Midterm Flashcards
What is the biological function of an endospore?
They enable organisms to endure extremes of temperature, drying, and nutrient depletion.
What makes up the mass of a gram positive bacterium’s cell wall?
peptidoglycan
Explain the process of gram staining
- Flood with crystal violet to stain cells purple
- Add iodine sol’n - cells remain purple
- Decolorize with alcohol - gram negative cell become colorless, gram positives remain purple
- Counterstain with safranin - gram negatives turn red, gram positives still purple
When does endospore formation commence?
When growth ceases due to a limitation in availability of some essential nutrient
shape of Spirochaeta
coiled
shape of staphaloccus
spherical
What lens do the lectron and the light microscope not share?
Which lenses do they share?
projector
condensor lens / objective lens
what happens to electron that pass through an electron microscope?
they are either refracted and reflected or absorbed by the specimen
Scanning electron microscope vs transmission electron microscope
Scanning produces a 3d image of the exterior of the cell // Transmission produces a 2d image of a slice of the inside of the cell.
Three main components of flagella
Basal body, hook, filament
The lipids in the cytoplasmic membrane of Bacteria and ________ contain ester linkages, while the cytoplasmic membrane of ________ contain ether linkages.
Eukarya / Archaea
Robert Hooke:
- Discovery of the microscope
- First to describe microbes
Antoni can Leeuwenhoek
- First to describe bacteria
- Microscope designed for do thread counts
- Found that microbes gave rise to other microbes and disproved spontaneous growth
Edward Jenner: First Concepts in Immunity
- Theory that exposure to cowpox provided immunity to small pox
- Exposed youth healthy boy to cowpox resulting in a mild form of the disease but no sickness.
- Introduced the concent of immunity and host defense
- Beginning of vaccinations
Pasteur and Spontaneous Generation
- Discovered that alcohol fermentation was biologically mediated
- Disproved theory of spontaneous generation
- Led to development of methods for controlling growth of microorganisms
- Developed vaccines for anthrax, cholera and rabies
Pasteur’s experiment disproving spontaneous generation
- Swan neck flask experiment
- Pulled out neck
- Purified liquid
- Slowly cooled liquid stayed sterile
- Tipped flask that is contaminated allowed liquid to go bad.
Koch: Infections disease
- Showled link bt microbes and infectious disease
- Identified causative agents of anthrax and tuberculosis.
- Kock’s postulates
- The standards for identifying microbes that cause disease for a long time
- Observe blood/tissue from diseased specimen.
- Identify possible cause
- Innoculate healthy specimen with diseased blood
- See if it gets sick
- Worked out how to grow cells (solid media, saw colonies of cells of diff shapes colours and sizes)
Elie Metchnikoff
- First to describe phagocytes
- Noticed that some cells would “eat” other smaller ones
- Led to initial discovery of the immune system
- Robert Hooke (1635–1703):
- Antoni van Leeuwenhoek (1632–1723):
- Edward Jenner (1749-1823):
- Ferdinand Cohn (1828–1898):
- Louis Pasteur (1822–1895):
- Robert Koch (1843–1910):
- Paul Ehrlich (1878):
- Élie Metchnikoff (1882):
- Robert Hooke (1635–1703): described microbes
- Antoni van Leeuwenhoek (1632–1723): described bacteria
- Edward Jenner (1749-1823): immunity
- Ferdinand Cohn (1828–1898): founded the field of bacterial classification and discovered bacterial endospores
- Louis Pasteur (1822–1895): disproved spontaneous generation
- Robert Koch (1843–1910): microbes cause infectious disease
- Paul Ehrlich (1878): mast cells, blood cell types
- Élie Metchnikoff (1882): phagocytes, innate immunity
- Frederick Griffith (1928):
- Alexander Fleming (1929)
- Oswald Avery, Colin MacLeod, Maclyn McCarty (1944):
- James Watson & Francis Crick (1953)
- Frederick Sanger (1977)
- Frederick Griffith (1928): “the transforming principle”
- DNA that is responsible for genetic info
- Alexander Fleming (1929) antibacterial penicillin
- Oswald Avery, Colin MacLeod, Maclyn McCarty (1944): DNA is the hereditary material of bacteria
- James Watson & Francis Crick (1953) structure of DNA
- Frederick Sanger (1977) dideoxy-sequencing of DNA
- Designed a way of sequencing DNA that is still used today
Frederick Sanger
- Developed DNA sequencing
- First to sequence complete bacteriophage DNA genome
Michael Smith
- Site-directed mutagenesis
- Specific alteration of the nucleic acid sequence within a fragment of DNA
- Figured out how to direct changes in DNA to code for diff proteins
Kary Mullis
- Developed Polymerase chain reaction (PCR)
- Discovered polymerase - able to withstand temperature chainges that occur throughout denatureation, annealing and extension
Barry Marshall and Robin Warren
- Discovered that bacterium (H. pylori) responsible peptic ulcer disease and some form of stomach cancer
- Bacterium is a normal flora in humans, only recently started causing problems.
Craig Venter
- Synthetic biology
- Put together pieces of DNA to make simple engineered organisms
- Now possible to create life in a desired fashion
- Michael Smith (1978)
- Kary Mullis (1983):
- Barry Marshall & Robin Warren (1985):
- Craig Venter (present):
- Michael Smith (1978) site-directed mutagenesis
- Kary Mullis (1983): PCR
- Barry Marshall & Robin Warren (1985): Link H. pylori to gastric ulcers
- Craig Venter (present): Synthetic biology
Applied vs. Basic microbiology
Applied = you have to have a plan for where your research is going.
Most big discoveries come bran basic research
2 themes that microbiology revolves around
- Understanding basic life processes
- Microbes are excellent models to work on and learn from
- Applying knowledge of basic life processes to the benefit of humans
- Medicine, agriculture, industry
Importance of microorganisms
- Oldest form of life
- largest mass of living material on Earth
- Carry out major processes such as cycling of carbon and oxygen
- Can live in harsh environments
- Other forms of life rely on microbes to survive
Genome
definition
eukaryotes
prokaryotes
A cell’s full complement of genes
Eukaryotic DNA found in teh nucleus
Prokaryotic DNA in single, circular DNA molecule called a chromosome
cynobacteria
created oxygen
last universal common ancestor
Evolution
define
The process of change over time that results in new varieties of species and organisms
Phylogeny
define and explain
Evolutionary relationships between organisms
Can be deduced from genetic information (especially rRNA) because it is what is making the proteins.
Three distinct lineages of cells
Bacteria
Archea
Eukarya
Microbial Communities
Communities in nature where populations of microorganisms with interacting assemblages exist.
Diverstiy and abundances of microbes are controlled by ___________ and ________________________
Dversity and abundances of microbes are controlled by resources and environmental conditions
The activities of microbial communities can affect the ___________ and ___________ properties of their habitates.
The activities of microbial communities can affect the chemical and physical properties of their habitats.
Microbes affecting their environment
- Interact with and change the physical and chemical environment
- Influence the whole ecosystem
*
Extreme environments
Bacteria and archea that are found in some of the harshest environments are call extremophiles
Prevalence of diseases cause my microorganisms in past and present
In the past the most prevelant caues of death were due to infectious diseases whereas now those numbers are much lower because our ability to deal with microbes has improved so much.
How are microbes involved in agriculture?
nitrogen and sulfur cycles
Microorganisms in our GI tract
Different microorganisms exist in different areas due to pH differences.
How are microbes involve din food productions
Cheese
Yoghurt
Ethanol production
pickling
Cytoplasmic Membrane - purpose
- Thin structure that surrounds the cell
- Vital barrier that seperates cytoplasm from environment
- Highly selective permeable barrier
- Enables [] of specific metabolites and excretion of waste products
Plasma Membrane structure
- Phospholipid bilayer
- Hydrophobilic and hydrophilic components
- Can exist in many diff chem forms due to variation in groups attached to glycerol backbone
- Fatty acids point inward and form hydrophobic environment
- Hydrophilic heads exposed to external env and cytoplasm
Methods for counting viable cells.
- We assume that all viable cells with divide to form colonies.
- Spread Plate (for small amounts) - a volume of culture is spread on a agar plate.
- Pour plate (for larger amounts) - a known volume of culture is pipetted onto a petri plate and agar gel is poured on top and allowed to gel.
- For counting, there must not be too many colonies. To get the right amount, dilutions are made.
What is the significance of the group attached to the ethanolamine?
Stabilizing components of the cytoplasmic membrane
- Stabilized by H bonds and hydrophobic interactions
- Mg2+ and Ca2+ help stabilize the membrane by forming ionic bonds w -ve charges on phospholipids
- Somewhat fluid
- Protens can move laterally
Classes of proteins on cytoplasmic membranes and their purpose
- Integral - embedded in membrane
- Peripheral - one portion anchored in the membrane
- Inner surface of membrane interacts with proteins involve din energy-yielding reactions and other important cell functions
- Outer surface proteins interact w a variety of proteins that binds substrates or process large molecules for transport
- Proteins allow the cell to ineract with other cells around it
- Proteins all for transport
Archeal Membranes
-
Ether linkages in phospholipids
- Bacteria and Eukarya have ester linkages in phospholipids
- Archeal lipids lack fatty acids - have isoprenes instead
- Major lipids are glycerol diethers and tetraethers
- Can exist as monolayers, bilayers or mixture
How are major lipids of archea different from bacteria?
Glycerol diethers can join a second one to make a diglycerol tetraether
Forms a lipid monoloayer
Helps archea survive in extreme environments - can maintain their membrane when temp/salt/etc are harsh
Membrane Functions (3)
- Permeability barrier
- polar and charged molecules must be transported
- Created [] gradients
- Water can leak through on its own (maintain water levels)
- Protein anchor
- Holds transport proteins in place
- Energy conservation
- Generation of the proton motive force
Properties of carrier-mediated transport system
Show saturation effect.
Highly specific
Three major classes of transport systems in prokaryotes
Energy required?
simple transport
group translocation
ABC system (ATP binding cassette)
All require energy of some form - usually proton motive force or ATP
Simple transport in Prokaryotic cells
Driven by the proton motive force
H+ ions want to get into the cell so they are transported in with a substance that needs to be transported
Group Translocation in Prokaryotes
driven by phosphoenolpyruvate.
The substance that needs to be brought into the cell is recognized and then chemically modified to be brought in.
ABC Transporter Prokaryotes
Periplasmic binding proteins are involved and energy comes from ATP
Uniporters
Transport in one direction across the membrane.
Symporters
function os co-transporters
Antiporters
Transport a molecule across the membrane while simultaneously transporting another molecule in the opposite direction
