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Microbiology Exam 2

Terms in this set (107)

chemical substances are acquired from the environment and used for cell growth and/or metabolism

Macronutrients (C, H, O, N, P, S)

required in relatively large quantities for cell structure and metabolism. 96% of the cell.

required in small quantities for enzyme and pigment structure/function.

organic nutrients

contain carbon atoms and are usually the products of living things

inorganic nutrients

a simple atom or molecule that has no carbon atom in its structure (with the exception of CO2)

used for all cellular structures and processes

obtain carbon from organic matter from other life forms

obtain carbon from CO2 which is then converted into organic compounds (self-feeders)

use organic molecules-chemicals

use light energy

aggregation of cells arising from single parent cell now replaced by colony forming unit

bacterial reproduction that results in growth

microbial growth

increase in a population of microbes

Extracellular digestion

a) walled cell is a barrier
b) enzymes are transported outside the wall
c) enzymes hydrolyze the bonds on nutrients
d) smaller molecules are transported across the wall into the cytoplasm. (monosaccharides, amino acids, fatty acids)

Mostly in the form of N2- nitrogen gas from the atmosphere, some bacterial can utilize it from other sources; must be converted to NH3 to combine with carbon.

major component of proteins and nucleic acids

from the atmosphere and/or organic salts (sulfates, phosphates, and nitrates)

major component of organic compounds such as lipids, carbohydrates, and proteins

organic compounds, H2O, salts, and certain naturally occurring gases

a) maintain pH
b) form hydrogen bonds in macromolecules
c) prime energy force in oxidation-reduction reactions of cellular respiration

inorganic phosphate, derived from phosphoric acid and found in rocks and oceanic mineral deposits.

key component of nucleic acids; phospholipids in cell membranes and coenzymes

widely distributed in the environment in mineral form (rocks and sediments like gypsum), as SO4, sulfides, hydrogen sulfide gas and elemental sulfur, found in organic substances like essential amino acids cysteine and methionine and certain vitamins

structural stability and shape of proteins by forming unique covalent linkages called disulfide bonds

essential to protein synthesis and membrane function

used in some types of cell transport

stabilizer of the cell wall and endospores of bacteria

component of chlorophyll, stabilizer of membranes and ribosomes, and important in cell energy reactions

component of cytochrome pigments (electron transport chain)

high levels in the blood allow increased, faster growth of bacteria; a problem with hemachromotosis, a genetic disease of individuals of European decent

low levels: diphtheria bacillus products its toxin; agent of bubonic plaque, Yersinia pestis, is more virulent; immune system is compromised.

toxic shock syndrome: highly absorbent tampons remove large amounts of magnesium from the vaginal mucus, resident s. aureus bacteria produce toxin responsible for TSS.

the fungus Aspergillus requires large amounts to produce aflatoxins, induce hepatoma and related liver diseases.

an organic compound such as amino acid or vitamin that cannot be synthesized by an organism and must be provided as a nutrient: most parasites lack the ability to synthesize all necessary organic compounds from raw materials

light and CO2 (photosynthetic bacteria)

photoheterotroph

light and organic compounds (green and purple non sulfur bacteria)

electrons from reduced inorganic compounds and CO2 (H, S, Fe)

chemoheterotroph

electrons from H atoms in organic compounds (all animals, most fungi, protozoa, bacteria)

optimum temperature

narrow range at which an organism grows best

min. or max temp

microbial growth ceases

cold loving, range from -15C to 15C, rarely pathogenic

grow slowly at low temps bet 20-30 C, causes food spoilage, (Listeria monocytogenes and S. aureus can grow in refrigerated food and cause food borne illness)

moderate temp loving; grow from 10-50 C, having optimal from 20-40 C; most human pathogens prefer 30-40 C

microbes that survive under short exposures to high temperatures and are contaminants of heated foods; often cyst forming, spore forming, or thick walled organisms.

heat loving; range is 45-80 C; most are spore-forming species of Bacillus and Clostridium; a small number are pathogens.

Hyperthermophiles

Archaea in deep sea and hydrothermal vents; 67-105 C

produced by phagocytes to kill invading bacteria; its build up can damage and destroy a cell

superoxide ion, peroxide, and hydroxides

destructive, metabolic products of oxygen, most cells are equipped with enzymes that neutralize these products; those that do not are anaerobic.

can cause irreparable damage to cells

Two step detoxification process

O2 + O2 + H2 ----SUPEROXIDE DISMUTASE---> H2O2 +O2
H2O2 + H2O2 -------CATALASE OR PEROXIDASE---> 2H2O + O2

Obligate aerobe

requires the presence of normal atmospheric oxygen (20%) and possesses the enzymes that detoxify oxygen; most fungi and protozoans, and many bacteria

facultative anaerobe

capable of growth in the absence of oxygen; oxygen is metabolized by aerobic respiration when present; when absent it uses an anaerobic mode of metabolism

aerotolerant anaerobes (facultative aerobe)

do not utilize oxygen, but survive in the presence of it because they can break down toxic oxygen by alternate pathways

requires a small amount of oxygen (<10%) Helicobacter pylori, the agent of gastric ulcers

obligate anaerobe

lacks the enzymes for using oxygen in respiration and the enzymes for processing toxic oxygen (clostridium, bactericides, fusobacterium, trichomonas

all microbes require some but these types grow best a higher CO2 levels than in normally present in the atmosphere (streptococcus pneumoniae)

coexistence of oxygen-using organisms and anaerobes in the mouth, where tooth crevices and the gingival sulk are important sites of anaerobic infections giving rise to dental caries and most gingival infections (gum disease)

in the large intestine

the majority of bacteria are anaerobic; anaerobic infections often accompany abdominal surgery; also gas gangrene, tetanus and infections arising from human or animal bites.

for most microbes is between 6 & 8, and most human pathogens grow optimally from 6.4 to 7.5

low pH; mold and yeast may tolerate

bacteria that decompose urine create alkaline conditions, since ammonium may be produced when urea is decomposed

osmotic pressure

most live under hypotonic or isotonic conditions

live in solutions that have a high solute concentration

live in high salt concentrations

atmospheric pressure

barophiles; bacteria that live and grow under high pressures (deep sea)

relationship required for survival

relationship not required for survival

relationship that is mutually beneficial to both microbes

one benefits the obligate relationship, the other is neither harmed nor benefited

one organism harms the other

two organisms complementing each other produce more pronounced effect than when one of them is present alone

one organism inhibits the other

complex relationship of an aggregate of microbes (catheter tip infections, plaques, heart valve and hip replacement surgery complications)

material collectively produced to form an extracellular metric as a result of quorum sensing

cells adhere to one another; allows attachment to substrates; sequesters nutrients; protect cells enclosed within; responsible for 80% of chronic infections; resistant to most antibiotic treatment

microbial culture

clinical and environment samples are inoculated into culture media with special inoculating tools

aseptic technique

observed to avoid contamination of cultures

inoculation techniques

streak plate and pour plate

chemical components are known with exact specifications

components are not chemically analyzed but have been proven to support growth

selective media

allows the growth of specific microbes while inhibiting others (TSA with salt for halophiles)

differential media

allows differentiation of certain kinds of microbes by colony appearance (fermentators from non fermentators)

2-4 C stores cultures for short periods of time

-20 C stores for years

-70 C in liquid nitrogen stores, indefinitely

freeze-drying process in vacuum; stores for decades

one cell becomes two

transverse fission

the division plane forms across the width of the cell

steps in binary fission

1) the parent cell enlarges its cell wall, cell membrane and overall volume
2) midway in the cell, the wall develops notches forming the transverse septum
3) bacterial chromosome is duplicated
4) the wall septum grows inward, and the chromosomes are pulled toward opposite cell ends; other cell components are distributed equally
5)the septum is synthesized completely through the cell center; the cell membrane patches itself so that there are two cell chambers.
6) cells may completely move free or may remain attached.

generation or doubling time

the time required for a complete fission cycle; with bacteria it is also a doubling time: one cell ->two cells -> four cells and so on.

Newly inoculated cells require an adjustment period of adjustment, enlargement, and synthesis; the cells are not yet multiplying at their maximum rate; the population is so sparse or dilute - sampling error

exponential (Log) phase

period of maximum activity

Stationary phase

factors become limiting for additional growth because of lack of food, space, and accumulation of wastes.

as limiting factors intensify, cells die at the rate that they are multiplied

Standard plate count

serial dilutions of samples; pour plate and spread plate techniques; CFU/ml (30-300 CFUs)

membrane filtration

water and fluid bacteriology

Most probably number

microbes growing in liquid media, statistical estimation, used in water and wastewater bacteriology

direct microscopic count

special counting chambers for estimating microbial numbers, should see nothing in dairy industry

number of CFU over final dilution factor

spectrophotometric

OD vs cell density-some microbes absorb the light when suspended in medium

coulter counter

rapid, electronic sensors detect cells passing through a tiny tube

genetic prospecting

genetic method of recovering and identifying unculturable organisms, especially prokaryotes. More prokaryote species have been added into data bases and refined prokaryote taxonomy in the process; uses polymerase chain reaction

sum of all chemical reactions in living systems; coupling of catabolism and anabolism by ATP

breaking down molecules; hydrolysis; release energy - exergonic

making molecules; dehydration synthesis or condensation; require energy - endergonic

function as organic catalysts; active sites that bind to substrates; speed up but not used in a chemical reaction; genetically determined.

enzyme properties

1) composed entirely of protein (holoenzyme containing a protein portion [apoenzyme] + a nonprotein ion called a cofactor or an organic molecule called a coenzyme)
2) ribozymes
3) catalysts
4) lowers activation energy
5) specific for a particular substrate because of shape and configuration of active site (lock and key)
6) usually ends in -ase
7) named after the substrate or type of relations catalyzed

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