Microbiology exam 1

phenomenon where a single species takes on various shapes dependent mostly on nutrient availability

division in 1 plane produces cells in pairs

divion in 1 plane produces cells in chains

random divion produces grapelike clusters

• regulate movement of materials in and out of the cell, via charges of phsopholipids, speciliazed pore proteins and vesicle cascades
• synthesizes cell wall components
• assists with DNA replication
• secretes enzymes
• maintains osmotic membrane potential which is used to generate energy in the form of ATP

• provides a rigid backdrop for the outer membrane to be bound in gram-negative bacteria
• prevents cell from bursting when fluids flow into the cell by osmosis
• extremely porous and therefore cannot regulate the entry of material into the cell

composed of peptidaglycan (or murrain)

• found primarily in gram-negative bacteria
• a lipid bilayer with proteins (receptors and antigens)
• attached to the peptidaglycan by a continuous layer of small lipoproteins (proteins combed with lipids ) molecules

• gap between cell membrane and cell wall
• generally present in gram-negative bacteria
• area of active cell metabolism
• contains enzymes and transport proteins

controls transport of some proteins through channel lproteins called porins

• inner cell membrane with thick cell wall (peptidaglycan) linked by teichoic acids (serves as a passageway for movement of ions in and out of the cell)
• no outer cell membrane and no preiplasmic space, very few lipids
• form protoplasts on enzyme digestion of cell wall
• may have as many 40 layers in its cell wall
• (in cell wall) 3rd amino acid in the peptide is lysine

• cell wall is thinner but more complex
• outer membrane and perilasmic space are present
• LPS (or endotoxin) present on outer membrane
• form spheroplasts on enzyme digestion of cell wall

• also called endotoxin
• integral part of the outer cell wall membrane
• released when the bacteria dies
• Lipid A, a component of LPS, is responsible for the toxic effects of gram-negative bacterial infection
• highly antigenic and higly specific to a species (down to strain level)

• mycobacteria
• inner cell membrane with a very thick cell wall
• its cell wall is comprised of thin peptidaglycan layer and thick lipid layer
• protected by lipids from harmful effects of acids and alkalis

wall deficient, vary in shape, often forming slender branched filaments and exhibit extreme pleomorphism (vary in form even within a single culture)

• although not bounded by membrane, contain very desely packed substances
• each granule contains a specific substance such as glycogen (energy source) or polyphosphate (used in metabolic processes)
• phosphate granules are called volutin
• become depleted uring starvation

• membrane enclose strucutres
• rigid gas filled vesicles (vacuoles) help aquatic bacteria to float
• lipid filled vesicles serve as storehouses of energy and source of carbon for building new molecules

long hollow tubules used to transfer DNA from 1 organism to another

• fimbriae
• short hollow tubules adhere to surfaces in order to immobilize an organism in a beneficial environment
• contribute to the pathogenicity of certain bacteria
• neisseria gonorrhea strains without the pili are rarely able to cause gonorrhea

layer of viscous polysaccharide material found lining the outside of cell wall

• protective structures of very thick layers of glycocalyx, and are used during infection by pathogenic organisms
• only certain bacteria are capable of forming capsules, and not all members of a species have capsules

• less tightly bound to the cell wall and is usually thinner than a capsule
• protects cell from drying
• helps trap nutrients near the cell
• sometimes binds cells together

• dormant resting stages
• contain very little water and are highly resistant to heat, drying, acids, bases and certain disinfectants
• depltion of nutrients induces spore formation
• structurally, it consists of core, cortex and spore coat
• contain dipicolinic acid and large amounts of Ca2+ which contribute to theat resistance of spores

flagellum at 1 end

tufts of flagella at 1 or both ends

flagellum at each end

flagella all over the cell

• all catabolic reactions involve electron transfer, which allows energy to be captures in high energy bonds in ATP
• oxidation
• reduction
• redox

important for free living microorganisms--usually do not cause diseases

important for all infectious microorganisms

• homolactic microbes
• heterolactic microbes

those that produce only lactic acid (no gas production)

• those that produce lactic acid, as well as other acids or alcohols and gases anre released
• often use 5C sugars

heterolactic microbe that causes pneumonia

heterolactic microbe that causes tetanus

Heterolactic microbe that causes botulism

heterolactic microbe that is responsible for tissue damage of gangrene

• fats are hydrolyzed to glycerol and 3 fatty acids
• glyceril is then metabolized by glycolysis
• fatty acids are broken down by a metabolic pathway called beta-oxidation and the products are then oxidized via the krebs cycle to obtain more energy

• lag phase
• log phase
• stationary phase
• death phase

• no crease in cell number
• cells are metabolically archive--growin in size, synthesizing enzymes, ATP and takin gin various molecules from teh medium
• some organisms adapt to new mediaum in a day or 2 while others take several days

• once cells adapt to the medium, poplation growth occurs in an exponential or logarithmic rate
• generation time for most bacteria is between 20 min to 3 hrs

• cell division decreases to the point that new cells are produced aat the same rate that old cells die
• number of live cells stays constant

• cells lose their ability divide
• medium contains limited amounts of nutrients and may contain toxic quantities of waste material

• Serial dilution/Standard plate counts
• Direct microscopic counts
• Metabolic activity
• Turbidity

sample is serially diulted by orders of magnitude (10x) in molten agar or water and then poured or streaked onto plates, respectively

samples can be applied to a petroff-hausser counting chaber and cell can be directly counted as they are

• cloudy appearance indicates the presence of organisms
• estimates of growht can be measure using a spectrophotometer

• indirect way to estimate bacterial growth
• rate at which metabolic products such as gases and/or acids are formed b culure reflects the mass of bacteria
• gas production can be detected by capturing the gas in small inverted Durham tubes placed in larger tubes of liquid medium containing bacteria
• acid production can be detected by incorporating pH indicators

• pH
• temperature
• oxygen
• moisture
• osmotic pressure
• nutritional factors

exist inside the cytoplasm

exist inside the periplasmic space in gram-negative bacteria

• exist outside the cell
• specialized nezymes that are prodded by the cell to break down compounds that are too large to diffuse through the cell membrane into smaller ones that can

those which are made with specific amounts of specific compounds

• those which contain extracts and digests instead of specific compounds
• eg. yeast extract, peptone

specialized media that encourages growth of somebacteria but discourages growth of others

specialized media that has a constituent that causes a visible change in the medium (color of pH) dependign on the metabolic activities of the organism, thus differentiating it from others

specialized media that encourages growth of a specific bacteria without discouraging growth of other bacteria