Lecture 1 - Micro overview Flashcards
Microbial disease results from complex dance between?
Complex dance between multiple microbial virulence factors and host resistance factors
Pathogens are organisms with unique, genetically endowed capacities to:
- Colonize the host
- overcome host immunity
- Replicate within the host environment and/or cause host tissue damage
What are virulence factors?
Molecule or activities that permit Pathogens to colonize host, overcome host immunity and replicate within the host environment and cause host tissue damage
Name 5 virulence factors:
Adherence factors toxins Inflammatory mediators, Anti-host enzymes Bacterial capsules
Opportunistic flora are what:
non-pathogenic normal flora that cause disease only under abnormal host conditions such as decreased competition from other microbes
Prokaryotic cells include ?
all bacteria
Archaea
Relationship between life forms is measured by?
Genetic similarity
Name the major infectious agents:
Eukaryotes (Fungus, protozoa, helminths)
Prokaryotes (Bacteria and archaea)
Viruses
Prions
T or F, Bacteria are prokaryotic cells. As such they contain membrane-bound organelles.
False, They contain NO membrane-bound organelles
Bacterial genetic material is:
contained in one, circular dsDNA molecule
How are bacterial ribosomes different than humans?
Bacterial are 70s ribosomes
Humans 80 s ribosomes
- 70s ribosome are a target for some antibiotics
Bacteria have what type of cell membrane?
A regular bi-lipid cell membrane around which is a rigid cell wall (another target for some antibiotics)
Name some of the surface molecules found in the cell membrane of bacteria
- Pili (fimbrae) used for attachment and conjugation
- Flagella used for locomotion
- Capsule used to protect from phagocytosis
- LPS a major virulence factor, found in th eouter membrane of G- bacteria
T or F, Bacteria typically live in complex ecological biosystems termed biofilms
True
Describe G+ cell walls
Thick cell walls and a single inner plasma membrane
Describe G- cell walls
Thin cell wall that is betewen the cell membrane and a unique outer membrane
T or F, Capsules often do not have anti-phagocytic properties
False, They often have strong anti-phagocytic properties
T or F, The bacterial cell wall is an essential, all enclosing, rigid, porous, protective-girdle that surrounds the bacterial cell.
True
What does the cell wall protect the cell from?
It protects the plasma membrane from osmotic pressure
Cell wall is a ridged mesh of ropelike, linear, polysaccahride chains cross-linked by peptides. What forms the polysaccharide chains?
Repeating, modified glucose-dimers called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
What is the membrane-bound enzyme that spot-welds the polysaccharide “girders” into place by cross-linking the peptides hanging from the girders to peptides dangling from the existing wall?
transpeptidases
T or f, Peptidoglycan is constantly being synthesized and degraded by proteases
False, by autolysins
The outer leaflet of the outer membrane of G- bacteria contains a toxic lipopolysaccharide termed:
Endotoxin (LPS)
In small amounts LPS is excellent at what:
What happens at large amounts?
activating the innate immune reaction
Large amounts: especially systemically, LPS can cause very serious problems like activating clotting system, leading to disseminated intravascular coagulation which can obstruct blood flow.
