뒤로Microbiology Key Concepts and Review
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Prokaryotes are cells that lack a nucleus and membrane-bound organelles. Examples include bacteria and archaea.
Eukaryotes have a nucleus and membrane-bound organelles. They include algae, protozoa, fungi, animals, and plants.
Four criteria to establish a microbe as the cause of a disease: 1) Found in every case, 2) Isolated and grown outside host, 3) Causes disease in healthy host, 4) Re-isolated from diseased host.
The Gram stain differentiates bacteria by cell wall structure: Gram-positive have thick peptidoglycan and stain purple; Gram-negative have thin peptidoglycan and stain pink.
The capsule is a firmly attached glycocalyx that prevents recognition by host immune cells and protects bacteria from desiccation.
Flagella provide motility to bacterial cells, allowing movement toward or away from stimuli.
Endospores are highly resistant dormant structures formed by some bacteria to survive unfavorable conditions.
Passive transport requires no energy and moves substances down their concentration gradient; active transport requires ATP to move substances against the gradient.
1) DNA replication, 2) Cell elongation, 3) Septum formation, 4) Cell separation into two daughter cells.
Generation time is the time required for a bacterial cell to grow and divide, doubling the population.
1) Lag phase: cells grow but do not divide, 2) Log phase: exponential cell division, 3) Stationary phase: growth rate equals death rate.
Enzymes are organic catalysts that lower activation energy to speed up biochemical reactions without being consumed.
Competitive inhibitors bind the active site; noncompetitive inhibitors bind elsewhere causing shape change and enzyme inactivation.
Cellular respiration uses oxygen or other electron acceptors to fully break down glucose for energy; fermentation extracts energy without oxygen using organic molecules as final acceptors.
An organism that requires oxygen for growth and gathers at the top of a culture tube.
An organism that can grow with or without oxygen but grows better with oxygen.
A complex community of microbes living on a surface, embedded in a sticky extracellular matrix, providing protection and division of labor.
A bacterial communication system that monitors population density to coordinate gene expression and behavior.
Small, circular DNA molecules in bacteria that replicate independently and often carry genes for antibiotic resistance or toxin production.
Each new DNA molecule consists of one original strand and one newly synthesized strand.
DNA is transcribed into RNA, which is translated into proteins.
A cluster of genes under control of a single promoter and operator, regulated together; can be inducible or repressible.
Point mutations include silent (no effect), missense (different amino acid), nonsense (early stop codon), and frameshift (insertion/deletion altering reading frame).
Bacterial enzymes that cut DNA at specific palindromic sequences, used in genetic engineering.
A technique to amplify DNA in vitro using cycles of denaturation, annealing, and extension with a thermostable DNA polymerase.
Gram-positive have thick peptidoglycan with teichoic acids; Gram-negative have thin peptidoglycan and an outer membrane containing lipopolysaccharide (LPS).
Mycoplasmas lack a cell wall and are pleomorphic, making them resistant to antibiotics targeting cell walls.
Stages: 1) Attachment, 2) Entry, 3) Synthesis of viral components, 4) Assembly, 5) Release of new virions.
Viruses are acellular, lack cytoplasm and organelles, and require host cells to replicate; cells are living and metabolically active.