second colloq Flashcards
Nutrition types of microorganisms
Autotrophs (from Carbon dioxide)
- Photoautotrophs
- Chemoautotrophs (from inorganic molecules)
Heterotrophs (Carbon from other organisms)
- Photoheterotrophs (Energy from light but Need Carbon)
- Chemoheteritrophs (from organic molecules)
- -> Paratrophs (from carbohydrates)
- -> Metatrophs (from starch, Cellulose, glycogen)
Passive Diffusion vs active transport
PASSIVE DIFFUSION
- by porins
- Ions and small hydrohilic molecules
ACTIVE TRANSPORT
- by permeases –> phototransferase system
- PEP in cytoplasm –> Energy and Phosphate to permease –> Phosphate to sugar –> sugar across membrane –> phosphorylated sugar in cell
Bacterial metabolism
sum of all chemical processes occuring in bacterial cell
catabolism: release of Energy by Breaking complexed; involves electron transfer
anabolism: requires Energy to build complexes
Bacterial enzymes
Oxidoreductase Transferase Hydrolase --> Addition of water Lyase --> breaks a compound Isomerase Ligase --> joining of two molecules using ATP
Aerobes
Anaerobes
Facultative anaerobes
Microaerophiles
AEROBES:
- require Oxygen
- final acceptor of electrons is Oxygen
ANAEROBES:
- Oxygen is toxis
- final acceptor of eletrons is Oxygen containing inorganics
FACULTATIVE ANAEROBICS
- can grow in both ways
MICROAEROPHILES
- require only very Little amount of Oxygen
- most of them are capnophiles
Energy production in glycolysis
- 2ATP, 2NADH, 2 Pyruvate
- under both anaerobic and Aerobic conditions
1- Substrate Level phosphorylation
2- six-carbon Glucose infot two three-Carbon molecules
3- Transfer of 2 electrons to NAD
4- capture of enegery in ATP
Energy production TCA cycle
- 38 ATP –> only in Aerobic conditions
1- oxidation of Carbon
2- Transfer of 2 electrons to coenzymes
3- capture of Energy in ATP
Energy production in PPP
- NADPH, 1 ATP
- pentoses are broken down
Stickland reaction
- Energy production using amino acids
- Alanine –> Acetate –> 1 ATP generated
- Proline –> 5 - Aminovalerate
Phases of bacterial growth in culture medium
1- Lag Phase: no increase in number but it mass; Adaptation of metabolism
2- Acceleration Phase
3- Log Phase: cell Count increases logarythmically
4- Deceleration Phase
5- Stationary Phase: Exhaustion of nutrients, incr. toxic metabolites
6- Death phase
Types of culture media
Selective media Nonselective media Differential diganostic media Specialized media Chemically defined media --> used for cultivation of mammalian cells Transport media Strorage media
Cultivation Methods for areobic and anaerobic pure cultures
AREOBIC:
- pour plate
- streak plate
ANAEROBIC:
- pre-reduced media (boiled, reducing Agent, Nitrogen, tube)
- Anaerobic chamber (hydrogen, Co2, Nitrogen, catalyst System)
- Anaerobic jar (water to gas Generator envelope in jar)
Organization of bacterial genome
Bacterial chromosome
Bacterial Plasmid
–> replicons
–> episomes
Mutations in microorganisms
- Transition
- Transversion
- Silent Mutation
- Missense Mutation
- Nonsense Mutation –> stop codon
- Conditional Mutation
- Frameshift Mutation
- Null mutation
Repari mechanisms of the DNA in bacteria
- direct DNA repair
- Excision repair
- Recombinational repair
- SOS repair
- Error-prone repair
Bacterial transformation
Purpose: to introduce a foreign Plasmid into Bacteria
1- naked DNA Fragments near cell
2- Entry of naked DNA
3- Recombination
4- DNA that has not recombined is broken down by enzymes
Bacterial transduction
importance: one mechanism by which antibiotic drugs become ineffective due to the Transfer of antibiotic resistance genes
1- heads of bacteriophages with DNA
2- tails are attached to heads
3- Bacterial cell released infective phages
4- Phage attaches and inserts its DNA
5- Phage DNA inserts itself as prophage intp chromosome
6- Phage DNA directs the cell’s metabolism to produce viral components
7- Empty Phage heads produced
–> LYTIC CYLCE
LYSOGENIC CYCLE
- prophage replicates and binary fission occurs before viral components are produced
Bacterial conjugation
–> Transfer of DNA from a donor bacterial cell to a recipients bacterial cell in the conjugal process involving cell-to cell contact
1- Plasmid produced
2- Conjugation Bridge produced
3- Conjugation complete
4- New cell with extra copies of certain genes
Why is human microbiome important?
- metabolism of Food products
- protects against infections
- essential grwoth factors
- stimulates immune response
Microbial flora of Skin and Eye and Ear
SKIN
- gram-positive
- fungi Candida in moist sites
EYE AND EAR
- outer ear: coagulase-negative Staphylococcus
- suruface of eye: same
- Disease: S.pneumoniae, S. Aureus, H.influenzae
Flora in upper and lower respiratory tract
UPPER RESP. TRACT
- Disease: S. pneumoniae, s. Aureus, H, influenzae
LOWER RESP. TRACT
- generally sterile
- chronic aspriration –> anaerobes –> peptostreptococcus
Flora in Mouth, esophagus, stomach
MOUTH
- streptococci, gram negative anaerobic rods
- viruses and yeast like fungi
ESOPHAGUS
- Bacteria, yeast-like fungi
- viruses that cause disease: Herpes Simplex
STOMACH
- lactic Acid producing Bacteria
- Acid tolerant bacteria
flora in small and large intestine
SMALL
- anaerobes –> peptostreptococcus
- yeast like fungi
LARGE
- bifidobacterium, eubacterium
- e. coli
flora in anterior urethra, vagina, cervix
ANTERIOR URETHRA
- lactobacilli, coagulase negative staphylococci
- fecaes and Urine cause disease
- disease: N. gonorrhoeae, C. trachomatis
VAGINA
- lactobacilli at birth for 6 weeks
- staphylococci, streptococci, enterobacteria
- puberty: lactobacilli reemerge
- disease: N. gonorrheae, Herpes Simplex, Papillomavirus
CERVIX
- not normally colonized with Bacteria
- disease: n. gonorrhoeae, c.trachomatis, actinomyces
Microbial flora of air, water, soil
PERSISTENT
- air: micrococci, fungal Spores
- water: specific aquatic Aerobic microorganisms
- soil: Nitrogen Fixing, Cellulose Splitting, pigmented bacteria, fungi, protozoa
TRANSIENT
- air: by sneezing, coughing (influenza)
- water: by feceas or Urine (Salmonella, shingellae, e. coli)
- soil: Faeces or Urine (eneterococci)
harmless symbiosis
- mutualism: both Benefit
- Commensalism: one Benefits
- Metabiosis: one creates Environment for other
- Satellism: grwo better in presence of other
Harmful symbiosis
- antibiosis: detrimental to at least one
- Competition: one takes away nutrients
- Predation: one “eats” other
- Parasitism: one lives at expense of other
Effects of physical factors on microorganisms
PH
- acidophiles
- neutrophiles
- alkaliphiles
TEMPERATURE
- psychrophiles
- mezophiles
- thermophiles
RADIATION
- ultraviolet light (denaturation of prot)
- ionizin Radiation (damages nucleic acids)
- microwave Radiation (water absorbs Energy of waves and released heat to surroundings)
- strong visible light
ULTRASONIC WAVES
- cavitation effect, proteins denature
HYDROSTATIC PRESSURE
OSMOTIC PRESSURE
- high conc. of salt –> hyperosmotic condition –> plasmolysis –> death of cell
Effects of chemical factors on micrororganisms
- acids
- Alkalis
- heavy metals
- alcohols
- Phenols
- dyes
Effect of biological factors on microorganisms
- natrual antibiotics: substances produced by certain fungi with toxic effect against Bacteria
- Bacteriocins: Toxins produced by Bacteria to inhibit the grwoth og closely related Bacteria
- Phytoncides: produced by plants in order to protect themselves
- Bacteriophages: viruses infecting and causing Lysis of the bacterial cells
Sterilization; methods
–> use of physical or chemical agents to destroy all microbial forms (including Spores)
PHYSICAL METHODS
- dry heat
- hot steam under pressure
- ionizing Radiation
- ultraviolet Radiation
- ultrasonic waves
- Filtration
CHEMICAL METHODS
- ethylene oxide gas
- Plasma gas
- hydrogen peroxide gas
- formaldehyde gas
Disinfection
–> use of chemical agents to destroy most of microbial forms, bacterial Spores and resistant ones survive
HIGH LEVEL
- chlorine –> for surgical Instruments with plasitc that cannot withstand sterilization
INTERMEDIATE LEVEL
- alcohols –> used to clean surfaces r Instruments
LOW LEVEL
- quaternary Ammonium compounds –> used to treat Instruments like blood pressure cuffs, stethoscopes…
Antisepsis
–> use of chemical agents on Skin or other Living tissue to inhibit or eliminate microorganisms; Spores survive
- iodophors
- triclosan
Main Groups of antibiotics and their mechanism of action
INHIBITORS OF CELL WALL SYNTHESIS
- inhibit synth. of peptidoglycan
- inhibit cross linkage of peptidoglycan
- inhibit synth. pf mycolic acids
INHIBITORS OF PROTEIN SYNTHESIS
- inhibits functions of bacterial 30S and 50S subunits
INHIBITORS OF NUCLEIC ACID SYNTHESIS
- inhibit bacterial DNA gyrase
- inhibit polymerase ß subunit
- disrupt bacterial DNA
ANTIMETABOLITES
–> inhibit Synthesis of tetrahydrofolic Acid
DISRUPTORS OF CELL MEMBRANE
–> bind to Phospholipids in cell membrane
