Topic 1 - 1 Flashcards
What are the 3 classes of microbes?
Prokaryotes
Small eukaryotes
Viruses
What is microbiota?
Microoranisms that live in or on a normal human body, without causing disease.
What is another name for microbiota?
Normal flora
What is mutualism?
A symbiotic (living together) relationship that benefits both species (in body, benefit humans and microbiota)
What is commensalism?
A symbiotic (living together) relationship that benefits only one species, but not at expense of the other species (in body, microbiota benefit without harming human)
Four outcomes of microoranisms encounters?
1) Pass through body harmlessly
2) Colonize the body and become part of the microbiata
3) Establish an infection in the body
4) Establish an infection in the body AND cause disease
Define Infection
Refers to the invasion or colonization of the body by pathogenic (disease-causing) microorganisms. Does NOT always result in damage to the body.
Define disease
Injury to the body that impairs function
What influences the relationship between the human body and a microorganism?
1) pathogenicity (ability to cause disease)
2) the resistance or susceptibility of the host (ex. defence mechanisms of the host, such as innate and adaptive immune responses)
Bacterial structure? (i.e. structures of a prokaryote)
Has cytoplasm, nucleoid, cytoplasmic membrane (phosphoypid bilayer), ribosome
Lacks membrane-bound organelles
Some have pili, flagella, capsule, cell wall
Size difference between eukaryotes and prokaryotes?
~10-100 times larger (10-100 um vs. 0.1 um)
Shapes of bacterial cells? (hint- 4 types)
Coccus (spherical)
rod-shapped (bacilus)
Spiral rods
vibroid (curved rods)
Bacterial Cell wall - what is it made of?
Peptidoglycan (PG), which is a covalently bonded glycan backbone w/ peptides
Cell envelope
Cell wall + cytoplasmic membrane
Flagella
Gives bacteria swimming motility (ability to move independently)
Pili
Hair-like structures, used for adherence
Capsules
Mediated attachment to surface & confer protection against predators (ex. phagocytes)
Staining difference btwn Gram positive and Gram negative?
Purple for Positive
Pink or Red for Negative
Structural differences btwn Gram + and Gram -?
Gram +: Has a thick PG layer, with glycopolymers teichoic acids (TA) and lipo-teichoic acids (LTA)
Gram -: Uses another outer membrane made with lipo-polysaccharide (LPS) & a thin layer of PG.
What do teichoic acids and lipo-teichoioc acids do?
TA and LTA are important in bacterial physiology (ex. shape determination and regulation of cell division)
Differences between eukaryotes and bacterial DNA structure and replication?
Circular vs. linear chromosomes One vs. many choromosomes One vs many orgins of replications Plasmids Operons vs. multiple promoters Nucleus vs. nucleoid (memberane vs. no membrane) Different DNA pols (ex. DNA gyrase) Faster vs slower (eukaryote) DNA replication
(bacteria left, Eukaryote right)
Differences between eukaryotes and bacterial RNA structure and replication?
mRNA lacks modifications shorter lifespan Different RNApol makeup Use sigma factors vs. GTF Instantaneous vs delayed translation
(bacteria left, Eukaryote right)
Differences between eukaryotes and bacterial ribosomes?
70S vs 80S
50S &a 30 S subunits vs. 60S and 40S
30S 16S rRNA vs 40S 18S rRNA (this confers selectivity for antibiotics btw)
(bacteria left, Eukaryote right)
Strain
A population of bacteria descended from a single cell
What is the timeline of any disease?
Encounter - agent meets host
Entry - agent enters host
Spread - agent spreads from site of entry
Multiplication - agent multiplies in host
Damage - agent and/or host response cause tissue damage
Outcome - agent or host wins out, or learn to coexist
What is a bacteria?
Single-celled prokaryotic organism
What does it mean to colonize?
To become part of normal flora/microbiota
What is an infection?
Pathogen colonizing a host body (can lead to disease, but NOT necessarily always)
What is disease?
Overt SYMPTOMS caused by infection
What is a pathogen?
Bacterium capable of harming a normal host
What is an opportunistic pathogen?
Pathogens that harms a compromised host
What influences hosts susceptibility?
Underlying disease or infection altering immune system (ex. AIDS< chemotherapy)
Age (Young - underdeveloped immune system, old - vice versa)
Host genetics and resistance genes
Human microbiome
