Exam 1 Flashcards
Father of modern microbiology
Pasteur
Most beneficial microbe
Saccharomyces cerevisiae
Germ theory of disease was whose idea
Pasteur’s
Triad of health composed of
Host
Agent
Environment
Allopathic medicine focuses on
Agent
Chiropractic focuses on
Host
Public health focuses on
Environment
Invented hand washing
Semmelweis
Invented antiseptic technique
Lister
Invented infection control/ epidemiology
Snow
Invented smallpox vaccine/ immunology
Jenner
4 processes of life
Growth
Reproduction
Responsiveness
Metabolism
Most important characteristic differentiating euks from pros
Nucleus
Inclusions
Reservoir of nutrients to be used in harsh times
Endospores
Defensive strategy against unfavorable conditions
Endospores only used by
Bacillus
Clostridium
Prokaryotic ribosomes
70S (30S+50S)
Eukaryotic ribosomes
80S (40S + 60S)
Where are 70S ribosomes found?
Prokaryotes
Mitochondria of eukaryotes
Growth requirements
Oxygen Temperature Ph Moisture Osmotic pressure Light Food
Most important factor affecting growth
Temp
Psychrophilic
Prefer cold temps
Mesophilic
Prefer moderate temps
Most pathogenic microbes are
Mesophilic
Thermophilic
Prefer high temps
Most microbes thrive in what pH?
6-9
Most animal pathogens work at what pH?
7
Most pathogens killed by direct
Sunlight
Inoculum
Sample of organism trying to grow
Medium
Collection of nutrients
Culture
Microbes that grow from inoculum
Colonies
Cultures visible on surface of media
Selective media
Substances that favor or inhibit growth of particular microbes
Ex of selective media
Sabouraud dextrose agar
Sabouraud dextrose agar selects for ___ and inhibits __
Fungi
Bacteria
Differential media
Visible changes in medium or differences in appearance of colonies to differentiate microbes
Ex of differential media
Blood agar
Ex of selective and differential media
MacConkey agar
MacConkey agar is selective for ___ and differentiates between types of Gram - microbes
Gram - Bacteria
Magenta/red dye
Safranin
Gram stain results
Gram + = purple
Gram - = magenta/red
Gram stain uses
Crystal violet primary stain
Safranin counterstain
Mycobacterial do not have typical
Peptidoglycan cell wall
Cell walls of mycobacteria have high ____ content, resistant to decolonization by acids
Waxy mycolic acid
Mycobacteria referred to as
Acid-fast bacteria
Acid fast stain uses
Carbol fuchsin Primary stain
Methylene blue counterstain
Acid-fast stain results
Acid fast cells = red
Non acid fast cells = blue
Endospores stain uses
Malachite green primary stain
Safranin counterstain
Endospore stain results
Endospores = green
Vegetative cells = magenta/ red
Characteristics of bacterial cell walls
- Give cells shape
- Protects from osmotic forces
- Assists in attaching to other cells
- Target of antimicrobial drugs
Categories of Bacteria
Gram +, Gram -, Mycobateria, Mycoplasma
Gram - membrane contains _________
Lipid A
Appearance of Mycoplasma under a microscope
“Fried egg” shape
Type of environment mycoplasma inhabits
Osmotically protected
Bacteria with no cell wall
Mycoplasma
Result of a cell in a hypertonic solution
Crenation
Result of cell in a hypotonic solution
Cell lysis or death (swells)
Prokaryotes all reproduce
Asexually
3 methods of prokaryotic reproduction
- Binary fission (MC)
- Snapping division
- Budding
Binary fission
Parent cell replicates its DNA and its membrane elongates, the 2 copies are separated and the membrane invaginates forming 2 daughter cells
Bacteria that replicate with snapping division
- clostridium
- corynebacterium (dyptheria)
Budding
DNA is replicated, the cell elongates to form a “bud”, the expanded part carries the new copy of DNA into the new membrane, buds off. 1 daughter cell and 1 parent cell at the end
Diplococci
2 cocci attached (a pair)
Streptococci
A chain of cocci
Tetrad
Square (4 cocci)
Sarcinae
Cube of cocci (8)
Staphylococci
Cocci divides in all directions, forms a cluster
Diplobacilli
2 bacilli attached
Streptobacilli
Chain of bacilli
Palisade
Only formed with snapping division
Structure of prokaryotic genomes
Made up of plasmids
Plasmids
Small molecules of extra-chromosomal DNA that replicate independently. Have survival advantages
NOT essential for normal metabolism, growth, or reproduction
Plasmids
Types of plasmids
- Fertility factors
- Resistance factors
- Bacteriocin factors
- Virulence factors
Fertility factors
F plasmids.
Carry instructions for conjugation
Resistance factors
R plasmids
Carry genes for resistance to antibiotics
Bacteriocin factors
Carry genes for toxins called bactericins
Kill competitors
Virulence plasmids
Carry instructions that let bacterium become pathogenic
Vertical gene transfer
Organisms replicate genomes and provide copies to descendants
Normal process in prokaryotes and eukaryotes
Horizontal gene transfer
Acquire genes from other microbes of the same generation but could be different species.
Donor- contributes genome
Recipient cell- takes genome, reproduces
3 types of horizontal gene transfer
- Transformation
- Transduction
- Bacterial conjugation
Transformation
Recipient cell takes DNA from the environment (without the donor offering; donor could be alive or dead)
Competent cell
A cell that can take up DNA and reproduce via transformation
Only a few types of bacteria can do this
Transduction
Transfer DNA form one cell to another via a virus
Generalized transduction
Transduction virus carries random DNA from donor to recipient
Specialized transduction
Only certain DNA from the donor is transferred
Conjugation
Transfer of DNA from one cell to another by conjugation pili
Donor cell requires F plasmid (F+)
Recipient lacks the F plasmid (F-)
Microscopic eukaryotic microbes
Fungi and Protozoa
Parasitic eukaryotic microbes
Protozoa and helminths
Percent of fungi that cause disease
30%
Mycoses
Fungi that cause disease
Thallus
Nonreproductive body of fungi
Mold thallus
Hyphae — long filaments
Yeast thallus
Sperical buds
Dimorphic fungi
Produce 2 types of thalli
Generally ______ of dimorphics cause disease
Yeast form
Mycelium
Tangled mass of hyphae
Typically subterranean
All fungi have some means of ______ but most reproduce _____
Asexual reproduction
Sexually
Asexual reproduction in fungi
Budding
Spore formation
Pseudohypha
Series of buds that remain attached to one another and to parent
Spore formation in fungi
Produce spores that disperse over long distances
Protozoa characteristics
Lack cell wall
Like moist environments
Few are pathogens
Most — asexually only
All protozoa have _____ and some have ____ and ____
Trophozoite; cyst and contractile vacuoles
Trophozoite form
Motile feeding stage
Can reproduce
Contractile vacuoles
Actively pump water, protect from osmotic lysis
Generalist virus
Infect many kinds of cells in different hosts
Specific virus
Only infect particular kind of cell in particular host
Helical virus
Spiral
Polyhedral virus
Geodesic dome (MC)
20 sides = icosahedron
Complex virus
Capsids of many shapes
Lysogeny viral replication
Infected host cells grow/reproduce for generations before they lyse
Lysogenic conversion viral replication
Phages carry genes that alter phenotype of bacterium
Animal virus remain dormant in host cells called
Latent viruses or proviruses
Incorporation of provirus into host DNA is
Permanent
Prions
Proteinaceous infectious agents
Lack NA
Prions only destroyed by
Incineration and autoclaving
Most predominant area for prion expression
Nervous system
Prions cause diseases known as what
Spongiform encephalopathies
2 common types of spongiform encephalopathies
Bovine spongiform encephalopathy
Variant Cruetzfeldt Jacob Disease
Normal microbiota AKA
Normal flora and indigenous microbiota
Resident microbiota
Remain part of normal microbiota for life
Transient microbiota
Remain in body for few hours, days, months, then disappear
Axenic sites definition
Free of any microbes
Axenic site examples
- Alveoli
- CNS
- Circulatory system
- Upper urogenital
- Uterus
When do we begin to develop microbiota
During birthing process
Opportunistic pathogens
Normal microbiota that cause disease under certain circumstances
Reservoirs
Sites where pathogens live until they can infect host
Zoonoses
Diseases naturally spread from animal host to humans
Humans are usually
Dead-end host
Human carriers
Infected, asymptomatic but can infect others
Case vs Carrier
Case= develop illness Carrier = never get sick
Isolation
Separate ILL persons who have disease
Quarantine
Separate WELL persons who have been exposed to disease
Contamination
Presence of microbes in or on body
Infection
Evades body’s external defenses
MAY or MAY NOT result in disease
3 major Portals of entry
Skin
Mucous membranes
Placenta
Parenteral route
Not technically portal of entry
Pathogens deposited directly into tissues
What is most common site of entry
Respiratory tract (mucous membrane)
Infection
Invasion of host by pathogen
Disease
Invading pathogen alters normal body functions
Pathogenicity
Ability of microorganism to cause disease
Virulence
Degree of pathogenicity
Antigenicity
Ability of substance to stim production of antibodies
Symptoms
Subjective characteristics of disease felt only by PATIENT
Signs
Objective; observed/measured by others
Syndrome
Group of symptoms and signs
Virulence factors
Adhesion Biofilms Extracellular enzymes Toxins Antiphagocytic factors
Bacterial pathogens attach to each other
Form biofilm
Ex: dental plaque