Hooke
-Built the first compound microscope and used it to observe mold
-Published Micrographia, the first manuscript that illustrated objects under the microscope
-Coined the term cell
Leeuwenhoek
-Built single-lens magnifiers, complete with sample holder and focus adjustment
-first to observe single-celled microbes (he called them "small animals
Magnification
an increase in apparent size of an image to resolve smaller separations between objects
Resolution
The smallest distance by which 2 objects can be separated and still be distinguished
Bright field microscopy
object against a bright field of light, you need a stain to increase contrast and make it visible
Dark field microscopy
view microbes as halos of light against a dark field, but could just be dust (Can see small images)
Why would I use a fluorescence microscope
In bright field microscopy an image appears dark against a bright background, but with this type of microscopy the object is self illuminated and appears vividly against a dark background, making it easier to see. It is also possible to be much more speci
TEM-Transmission Electron Microscopy
electrons pass through specimen, reveals internal structure
SEM-Scanning Electron Microscopy
electrons scan the specimen surface, reveals external features in 3-D
Cell Membrane
The phospholipid bilayer that encloses the cytoplasm. The structure that defines the existence of the cell
Cell Wall
A rigid structure external to the cell membrane. The molecular composition depends on the organism; it is composed of peptidoglycan in bacteria
Nucleoid
non-membrane bound area of the cytoplasm that contains the chromosome in the form of looped coils
Selective Transport
essential for survival, prevents a cell from coming to equilibrium
Passive Transport
molecules move along their concentration gradient
Active Transport
molecules move against their concentration gradient, requires energy (ATP)
Chemotaxis
movement of bacterium in response to chemical gradients
Structure of Peptidoglycan
a polymer of the disaccharide NAG-NAM bound to a 4 amino acid peptide that is cross linked to give the cell wall rigidity
NAM-NAG- tetrapeptide- cross linked between strands
Gm+ Cell Wall
Capsule made of polysaccharides => S-layer of protein (not all species) => Thick cell wall of amino acid cross-links in peptidoglycan (20-30 layers) and Teichoic acids for strength => plasma membrane
GM- cell wall
Outer membrane => one or two thin layers of peptidoglycan
Which is unique to Peptidoglycan? L or D?
D amino acids
Where is teichoic acid and what is the purpose?
An acid located in the cell wall of Gm+ bacteria used to increase strength.
capsule
made of polysaccharides
not all species have it
most pathogens have it
slimy, prevents macrophage bindng and increases resistance to immune system
What is the purpose of mycolic acid in mycobacteria?
Increased resistance to chemical damage and dehydration, prevent effectiveness of hydrophobic antibiotics, allow bacterium to grow inside macrophages which hide it from the immune system.
What is the outer membrane of Gm- bacteria
Lipopolysaccharide (LPS)
LPS is a ___?
Endotoxin, causes fever, inflamation and sepsis
O Antigen on LPS is responsible for?
Serotype specificity
each bacterial strain has a unique LPS, structure of the O polysacccharide is unique to each serotype
Toxic part of LPS
Lipid A
3 parts of LPS Structure
1. O-Polysaccharide
2. Core Polysaccharide
3. Lipid A
Gram Stain: Which bacteria are purple vs pink and why
Gm+: purple due to thick cell wall retaining crystal violet
Gm-: red because thin cell wall doesn't retain crystal violet, it is rinsed off and the Gm- bacteria are counter stained red
Purpose of flagellum- how does it work in general?
Spiral filaments of protein.
Spin clockwise (tumble) or counterclockwise (swim)
Facilitated Transport
helps solutes move across a membrane from an area of high concentration to one of low concentration. Does not use energy.
Active Transport
helps solutes move across a membrane from an area of low concentration to one of high concentration. Requires energy.
Coupled Transport
energy released by driving an ion down it's gradient is used to move an ion up it's gradient
Symport
two molecules travel in the same direction
Antiport
actively transported molecule moves in the opposite direction of the driving ion
Siderophore
specialized molecules secreted to bind ferric ion (Fe3+) and transport it into a cell
Group Translocation
Uses energy to chemically alter the substrate during transportation. Ex. Phosphotransferase system => uses PEP to attach phosphate to specific sugars.
Spontaneous Generation
Theory that living creatures could arise without parents.
Spontaneous Generation: How/who disproved the theory? What was the experiment?
Disproved when Redi showed that maggots were offspring of flies, and Spallanzani showed that sterilized boiled broth could not grow microbes. [Possibly improper sterilization was a flaw.] Louis Pastuer - swan neck flasks, microbial basis of fermentation
Selective media
favor the growth of one over the other
Differential media
exploit differences between two species that grow equally well
Growth Curve
...
Growth Curve: Lag Phase
Bacteria are preparing their cell machinery for growth
Growth Curve: Log Phase
Growth approximates an exponential curve (straight line, on a logarithmic scale)
Growth Curve: Stationary Phase
Cells stop growing and shut down their growth machinery while turning on stress responses to help retain viability
Growth Curve: Death Phase
Cells die with a "half-life" similar to that of radioactive decay, a negative exponential curve.
Biofilm
protects a bacterial colony and makes it difficult to kill
What is an Endospore?
Dormant, tough, temporarily non-reproductive structure from certain bacteria
When do Endospores appear?
When there is lack of nutrients- (Starvation)
Why are endospores important?
Allows bacteria to lay dormant for very long times
Genus of bacteria that make spores.
Bacillus
Do spores Grow?
No, they germinate
How do you get rid of spores?
heat
Eutrophication
Sudden infusion of large quantities of a formerly limiting nutrient. (Ex. Algae blooms)
-phile
lover
-phobe
hater
Obligate
the same no matter what environment (needs oxygen)
Facultative
different and environment dependent (without oxygen)
Extremophiles, psychrophiles, vs mesophiles, vs thermophiles. What is the main cellular structure that changes between the optimal growth temps of these?
All have membranes and proteins customized for their growth temperatures.
Why can't psychrophiles survive at thermophile temps?
Thermophiles growth temperature exceeds psychrophiles optimum temperature.
Does Internal pH change for alkaliphiles like the internal temp of the thermophile? Why? How do bacteria manage the extreme pHs?
- No? A bacterial cell's temperature matches that of its immediate environment.
-Alkaliphiles can manage their internal pH to an extent.
-Under extremely alkaline conditions, the cells can use the Na+/H+ antiporter to bring protons into the cell in exchan
Know classifications on Microbial Responses to Oxygen
1) Strict aerobes can only grow in oxygen
2) Microaerophiles grow only at lower O2 levels
3) Strict Anaerobes dies in the least bit of oxygen
4) Facilitated anaerobes can live with or without oxygen
5) Aerotolerant Anaerobes grow in oxygen while retaining
sterilization
kills all living organisms
disinfection
killing or removal of pathogens from inanimate objects
Antisepsis
killing or removal of pathogens from surfaces of living tissues
Sanitation
reducing microbial population to safe levels
Pasteurization
Many different time and temperature combinations can be used to kill different pathogens. Kills (Coxiella burnetii) Q fever.
Joseph Lister
developed carbolic acid to clean wounds and surgical instruments
Antibiotics
- Kills Bacteria
- Chemical compounds synthesized by one microbe that kill the growth of other microbial species
Why do you have to finish all of your antibiotics?
Can cause bacterial evolution is course of antibiotics is not finished and creates drug resistant strains.