Microbiology Flashcards
bacteria
single celled members of Eubacteria and Archaea prokaryotes most are decomposers some live naturally in the human body a few cause diseases some can live without oxygen some are photosynthetic and produce oxygen
prokaryotes
no nucleus or membrane bound organelles
have smaller ribosomes than eukaryotes
have a cell wall
bacteria are prokaryotes
eukaryotes
have a nucleus and membrane bound organelles, ribosomes, and some have a cell wall (plants and fungi)
protozoans, fungi, plants, and animals
bacterial cell wall
made up of peptidoglycan (gram + or gram -)
may have flagella, fimbrae, pilli, glycocalyx
internally-single chromosome (circular, free floating), ribosomes, some may have plasmids or endospores
gram +
thick layer of PG
gram -
thin layer of PG with an outer membrane of lipopolysaccharides
flagella
for movement
fimbrae
hairlike structures for attachment to surfaces
pilli
exchange ofDNA
glycocalyx
sugar containing layer
can protect the bacteria or attach it to surfaces
plasmids
small circular piece of DNA that replicates independently of the chromosome
endospore
tough survival structure
found in Bacillus and Clostridium
ribosome
slightly smaller than those of eukaryotes function different from ribosomes in eukaryotes
cocci
round
bacilli
rod-shaped
spirals
loose or tight spirals
Gram stain
positively charged stain
decolorizing with alcohol to remove stain from cells with thinner gram - walls
gram + =purple
gram - =safranin
eneric/coliform bacteria
E. coli, Salmonella, and Shigella
cause infections of GI tract and serve as indicators of pollution
only found in the gut or in feces
Mycobacterium
has outer layer of waxy lipid
causes TB and leprosy
Clostridium
gram + rod
causes tetanus, botulism, and gas gangrene
Borrelia
spirochete
causes Lyme disease transmitted by a tic
Treponema
spirochete
causes syphillis
protozoans
eukaryotic
single-celled
move using flagella, cilia, or amoeboid motion
cyst
tough survival stage in protozoans
stages that transmits disease
trophozoite
stage in protozoans
in this stage when not in cyst stage
malaria
caused by protozoans
complex life cycle and mainly affects RBCs in humans and digestive tract in mosquitos
amebiasis
protozoan disease of the intestine
caused by Giardia and Cryptosporidium
sleeping sickness
protozoan disease
goes from blood to brain
transmitted by the Tse Tse fly
toxoplasma
complex life cycle involving cats
fetus can be infected if a woman gets this disease during pregnancy
fungi
single and multi cellular
decomposers-absorb nutrients from dead material
reproduce by sexual or asexual spores
spores can be involved in the transmission of fungal diseases and are most common causes of respiratory allergies
molds
multicellular fungi
composed of strands of cells all joined into one
some have chitin in their cell wall
Penicillium and mushrooms
yeasts
single-celled fungus
can carry out fermentation
important for production of bread, wine, and beer
lichens
symbiotic relationship between a fungus and algae
algae provides food through photosynthesis, mold attaches to surface and absorbs nutrients
dermatophytes
fungi that cause diseases in the skin
break down keratin
ringworm-Epidermophyton and trichophyton
Candida
yeast
infects mouth, intestines, or vagina
often seen in immunosuppresed patients (HIV or chemo patients)
parasitic worms (helminths)
primitive flatworms and roundworms
lay large numbers of eggs
some form cysts inside of the tissues of their hosts which can then be involved in disease transmission
intestinal parasitic diseases
most common site for worms
Ascaris, hookworms, pinworms, and tapeworm
Trichinella
worm
acquired from eating under cooked or uncooked pork
leaves intestines and forms cysts in muscles
Schistosoma
roundworm hookworm
enter the body by drilling through skin
tapeworms
acquired by eating under cooked or uncooked beef, pork, or fish
viruses
smaller than all other organisms
simple structure- protein coat (capsid), nucleic acid/genome (DNA or RNA), some have an outer membrane (envelope)
not cells-no cell wall, cell membrane, nucleus, or organelles
not prokaryotes or eukaryotes
obligate intracellular paracites
must live inside of a host cell to help carry out normal cellular functions such as replication
replication of viruses
synthesis and assembly of subunits- many copies of the parts of the virus are made inside the host cell and then put together to make many viruses
stages of viral replication
attachment- host and tissue specific
penetration- virus enters host cell by endocytosis or fusion of the envelope
uncoating- genome released from inside the capsid
synthesis- host cell makes viral proteins and nucleic acid
maturation/assembly- viral subunits put together
release- virus exits host cell
latency
some viruses don’t complete replication but exist as DNA inserted into the host’s DNA
virus may reactivate and replicate at a later time
e.g. herpes, HIV, and chicken pox/shingles
viroids
atypical virus
made up only of small pieces of RNA with NO PROTEIN
prions
atypical virus
made only of protein with NO DNA or RNA
cause destruction of the brain
e.g. BSE (mad cow disease)
viral diseases-respiratory tract
influenza (changes its surface proteins often so it avoids the immune response and can infect you repeatedly) and the common cold
viral diseases-skin
chicken pox, shingles, measles, rubella, warts, herpes
viral diseases-digestive tract
hepatitis, mumps, gastroenteritis
viral diseases-nervous system
rabies, polio, encephalitis
can also cause mononucleosis, HIV, and viral fevers (e.g. yellow fever)
epidemiology
study of disease transmission
can be transmitted by contact, respiratory, enteric, environmental, or vectors
pathogens
disease causing microbes
zoonoses
pathogens that come from animals
nosocomial infections
hospital acquired infections
normal flora
the microbes that live in and on certain areas of the human body normally and are not harmful
they are beneficial
exotoxins
secreted by certain bacteria
endotoxins
part of the cell wall of gram - bacteria
physical methods of controlling microbes & infections
heat- denatures proteins (boiling, autoclaving)
ionizing radiation- create toxic free radicals inside cells (x-rays and gamma rays)
UV radiation- damages DNA
chemical methods of controlling microbes & infections
most chemicals denature proteins
e.g. alcohol, iodine, chlorine, and phenolics
hydrogen peroxide most effective against anaerobic bacteria
antibacterial drugs
inhibit PG synthesis and damage cell wall (e.g. penicillins, cephalosporins, and bacitracin) and are most effective against gram + bacteria and those that interfere with protein synthesis (e.g. tetracycline, erythromycin)
sulfa drugs- block DNA and RNA synthesis by mimicking enzyme substrates
antiviral drugs
resemble nucleotides and block DNA synthesis
e.g. acyclovir and AZT
antifungal drugs
target plasma membrane of fungi
e.g. polyenes and azoles
immunology
protection against disease
include the blood and certain organs
leukocytes (WBCs)
neutrophils, eosinophils, basophils, lymphocytes, and monocytes
neutrophils
most abundant type
phagocytic
protects mainly against bacteria
eosinophils
contain toxic granules
protect against parasites
basophils
contain granules full of histamine and other mediators that cause inflammation
lymphocytes
T & B cells involved in specific immunity
NK cells involved in nonspecific immunity
monocytes
can do phagocytosis or kill infected cells
leave the blood stream and become macrophages or dendritic cells
plasma
fluid portion of blood
contains antibodies and complement (which triggers inflammation)
lymph nodes
found in a network throughout the body
each protects a particular area or region of tissue
acts as a site for interaction between various cells of the immune system and foreign material (antigen)
thymus
where T cells mature
spleen
function similar to lymph notes except it protects the blood stream instead of tissues involved in removing old RBCs
bone marrow
site where all blood cells are made (with both WBCs and RBCs)
nonspecific defense barriers
first line of defense
skin, mucus lining of respiratory and GI tracts, and stomach acid
nonspecific defense mechanisms
second line of defense includes phagocytosis (ingestion and destruction of bacteria and other materials), inflammation (protects against infection and repairs damage), fever (inhibits viral and bacterial replication), and interferons (blocks viral replication
inflammation
key mechanism for tissue repair
increases in blood vessel diameter and permeability
increased blood flow to the inflamed area
deposit fluid in the inflamed area
trigger a migration of phagocytes out of the circulation to destroy any invading bacteria
specific defenses
third line of defense
involves recognition and memory
response is stronger when immune system is re-exposed to a particular material
antigens-substances that the specific response recognizes and reacts to
involves T-cells and B-cells
T-cells
carry out cell-mediated response
produce cytokines- signalling molecules
protect against viral, fungal, and parasitic infections
helper T-cells
CD4
activate other T cells, B cells, macrophages, and NK cells
suppressor T-cells
shut down other cells
cytotoxic T-cells
CD8
kill virus-infected or cancer cells by binding to them and exposing them to toxins and perforins
NK cells
kill virus-infected or cancer cells, but do so nonspecifically
B-cells
produce antibodies (immunoglobulins) that bind specifically to antigens protect against bacterial and viral infections
IgA
protects mucous membranes
respiratory and digestive tract
IgG
most common in serum
protects against toxins and can cross the placenta
IgD
on the surface of B cells
IgE
on the surface of mast cells and basophils and protects against parasitic infections
involved in allergies such as hay fever and food allergies
IgM
largest
mainly in the blood stream
self recognition
immune system recognizes things that belong in the body
only attacks those that don’t belong in the body
autoimmunity-immune system attacks itself
nonself recognition
immune system recognizes things that don’t belong in the body
attacks these
autoimmunity
type of immune disorder where the immune system attacks and damages some part of the body
e.g. rheumatoid arthritis, lupus erythematosus, Graves disease
hypersensitivity
type of immune disorder where the immune system responds to a harmless material and that reaction causes death or damage to some part of the body
e.g. hay fever, asthma, hives, food allergies, Rh disease, and contact dermatitis
immunodeficiency
type of immune disorder where some part of the immune system is missing or does not work
result is recurrent infections
can be genetic or caused by outside factors such as malnutrition or infection
