35 Questions
What is the term for the diagram representing evolutionary relationships among organisms?
Phylogeny
What are the bacterial growth phases on the bacterial growth curve? (in correct order)
Lag phase, exponential growth, stationary, death phase
What is the optimal osmotic pressure for most pathogenic bacteria growth?
0.65% NaCl
Which bacterial species is mostly non-pathogenic?
Bacillus subtilis
Which type of bacteria grow best at optimal temperature?
Mesophiles
What is the term for the basic taxonomic unit of organisms?
Species
What is the term for bacterial (biological) mechanisms that lead to disease?
Virulence factors
What is the main difference between aerobes and anaerobes?
Oxygen requirement
What is the term for the measurement of pathogenicity?
Virulence
What is the significance of carbon dioxide for bacterial growth?
Required for growth in some bacteria
How is the size of bacteria populations typically expressed?
By the number of cells present
What are the specific environmental factors required for bacterial growth and metabolism?
Nutrients, pH, ionic strength, gaseous requirement, temperature
Where do most pathogenic bacteria grow best in terms of pH?
Neutral pH (7.0)
Which of the following is NOT a gaseous requirement for bacterial growth?
Hydrogen
What is the main purpose of nutrients in bacterial growth and metabolism?
Energy production and molecule sources
Which of the following is considered a factor influencing bacterial growth?
Ionic strength
What are some examples of nutrients required for bacterial growth?
Glucose, nitrates, fatty acids
Which type of pathogen causes disease by multiplying in the environment?
Facultative pathogen
Which term is defined as the invasion and/or multiplication of pathogens in an individual host?
Infection
What type of pathogens must infect a host and cause disease to multiply and be transmitted?
Obligate pathogens
Which pathogen becomes pathogenic under certain conditions like impaired host immunity?
Opportunistic pathogen
What is defined as how bacteria sustain themselves within host organisms at different levels?
Host-Pathogen interaction
Which stage of infection involves the initial attachment of pathogens to host cells?
Adhesion
What is the definition of metabolism?
The sum of all chemical reactions needed to support cellular function
What are consequences of infection?
All the above
What is the role of ATP in bacterial growth and metabolism?
Supplying energy for cellular work
Which environmental factor is NOT essential for bacterial growth?
Humidity level
What is binary fission in bacteria?
The replication method by which bacteria divide into two daughter cells
What is the generation time of bacteria?
The length of time for one bacterial cell to yield two daughter cells
What is the primary function of virulence factors expressed by pathogens?
Code for factors that cause disease
In the context of bacterial pathogenesis, what occurs during the infection stage before disease onset?
Subclinical disease
What is a common outcome of the host's biological response to pathogens?
White blood cell dispatch
What three components are needed to contribute to disease?
Host, Pathogen, Environment
What is the iceberg concept of disease primarily associated with?
Severe diseases and death
During bacterial pathogenesis, what does 'toxemia' refer to?
Acute systemic disease caused by toxins
Study Notes
Bacterial Growth and Metabolism
- Bacterial growth curve has 4 phases: lag phase, log phase, stationary phase, and death phase
- Nutrient exhaustion and accumulation of toxic products lead to stationary phase
- Bacterial growth requires specific environmental factors: nutrients, pH, ionic strength, osmotic pressure, temperature, and gaseous requirements
- pH affects bacterial growth, with most pathogenic bacteria growing best at neutral pH (7.0)
- Temperature affects bacterial growth, with optimal temperature for enzyme-catalyzed metabolic reactions
- Generation time is the length of time required for a single bacterial cell to yield two daughter cells, ranging from 30 minutes to 20 hours
Phylogeny and Taxonomy
- Phylogeny is the study of evolutionary relationships among organisms
- Phylogenetic tree is a diagram representing evolutionary relationships among organisms
- Phylogeny is based on comparative gene sequence analyses of conserved genes (rRNA genes)
- Polyphasic taxonomy classifies bacteria based on genotypic, phylogenetic, and phenotypic properties
- Taxonomy studies bacterial identification, nomenclature, and classification
Bacterial Pathogenesis
- Bacterial pathogenesis is the study of biological mechanisms that lead to disease
- Infectious disease is a disease caused by pathogens and transmittable to other hosts
- Stages of infection: exposure, adhesion, invasion, and colonization
- Infection outcomes: no colonization, infection, subclinical disease, disease, and persistence (carriers)
- Inflammation is a biological host response to harmful stimuli such as pathogens and/or their metabolites
Host-Pathogen Interaction
- Host-pathogen interaction is defined as how bacteria sustain themselves within host organisms on a molecular, cellular, organismal, or population level
- Types of pathogens: obligate, facultative, and opportunistic
- Obligate pathogens must infect a host and cause disease to multiply and be transmitted
- Facultative pathogens can infect and multiply in hosts but are also capable of multiplying in the environment
- Opportunistic pathogens do not ordinarily cause disease but can become pathogenic under certain conditions (e.g., impaired host immunity)
Spore Formation
- Spore formation is a mechanism of survival for bacteria, allowing them to withstand extreme temperatures, radiation, and chemicals
- Spores are highly resistant to environmental stressors, making them difficult to kill
Test your knowledge on bacterial growth and metabolism, including topics such as the bacterial growth curve, nutrient exhaustion, accumulation of toxic products, spore formation, cell death, and disease. Explore concepts like progressive cell multiplication, increase in cell size, active metabolism, and the four phases of bacterial growth curve in liquid medium.
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