Lecture Flashcards
Who is the father of microbiology?
Anton Von Leuwennock; first one to figure out how to magnify things
What were the parts on the first microscope?
- single lens = simple microscope
- stage was a needle
- could magnify 100-200x
What did Anton Von Leiwennock call microorganisms?
Animalicules
What is a compound microscope?
Has a dual lens system
How many times can microscopes magnify something today?
Up to 2000x
What two factors influence magnification?
- Contrast
2. Resolution
Define contrast
How much something stands out when compared to surrounding background
Define resolution
Ability to tell 2 points from each other
What ways can one enhance contrast?
- Stain the specimen
2. Modification of the light source
What are 3 different stains?
Simple stain
Gram stain
Fluorescent stain
What is a drawback of staining?
Can’t maintain viability of specimen
What is a positive of modification of the light source?
Allows for viability of specimen
How does a phase contrast microscope work?
Uses filters to align the light hitting the specimen
What are the two types of electron microscopy?
Transmission electron microscopy (TEM)
Scanning electron microscopy (SEM)
What is a drawback of electron microscopy?
Can’t maintain viability of specimen
Describe transmission electron microscopy (TEM)
Passes electrons through specimen to allow for visualization of sub-cellular structures
Describe scanning electron microscopy (SEM)
Reflects electrons off surface of specimen; detects deflected electrons and generates a 3D image of specimen allowing to see surface detail
Scanning electron microscope (SEM) max. Magnification
100,000x
Transmission electron microscope (TEM) max. Magnification
1,000,000x
How can you enhance resolution?
Better optics
What is the max. resolution of a light microscope?
0.2 μm
What is the max. resolution of SEM?
1 nm
What is the max. resolution of a TEM?
0.5 nm
What is the current tree of life identification based on?
Genetic similarities/differences. Based on the 16s rRNA gene for prok. And archaea and the 18s rRNA gene for euk.
What are the 3 domains of life?
- Bacteria
- Archaea
- Eucarya
Conserved regions in the 16s rRNA gene?
- unspecific applications
- same among all prok.
Variable regions in the 16s rRNA gene?
- group or species-specific applications
- species-specific, used to identify
What do changes in sequences of conserved regions result in?
Loss of function of 16s rRNA gene (translation)
What do changes in sequences of variable regions result in?
- Not necessarily loss of function but may lead to misidentification of organism.
Which categories are applied in naming in microbiology?
Class, Genus, Species
What groups of microorganisms are included in the domains?
- viruses (not included in any of the domains)
- bacteria - prok.
- archaea - prok.
- fungi - euk.
- protozoans - euk.
- algae - euk.
Differences between prok. and euk.: nucleus
euk. only
nucleoid in prok.- chromosomes but no membrane
Differences between prok. and euk.: membrane-bound organelles
euk. only
Differences between prok. and euk.: number of chromosomes
- euk. have more than 2
- prok. have one
Differences between prok. and euk.: cell membrane
both euk. and prok.
Differences between prok. and euk.: cell walls
- some euk. have
- all prok. have
Differences between prok. and euk.: size
- euk. larger
Viruses
- not living (?)
- no metabolism
- reproduction via host cell only
not thought to communicate with their environment (adaptation and evolution?)
Algae
- euk.
- oxygenic photosynthesis (O2 as waste product)
- fix CO2 at significant rates - being looked at as solution for global warming
- has cellulose cell walls
- not pathogenic but dinoflagellates (red tide) do produce neurotoxins for humans (ng levels can kill)
Protozoa
- euk.
- pathogenic/parasitic
- have no cell walls
- divided into groups based on motility
Groups protozoans are divided into
Based on motility
- amoeba
- falgellates
- ciliates
- sporozoites
amoeba
- euk.
- protozoa
- amorphous (no shape)
- motility via cytoplasmic streaming
- eg. Entamoeba histolytica –> causes dysentary
Flagellates
- euk.
- protozoan
- motility via flagella
- eg. Typanasoma spp. –> causes sleeping sickness; attacks CNS via tsetse fly; neurological disorder; eventual permanent sleep and organ failure
ciliates
- euk.
- protozoan
- motility via cilia
- eg. Paramecium spp. –> feed on large complex carbs and other MOs; found in termite guts to allow for cellulose degredation
Sporozoite
- euk.
- protozoan
- spreads between hosts via cysts (spores)
- obligate intracellular parasite
- eg. Plasmodium spp. –> causes malaria; spread by mosquito (Anopheles spp.)
Fungi
- euk.
- cell walls made of chitin (insects and cell fish have chitin cell walls too)
- non-motile
- grouped based on reproduction
- primary ecological role is degradation of complex organics
- a few are pathogenic
Yeasts
- euk.
- fungi
- fermentation is primary metabolism under anearobic conditions
- produce majority of alcohols and organic acids used commercially
- a few pathogens (vaginosis and thrush)
- eg. Sacchoromyces cerevicea –> bakers/brewers yeast; non-pathogenic
- do not produce spores
- mode of reproduction is budding (uneven cell division); brewing industry monitors bud scars
Molds
- euk.
- fungi
- filamentous morphology; each filament called hyphae; mycilia contain many hyphae
- mode of reproduction: produce spores (which gives mold color)
- spores are at the tip of aerial hyphae
eg. Penicillium spp. –> produces antibacterial penicillin; attacks cell wall on gram + cells; breaks NAM and NAG bonds; resistance forms by changing linkage of NAM and NAG bonds
Mushrooms
- euk.
- fungi
- filamentous
- “mushroom” portion is reproductive structure, below is large colony of filaments
- mode of reproduction: spores; occurs in “mushroom” gills
- eg. Agaricus spp.
Slime Molds
- protoza or fungi?
- degradation of complex organics
- no cell walls
- ameboid morphology
- differentiate into filamentous morph. (terminal differentiation)
- motile via cytoplasmic streaming
- produce spores
- show rudimentary behavior when responding to stress and in forming pore structures
- when not stressed, individual amoeboid cells replicate
What are the 3 basic morphologies within prokaryotes?
- coccus (s); cocci (pl)
- bacillus (s); bacilli (pl)
- spirillium (s); spirilli (pl)
Bacteria represent _______, while archea represent _________.
“common” prokaryote (eg. Escherichia coli); extreme prokaryote, eg. extremes in temp., pH, salt conc., contaminated environments (eg. Thermus aquatreus)
Bacteria and archea have similar ________ but can have different
structures; chemical compositions
Cell wall of bacteria are comprised of __________, while cell wall of archea are comprised of __________.
peptidoglycan; pseudomurein
Cell wall
- common to all prokaryotes
- can vary in thickness
- located extracellular to cell membrane
- rigid structure that is porus
- rigidity confers morph. and maintains intracellular pressure
- porous allows nutrients in and waste out
Composition of bacterial cell wall
- made up of peptidoglycan
- peptidoglycan = NAM (N-acetylmuramic acid) + NAG (N-acetylglucosamine)
- creates tortuous path for substrates to travel across
- concentration gradient drives movement of substrates
- non-selective but excludes based on size
Outer membrane
- phospholipid bilayer
- fluid mosaic model
- selective because of transport proteins
- heavily populated by porins (open, non-selective channels) –> make OM less selective
Cell membrane
- phospholipid bilayer held together by hydrophobic forces
- job is to prevent things from crossing
- transport proteins make it selective
- hydrophobicity of CM prevents movement of substrates across
- fluid mosaic model
Fluid mosaic model
- susceptible to temp. changes
- as temp. increases, too much fluidity and membrane falls apart
- as temp. decreases, not enough fluidity to maintain needed nutrient transport
- to survive temp. fluctuation some prok. can adjust ratios of saturated/unsaturated fatty acids
- as temp. increases, increase in amount of fatty acids to prevent more membrane fluidity
- as temp. decreases, increase in unsaturated fatty acids to maintain membrane fluidity
Lipopolysaccharides (LPS)
- on gram (-) cells only
- hair-like extensions
- negatively charged
- associated with OM only
- highly immunogenic
- easily pop out of OM due to fluidity
- Lipid A in OM
- core polysaccharides made of 7 carbon sugars middle part
- O side chain made of 6 carbon sugars, part that sticks up highest
Teichoic acid
- on gram (+) cells
- negatively charged
- stick out from CW, CW anchors them
- typically don’t find in high conc. outside of cells
- don’t know function
Fimbriae
- short hair-like extensions from cell surface that play a role in adhesion
- eq. some bacteria in gut, in aquatic systems, in mouth
Pili
- pilus (s)
- longer extensions out from surface of cell
- not sure of function
Sex pilus
- conjugation
- hollow tube extends from donor to recipient and transfers DNA
Gas vacoules or vesicles
- seen in aquatic species
- used in flotation or movement within a water column
- protein-bound structures that expand or contract to control bouyancy
Storage polymers
- coping mechanism some cells use to deal with nutrient deprivation
- eg. carbon - glycogen and PHB
- eg. polyphosphate granules
- eg. elemental sulfur
- eg. magnetite: responds to magnetic fields
Glycocalyx
- capsule, slime layer, exopolymer and exopolysaccharide
- outtermost layer to cell
- sticky due to sugar composition
- provide high degree of chemical resistance but porus for nutrients
- protects against dessication
- resists UV damage
- resists phagocytosis
Prokaryotic spores
- spores or endospores
- highly resistant to temp., dessication, chemicals, etc.
- form of survival (not reproduction), occurs in response to stress
- sporulating cell becomes the spore
- 1 cell becomes 1 spore
