MCB 100 Exam 2

“universal tree of life” is based on sequence comparison of

16s rRNA genes

form fruiting bodies and sporulate under starvation conditions, stain Gram -

myxobacteria

spore forming Gram + bacteria, often mistaken for fungi

actinomycetes

bacteria (Gram +) use this to protect against environmental extremes

endospores

free-swimming, swarming planktonic stage, attachment and aggregation into biofilm/colony (fruiting body) stage, and sometimes a spore/endospore stage

biofilms

attach to a surface and to each other through a slimy layer/matrix comprised of an extracellular polysaccharide coating to hold together

biofilms

particularly resistant to antibiotics and contribute to a number of medical problems

biofilms

light microscope, Schaeffer-fulton stain

sporulation

flourescence microscope, crystal violet stain and filtration

biofilms

species found in marine environments attached as biofilms to “marine snow”

vibrio

movement (not adhesions) involves flagellar, twitching, or gliding motility

motility

protein for flagella that is a long helical structure made of polymerized subunits

flagellin

vertebrate immune system takes advantage of similarity by having this pattern recognition receptor evolved binding and sense flagellin

TLR-5

Counter-clockwise (default): aligns flagella into single rotating helical bundle, bacteria swim straight
clockwise: breaks flagella bundle apart, causing bacterium to tumble in place

chemotaxis in E.coli: “Random Walk Model”

movement involved of the bacterium in response to stimuli

taxis

severe human and animal disease caused by Gram + pathogen Listeria monocytogenes and Listeria ivanov

Listeria

food-borne pathogen that occurs most often in immunocompromised individuals that can transit to placenta

Listeria

a psychrophile that can readily grow at low temperatures

Listeria

important step for the colonization of a new environment or host

adhesion/attachment

attachment proteins that facilitate adhesions to surface, proteins, sugars, or other bacterial or eukaryotic cells

adhesins

have adhesins at their tips that mediate attachment to surfaces

pili (or fimbriae)

adherent bacteria generate two kinds of daughter cells

one stationary, the other mobile

Gram - adhesins

pili (or fimbriae)

Gram + adhesins

fibrillar adhesins

proteins embedded on surface of Gram - or +. Cloaer to surface and mediate tight-binding interaction of bacterium with the host cell

afimbrial adhesins

(attachment to a surface at a particular site) is an essential first step for bacterial to colonize

adherence

microbes that reside outside or on the surface of host cells or in the medium

extracellular pathogens

often produce toxins and other enzymes that help them fight the host immune system and survive

extracellular pathogens

microbes that can enter and reside inside host cells

intracellular pathogen

can evade host cell immune system and other mechanisms from killing them

intracellular pathogens

extracellular pathogen that is a skin infection with normal microbiota

acne

Gram + that colonizes sebaceous glands and eats the oils in sebum, generate at low pH

P. acnes

found in pores which can produce blackheads or white heads

S. epidermidis

gastritis/ulcers/stomach cancer

Helicobacter pylori

Gram - that adapts to harsh environment of stomach by using flagella to penetrate mucus lining of stomach

Helicobacter pylori

cause life-threatening infections like toxic shock syndrome and sometimes “flesh-eatin” skin infections

S. aureus (MRSA)

many pathogens secrete enzymes that break down host macromolecules to release nutrients that the bacteria absorb or transport inside

nutrient acquisition

hydrolyze sygars/polysaccharides

glycosidases

cleave sialic acid residues from host glycolipids or glycoproteins

neuraminidases or sialidases

degrade polysaccharide hyalruonic acid

hyaluronidases

degrade proteins (collagenases, elastases act as “meat tenderizers”)

proteases

degrade DNA/RNA in pus that is released from damages host cell

nucleases

cleaves lipids in membrane which lyse host cells, releasing content

phospholipases

some pathogens produce and secrete toxins (e.g., pore-forming hemolysins) that disrupt host cells to release cytosolic contents (nutrients and iron)

toxins

Gram - that causes zoonotic disease brucellosis, results in spontaneous abortion in infected animals

Brucella abortus

B. abortus can grow rapidly in placenta due to high concentration of

erythritol

free iron is low due to binding and sequestration by lactoferrin, transferrin, ferritin, and heme

iron acquistion

many bacteria secrete ____ that chelate iron with very high affinity

siderophores

some bacteria have this on their surface to bind transferrin, lactoferrin, ferritin, hemin or hemoglobin

uptake receptors

uses Mn²⁺ instead of Fe²⁺

Lyme disease

severe human and animal disease caused by Gram - pathogen. food-borne that induces inflammatory diarrhea

Salmonellosis

pathogens that produce and/or secrete virulence factors that are hydrolytic or proteolytic enzymes

exoenzymes

most highly virulent bacterial pathogens produce metabolites, peptides and/or proteins that act on or inside host cells

toxins

modify host cell function to cause cytopathic effects

cytotoxic

kill host cells

cytolytic or cytoethal

bacterial membrane components that contain endotoxins or lipid-derived toxins

small molecule toxins

enterotoxins (toxic shock syndrome toxin), superantigens

small peptide toxins

exotoxins like pore-forming and A-B type protein toxins

large protein toxins

enzymes delivered into host cells by specialized bacterial secretion systems

toxic effector proteins

toxic membrane components (LPS, LTA, PG) from bacteria that are released into the medium when the bacteria are lysed

endotoxins

moiety of cell membrane component of Gram - bacteria has highly potent toxic effects

Lipid A

glycopeptide fragment of Gram - peptidoglycan (PG)

tracheal cytotoxin (TCT)

causative agent of highly contagious disease known as whooping cough, TCT is released from growing cells

bordetella pertussis

compounds, either secondary metabolites or bacterial components, made by bacteria that have toxic effects on host

small molecule toxins

polyketide-derived macrolides (lipid-like toxins)

mycolactones

an emerging human pathogen harbored by aquatic insects that is the causative agent of buruli ulcers

mucobacterium ulcerans

some pathogens such as Gram + staphylococcus aureus and streptococcus pyogenes produce peptide toxins that over-stimulate host inflammatory responses and result in toxic shock

superantigens

poke hole in host membranes to form transmembrane channels, resulting in irreversible osmotic swelling and lysis

pore-forming toxins — protein exotoxins

enzymes that degrade the host membrane by hydrolyzing membrane phospholipids, usually called phospholipases, hemolysins, or cytolysins

cytoytic toxins — protein exotoxins

contain an A part with toxic and B part that binds to receptors on surface of host cells

AB type toxins

diphtheria toxin

AB

botulinum neurotoxin

AB

cholera toxin and pertussis toxin

AB₅

anthrax toxin

A₃B₇

disease explained entirely by action of single secreted protein toxin

diphtheria

elongation factor 2 by A part blocks protein synthesis and kills the cell

ADP-ribosylation

from clostridium botulinum and tetanus neurotoxin (TeNT) from clostridium tetani are secreted single-chain AB type toxins that have A domains with zinc-dependent metalloprotease activity

botulinum neurotoxins

deliver toxic effectors/proteins (also nontoxic proteins) into the medium and on the surface

secretion systems

inner membrane components are shared with Gram + and Gram - bacteria

type I, II, V

deliver toxic effector proteins directly into adjacent cells

Gram - secretion systems

secretion types for Gram - bacteria only

type III, IV, and VI

effectors can be delivered to eukaryotes and prokaryotes

T6SS

type of secretion system that is mycobacteria only

type VII

bacteria that directly injects its toxin into hosts

salmonella enterica

prominent archaeal members are extremophiles:

thermophiles and halophiles

almost all archaea have this layer made of proteins or glycoproteins on outermost surface

S-layer

somewhat similar to bacteria and eukaryotes

function in formation of biofilms

adhere cells to one another and inanimate objects

glycocalyces

similarities and differences compared to bacteria

consist of basal body, hook, and filament

numerous differences with bacterial flagella — evolved from different protein

flagella

many archaea have this

some archaea make these structures called hami

function to attach archaea to surfaces

fimbriae and hami

some bacteria but all archaea and eukaryotes lack

peptidogylcan

membrane lipids are branched and cyclized

archaeal

this membrane uses ether-linked lipids

archaeal

this membrane used ester-linked lipids

bacterial

have 70S ribosomes, but different ribosomal proteins

archaeal and bacteria

lipids that are mechanically stronger, energetically more stable at high temps and high salt concentrations

archaea

largest group of archaea

methanogens

are obligate anaerobes

methanogens

convert carbon dioxide, hydrogen gas, and organic acids to methane gas

methanogens

eukaryotic photoautotrophs (energy and carbon from light and CO₂) that are mostly aquatic

algae

have chlorophylls a and b and carotene. also includes diatoms, water molds, a major source of oxygen supply

chrysophyta (golden, yellow-green algae)