I - Generalities Flashcards
Cells: DNA within a nuclear membrane
Eukaryotes
Cells: Uses mitotic division
Eukaryotes
Cells: DNA associated with histones
Eukaryotes
Cells: Has more than one chromosome
Eukaryotes
Cells: Has membrane-bound organelles
Eukaryotes
Eukaryotes: Ribosomes
40s + 60s = 80s
Cells: DNA within a nucleiod
Prokaryotes
Cells: Uses binary fission
Prokaryotes
Cells: Has only one chromosome
Prokaryotes
Prokaryotes: Ribosomes
30s + 50s = 70s
Cell Walls: Plants & Algae
cellulose
Cell Walls: Fungi
chitin
Cell Walls: Diatoms
silica
Cell Walls: Prokaryotes
peptidoglycan
Cell Walls: Archaea
pseudopeptidoglycan
Cell Walls: Protozoa & Animals
none
An ancestral eukaryotic cell is thought to have engulfed the bacterial ancestor of
mitochondria
An early eukaryotic cell, already possessing mitochondria, engulfed a photosynthetic bacterium and retained it in symbiosis resulting in
chloroplasts
Microorganisms: Has cells
bacteria, fungi, protozoa & helminths
Microorganisms: 0.02-0.2 μm
viruses
Microorganisms: 1-5 μm
bacteria
Microorganisms: 3-10 μm
fungi (yeasts)
Microorganisms: 15-25 μm
protozoa & helminths (trophozoites)
Microorganisms: Has either DNA or RNA
viruses
Microorganisms: Has both DNA & RNA
bacteria, fungi, protozoa & helminths
Microorganisms: Has no nucleus
viruses
Microorganisms: Has prokaryotic nucleoid
bacteria
Microorganisms: Has eukaryotic nucleus
fungi, protozoa & helminths
Microorganisms: Has no ribosomes
viruses
Microorganisms: Has 70s ribosomes
bacteria
Microorganisms: Has 80s ribosomes
fungi, protozoa & helminths
Microorganisms: Doesn’t have mitochondria
viruses, bacteria
Microorganisms: Has mitochondria
fungi, protozoa & helminths
Microorganisms: Has a protein capsid and lipoprotein envelope
viruses
Microorganisms: Has a rigid wall with peptidoglycans
bacteria
Microorganisms: Has a rigid wall with chitin
fungi
Microorganisms: Has a flexible membrane
protozoa & helminths
Microorganisms: Motile
some bacteria, most protozoa & helminths
Microorganisms: Replicates via Binary Fission
bacteria
Microorganisms: Replicates via Budding or Mitosis
fungi
Microorganisms: Replicates via Mitosis alone
protozoa & helminths
Obligate intracellular but acellular parasites of plants, naked RNA, no human diseases
viroids
Mobile genetic elements
Transposons
DNA pieces that move readily from one site to another either within or between the DNA of bacteria, plasmids and bacteriophages
“jumping genes” (transposons)
DNA replication followed by insertion of a new copy into another site
Replicative Transposition
DNA is excised from the site without replicating and then inserts into the new site
Direct Transposition
Prions: Normal form of protein encoded by the host’s chromosomal DNA, suceptible to protease and soluble in detergent
PrPc
Prions: Abnormal isoform of PrPc which modifies folding of normal prion-like proteins found in the body and has a high beta-sheet content
PrPres / PrPsc
Appearance of vacuolated neurons with loss of function and lack of immune response or inflammation
Spongiform Encephalopathies
Human Prion Diseases
Creuzfeld-Jakob (CJD, cortical), Kuru (“k/guria” - to shake, cerebellar), Variant CJD (vCJD), Gerstmann-Straussler-Scheinker (GSS), Fatal Familial Insomnia (FFI), Sporadic Fatal Insomnia (SFI)
Animal Prion Diseases
Scrapie (sheep/goat), Transmissible Mink Encephalopathy, Bovine Spongiform Encephalopathy (Mad Cow), Chronic Wasting Disease (mule/deer/elk)
Prions are _____ to standard viral disinfection procedures and have very long incubation periods as long as ____.
impervious, 30 years
Prions: Transmission
infected tissue, cuts in skin, transplantation of contaminated tissue (cornea), contaminated medical devices (brain electrodes), ingestion of infected tissue (cannibalism), inherited
Prions: Susceptible Populations
women and children of the Fore tribe in New Guinea, neurosurgeons, neurosurgery patients, transplant surgeons, transplant patients
Prions: Spectrum of Disease
loss of muscle control → shivering → myoclonic jerks and tremors → loss of coordination → rapidly progressive dementia → death
Prions: Treatment
none
Prions: Prevention
cessation of ritual cannibalism, elimination of animal products from livestock feed, disinfection of neurosurgical tools (5% hypochlorite, Na hydroxide, autoclaved at 15psi for 1 hour)
Bacteria: Spheres
cocci
Bacteria: Rods
bacilli
Bacteria: Spirals
spirochetes
Cocci: Pairs
diplococci
Cocci: Chains
streptococci
Cocci: Clusters
staphylococci
Smallest Bacteria
Mycoplasma
Largest Bacteria
Thiomargarita namibiensis
Largest Medically Relevant Bacteria
Borrelia burgdorferi
All bacteria have a cell wall composed of peptidoglycan except
Mycoplasma
sugar + peptide side-chains crosslinked by transpeptidase
peptidoglycan
Kill bacteria by cleaving the glycan backbone (β 1→4 linkage between GlcNAc and MurNAc) of the peptidoglycan
lysozymes
Facilitate the passage of small, hydrophilic molecules into the cell
porin proteins
Have thicker and multilayered peptidoglycan and teichoic acid
Gram (+)
Have thinner and single-layered peptidoglycan, lipopolysaccaride and periplasmic space
Gram (-)
The outer membrane of gram (-) bacteria contains _____ which consists of _____ and _____.
endotoxin (lipopolysaccharide), lipid A, O antigen
Only gram (+) bacteria with endotoxin
Listeria monocytogenes
Steps in Gram Staining
primary stain (crystal Violet) → mordant (Iodine) → decolorizing agent (Acetone) → counterstain (Safranin)
Bacteria not seen in Gram Stain
Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella, Chlamydia
Essential Components of Bacteria: Lipoprotein bilayer without sterols
cytoplasmic membrane
Essential Components of Bacteria: Site of oxidative and transport enzymes
cytoplasmic membrane
Essential Components of Bacteria: RNA and protein in 50s and 30s subunits
ribosomes
Essential Components of Bacteria: Protein synthesis
ribosomes
Essential Components of Bacteria: DNA, genetic material
nucleoid
Essential Components of Bacteria: Invagination of plasma membrane
mesosome
Essential Components of Bacteria: Participates in cell division and secretion
mesosome
Essential Components of Bacteria: Space between the plasma membrane and outer membrane
periplasm
Essential Components of Bacteria: Contains many hydrolytic enzymes including β-lactamases
periplasm
Non-Essential Components of Bacteria: Polysaccharide, protects against phagocytosis
capsule
Non-Essential Components of Bacteria: Glycoprotein, attachment, conjugation
pilus, fimbria
Non-Essential Components of Bacteria: Polysaccharide, mediates adherence to surfaces, biofilm
glycocalyx
Non-Essential Components of Bacteria: Protein, motility, H antigen (flagellin protein)
flagellum
1 Flagellum
Monotrichous
2 Flagella
Amphitrichous
Tuft of Flagella
Lophotrichous
Side Flagella
Peritrichous
Non-Essential Components of Bacteria: Keratin-like coat, dipicolinic acid, resistance to heat and chemicals
spore
Non-Essential Components of Bacteria: DNA, genes for antibiotic resistance and toxins
plasmid
Non-Essential Components of Bacteria: Glycogen, lipids, polyphosphates, site of nutrients in cytoplasm
granule
All bacterial capsules are composed of polysaccharide except
Bacillus anthracis (polypeptide of D-glutamate)
The capsule of Bacillus anthracis is composed of
polypeptide of D-glutamate
Formed by gram (+) rods especially Bacillus and Clostridium
spore
Extrachromosomal, double-stranded, circular DNA capable of replicating independently of the bacterial chromosome, can sometimes be integrated into the bacterial chromosome
plasmids
Plasmids: From cell to cell by conjugation, large, contain about a dozen genes for synthesis of the sex pilus and for the enzymes required for transfer
transmissible plasmids
Plasmids: Small, do not contain the transfer genes, frequently present in many (10-60) copies per cell
non-transmissible plasmids
Bacterial Growth Curve: Cells are depleted of metabolites as the result of unfavorable conditions, adaptation to new environment, nutrients are incorporated, vigorous metabolic activity but do not divide (zero growth rate)
Phase 1: Lag Phase
Bacterial Growth Curve: Rapid cell division occurs, β-lactam antibiotics act during this phase (constant growth rate), continues until either one or more nutrients in the medium become exhausted or toxic metabolites accumulate and inhibit growth
Phase 2: Log or Exponential Phase
Bacterial Growth Curve: Exhaustion of nutrients or the accumulation of toxic products cause growth to cease completely (zero growth rate), spores are formed
Phase 3: Maximum Stationary Phase
Bacterial Growth Curve: Most of the cells die because nutrients have been exhausted (negative growth rate)
Phase 4: Decline or Death Phase
Oxygen metabolism generates toxic products such as
superoxide, hydrogen peroxide
Enzymes needed to survive in aerobic environments
superoxide dismutase, peroxidase, catalase
Aerobic Bactera: Completely dependent on oxygen for ATP-generation
Obligate Aerobes
Aerobic Bactera: Uses fermentation but can tolerate low amounts of oxygen (< 0.2 atm) because they have SOD
Microaerophiles
Anaerobic Bactera: Utilize oxygen if it is present but can use fermentation in its absence
Facultative Anaerobes
Anaerobic Bactera: Exclusively anaerobic but insensitive to the presence of oxygen
Aerotolerant Anaerobes
Anaerobic Bactera: Cannot grow in the presence of oxygen because they lack 3 important enzymes
Obligate Anaerobes
Obligate Aerobes
Nocardia, Neisseria, Pseudomonas, Mycobacteria, Mycoplasma pneumoniae, Bordatella, Brucella, Bacillus cereus, Legionella, Leptospira
Obligate Anaerobes
Actinomyces, Bacteroides, Clostridium
Microaerophiles
Borrelia, Treponema, Campylobacter, Helicobacter, Streptococcus
Facultative Anaerobes
Bacillus anthracis, Escherichia coli, Listeria, Corynebacterium, Mycoplasma (non-pneumoniae), Staphylococcus
Aerotolerant Anaerobes
Propionibacterium, Lactobacillus vaginalis
Bacterial genetic material consists of _____ located in the _____.
single chromosome of circular DNA, nucleoid
Bacteria are _____ while eukaryotic cells are _____.
bacteria - haploid, eukaryotes - diploid
Bacterial DNA is _____ while human DNA is _____.
bacteria - circular, humans - linear
Extrachromosomal pieces of DNA encoding both exotoxins and enzymes
plasmids
DNA that moves readily from one site on the bacterial chromosome to another or from the bacterial chromosome to a plasmid
transposons
Movement of genes from inactive storage sites into active sites of transcription
Programmed Rearrangements
Prokaryote DNA transfer from one bacterium to another
Conjugation
Prokaryote DNA transfer by a virus from one cell to another
Transduction
Purified prokaryote/eukaryote DNA taken up by a cell
Transfromation
Cycles of Transduction
Lytic, Lysogenic
Occurs when normal flora occupy receptor sites preventing pathogens from binding
Colonization Resistance
Normal Flora: Skin
Staphylococcus epidermidis
Normal Flora: Nose
Staphylococcus aureus (anterior nares)
Normal Flora: Mouth
Viridans Streptococci
Normal Flora: Dental Plaque
Streptococcus mutans
Normal Flora: Colon
Bacteroides, Escherichia coli
Normal Flora: Vagina
Lactobacillus vaginalis (Döderlein), Escherichia coli, Streptococcus agalactiae
