Microbio Final CUMULATIVE INFO + unique bacterial info

What is the difference between the horizontal gene transfer mechanisms of transduction, transformation and conjugation?

transduction: use of bacteriophage

transformation: uptake of free DNA

conjugation: direct cell-cell contact (use of sex pillus)

What human activities have led to an increase in antibiotic resistance?

medical misuse (taking antibiotics for a virus), agricultural practices (giving to animals as preventative measures), human behaviors (unprotected sex, not finishing full dose of antibiotics)

What are the main targets (modes of action) for antibiotics against bacteria and what mechanisms do resistance bacteria use to protect themselves?

main targets: peptidoglycan, DNA gyrase, RNA polymerase, ribosome, replication, cytoplasmic membrane, metabolism

bacterial mechanisms: natural resistance, pump out, chemically alter, modify targets (mutations)

What are the three branches of the molecular-based tree of life and a distinguishing characteristic of each?

bacteria: peptidoglycan

archaea: ether linked lipids (membrane structure)

eukarya: organelles

How do you determine how closely two organisms are related to one another from a 16S rRNA-based phylogenetic tree?

look at which organisms are closer together/branch more closely off of each other

Structurally, what are key differences between the cell envelopes (membranes and cell walls) of Archaea vs. Gram-positive bacteria vs. Gram-negative bacteria?

gram-negative bacteria: ester-linked cytoplasmic membrane w/ fatty acids, thin peptidoglycan cell wall (NAG and NAM), LPS outer membrane with direct crosslinks

gram-positive bacteria: ester-linked cytoplasmic membrane w/ fatty acids, thick peptidoglycan cell wall with glycine interbridges, no outer membrane

archaea: ether-linked cytoplasmic membrane with isoprenes (mono or bilayer), pseudopeptidoglycan cell wall (NAG or NAT) or s-layer, no outer membrane

What the difference between a lytic and lysogenic bacteriophage?

lytic: kill/lyse host

lysogenic: phage inserts itself into host genome

What are the unique enzymes needed to replicate RNA virus genomes that are NOT found in host cells?

reverse transcriptase (RNA → DNA) and RNA replicase (RNA → RNA)

What structures are found in a virus?

genome (containing ds or ssDNA), capsid (protein coat), some have an envelope

How is fermentation different than respiration?

fermentation does not require an ETC, respiration does require an ETC

When do aerobic respiration and anaerobic respiration occur?

aerobic respiration will occur in the presence of O2, anaerobic respiration will occur in the absence of O2, both will require an ETC (depends on whether O2 will be the final electron acceptor)

Does substrate level phosphorylation occur during fermentation and/or respiration? Does oxidative phosphorylation (via ATP synthase) occur during fermentation and/or respiration?

substrate level phosphorylation will occur in ALL living cells (ATP yielded during glycolysis or TCA), oxidative phosphorylation will occur only during respiration (dependent on PMF and ATP synthase)

What happens during the process of binary fission growth?

one cell splits itself into two identical daughter cells

What are the stages of bacterial growth in batch culture?

log, exponential, stationary, death (semi log plot)

What molecule is responsible for the process of DNA replication?

DNA polymerase

What molecule is responsible for the process of transcription?

RNA polymerase

What molecule is responsible for the process of translation? (i.e., the Central Dogma)

mRNA

What happens to gene expression when a transposon “hops” into a gene?

typically will render the gene nonfunctional

How do repressor and activator proteins work to regulate gene expression in bacteria?

repressor proteins bind downstream of the promoter which will block the RNA polymerase or block it

activator proteins will bind upstream of the promoter which will help RNA polymerase bind

What is a two-component regulatory system?

contains the sensor histidine kinase + response regulator

sensor histidine kinase will phosphorylate itself and then response regulator which will be an activator or repressor

What are benefits provided to humans from their microbiome?

compete with pathogens, produce compounds to inhibit pathogens, synthesize vitamins, train immune system

What sites in the human body do or do NOT normally have a microbiome associated with them in healthy individuals?

normally in every exposed external and internal surface (GI tract)- should NOT be in nervous system, blood, liver, heart, or kidneys

How do the innate and adaptive immune responses differ from one another; what are their defining characteristics?

innate: rapid, nonspecific, no memory, uses phagocytes (macrophages)

adaptive: delayed response, highly specific (due to somatic recombination), MEMORY, uses T cells (cytotoxic and helper) and B cells (plasma and memory B cells- basis for vaccines)

How do vaccines work to protect us against exposure to a pathogen?

injection of a killed, attenuated, or part of organism (NEVER LIVE SAMPLE) to train adaptive immune response

Norovirus

-VIRUS

-#1 cause of FOOD INFECTIONS

-low infectious dose

-spread through surface contact/aerosols

Salmonella typhimurium

-#2 cause of FOOD INFECTIONS from raw/undercooked food
-intracellular pathogen

-10^5-10^8 infectrious dose

-self-limiting 2-5 days generally but can become chronic

Clostridium perfringens

-#1 cause of FOOD POISONING

-10^8 cells infectious dose

-GI form spores and enterotoxin

-feel symptoms within 7-15 hours

Campylobacter

-FOOD INFECTION

-raw/undercooked poultry

-10^4 infectious dose

-7-10 days of disease

Staphylococcus aureus

-FOOD POISONING

-enterotoxin forms in bacteria growing in food

-heat stable toxin

-known as a superantigen that causes strong inflammatory response 1-6 hours after consumption

Clostridium botulinum in adults

-FOOD POISONING

-strong heat labile neurotoxin

Clostridium botulinum in infants

-FOOD INFECTION

-weak microbiome which cannot fight off toxin which will grow in baby

EHEC

-hemorrhagic

-kidney failure, bloody stool

-can cause hospitalization

ETEC

-traveler’s diarrhea

EPEC

-pediatric

EIEC

-intracellular

What does e. coli cause? food infection or food poisoning?

FOOD INFECTION

Yersinia enterocolitica

enteric fever

Bacillus cereus

rice

Shigella

shiga toxin

Vibrios

aquatic microbio

Salmonella enterica typhi

-PATHOGEN

-typhoid fever

-bacterial infection

Vibrio cholerae

-PATHOGEN
-10^8-19^9 dose

-makes AB enterotoxin

-SEVERE diarrhea; try to stay hydrated

Giardia intestinalis

-PATHOGEN
-produces chlorine-resistant cysts, requires filtration, causes diarrhea

-carried in beavers

Cryptosporidium parvum

-PATHOGEN
-produces chlorine-resistant cysts, requires filtration, causes diarrhea

-carried in cattle

-common source of recreational water diseases

Legionella pneumonia

-BACTERIAL INFECTION

-emerging pathogen from built environment

-spread through aerosols

-intracellular respiratory pathogen

What are the viral mosquito-borne diseases?

yellow fever, dengue fever, zika, west nile

What are the parasitic mosquito-borne diseases?

malaria (caused by plasmodium)

-48 hour RBC cycle