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Microbiology2
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95
Microbiology
Undergraduate 3
10/19/2009

Additional Microbiology Flashcards

 


 

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Term
Macrophages
Definition
-antigen presenting cell-fixed in tissue-present antigen to helper T cells via MHC2
Term
Dendrite Cells
Definition
-antigen presenting cells-best at presentation to naive T cells-present antigen via MHC2-transport antigen to lymph nodes
Term
B Lymphocytes
Definition
-may serve as antigen presenting cells-recognize free antigens via antigen receptors on surface-differentiate into plasma cells
Term
T lymphocytes
Definition
-helper T cells
-TH1 cells
-TH2 cells
-Cytotoxic T cells
Term
helper T cells
Definition
-helper T cells:express CD4 on surface,bear specific antigen receptors, recognize antigens presented via MHC2,secrete cytokines to regulate immune function
Term
TH1 cells
Definition
pro inflammatory
Term
TH2 cells
Definition
humeral response(antibody response)
Term
cytotoxic T cells
Definition
-express CD8 on surface
-bear specific antigen receptors(t cell receptors)
-target and destroy injected or cancerous cells
-secrete degradative chemicals:perferins, granzymes
Term
human leukocyte antigens
Definition
-discovered during transplantation in mice
-transmembrane proteins important for: allowing immune cells to recognize self and presenting foreign antigens to T cells
-highly polymorphic (only identical twins have exact same)
-located on chromosome 6
Term
MHC1
Definition
-synthesized in ER-viruse protein replicating in cell are degraded into peptides, peptides shuttled into ER-peptines loaded into MHC1 and transported to surface
-interact with cytotoxic t cells
Term
MHC2
Definition
-synthesized in ER-APC's phagocytose antigen-degrade antigens into phagosomes-phagosome and post-golgi vesicles fuse-degraded peptides loaded into MHC2 and transported to cell surface to interact with helper t cells
Term
artificially acquired active immunity
Definition
vaccines
Term
naturally-acquired active immunity
Definition
natural exposure to pathogen
Term
artificially-acquired passive immunity
Definition
anti-toxin, anti-venom
Term
naturally acquired active immunity
Definition
maternal antibody transferrance
Term
adaptive immunity
Definition
-peptides (MHC) are best antigens-polysaccharides are good antigens-a memory response to a specific antigen developes (secondary exposure)
Term
Humoral immunity
Definition
production of antibodies by B cells-cells mediated immunity-cytotoxic T cells activated to destroy infected cells CD8
Term
Humoral response
Definition
-billions of different B cells (antibodies attach to membrane, each cell binds to diff antigen)
-colonal selection (cells that bind to antigens replicate, differentiate to plasma, secrete antibodies)
Term
antibody structure
Definition
-5 isotopes of antibody(differ in heavy chain constant regions)-IgM:first antibody produced in immune response-IgG:primary circulating antibody in blood-IgD:on surface of mature B cell
-IgE:bound by mast cells and basophils-IgA:secreted across mucosa (Peyer's patch)
Term
Antibody Response
Definition
Primary exposure:antibodies appear in serum after several days (B cells bind with antigen create antibodies)-some B cells become memory cells
Secondary Exposure: antibodies appear in blood within hours
Term
How cytotoxic T cell is activated
Definition
-TH0 binds to MHC2 on antigen presenting cell-SIGNAL 1: T cell receptor binds to antigen,CD4 binds to MHC2
-SIGNAL 2:(constimulation)CD28 on T cell bind B7 on APC, cell is activated to TH1 or TH2
Term
Cell Mediated immune response
Definition
activated Tc binds to MHC1, T cell receptor binds antigen,CD8 binds MHC1, T cell secretes degradative chemicals(perforins-preforate membrane & granzymes-induce programmed cell death apoptosis)
Term
effector cell
Definition
does not need second signal
Term
STD
Definition
horizontal transmission; CAUSATATIVE BACTERIUM
-chlamydia trachomatis:most frequent
-neisseria gonorrheae:men get dysuria and pyuria
-treponema pallidum(syphilis):primary-chancre,secondary-disseminated rash,tertiary-inflammatory lesions:gummas, congenital:mother to baby
CAUSATATIVE BACTERIUM
Term
staphylococcus aureus
Definition
localized infections
-furuncles(boils)
-coagulase (clot former)
Term
Human Microflora
Definition
-humans colonized with many microbes
-normal flora=commensal org.
-change constantly and vary with types of tissue,condition:pH,moisture,microbes present
-can cause disease if reach abnormal location
Term
Human Microflora: Skin
Definition
difficult to colonize:dry, salty,acidic, protective oils
-billions microbes in moist areas
-mostly anaerobes
Term
Microflora:Nose, mouth
Definition
-Nasopharynx & oropharynx
-dangerous if enter bloodstream
-can form biofilm around teeth (plaque,gum disease, streptococcus)
Term
Microflora: Stomach
Definition
-very high acidity
-few microbes survive(helicobacter pylori)
-loss of acidity:achlorydira (malnourishment, allows pathogens to grow)
Term
microflora: Stomach
Definition
-contains vast majority of human microflora
-bacteria ferment ingested food
-provide nutrients, inhibit pathogens
Term
Human Genitourinary Microflora
Definition
-kidney and bladder are sterile
-urethra and vagina contain bacteria
-probiotic treatment
Term
risks, benefits of microflora
Definition
-makes vitamins
-digest food
-prevents colonization by pathogens
-makes immunomodulins
-opportunistic pathogens:surface breach allows bacterial entry
Term
innate immunity
Definition
-barriers to infection
-nonspecific reaction to destroy invaders
Term
adaptive immunity
Definition
-reaction to specific antigens
-body reacts to antigens when exposed (retains memory of those antigens)
Term
Neutraphils
Definition
phagocytic cells- 60/70% of WBC
Term
manocytes
Definition
phagocytic cells
-5% WBC
-in tissues differentiate into macrophages and dendritic cells
Term
Basophils and Eosinophils
Definition
-leukocytes
-release toxins to posion microbes
-inhance inflammation
Term
lymphocytes
Definition
-T cells:modulate specific immune responses
-B cells:produce antibodies to bind antigens
Term
innate host defense
Definition
-skin: keratin, oil, cells that phagocytose microbes,dead skin cells, washing
-mucous:trap/destroy pathogens, mucous layers slough off
-cillia:removes microbes from lungs
-toll like receptor proteins on tissues (gut-m cells, skin-langerhans cells)
Term
chemical barriers to infection
Definition
-acidic pH-high salt content-lysozyme-bile,antimicrobial peptides
Term
accute inflammatory response
Definition
-infection releases microbes to tissue
-macrophages phgocytize bacteria-capillary cells express selectins(slows macrophage movement)-macrophages/neutrophils:squeeze between capillary cells,leave capillary and attack bacteria
-damaged tissue secretes bradykinin, mast cells degranulate(release histamine, stimulate blood vessels to open further), prostaglandin stimulates nerve cells(signal itching, pain)
Term
Phagocytosis
Definition
-phagocytes must avoid attacking host cells(CD47 prevents attack),phagocyte toll like receptors bind bacterin and bind opsonized bacteria(cells coated with antibodies)
-phagocytes kill, digest engulfed bacteria with oxidative burst (produce peptide to kill bacteria)
Term
innate defense by interferon
Definition
-interferons produce d by infected host cells(infected with viral/bacterial path. secrete interferon proteins)
-nearby cells respond to interferons
-type 1:IFN arms recipient cells to resist virus(inhibit protein synthesis)
-type 2:IFN modulates adaptive immune function(nearby immune cells become more sensitive)
Term
natural killer cells
Definition
-destroy injected/cancerous cells
-healthy cells make surface MHC1 protein(infected cells stop making MHC1)
-antibodies bind viral proteins on surface-NKC kill antibody bound or MHC1 less cells(secretes perforin protein into target cell(
Term
complement
Definition
-series of 20 serum proteins
-activated by Ag-Ad complexes(classical pathway)
-cell wall(polysacch,alt pathway)
-mannose or other sugar on bact. cell wall(lactin pathway)
Term
Functions of Complement
Definition
-lyses cell membranes
-opsonization(coats cell wall)
-enhanced inflammation(mast cell and basophil degranulation)
Term
Fever
Definition
-pyrogens induce temperature rise(exogenous pyrogens (LPS))
-endogenous pyrogens (interferons,TNF,IL-6,IL-1)
-signal brain to raise temp
-high fever stresses invading microbes
(non optimal growth temp and reduces iron availability)
Term
Bacteria vs. eukaryotic genes
Definition
-replication is same
-E. genes are much larger
Term
DNA
Definition
-linked chain of sugar and phosphate(covalent linkage)
-5` to 3`(add to 3`) and need available OH group to continue replication
Term
replication
Definition
-semiconservative(each next generation has one old and one new)
Term
bacteria nucleoid
Definition
condensed bacterial DNA. (30-50 loops of DNA)
Term
super coiling of nucleoid
Definition
circular DNA(has no free end;break in the loop will cause DNA to be relaxed)
Term
super coiling stress
Definition
constraining the supercoils involves wrapping the DNA around proteins in the cell
Term
topoisomerase
Definition
binds to DNA breaking one or both strands and passes the DNA strands through the break before resealing it. the enzyme holds the cut ends of the DNA so it doesnt rotate
Term
topoisomerase type 1
Definition
cuts one strand and passes the other strand through the break before resealing the cut-changes DNA one supercoil at a time
Term
topoisomerase type 2
Definition
cuts both strands and passes them from somewhere else in the DNA or even another DNA through the break before resealing it. -changes 2 supercoils at a time
Term
gyrase
Definition
a type 2 toposiomerase that adds negative supercoils (allows DNA strand to unwind)
Term
primosome
Definition
structure of protein that initiate replication at the origin
Term
DNA helicase
Definition
unwinds the helical DNA at replication forks (melts DNA) (recruits primase)
Term
Primase
Definition
lays down the primers that are necessary for DNA polymerase activity. the primers are composed of RNA
Term
DAN polymerase 3
Definition
does most of the replication using 5`-3` polymerase activity. uses clamp to bind to strand
Term
DNA polymerase 1
Definition
removes primers and fills in the gaps during replication
Term
RNASE H
Definition
removes RNA strands of a DNA
Term
DNA ligase
Definition
seals the nicks by linking3` hydroxyl groups with adjacent 5` phosphate groups. forms new phosphodiaster bond
Term
single stranded DNA binding protein
Definition
binds single stranded DNA at replication fork and blocks potential hybridization
Term
where does replication begin?
Definition
OriC
Term
Plasmids
Definition
-extra chromosomal pieces of DNA
-1.low copy number plasmids, segragation similar to chromosome
-2. high copy number plasmids,divide continuously and segregate randomly=
Term
plasmid replication
Definition
-similar to chromosomal replication
-"rolling cirlce" replication with no lagging strand
Term
plasmid genes
Definition
-advantageous under special conditions:antibiotic resistance genes, resistance to toxic metals, metabolize rare food sources, virulence genes to allow pathogenesis
Term
restriction enzymes
Definition
-cut DNA at specific sites
-normally protect bacteria from viral DNA
Term
PCR
Definition
-uses short oligonucleotid
-primers bind complementary sites
-requires primer
Term
sanger method
Definition
-determines sequence of up to 1000 bases
Term
Initiation
Definition
bind polmerazing machine, first monomer to template(DNA polymerase, RNA polymerase, ribosome)
Term
Elongation
Definition
read template, add next monomer(DNA, RNA,Protein)
Term
Termination
Definition
-release machine and completed product
Term
RNA polymerase
Definition
-4 proteins in one complex
-binds to DNA at sigma factor(promoter)(release of factor initiates reaction), reads sequence
-does not require a 3` hydroxyl group for initiation (sigma 70:guides to most genes, sigma 32:active when cell is stressed by heat;heat shock response, sigma 32:active when cell is stressed by heat)
Term
Transcription initiation
Definition
-sigma factor binds core RNA polymerase which binds to promoter
-polymerase unwinds DNA at promoter
Term
Transcription Elongation
Definition
-core polymerase adds RNA to 3` end
-mRNA is complementary to template and identical to non-template
Term
Transcription termination
Definition
-Rho independent termination:series of U residues downstream pause site
-does nto require another protein to end transcription based on DNA sequence and structure of RNA
Term
Translation of RNA to protein
Definition
-64 codons
-Initiation: Initiation factor bind ribosome to 1st codon(AUG:begin)
-Elongation:movement of ribosome along mRNA(tRNA carry a.a. to A site),Ribosomes move forward 1 codon at a time shifting the location then leave through E site.
-Termination:releasing factors undock ribosome from mRNA, release factors recognize stop codons
Term
Shine Dalgarno
Definition
-place where ribosome initially attaches to RNA
Term
Gene transfer
Definition
-transformation:direct uptake of DNA from medium
-conjugation:bacterial sex, use of pilus
-transduction:viruses inject DNA into cell
Term
recombination
Definition
-entering DNA replaces chromosomal DNA(if sequence is overall very similar)
-used to repair damaged DNA
Term
Mutation
Definition
-point mutation:change in one base pair
-nonsense point:change codon to stop
-frameshift:one or more base pairs is inserted or deleted
-Mutagens cause mutations: electromagnetic radiation, chemicals, spontaneous tautomers during replication
Term
DNA Repair
Definition
-Mismatch Repair:mispaired base cut out of strand
-Thymidine dimers:induced by UV
-Damaged bases:excised by specific enzymes
-Recombinational repair:occurs just after strand has replicated, undamages strand is copied and replaces damaged one
-SOS repair:extensive DNA damage inactivates LexA, activation of many repair genes, rapid polmerization of DNA
Term
Mobile genetic elements
Definition
-chromosomal sequence is not fixed
-retrotransposon inserts into chromosome(found in all species)
-can jump from one site to another
-can copy itself to a new site
Term
horizontal gene transfer
Definition
-movement of genes between cells(other than through cell division)
-transformation, conjugation, transduction
-transposons carry genes into chromosome
-plasmids carry genes between cells
-spreads useful genes among bacteria
Term
pathogenesis
Definition
-process by which microbes cause disease in a host
Term
primary pathogens
Definition
-"frank pathogens":are disease causing microbes possessing the means to breach the defenses of a healthy host
-
Term
opportunistic pathogens
Definition
cause disease in a compromised host
Term
pathogenicity
Definition
an organisms ability to cause disease
Term
virulence
Definition
measure of the degree of severity of disease
Term
infection cycle
Definition
the route an organism takes to spread
Term
fomite
Definition
inanimate object through which pathogens can be transferred
Term
vector
Definition
insects (mosquitos) horizontal transmission
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