Chapter 1: Review Flashcards
Significance of Microorganisms
Ubiquitous, abundant, diverse (growth rate, metabolism, requirements of growth, staining characteristics, susceptibility to antibiotics)
Job of clinical microbiologist:
culture organisms from patient specimens, classify/identify organism, predict and interpret antimicrobial susceptibility patterns
Prokaryotes:
– No organelles
– Unicellular
– 70S ribosomes
– Bacteria will be our focus
Eukaryotes:
– Organelles
– Unicellular or
Multicellular
– 80S ribosomes
– Protozoa and Fungi will be
our focus
Where is ETC in bacterial cells?
plasma membrane
Granules in cytoplasm are used for __
storage
Bacteria with no cell wall include (2):
mycoplasma and ureaplasma
Appendages (3):
flagella, pili, fimbriae
Gram-positive cell wall:
One plasma membrane
Gram-negative cell wall:
Two plasma membranes and LPS
Endotoxins:
In the LPS, so only gram-negative
Exotoxins:
Secrete toxins, mainly gram-positive cells.
Ex.) leukocidin, toxic shock syndrome toxin, diptheria toxin
Typical bacteria size:
1-3 µm
Microscopic shapes:
cocci, bacilli, spiral
Cell wall of fungi is made up of __
polysaccharides
Viruses:
- Acellular
- DNA or RNA
- Capsid
- Enveloped or non-enveloped
- Obligate intracellular parasites
- Host or host cell specific
Taxonomy is based on __
genotype and phenotype
Gram stain procedure:
- Heat fix (methanol can be used)
- Crystal violet (primary)
- Iodine
- Alcohol-acetone (decolorizer)
- Safranin (counterstain)
negative = red or pink
positive = purple or blue
Acid-fast stain:
- Ziehl-Neelsen method (heat)
- Kinyoun (detergent)
– Carbolfuchsin (primary stain (red))
– Acidified-alcohol (decolorizer)
– Methylene blue (counterstain) - Auramine-rhodamine
– Fluorochrome stain (appears yellow or orange under fluorescent microscope)
Major nutritional needs:
– Carbon source for cellular constituents
– Nitrogen source for proteins
– Adenosine triphosphate (ATP) energy source for cell functions
Trace elements:
Phosphorus (P), sulfur (S), sodium (Na), potassium (K), chlorine (Cl), calcium (Ca)
Types of growth media:
- Minimal medium
- Nutrient medium
- Enriched medium
- Selective medium
- Differential medium
- Transport medium
Environmental Factors Influencing Growth:
- pH
- temperature
- gaseous composition of the atmosphere
Generation time:
Time required for one cell to become two
Growth curve:
Lag, log, stationary, death
Determination of cell numbers:
Direct counts, plate, counts, density
Fermentation:
– Anaerobic process carried out by both obligate, aerotolerant, and facultative anaerobes
– Electron acceptor is an organic compound
– Less efficient in energy generation than respiration
Respiration:
– Aerobic respiration is an efficient energy-generating process in which molecular oxygen is the final electron acceptor
– Certain anaerobes can carry out anaerobic respiration, they do not use molecular oxygen as final electron acceptor, but nitrate and sulfate for example
DNA:
– Storage of genetic information (genetic potential)
– Replication produces DNA copies.
Types of fermentation:
Alcohol, homolactic, heterolactic, propionic, mixed acid, butanediol, butryic acid
RNA:
– Produced by transcription of DNA
– mRNA
Translation:
mRNA is read by ribosome.
Codon: a group of three nucleotides
- tRNA matches codon with anticodon
Transformation:
Uptake and incorporation of naked DNA
Transduction:
Transfer of genes by bacteriophage
Conjugation:
Transfer of genetic material from a donor to a recipient strain of bacteria
Restriction enymes:
Enzymes that cut at specific sequences
