Microbiology: A Focus on Bacteria, Fungi, and Viruses Flashcards
What is the microbiome?
Microbes live on and within the human body
What is mutualism?
Both species benefit
What is commensalism?
One benefits, the other is not harmed
What is parasitism?
One benefits, the other is harmed
What does PCR do?
Tests for specific gene in a complex
What is the first line of defense that pathogens need to get past?
Epithelium
What is the incubation period?
The time it takes the pathogen to enter the body and show the first symptom
What are the factors that influence the incubation period?
- Health of host
- Growth rate of pathogen
- Degree of exposure
What are two adhesion mechanisms of pathogens?
Pili and fimbrae
What is an acute infection?
- Symptoms develop quickly
- Clears quickly
- Host has immunity for reinfection
What is a chronic infection?
- Symptoms develop slowly
- Can last months to years
What is a latent/persistent infection?
Illness never goes away, becomes dormant in the body and can be awakened with low immunity
What transmission is person to person?
Horizontal transmission
What transmission is mother to baby?
Vertical transmission
What transmission is from an animal or arthropod?
Vector transmission
What is the degree of pathogenicity of a pathogen?
Virulence
What factors determine virulence of a pathogen?
Ability to invade and multiply within the host
What are factors within the host that can influence a pathogen’s virulence?
- Diet
- Hormones
- Hygiene
- Health
What is a strict pathogen?
Always causes disease
What is an opportunistic pathogen?
Already part of normal microbial flora, takes advantage of weakened immune system
How do bacterial cells hold their genetic information?
- No nucleus
- Chromosomes form a nucleotide
Are bacterial cells eukaryotic or prokaryotic?
Prokaryotic
What is the spherical shape of a bacterial cell classified as?
Cocci
What is a diplococcus?
Pair of cocci cells
What is a streptococcus?
Chain of cocci cells
What is a staphylococcus?
Pyramidal shape of cocci cells
What is a tetrad?
4 cocci cells
What is a sarina?
Cube of eight cocci
What is a rod shaped cell classified as?
Bacilli
What is a diplobacilli?
Two bacilli cells
What is a streptobacilli?
Chain of bacilli cells
What is a palisades?
Looks like dominos of bacilli cells together
What is the intermediate shape between coccus and bacillus called?
Coccobacilli
What is a vibrio?
Curved or comma-shaped rod
What is a spirillum?
Thick, rigid spiral
What is a spirochete?
Thin, flexible spiral
What is it called when a bacterial cell does not have any characteristic shape and can change their shape?
Pleomorphic
What does gram positive stain?
Purple, retains crystal violet from iodine
What does gram negative stain as?
Pink, does not retain crystal violent and appears transparent (counter stain is pink)
What type of cells have a large peptidoglycan wall?
Gram positive
What type of cells have a lipopolysaccharide layer?
Gram negative
What type of cells have an outer membrane?
Gram negative
What is the LPS layer made out of?
Lipids and carbohydrates
What is peptidoglycan made out of?
Sugar and amino acids
Can the LPS play a role in a pathogen’s ability to cause disease?
Yes
Is gram positive or negative cells more resistant to antibiotics? Why?
- Gram negative
- Has impenetrable cell wall
Do gram negative or gram positive develop resistance to antibiotics more quickly?
Gram negative
Can all bacteria be reliably classified through gram staining?
No
What are acidophiles?
Acid loving, grow optimally around pH of 2
What are alkalophiles?
Base loving, grow well at pH values near 10
What aciduric?
Acid tolerant, can survive in acidic conditions but do not necessarily grow
What are psychrophiles?
Prokaryotes that grow very poorly at temperatures above 15 degrees C
What are thermophiles?
Thrive at 100 degrees C
What structure covers the outer layer of the cell wall and is composed of polysaccharides?
Capsule
What is a virulence factor that mediates attachment of bacterium to host tissues?
Capsule
What structure can inhibit phagocytosis by neutrophils and macrophages?
Capsule
What is one of the causative agents of dental caries?
Streptococcus mutans
How do Streptococcus mutans attach to the tooth surface?
Capsule
What is a slime layer?
Some bacteria have a loosely adherent colloidal material that they secrete, usually similar to the capsule
What are pili?
Long hair-like tubular microfibers
What are fimbriae?
Bristle-like short fibers
What do pili and fimbrae do?
- Attachment
- Transfer of DNA
- Mobility
Do gram positive or gram negative cells have pili and fimbrae?
Gram negative only
Where does the flagella extend from?
Interior cell body, not from the capsule
What is the function of the flagella?
Mobility
Do gram positive or gram negative cells have flagella?
Both
What is the initial phase characterized by cellular activity but no growth?
Lag phase
What happens to the cells in the lag phase?
Cells increase in size but there is no cellular division