Flashcards in Midterm 1 Deck (100)
An organism that is a single cell for most or all of its life
Approximately how many microbes are on earth?
9.2 x 10^29 - 3.2 x 10^30
How many species of microbes have been described to date?
What is the Human Microbiome Project?
34 trillion microbes live in and on us - in 2008, we tried to classify them by what attributes they give us health-wise
How many species of microbe are associated with the health of an individual?
Who utilized the "modern" microscope? And why was it modern?
It was modern because it was compound
What book did Robert Hooke publish?
What was Antony van Leeuwenhoek's microscope? What type of microscope did he use?
A simple microscope- very small, with 50-300x magnification
He used dark-field illumination
What did Tyndall find?
That bacteria can be carried on dust, and it can be highly heat resistant
What did Ferdinand Cohn discover?
-Found that they were highly heat resistant and had implications for human health
Who developed early culture techniques and a classification system for bacteria?
What did Redi, Needham, and Spallanzi look at? How did their experiments differ?
They all looked at spontaneous generation
Redi: Maggots do not spontaneously arise on meat
Needham: Looked at microorganisms- Boiled mutton, cooled flasks, and stoppered them tightly
Spallanzi: Stopped flasks before boiling
What are some main contributions Louis Pasteur made?
Sterilization (Pasteurization), Vaccine for rabies, anthrax, and cholera, contributions to wine and silk industry
When was disease still considered supernatural?
Before the 1800's
Who realized pathogens can be passed between people?
-Realized that mothers giving birth via doctor contracted more streptococcal infections that via midwife
Who introduced aseptic surgery techniques?
Who was Robert Koch? What did he contribute?
Established Bacillus cause anthrax
Established Mycobacterium cause tuberculosis
Nobel prize 1905
What are Koch's postulates?
1. Pathogen must be present in all cases
2. Pathogen must be purely cultured
3. Pathogen from pure culture must cause disease in healthy animals
4. Pathogen must be isolated and cultured from the newly infected/sick animal again
What are some cellular organisms studied by microbiologists?
Fungi, Protists, Bacteria, Archaea
What are some acellular organisms studied by microbiologists?
Viruses, Viroids, Virusoids, Prions
What are properties that ALL cells have?
Metabolism, Growth, and Evolution
What are properties of SOME cells?
Differentiation, Communication, Genetic exchange, Motility
What are the 3 domains?
Eukaryotes, Archaea, Bacteria
What is the pseudonym for DKPCOFGS?
Dear King Philip Came Over From Great Spain
What is the mnemonic order of taxonomy?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Usually single celled
Lack internal structures
No true nucleus
Unique membrane composition- Lacks peptidogylcan
Initially grouped with bacteria
rRNA sequences led to the separation
Protists and fungi
Larger than most bacteria
Last Universal Common Ancestor
Who came up with the endosymbiont hypothesis?
Lynne Margulis, 1967
Interaction between 2 organisms where 1 lives inside the other
How do we define specific microorganisms?
Collection of strains sharing many properties that differ significantly from other groups of strains
What are the 4 different types of strains?
Biovar, Morphovar, Serovar, and Pathovar
Can be detected by antibodies
Cause different diseases in different places
When were microbes first visualized?
Human eye resolution
Light microscope resolution
How do you define the limit of resolution?
When 2 dots are distinctly 2 dots (just distinct)
What is the formula for resolution?
*Keys of microscopy are resolution and magnification*
0.61 wavelength / NA
NA= numerical aperture= nsinø, where n is the refractive index
When were spectacles first used?
Who built the first compound microscope?
Pros and cons of bright field microscopy?
Pro: Can be alive
Con: Can stain structures
Pros and cons of dark field microscopy?
Pro: Improved observation of internal structures b/c direct light does not enter the eyepiece
Phase contrast microscopy
Shift the phase of light 1/2 wavelength out of phase to exaggerate difference in light
-gives a look at many dimensions within the cell
Specimen is stained or tagged with F.
First filter removes short wavelengths, light hits the specimen, emit long wave rads, and dichromatic mirror lets through the longer wavelengths and reflects shorter ones
Allows you to focus on 1 plane of the specimen
Specimens must be dead, it is expensive, and a lot of preparation, but MUCH higher resolution: 0.2nm
Scanning electron microscope
Excellent depth of field
What is STEHM?
Scanning Transmission Electron Holography Microscope
-Clusters or single
-How they cluster is used for identification
Rod (Bacilli) bacteria
-Pairs, chains, or clusters
-Shape of the end varies
-Similar to rods
-Indicative of cholera
-Have tufts of flagella
-Long processes or appendages of the cell
-Bacteria form long filaments called hyphae
-They are pleomorphic (can form other structures)
Why is small size important for bacteria?
To maintain a good Surface Area : Volume ratio
-Some bacteria have DNA outside their nucleus
-We can manipulate this DNA
-Defines the cytoplasm
-Barrier to molecules
-Has some proteins embedded (integral membrane proteins)
-Some proteins attached (peripheral membrane proteins)
-Fluid mosaic model
-Amphiphilic (1 hydrophobic, 1 hydrophilic)
-Phospholipids based on glycerol
-Polar head groups exposed to aqueous environment
Plasma membrane function
-Concentration gradient (high to low)
-Concentration gradients via protein transport
-Plasma membrane & all external layers
-Fluid mosaic model
-Large # of metabolic processes associated with this
Bacterial cell wall
-Determines shape of cell & protects against osmotic cell
-May contribute to pathogenicity
-Target of many antibiotics
-Differentiates gram positive and negative
-Found in gram + and - cells
-Built from identical subunits
Gram negative peptidoglycan layer is _____ nm thick
Gram positive peptidoglycan layer is _____ nm thick
-Long string of NAG-NAMs w/ lots of peptides sticking out
-Cross-linking between NAG-NAMs (covalent bonds) - Used to classify organisms
Gram positive cell walls
-Thick cell walls - mainly peptidoglycan
-Rich in teichoic acids
-Glycerol/Ribitol linked via phosphoral groups to other acids
-Peptidoglycan layer is porous
-Narrow periplasmic space
Bacterial intra-cytoplasmic membrane
-Some bacteria have it
-Inclusions are aggregates- organic/inorganic material that can be membrane bound or free in the cytoplasm
-Inclusions often used to store molecules
-Way to store energy
-Method of storing carbon
-Repeating building blocks
-Bacteria can use these to store carbon and energy
-Monomer units linked by ester bonds
-Consists of basal body, hook, and hollow filament
-External components through filament
-Can spin and move at rapid rates
-Can't see them without adding a flagella stain
Gram negative cell walls
-Very thin layer of peptidoglycan
-Very thick periplasm
-Phospholipids, proteins, lipoproteins, and lipopolysaccharides
-Protects cells from host invasion
-No secretory system
-Move towards food & away from danger
-Movement can be directional, up/down a gradient, or either an attractant or repellent
-Can develop signalling
-Flagellum is a rigid helix that rotates & allows for movement
-Chemo-sensing system linked to signalling pathway
-May respond to signals present in nM concentrations
-Short, jerky motions
-Cells must be in contact with one another
-Lays down a slime & slides against it
-Type of differential staining
-Differentiate organisms by thickness of peptidoglycan layer (thick in +, thin in -)
-Stain is driven into cells with heat
-For acid-fast cells, acidified alcohol cannot wash away the stain
-Stain is driven in with heat, the decolorization, then counterstaining with safranin
-Cells with a polysaccharide capsule will not take up India ink
-Increase the thickness of flagella so that they can be seen under a microscope
-Layer made of protein or glycoprotein
-Binds to outer membrane in gram negative cells
-Binds to peptidoglycan surface in gram positive cells
-Protection, shape maintenance
Fimbriae and Pili
-Proteins that extend from the outer membrane
-Roles in DNA uptake, motility, and conjugation
-Gram + bacteria
-Exist within cells
-Peptidoglycan layer becomes cortex
-Not all endospores successfully germinate
-Formed through asymmetric replication
-Have no activity - everything it needs is inside it
-2 different types of cells
-Mother cell gets one copy of DNA and then dies
-Get 1 cell in the end
-Irregularly shaped region that contains the chromosome and associated proteins (no membrane)
Extrachromosomal, linear, or circular
-Cells may contain multiple copies or even types of these
-Replicate autonomously (don't contain DNA essential to the host)
-Metabolic function and antibiotic production
-Chromosomes are membrane-bound
-Organelles allow internal compartmentalization
-Divided into protists and fungi
-Fungi are monophyletic, while protists are not
-Nucleus is composed of a double membrane and is quite large
-Composed of alpha (-) and beta (-) tubules
-Maintain cell shape
-Role during cell division
-Composed of actin
-Cell shape and motility