Intro to microbiology Flashcards
What are the 3 domains of life?
Archaea, Bacteria, and Eukarya
What are the differences between prokaryotes and eukaryotes?
- presence of nucleus
- structure of ribosomes
- enzymes involved in DNA replication/RNA synthesis
What eukaryotes cause disease?
Fungi, protazoa, parasitic worms (helminths), ectoparasitic arthopods
What are the two classifications that make up the scientific name of an organism? Which one is capitalized?
genus and species
genus is capitalized
What is the name of microbes living in and on our bodies? Where on our bodies do they live? What is the name of their collective genome?
microbiota
skin, nares, oral cavity, intestines, and genitourinary tract
microbiome
What are the possible shapes of bacteria and what are their names (singular and plural)?
- spheres [cocci (pl.) coccus (sing.)]
- rods [bacilli (pl.) bacillus (sing.)]
- spirals [spirilla (pl.) spirillum (sing)]
- slightly curved rods (vibrios)
- flexible spirals [spirochaetes]
- short rods [coccobacilli]
What is the name for bacteria that adopt multiple shapes?
pleomorphic
What are the typical bacterial arrangements and their names?
diplococcus or diplobacillus (two cells), streptococcus or streptobacillus (chains), and staphylococcus (clusters)
What is the typical size range of bacteria? What instrument are they visible with?
0.2-0.5 micrometers
light microscope
What are plasmids? What do they frequently carry?
Extrachromosomal genetic material often required for virulence 1. genes for antibiotic resistance 2. genes for adherence to host cells 3. toxin genes
Name the difference in bacterial and eukaryotic organelles
Bacteria–> no ER, Golgi, or lysosomes
bacterial ribosomes = 70S
eukaryotic ribosomes= 80S
Name of bacterial cell asexual reproduction
Binary Fission
Gram Staining Characteristics:
color after staining, membrane components
Why is this an important identification?
Gram positive:
- purple after staining
- cell wall peptidoglycan (thicker)
- teichoic acids
Gram negative:
- pink after staining
- cell wall peptidoglycan (thinner)
- outer membrane–> (outer half) lipopolysaccharide (LPS) (inner half) phospholipids
Important to know when determining treatment plan.
Accumulation of this protein can cause septic shock during an infection by a gram negative bacteria. Why does this happen?
LPS
excessive inflammatory response
What is the name of proteins on the outside layer of gram negative bacteria that for pores or channels? What is their function?
porins
small molecules can diffuse passively
What is the procedure used to identify organisms resistant to Gram staining. Name an example of an organism that would require this type of identification.
Acid-fast
use to identify bacteria with waxy cell wall
Mycoplasmas– lack a cell wall
Mycobacterium tuberculosis (causal agent TB)
Describe a bacterial capsule. What is its purpose?
gelatinous layer that surrounds bacterium composed of mainly polysaccharides
inhibits phagocytosis
What are protein fibers that rotate and allow bacterial cell to move through fluids?
flagella
What are proteinaceous rod-like structure on surface of bacteria that allow adherence to various surfaces? Why are they important?
Pili (sing. pilus)
Important for colonization and initiation of infection
In what conditions would bacteria produce spores/endospores?
Describe the structure of spores and to what they are resistant.
What are medically relevant bacteria that form spores?
When nutrients such as C or N are scarce and allows the bacteria to remain dormant for years
Spores have thick multilayer coat, highly dehydrated, contain bacterial DNA with small amounts cytoplasm. They are resistant to heat, chemicals, and desiccation.
When favorable conditions return, the bacteria reconvert to metabolically active cells.
Example: Clostridium (tetanus and botulism) and Bacillus (anthrax)
What is a biofilm? Where do they grow?
communities of bacteria embedded in a polysaccharide matrix that adhere to a surface
mucosal surfaces, teeth, implanted devices, catheters
What is the name for bacterial that only replicate inside the host cell? What is an example of this type of bacterai?
obligate intracellular parasites
Example: Chlamydia
What is the name of bacteria that have complex nutritional requirements?
nutritionally fastidious
What does it mean for a bacteria to be a:
- strict anerobe
- strict/obligate anaerobe
- facultative anaerobes
- microaerophile
- oxygen must be present for the organism to grow (divide)
- cannot grow in the presence of oxygen
- can grow whether or not oxygen is present
- grow best at low oxygen concentration
What is a unique ability of strict anaerobes and facultative anaerobes?
the ability to ferment sugars, producing acids as a by-product
What conditions are important for bacterial growth? What are mesophiles?
temperature and pH
bacterial that can grow between 25-40 degrees celciius
What is the typical pH conditions that medically relevant bacteria are able to grow? What is an example of a bacteria that is an exception to this rule?
pH 7.2-7.4 Helicobacter pylori (causal agent or gastric ulcers) grows in the stomach (low pH)
Why is it important to know environment and nutrient requirements of an organism?
so that clinical specimens are cultured under the appropriate conditions
What is a selective component in bacteria cultures? What is an example?
have components that inhibit the growth of some organisms but not other
bile salts inhibit the growth of gram positive organisms but not gram negative
What is the name of visible bacterial masses found on solid media cultures?
colonies
What are differential media cultures? What is an example?
contain an indicator
a dye the changes color due to metabolic activity,
What are the criteria through which most medically important bacteria are identified?
morphology, staining properties, cultural requirements, and biochemical properties
What is the study of fungi called? Fungal infections?
mycology and mycosis