative anaerobes

Nutritional requirements for growth: Heterotrophs

• Require more complex substances for growth • Require an organic source of carbon and obtain energy by oxidizing or fermenting organic substances • All human bacteria fall in this category

Prokaryotes

- no organelles -unicellular - no membrane-bound nucleus -single, circular DNA chromosome - have both cell (plasma) membrane and cell wall

Archaebacteria

- resembles eukaryotes -found in microorganisms that grow under extreme environmental conditions - Cell wall lacks peptidoglycan

Shapes of bacteria: rod-shaped

Bacilli

Taxonomy (species): Term for biochemical test result differences

Biovarieties (biovar)

Bacterial Growth Media Types: used to detect small numbers of aerobes, anaerobes and microaerophiles

Broths

Taxonomy: Genus names

Capitalized - When in print, genus and species are italicized. - When written, genus and species are underlin

Taxonomy: Family names

Capitalized with "aceae" endings

Atmospheric Requirements: organisms grow better with extra CO2

Capnophilic

Shapes of bacteria: spherical

Cocci

Bacterial Growth Media Types: contains additives that allow visualization of metabolic differences in bacteria

Differential medium

Shapes of bacteria: cocci in pairs

Diplococci

Metabolic Pathways for conversion of glucose to pyruvate

Embden-Meyerhoff-Parnas (EMP) Pentose Phosphate pathway Entner-Doudoroff pathway

Bacterial Growth Media Types: nutrient medium with extra growth factors, such as blood which encourages small numbers of organisms to flourish

Enriched medium

Atmospheric Requirements: organism that can grow with or without oxygen

Facultative anaerobes

Cell appendages: sticky, hairlike projections that aid in attachment to other bacteria or surfaces

Fimbriae

Cell appendages: exterior protein filaments that rotate and cause bacteria to be motile

Flagella

Gram Stain Method

He CIAS - heat fix (methanol) -Crystal violet -Iodine -Alcohol-acetone -Safranin

Type of stain: negative stain for capsules, surrounds certain yeasts

India Ink

Taxonomy: name the seven classifications after "domain"

Kingdom, Phylum, Class, Order, Family , Genus, Species

Main oxidative pathway is the _____.

Krebs cycle aka. tricarboxylic acid cycle (TCA cycle)

Slime Layer

Made of polysaccharides - Inhibit phagocytosis - Aid in adherence to host tissue or implants

Term for an organism that grows in moderate temperatures 20-40 C

Mesophiles

Type of stain: stain for Corynebacterium diphtheriae to show metachromatic granules and as counter-stain in acid-fast stain procedures

Methylene Blue

Atmospheric Requirements: organisms grow better in low oxygen environments

Microaerophilic

Types of flagella

Monopolar, bipolar, peritrichous

Shapes of bacteria: coffee-bean shape in pairs

Neisseriae

Bacterial Growth Media Types: more complex, made of extracts of meat or soy beans

Nutrient medium

Atmospheric Requirements: organism that requires oxygen

Obligate aerobes

Atmospheric Requirements: organism that cannot grow in the presence of oxygen

Obligate anaerobes

Viruses: require host cells for replication and are usually host and/ or host cell specific

Obligate intracellular parasite

Gram Negative (GN) Cell Wall

PINK Two layers; inner layer is much thinner than GP cell walls - contains lipid A, o antigen, and porin Outer membrane functions: - Acts as a barrier to hydrophobic compounds and harmful substances -Acts as a sieve, allows water-soluble molecules to enter through porins - Enhances attachment to host cells

Gram Positive (GP) Cell Wall

PURPLE • Very thick protective peptidoglycan layer • Many GP antibiotics act by preventing synthesis of peptidoglycan • contain teichoic acid and lipoteichoic acid (LTA)

Taxonomy (species): Term for based on susceptibility to specific bacterial phages

Phage typing

Cell appendages: connect bacteria and mediate DNA exchange

Pili

Capsule (bacteria)

Protect the bacteria from phagocytosis - Capsule usually does not stain, but can appear as a clear area (halo-like)

Bacterial Growth Media Types: contains additives that inhibit the growth of some bacteria while allowing others to grow

Selective medium

Taxonomy (species): Term for serologic differences

Serovarieties (serovar)

Shapes of bacteria: helical

Spirochetes

Taxonomy: Species names

Staphylococcus sp. is used when referring to the genus when the species is not identified. Can be referred to as singular or plural - "sp." - singular (Staphylococcus sp.) - "spp." - plural (Staphylococcus spp.) Abbreviations - First letter of the genus, followed by a period and the species epithet - Ex: Staphylococcus aureus changes to S. aureus

Taxonomy (species): Term for phenotypic differences

Subspecies (subsp.)

Bacterial Growth Media Types: holding medium to preserve those bacteria present but does not allow multiplication

Transport medium

Acid Fast Cell Wall

mainly Mycobacteria and Nocardia - Have a GP cell wall structure but ALSO a waxy layer of glycolipids and fatty acids (mycolic acid) -Waxy layer makes them difficult to gram stain - Cannot be decolorized by acid-alcohol, hence the name "acid fast" - Incorporates Carbolfuchsin and acid-alcohol decolorizer

Absence of a Cell Wall

mainly Mycoplasma and Ureaplasma - Lack of cell wall results in a variety of shapes microscopically

Three methods of gene transfer

transformation, transduction (foreign DNA is introduced into a bacterial cell by a virus or viral vector), conjugation (temporary union of two bacteria or unicellular organisms for the exchange of genetic material)

Nutritional requirements for growth: Autotrophs

• Able to grow simply, using only CO2 , water and inorganic salts • Obtain energy via photosynthesis or oxidation of inorganic compounds • Occur in nature and do not normally cause disease

Fermentation

• Anaerobic process in obligate and facultative anaerobes • The electron acceptor is an organic compound • Does NOT require oxygen • Less efficient in generation of energy