quiz 9 Flashcards
What is the human microbiome mostly composed of?
Commensal bacteria that benefit humans without causing harm.
Name two examples of bacterial infections caused by pathogens.
Acne (infected hair follicles) and stomach ulcers (H. pylori).
What is the role of cilia in the lungs?
They pump bacteria out of the airway.
What type of immunity recognizes lipopolysaccharides (LPS)?
Innate immune system.
Define opportunistic pathogens.
Microbes that are commensal at low levels but pathogenic at high levels or in immunocompromised hosts.
What is LD50?
The number of pathogenic cells that cause 50% of infected animals to die.
What is a primary pathogen?
A microbe that causes disease in a healthy host.
How do AB toxins work?
B subunit binds to cell receptors, and A subunit acts as the toxin, disrupting cell functions.
What are fomites?
Inanimate objects that carry pathogens.
How does sickle-cell disease provide resistance to malaria?
It alters red blood cells, making them less susceptible to infection by malaria parasites.
Name two mechanisms toxins use to kill cells.
Creating pores in cell membranes and disrupting cellular pathways.
What are “pre-biotics”?
Foods that encourage the growth of beneficial gut bacteria like Bacteroidetes and Lactobacilli.
What is the purpose of virulence genes?
To increase the fitness of a pathogen by helping it infect better or evade the host immune system.
Give an example of a vector and the disease it transmits.
Mosquitoes - Malaria.
What are pathogenicity islands?
Sections of DNA carrying genes involved in virulence, often transferable between organisms.
