Generalities Flashcards
DNA within a nuclear membrane: Prokaryotes or Eukaryotes?
Eukaryotes
Mitotic division: Prokaryotes or Eukaryotes?
Eukaryotes
DNA associated with histones: Prokaryotes or Eukaryotes?
Eukaryotes
Chromosome number of Prokaryotes
One
Chromosome number of Eukaryotes
More than one
Membrane-bound organelles: Prokaryotes or Eukaryotes?
Eukaryotes
Size of Ribosome of Prokaryotes
30s 50s (70s)
Size of Ribosome of Eukaryotes
40s 60s (80s)
Cell wall containing Peptidoglycan: Prokaryotes or Eukaryotes?
Prokaryotes
Noncellular pathogens that can only reproduce when present within a living cell
Virus
Basic unit of life
Cell
Obligate intracellular but acellular parasites of plants with naked RNA; Do not cause human diseases
Viroids
Mobile genetic elements
Transposons
DNA pieces that move readily from 1 site to another either within or between the DNA of bacteria, plasmids and bacteriophages
Jumping genes
DNA replication followed by insertion of new copy into another site
Replicative Transposition
DNA is excised from the site without replicating and then inserted into the new site
Direct Transposition
Infectious proteinaceous agents with high beta-sheath content; Expressed in neurons
Prions
Susceptible to protease; Soluble in detergent
PrPc
Appearance of the vacuolated neurons with loss of function and lack of an immune response or inflammation; With prion proteins inside
Spongiform Encephalopathies
Approximate diameter: Viruses
0.02-0.2 um (under electron microscope only)
Approximate diameter: Bacteria
1-5 um
Approximate diameter: Fungi
3-10 um (yeasts)
Approximate diameter: Protozoa and Helminths
15-25 um (trophozoites)
Nucleic Acid: Viruses
Either DNA OR RNA
Nucleic Acid: Bacteria, Fungi, Protozoa, Helminths
Both DNA AND RNA
Type of Nucleus: Viruses
None
Type of Nucleus: Bacteria
Prokaryotic
Type of Nucleus: Fungi, Protozoa, Helminths
Eukaryotic
Ribosomes: Fungi, Protozoa, Helminths
80s (40s 60s)
Ribosomes: Viruses
Absent
Ribosomes: Bacteria
70s (30s 50s)
Mitochondria: Fungi, Protozoa, Helminths
Present
Mitochondria: Viruses, Bacteria
Absent (metabolic enzyme of bacteria: in the cytoplasm)
Nature of outer surface: Viruses
Protein capsid and Lipoprotein envelope
Nature of outer surface: Bacteria
Rigid wall containing Peptidoglycan
Nature of outer surface: Fungi
Rigid wall containing Chitin (cell wall)
Nature of outer surface: Protozoa and Helminths
Flexible membrane (Cholesterol - lipid bilayer)
Motility: Viruses
None
Motility: Bacteria
Some (those with flagella)
Motility: Fungi
None
Motility: Protozoa and Helminths
Most
Method of Replication: Viruses
Not binary fission
Method of Replication: Bacteria
Binary Fission
Method of Replication: Fungi
Budding or Mitosis2
Method of Replication: Protozoa and Helminths
Mitosis3
Only vertebrate flagellated cell
Sperm
Human Prion Disease: Present with higher cortical function impairment; Sensorial changes, loss of cognition
Creutzfeldt-Jakob Disease
Human Prion Disease: Present with cerebellar function impairment; Loss of correlation
Kuru Disease
Animal Prion Disease of sheep and goats
Scrapie
Most common Animal Prion Disease
Bovine Spongiform Encephalopathy (BSE) or Mad cow Disease
Animal Prion Disease of mule, deer, elk
Chronic Wasting Disease
Pathogenesis of Prion Diseases
Very long incubation periods, as long as 30 years
Transmission of Prion Diseases
Via infected tissue, cuts in skin; transplantation of contaminated tissues (cornea); use of contaminated medical devices (brain electrodes); ingestion of infected tissue (cannibalism); via inherited syndrome
Spectrum of Disease: Prion Diseases
Progressive neurodegenerative disease: loss of muscle control, shivering, myoclonic jerks and tremors, loss of coordination, rapidly progressive dementia, death
Treatment of Prion Diseases
No treatment available
Same amino acid sequence
Isomers
Proteins with same amino acid sequence but different folding patterns
Conformers
Bacterial shape: Spheres
Cocci
Bacterial shape: Rods
Bacilli
Bacterial shape: Spirals
Spirochetes
Bacterial shape: Spherical rods
Coccobacilli
Pattern of Cocci: Pairs
Diplococci
Pattern of Cocci: Chains
Streptococci
Pattern of Cocci: Clusters
Staphylococci
Smallest bacteria
Mycoplasma sp.
Largest bacteria
Thiomargarita namibiensis
Largest medically important bacteria
Borrelia burgdorferi (causes Lime Disease)
Sugar backbone of Peptidoglycan
Glycan
Peptide side of Peptidoglycan
Peptido
Cross linkage of Peptido and Glycan
Transpeptidase
Kill bacteria by cleaving the glycan backbone of peptidoglycan (beta1-4 linkage between GlcNAc and MurNac)
Lysozymes
Play a role in facilitating the passage of small, hydrophilic molecules into the cell
Porin proteins
Peptidoglycan of Gram (+)
Thicker; Multi-layer
Peptidoglycan of Gram (-)
Thinner; Single-layer
Teichoic Acids in Gram (+)
Present
Teichoic Acids in Gram (-)
Absent
Lipopolysaccharide in Gram (+)
Absent
Lipopolysaccharide in Gram (-)
Present
Periplasmic space in Gram (+)
Absent
Periplasmic space in Gram (-)
Present
Endotoxin in LPS: Gram (+) or (-)
Gram (-)
Endotoxin consists of
Lipid AO antigen
All gram (+) bacteria have NO Endotoxin EXCEPT
Listeria monocytogenes
Gram staining: Step 1
Primary Staining
Gram staining: Step 1 stain
Crystal Violet
Gram staining: Step 2
Fix stain
Gram staining: Step 2 mordant
Iodine
Gram staining: Step 3
Decolorizing
Gram staining: Step 3 agent
Acetone or Alcohol
Gram staining: Step 4
Counterstain
Gram staining: Step 4 stain
Safranin
Color changes in Gram Staining
Gram (+) - VioletGram (-) - Pinkish red
Staining for Mycobacteria
Acid Fast Staining
Acid Fast Staining: Reagent
Carbolfuschin
Acid Fast Staining: 2 Methods
Ziehl-Nielsen (with heat)Kinyoun (without heat)
Approach to Spirochetes
Dark Field Microscopy
No cellwall
Mycoplasma spp.
Approach to Legionella spp.
Silver Staining Method
Approach to Chlamydiae and Rickettsiae
Giemsia Staining (Rickettsiae: also Tissue Staining)
Bacteria not seen in gram stain
TreponemaRickettsiaMycobacteriaMycoplasmaLegionellaChlamydia
Site of oxidative and transport enzymes; Lipoprotein bilayer without sterols
Cytoplasmic membrane
Protein synthesis; RNA and protein in 30s and 50s subunits
Ribosome
Genetic material; DNA
Nucleoid (no nuclear membrane)
Participates in cell division and secretion; Invagination of plasma membrane
Mesosome
Contains many hydrolytic enzymes, including beta lactamases; Space between plasma membrane and outer membrane
Periplasm (only in gram -)
Cell parts that confer virulence
CapsulePilus or FimbriaGlycocalyxFlagellumSporePlasmidGranule
Polysaccharide; Protects against phagocytosis
Capsule
Glycoprotein; For attachment or conjugation
Pilus or Fimbria
Polysaccharide; Mediates adherence to surfaces
Glycocalyx
Protein; Motility
Flagella
Keratin-like coat, Dipicolinic acid; Resistance to heat and chemicals; Formed by gram (+) rods: Bacillus, Clostridium spp.
Spore
DNA; Genes for antibiotic resistance and toxins (exotoxins); Extrachromosomal, double-stranded, circular DNA capable of replicating independently o the bacterial chromosome
Plasmid
Glycogen, lipids, phosphates; Site of nutrients in cytoplasm
Granule
Al bacterial capsules are composed of polysaccharide EXCEPT
Bacillus anthracis (Polypeptide D-glutamate)
Flagella movement of Eukaryotic Cell
Whip-like
Flagella movement of Prokaryotic Cell
Rotatory
F pilus
Sex pilus
1 Flagellum
Monotrichous
Flagella on both ends
Amphitrichous
Multiple Flagella
Lophotrichous
1 sided or 1 end Flagella
Peritrichous
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
Small, do not contain transfer genes; Frequently present in many (10-60) copies per cell
Nontransmissible plasmids
Toxic proteins produces by certain bacteria that are lethal for othee bacteria
Bacteriocins
Degradative enzymes produced by Pseudomonas capable of cleaning up environmental hazards such as oil spills and toxic chemical waste sites
Bioremediation
Cells are depleted of metabolites as the result of unfavorable condition; Adaptation to new environment; Zero growth rate
Phase 1: Lag Phase
Rapid cell division occurs; Beta lactam antibiotics act during this phase; Constant growth rate
Phase 2: Log or Exponential Phase
Exhaustion of nutrients or the accumulation of toxic products cause growth to cease completely; Spores are formed; Zero growth rate
Phase 3: Maximum Stationary Phase
Most of the cells die because nutrients have been exhausted; Negative growth rate
Phase 4: Decline or Death Phase
Toxic products from Oxygen Metabolism
SuperoxideHydrogen peroxide
Needed to survive in aerobic environments
Superoxide dismutasePeroxidaseCatalase
Completely dependent on oxygen for ATP-generation
Obligate aerobes
Use fermentation but can tolerate low amounts of oxygen because they have superoxide dismutase
Microaerophiles
Utilize oxygen if it is present but can use fermentation in its absence
Facultative anaerobes
Exclusively anaerobic but insensitive to the presence of oxygen
Aerotolerant anaerobes
Cannot grow in the presence of oxygen because they lack superoxide dismutase, peroxidase and catalase
Obligate anaerobes
Drug of choice for anaerobes
Metronidazole
Obligate aerobes
NocardiaNeisseriaPseudomonasMycobacteriaBordetellaBrucellaBacillus cereusLegionellaLeptospira
Obligate anaerobes
ActinomycesBacteroidesClostridium
True or False: Bacteria are diploid.
False (Haploid)
True or False: Bacteria DNA is linear.
False (circular)
Move readily from one site on the bacterial chromosome to another or from the bacterial chromosome to a plasmid
Transposons or Jumping Genes
The movement of genes from inactive (storage) sites into active sites of transcription; Can lead to antigenic variation
Programmed rearrangements
Relapsing fever is caused by
Borrelia recurrentis
DNA transferred from one bacterium to another
Conjugation
DNA transferred by a virus from one cell to another
Transduction
Purified DNA taken up by a cell
Transformation
Pathways of Transduction
Lytic PathwayLysogenic Pathway
3 types of Molecular Changes
Base substitutionFrameshift mutationTransposons or Insertion sequences
Study of Mutagenicity
Ames Test
Microorganisms that are permanent residents of the body; With low virulence
Normal Flora
Occurs when normal flora occupy receptor sites preventing pathogens from binding
Colonization resistance
Normal Flora: Skin
Staphylococcus epidermidis (have glycocalyx)
Normal Flora: Nose
Staphylococcus aureus (anterior nares)
Normal Flora: Mouth
Viridans streptococci
Normal Flora: Dental plaque
Streptococcus mutans
Normal Flora: Colon
BacteriodesE. coli
Normal Flora: Vagina
Lactobacillus vaginalisE. coliStreptococcus agalactiae
MRSA
Methicillin-resistant Staphylococcus aureus
