2094 Microbio Exam 1 Ch. 1-7
What are the properties of a living organism?
-Responsiveness to environmental changes -Growth and development -biological evolution -Ability to reproduce -Have a metabolism and energy use (w/out energy input, life would cease, death would occur) -Maintain homeostasis and regulation -cells and organization
What happens if there's too much negative (-) or positive (+) supercoiling?
Too much (+): same direction = breaks DNA. Too much (-): opposite= too floppy and loose and cell in danger of death
What are siderophores?
low molecular weight organic molecules that bind ferric iron (usually by removing it from another molecule in nature or a human) and supply it to the cell. Different in gram- and gram+ bacteria.
What are ribosomes? What are the two main subunits? What rRNAs are located in each one?
organelle where protein synthesis occurs, message encoded in mRNA is translated here. Complex protein/RNA structures. 2 main subunits -small subunit. (16s rRNA) -large subunit. (23S and 5S rRNA)
What are the different kinds of membrane proteins?
-Peripheral membrane proteins: attached loosely to the membrane (usually inner membrane) and easily removed -Integral membrane proteins: embedded w/in the membrane, amphipathic; transport proteins that move things in and out
Who is Anton Von Leeuwenhook and what did he do?
(1632-1723) earned his living as a draper and haberdasher, but was an amateur microscopist who may have been inspired by Hooke's work in Micrographia. He could magnify his microscopes about 50-300x and may have used light to illuminate his slides and create a dark-field illumination. He sent detailed letters of his findings to the Royal Society of London, giving the scientific world descriptions of bacteria and protists.
What were the experiments leading to the discovery that microbes cause disease? What scientists were involved and what were their experiments?
-Agostini Bassi (1773-1856), showed a disease of silkworms was caused by a fungus. -M.J. Berkeley (1803-1889), demonstrated the Potato Blight of Ireland was caused by a water mold. -Heinrich de Bary (1831-1888), showed smut and rust fungi caused cereal crop diseases. -Luis Pasteur demonstrated microorganisms carried out fermentations, helping the French wine industry and publishing papers on fermentation from 1857-1860. His experiment developed pasteurization to avoid wine spoilage by microbes. -Joseph Lister (1827-1912), provided indirect evidence that microorganisms were the causal agent of disease. Developed an antiseptic surgery system (heat sterilizing tools and spraying phenol over dressings) to prevent microorganisms from entering wounds. His patients had fewer postoperative infections. -Robert Koch (1843-1910), established the relationship between Bacillus anthracis and anthrax disease. He used criteria developed by his teacher, Jacob Henle, now known as Koch's postulates, and still used today to establish the link between a particular microorganism and disease.
What are 5 extracellular appendages that can be found on bacteria? (none are required, can have more than one).
1. Capsules or Glycocalyx: aids in attachment to solid surfaces. e.g., biofilms in plants and animals and on surfaces in moving water. Usually made of carbohydrates and not easily removed 2. slime layers: Similar to capsules except diffuse, unorganized, and easily removed. Slime may facilitate motility. Carbohydrate usually 3. S-layers: Rigidity/structure. Usually protein 4. Pili and Fimbriae 5. Flagella: Extend beyond the cell envelope in bacteria. Function in protection, attachment to surfaces, horizontal gene transfer, cell movement.
What are 6 things found in the bacterial cytoplasm?
1. Cytoskeleton 2. Membrane infoldings 3. Inclusions 4. Ribosomes 5. Nucleoid 6. Plasmids
What are Koch's postulates?
1. The microorganism must be present in every case of disease but absent in healthy organisms 2. The suspected microorganisms must be isolated and grown in a pure culture 3. The same disease must result when the isolated microorganism is inoculated into a healthy host 4. The same microorganism must be isolated again from the diseased host
How long have microbes been on earth?
3.5-3.7 bya
When did life first arise?
3.5-3.7 bya (billion years ago) in the form of hopanoids (which are found in the plasma membranes of extant bacteria), which formed hopanes (molecules) that indicate that bacteria was present when the rock was formed.
Explain the Gram stain-steps, what each step accomplishes (mechanism of the stain steps), what the colors of Gram positive and Gram negative cells after each step?
4 steps: Crystal Violet, Iodine, Decolorizer, Safranin. 1. Crystal violet stains proteins (in OM, PG, CM and inside if allowed in) 2. The iodine acts as a mordant, binds to the CV and enlarges the Protein-CV complexes. 3. Decolorizer is usually alcohol or alcohol + acetone ; a.) Dissolves lipids (aka any accessible/available membranes) although does not completely remove them (pokes holes in them) Alcohol may also remove/extract some lipids from outer layer of Gramnegative cell wall, making crystal violet dye removal easier. b.) Also causes dehydration, removing the water layer around proteins; dehydration causes shrinkage of pores/holes in PG. c.)Thus, constriction due to dehydration prevents loss of crystal violet during decolorization step for Gram positives but the thinner peptidoglycan layer and larger pores of Gram-negative bacteria do not prevent loss of crystal violet. 4. Safranin stains proteins (cytoplasm, PG, membranes) and both gram-&+ are stained red, but cannot see red over purple in G+ so G+ remains purple, while G- turns red.
Define prokaryote.
A descriptive grouping for microorganisms that lack membrane-bound organelles (e.g., membrane-bound nucleus, golgi apparatus, ER, cytoskeleton)
What is a microbe? What groups of organisms are considered microbes-what are the divisions and types?
A microbe is an organism or acellular entity too small to be seen clearly by the unaided eye (generally <1 mm or less in diameter). They are relatively simple in construction and lack differentiated tissues. The groups of organisms considered to be microbes can be both cellular and acellular. Cellular microbes include fungi, protists, bacteria, & archaea. Acellular microbes include viruses (protein & nucleic acid), viroids (RNA), satellites (nucleic acid enclosed in protein shell), and prions (protein).
What is the cytoskeleton? What are the homologs of actin, microtubules, and intermediate filaments?
A network of structures made from filamentous proteins (e.g. actin and tubulin) & other components in the cytoplasm of cells. Eukaryotic cytoskeletal elements | Homologs -Actin filaments | FtsA, participates in cell division -Microtubules/tubulin | FtsZ forms ring during septum formation in cell division -Intermediate filaments | CreS, responsible for curved shape
Outline a set of experiments that might be used to decide if a particular microbe is the causative agent of a disease-explain how Koch showed the cause of TB using Koch's postulates.
A set of experiments that might be used to decide if a particular microbe is Koch developed a staining technique to examine human tissue. M. tuberculosis could be identified in diseased tissue. Koch grew M. tuberculosis in pure culture on coagulated blood serum. Koch injected cells from the pure culture of M. tuberculosis into guinea pigs. The guinea pigs subsequently died of tuberculosis. Koch isolated M. tuberculosis in pure culture on coagulated blood serum from the dead guinea pigs.
What is binary fission?
A type of simple cell division used by prokaryotic cells to reproduce & split into two. Cell prepares for division and elongates. Only the nucleoid is present as a single entity and its replication and partitioning into each half of the elongated cell is a critical event. Finally a septum (cross wall) is formed at midcell, dividing the parent cell into 2 daughter cells, each having own nucleoid.
Briefly explain the evolution of eukaryotes from bacteria. What is the endosymbiotic hypothesis?
Aerobic bacteria eventually evolved to produce the first eukaryotic cells around 2.5 bya. Eukaryotes emerged when Archaea engulfed Bacterium and bacterium evolved into Mitochondria (AKA, the Endosymbiotic hypothesis).
What is lysozyme? What happens when cells are treated with lysozyme?
An enzyme that attacks PG by hydrolyzing (& breaking) the bond that connects NAG & NAM. Very FAST method of removing PG and causing the cell to bursts.
What is penicillin? What happens when cells are treated with penicillin?
Antibiotic derived from fungi/mold. SLOWly removes PG by preventing formation of new crosslinks (irreversibly bind to the PBPs so the PBPs can't function) The new PG eventually is depleted and floats off due to not being crosslinked to the old
Compare and contrast Bacteria, Archaea and Eukarya.
Bacteria: Prokaryotic, usually single-celled, most lack membrane-bound nucleus, most HAVE PG in cell wall, have standard phospholipids, ubiquitous and some live in extreme environments Archaea: Prokaryotic, usually single-celled, most lack membrane-bound nucleus, LACK PG in cell wall, have unique membrane lipids, many live in extreme environments, some have unusual metabolic characteristics Eukarya: PROTISTS-generally larger than bacteria and archaea, algae (photosynthetic), protozoa (may be motile, "hunters, grazers"), slime molds (2 life-cycle stages), water molds (devastating disease in plants) FUNGI- yeasts (unicellular), molds and mushrooms (multicellular & unicellular & multicellular forms can be seen w/the unaided eye sometimes
What sizes are bacterial cells? Are they all the same size? Are viruses larger or smaller in general?
Bacterial cells are usually tiny, but not always. They are not all the same size bc they can range from 0.3 micrometers-500 micrometers. Viruses are generally smaller than bacteria; the larger viruses are comparable in size to the smaller bacteria.
What did people believe caused diseases?
Believed to be caused by supernatural forces, poisonous vapors, or imbalances of 4 bodily fluids, aka, "humors".
How is DNA organized? What is supercoiling?
DNA binding proteins organize the DNA into supercoils (anchor proteins, Gyrase, Topoisomerase I). It's called supercoiling bc DNA is already a helix so helix turns = coils. Any additional twists are supercoils. Tightly regulated. SC Stores energy (potential energy) to help separate the DNA strands when it is time for replication and transcription
Compare and contrast cell envelope and cell wall.
Cell Wall (refer to as PG): -In gram+, refers ONLY to PG -In gram-, refers to both PG & outer membrane Cell envelope: -In gram+, includes plasma membrane, PG, & external structures -In gram-, includes plasma membrane, PG, external structures, and outer membrane
What is the definition of evolution?
Change in allele frequency over time, primarily occurs through natural selection for mutations ALREADY PRESENT in a population
What's the charge on DNA and how it is neutralized?
DNA is negatively charged (anionic). Cations in the cell bind to the DNA and neutralize the charge.
What are plasmids? What are the major categories of plasmids?
Double-stranded DNA that can exist independently of the chromosome. Usually small, closed circular DNA molecules. Episomes (a type of plasmid)—may integrate into chromosome. Inherited during cell division. Also supercoiled. Classification via mode of existence, -spread, and function (resistance, fertility, colicin, degradative, and others)
What are the functions of the plasma membrane?
Encompasses the cytoplasm; absolute requirement for all living organisms. Selectively permeable barrier. Interacts with internal and external environment (receptors for detection and response to chemicals, transport system embedded in cm, aids in metabolic processes such as electron transport and ATP production).
What evidence supports the LUCA hypothesis?
Evidence that supports the LUCA hypothesis is that all life has a common code- info stored in DNA that uses common decoding mechanism (RNA to protein). Regions of similarity in DNA include rRNA, other genes, whole genomes. And detect mutation rates and determine age.
Overview-what are the parts of the bacterial cell?
External Structures: -Capsule/Slime layer/glycocalyx -Flagella, pili, fimbriae Cell Envelope: -plasma membrane -Peptidoglycan (shouldn't be referred to as the cell wall) -Outer membrane (if present) Cytoplasm: -Ribosome, enzymes, nucleoid inclusions, gas vesicles (not membrane inclusions)
What is lipopolysaccharide, what are the 3 main parts, and what is the importance of LPS?
Found in the outer membrane of gram- bacteria, large, complex molecules that contain both lipids and carbohydrates, & consist of 3 parts: 1. lipid A 2. core polysaccharide 3. O side chain LPS is important bc; -Contributes to the negative charge on the bacterial surface bc the core polysaccharide usually contains charged sugars & phosphate -Helps stabilize outer membrane structure bc lipid A is a major constituent of the exterior leaflet of the outer membrane -Helps create permeability barrier bc the geometry of LPS and interacting molecules are thought to protect bacteria from antibiotics, detergents, toxins, etc. that could kill bacteria -Helps protect pathogenic bacteria from host defenses bc of O side chain (O antigen) -Lipid A portion can act as a toxin and is called endotoxin. if LPS or lipid A enters bloodstream, septic shock may develop
What is the structure and function of peptidoglycan? DRAW it out schematically (not using chemical structure).
Functions to maintain shape, protect cell from osmotic lysis and toxic material, may contribute to pathogenicity, influences nutrient uptake, motility, attachment, & reproduction. In gram+, stains purple & has thick PG. In gram-, stains pink or red & has thin PG along w/OM. Structure involves meshlike polymer of identical subunits forming long strands. There are 2 alternating sugars, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Alternating D- & L- amino acids. PG strands have helical shapes, PG chains are cross-linked by peptides for strength.
How does their size compare to other types of cells?
Generally, their size is smaller than most types of cells. E.g., the average human red blood cell is 10-20 micrometers, & bacteria are usually still 10x smaller (although, some cyanobacterium can be the same size in diameter).
What are protoplasts?
Gram (+) bacteria lacking cell wall Done to evade action of some cell-wall-acting antibiotics
How many layers in Gram positive and Gram negative?
Gram+ has 50-200 layers. Gram- has 1-2 layers.
How are flagella different in Gram positive and Gram negative bacteria?
In gram+, flagella have only 2 rings (Ms, C). In gram-, flagella have 4 rings (L, P, Ms, C)
What are inclusions?
Granules, crystals, or globules of organic or inorganic material that are stockpiled by the cell for future use. Storage inclusions store nutrients, metabolic end products, energy, building blocks
What characteristics is the early earth environment hypothesized to have?
Harsh environment, sulfuric acid, no free oxygen, storms, hot, strong UV light, atmosphere rich in carbon dioxide, water vapor, and nitrogen
What did Pasteur contribute to immunology?
He, along w/Pierre Roux, discovered that incubation of cultures for long intervals between transfers caused pathogens to lose their ability to cause disease (termed 'attenuation'). He (along w/coworkers) also developed vaccines for chicken cholera, anthrax, and rabies.
Understand how hypertonic, hypotonic and isotonic environments affect cells.
Hypotonic environments -Solute concentration outside cell less than inside cell. -Water moves into cell and cell swells. -Cell wall protects from lysis. Hypertonic environments. -Solute concentration outside cell is greater than inside. -Water leaves cell. -Plasmolysis occurs. Isotonic environments -can survive and grow normally -H2O concentrations are normal in & out -cell is flaccid
What are growth factors?
If the cell is unable to divide de novo, growth factors must be supplied by environment. Possible growth factors can be organic compounds such as; -amino acids (for protein synthesis) -purines and pyrimidines (for nucleic acid synthesis) -vitamins (function as enzyme cofactors)
What is a microbial species?
In terms of many eukaryotic microbes, a microbial species is defined as 2 organisms being able to mate and have fertile offspring. But in Bacteria and Archaea, microbial species are defined as a collection of strains that share many stable properties and differ significantly from other groups of strains
What structures can increase the surface area in cells with a larger diameter?
Infoldings in mitochondria (cristae), and microvilli
What did John Tyndall do?
John Tyndall dealt a final blow to spontaneous generation by demonstrating that dust carries germs and that if dust is absent, broth remained sterile even if directly exposed to air. He provided evidence for the existence of exceptionally heat-resistant forms of bacteria.
What does it mean that membranes are fluid mosaics?
Membranes are lipid bilayers w/in which proteins float. So, bacteria membranes has roughly equal amounts of lipids and proteins. Membrane include amphipathic lipids (phospholipids) that have polar, hydrophilic heads, as well as non-polar, hydrophobic tails. Membrane proteins can either be peripheral (loosely connected to membrane; easily removed) or integral (amphipathic; embedded w/in membrane)
What are all the common shapes and arrangements?
Most common shapes & arrangements are -cocci: roughly spherical (beachball) cells, can form chains (streptococci), clusters (staphylococci), pairs (diplococci), tetrads (4 cocci in a square), sarcinae (cubic configuration of 8 cocci) -bacilli (aka, rods): differ considerably in their length-to-width ratio, can occur singly or form pairs (diplo), chains (strepto or staphylo), tetrads & sarcinae (blocks), -Several others like vibrios (comma-shaped), spirilla (rigid, spiral shaped helices, w/tufts of flagella), spirochetes (flexible, spiral-shaped bacteria that have a unique, internal flagellar arrangement), pleomorphic (variable in shape and lacking a single characteristic form)
What are microcompartments?
Large polyhedrons formed by protein shells with one or more enzymes. Contain the enzyme RubisCO for CO2 fixation. Found in cyanobacteria and other carbon fixing bacteria. Carboxysomes are a good example.
Who or what was LUCA?
Last Universal Common Ancestor. The cellular form that outcompeted other protocells and gave rise to all of life. It's at the center of the universal phylogenetic tree, labeled "origin" where data indicates the last universal common ancestor to all 3 domains should be placed. Constructed through the use of polymerase chain reactions (PCR) to amplify and purify SSU rRNA genes and sequence the genes to then compare genes from other organisms.
Describe Pasteur's experiments to disprove spontaneous generation and what critics said of each attempt. Be able to draw out his experiments that we discussed.
Louis Pasteur first tries to disprove spontaneous generation by conducting an experiment using filtered air through cotton and found that objects resembling plant spores had been trapped. If a piece of cotton was placed in sterile medium after air had been filtered through it, there was microbial growth. Next he placed natural solutions in glass flasks with long, curved necks, (swan-neck flasks) then the solution was boiled and flasks were left exposed to air, and there was no growth of microorganisms. He inferred that growth didn't occur bc dust and germs were trapped on the walls of the curved necks.
What are magnetosomes?
Magnetite particles for orientation in Earth's magnetic field. Found in aquatic bacteria. Helps form magnetosome chain.
What is cytoplasm?
Material bounded by the plasma membrane. Holds all the other components (w/exception of nucleus in eukaryotes) w/in cell.
What are intracytoplasmic membrane infoldings and what do they do?
May be bundles of spherical vesicles, flattened vesicles, or tubular membranes. Observed in many photosynthetic bacteria. Observed in many bacteria with high respiratory activity. Increase the surface area
How are microbes (and other life) classified?
Microbes (and other life) are classified by a 3 domain system based on a comparison of ribosomal RNA (rRNA) genes that divides microorganism and all of life into -Bacteria (true bacteria) -Archaea -Eukarya (eukaryotes) Carl Woese (1980) is responsible for the 3 domain system bc he used rRNA sequencing to create a tree of life (universal phylogenetic tree) that showed the relatedness between organisms.
Explain the role of microscopes and culture techniques on the development of the field of microbiology.
Microscopy led to the discovery of microorganisms, and Robert Hooke used the microscope and his findings to publish Micrographia (1665). Culture techniques were a major development as they not only contributed to the rebirth of microbiology, but they also developed liquid media and the methods for sterilizing it so that microbes could be cultured. These techniques were then applied to understanding the role of microorganisms in disease.
Another word for shape is ______________.
Morphology
What is chemotaxis?
Movement toward a chemical attractant or away from a chemical repellent. Changing concentrations of chemical attractants and chemical repellents bind chemoreceptors of chemosensing system. In presence of attractant/repellant, tumbling frequency is reduced; runs toward/away from compound are longer. Behavior of bacterium altered by temporal concentration of chemical
How do spirochetes move? Where are their flagella located?
Multiple flagella form axial fibril which winds around the cell. Flagella remain in periplasmic space inside outer membrane. Corkscrew shape exhibits flexing and spinning movements.
What is facilitated diffusion? How does it work?
No ATP needed, molecules move through a membrane from an area of greater concentration to an area of lesser concentration, concentration gradient impact nutrient uptake, so very similar to Passive diffusion. However, f.d. uses membrane bound carrier molecules (permeases), rate increases w/concentration gradient, & effectively transports glycerol, sugars, amino acids, & ions.
Are all microbes disease-causing? This is not a yes or no question.
No, not all microbes are disease causing. For example, although some bacteria like e.coli can cause disease, many kinds of bacteria exist naturally in human and animal bodies and often have mutualistic relationships w/their hosts. Another example is that viruses can cause several diseases and even cancer, but Archaea, on the other hand, is not known to cause any disease.
What enzymes are responsible for supercoiling?
Nucleoid-associated proteins (NAPs) are DNA binding proteins that organize the DNA into supercoils (anchor proteins, Gyrase, Topoisomerase I). Example of a NAP is HU protein.
What are the role of the origin, terminus, and replisome?
Origin of replication—site at which replication begins Terminus—site at which replication is terminated, located opposite of the origin. Replisome—group of proteins needed for DNA synthesis.
What are the tools invented that aided in the study of microbes (besides the microscope)?
Petri dish, Agar, nutrient broth and nutrient agar, methods for isolating microorganisms, porcelain bacterial filters.
What is the structure of phospholipids? (2 slides, 16 and 17) (you don't have to be able to draw the chemical structure)
Phospholipids are organic molecules so they are made up of P, O, S, H, C, N. Saturation levels of membrane lipids reflect environmental conditions such as temperature (more saturated=less mobile; less saturated=more mobile). They are structurally dynamic.
What are pili and fimbriae? What are their main functions?
Pili and Fimbriae NOT enclosed by a membrane but attached to a membrane. -Fimbriae (s., fimbria) short, thin, hairlike, protein appendages (up to 1,000/cell) -Pili (s., pilus). longer, thin, hairlike, protein appendages (not as many) BOTH mediate attachment to surfaces, Sex pili (s., pilus): Longer, thicker, less numerous (1 to 10/cell), Required for conjugation aka one type of horizontal gene transfer.
What are S layers?
Regularly structured self assembling layers of protein or glycoprotein. In Gram- bacteria, S layer adheres to outer membrane. In Gram+ bacteria, associated with peptidoglycan. Protect from ion and pH fluctuations, osmotic stress, enzymes, and predation. Maintains shape and rigidity. Promotes adhesion to surfaces. Protects from host defenses. Potential use in nanotechnology
What is passive transport (diffusion)? What are the only 3 molecules to get across membranes via passive diffusion?
Requires NO ATP. Molecules move from region of higher concentration to lower concentration between the cell's interior and exterior (goes both ways until equilibrium is reached). Molecules move w/gradient. Only H2O, O2, and CO2 molecules get across the membrane via passive diffusion.
What is active transport? How is it fundamentally different than passive transport?
Requires energy, ATP, or PMF (proton motive force). Moves material against concentration gradient, concentrates molecules inside the cell, does involve carrier proteins (permeases) but is diff from p.t. bc it involves energy. 3 types; 1. Primary Active Transport/ABC transporter (ATP Directly) 2. Secondary Active Transport (PMF) 3. Group translocation (ATP Indirectly)
What is group translocation?
Requires energy. Chemical modification of the transported substance as it's brought into the cell. Energy is downstream, not direct. Best known translocation system is driven by phosphoenolpyruvate and is thus called the sugar phosphotransferase system (PTS)
What are ribozymes? Do they still exist?
Ribozymes are catalytic RNA molecules that form peptide bonds, perform cellular work and replication. They do still exist in cells today and are important in forming peptide bonds that hold together amino acids, the building blocks of proteins.
Who is Robert Hooke and what did he do?
Robert Hooke (1635-1703) credited w/publishing first drawings of microorganisms in scientific literature. In 1665, he published Micrographia, which was extremely important for its detailed drawings and info on building microscopes, which may have inspired the amateur microscopist, Antony van Leeuwenhoek.
How do flagella move?
Rotates like a propeller. Very rapid rotation. -In general, counterclockwise (CCW) rotation causes forward motion "smooth swimming" called a Run -In general, clockwise rotation (CW) disrupts run causing cell to stop and reorient (aka, Tumble) Can also Swarm on moist surfaces as a type of group behavior by bacteria.
How does the surface to volume ratio change as cells increase in diameter? Why does the surface to volume ratio matter?
S/V ratio is affected by shape and diameter, e.g., a bacillus w/the same volume as a coccus has a higher S/V ratio than the coccus. This means that the bacillus can have a greater nutrient influx across the plasma membrane. S/V ratio is important bc the higher it is, the better the uptake of nutrients and diffusion for the cell.
What is the relationship between DNA, RNA and proteins in cells today as well as ancient cells?
SSU rRNA genes show bacterial lineage (genome sequences closely related to proteobacteria). New genes and genotypes continue to evolve, producing a mosaic of genetic information, e.g., antibiotic bacteria. Bacteria and Archaea increase genetic pool by horizontal gene transfer w/in the same generation of genetic info from cell to cell in some cases.
What is the function of capsules? What are the usually constructed from?
Serves as protection and aids in attachment to solid surfaces. e.g., biofilms in plants and animals and on surfaces in moving water. Usually made of carbohydrates & polysaccharides. Well organized and not easily removed
What are gas vacuoles?
Small hollow cylinders of multiple copies of a protein that prevent water entry but allow gas entry. found in aquatic, photosynthetic bacteria and archaea provide buoyancy: regulates level/position in water Descend by collapsing and rise by constructing
What are some limitations of the postulates?
Some organisms can't be grown in a pure culture. Using humans in completing the postulates is unethical. Some diseases are unique to certain animals or even humans.
What ringed lipid is found in bacterial cells?
Steroids (e.g., Hopanoids) are complex, ringed lipids found in cell membranes, and some (like Hopanoids) can be structured to be more hydrophobic than phospholipids
What are the subfields of microbiology and what do they study?
Subfields include; -Medical microbiology: deals w/diseases of humans and animals -Agricultural microbiology: concerned w/the impact of microorganisms on food production -Food microbiology: study the microbes used to make food and beverages as well as microbes that cause food spoilage or are pathogens that spread through food (e.g., e. coli)
What was the idea of spontaneous generation? Name the individuals and their experiments that lead up to Pasteur's disproval of spontaneous generation.
That living organisms could develop from nonliving or decomposing matter. The view was challenged by Francesco Redi (1626-1697) who discredited spontaneous generation by using covered and uncovered jars to show that maggots on decaying meat came from fly eggs. Then John Needham (1713-1781) experimented w/mutton broth in flasks which he then boiled and sealed. The results showed that the broth still became cloudy and contained microorganisms. Later, Lazzaro Spallanzani (1729-1799) experimented w/seeds that were sealed and then boiled and there was no microbial growth. Finally, Louis Pasteur disproves spontaneous generation by conducting the "swan-neck flask" experiments in which natural solutions were poured in flasks with long, curved necks, then the solution was boiled and flasks were left exposed to air, and there was no growth of microorganisms.
What are the 2 types of microbial cells and what are their characteristics?
The 2 types of microbial cells are eukaryotic and prokaryotic. The characteristics of a eukaryotic cell is that it has a membrane-enclosed nucleus and other membrane-enclosed organelles, they're more complex morphologically, & are usually larger than prokaryotic cells. The characteristics of a prokaryotic cell are the lack of a true membrane-enclosed nucleus & no division into compartments by membranes.
What are flagella and what are they made from? What is the function?
Threadlike, locomotor appendages extending outward from plasma membrane and cell wall. Thin, rigid protein structures composed of 3 parts; -filament: longest and most obvious portion, extends from cell surface to tip (has cap protein and junction) -basal body: embedded in cell envelope ('base') -hook: links filament to basal body and gives flexibility Functions. -Motility and swarming behavior. -Attachment to surfaces. -May be virulence factors. cap---> junction--->hook--->L-ring--->P-ring--->Ms-ring--->C-ring
Explain the evolution from early anaerobic microbes to later aerobic ones, and how cyanobacteria contributed
The evolution from early anaerobic microbes to later aerobic ones begins with LUCA splitting into 2 lineages, Bacteria and Archaea at 3.5 bya. Bacteria were initially anoxygenic photosynthetic machinery that resembled plants but didn"t release O2 (anaerobic), but eventually they evolved oxygenic photosynthesis that released O2 (gave rise to algae later plants)(AKA, cyanobacteria). Because of their O2 emissions, cyanobacteria catalyzed the Great Oxidation Event in which O2 drastically changed the atmosphere, caused the Earth's temperature to drop, and killed many anaerobic bacteria in the First mass extinction. The first mass extinction led to the evolution of Aerobic bacteria.
What is the nucleoid, where is it, and how it is different from a eukaryotic nucleus?
The location of cell's chromosome (DNA) and associated proteins. Usually 1 circle of double-stranded DNA molecule. Supercoiling and nucleoid proteins (different from histones) aid in folding and fitting loops of DNA. Usually not membrane bound (prokaryotic).
How are the major groups defined? What is PCR?
The major groups are defined through evolutionary history/phylogeny/hypothesis of relationships that is obtained through obtaining DNA sequences from rRNA. This process begins by lysing the cells from organism 1 to release contents and isolate, then you use the polymerase chain reaction (PCR) to amplify and purify SSU rRNA genes, then you sequence those genes, then repeat this process for other organisms, and, finally, align the sequences to be compared.
What is microbial ecology and how is it different from microbiology studies by scientists like Koch and Pasteur?
The study of microbes in soil and aquatic habitats (in their environments)with a variety of culture and molecular approaches to study the vast diversity of microbes in terms of morphology, physiology and relationships. It's different from microbiology studies by scientists like koch and pasteur bc it focuses more on their environment (e.g., soil) wheras microbiology studies focuses more on removing microorganisms from their normal habitats and growing them isolated from other microbes to study them.
What are the methods for the uptake of nutrients
Transport Mechanisms: -Passive mechanism (no ATP): passive diffusion, facilitated diffusion -Active mechanisms (needs energy, ATP, or PMF): primary and secondary active transport, group translocation
What are porins, what are their general structure? What are their properties?
Type of integral membrane protein that clusters together to form a trimer (3 circles clustered together) in the outer membrane. Center of each porin monomer is water-filled channel, each porin protein spans the OM, is tube shaped & narrow, and channel allows passage of nutrients & hydrophilic molecules that are small.
How do ABC transporters work?
Use ATP directly, use ATP-Binding Cassette (ABC) transporters, observed in bacteria, archaea, & eukaryotes. Consists of 2 hydrophobic membrane spanning domains (transporters), 2 cytoplasmic ATP-binding domains, substrate binding domains (solute-binding proteins).
What are the three mechanisms of secondary active transport?
Uses ion gradients to cotransport substances, energy comes from ion gradients across the membrane (Aka, PMF). Uniporters transport only 1 substance at a time, cotransporters transport 2 substances at a time. Cotransporters can be split into Symporters (both substance move in the Same direction) or Antiporter (substances move in opposite directions; Against). 3 mechanisms/methods used by s.a. transporters result from -bacterial metabolic activity in which e.t. generates proton gradient -an enzyme called V-type ATPase hydrolyzes ATP & uses energy to create proton gradient -proton gradient is used to create another ion gradient, e.g., Na gradient
What are some other methods of division?
Variations on binary fission: must accomplish the same purpose and separate out DNA, build new membrane and PG; produce new cells. -Multiple fission: new cells within the parent (some Cyanobacteria) -Spores in genus Streptomyces -budding
What are acellular microbes?
Viruses, viroids, satellites, prions are acellular microbes.
Predict the difficulties that might arise when using Koch's postulates to determine if a microbe causes a disease unique to humans.
You would have to use human subjects (bc the disease is unique to humans) and that would be unethical.
Draw out the cell cycle parts and label what happens in each.
ch7- pg. 131; slide 7
What are the three main parts of flagella?
filament, hook, basal body
Why are microbes important and what are some characteristics? (How are microbes beneficial to the environment? How are microbes beneficial on farms? What are some of the ways humans use microbes?)
play a major role in recycling essential elements, act as a source of nutrients, and some even photosynthesize and produce 50% of the O2 that we breathe. Beneficial to the environment bc they photosynthesize and produce 50% of O2 and decompose and recycle nutrients. They also help with bioremediation and sewage treatment. Beneficial on farms bc they're essential in the gut of cows for digestion and microbial products act as natural pesticides. Some of the ways humans use microbes are in food, beverages, antibiotics, vitamins, medicines, vaccines, and fermentation processes.
What is motility?
the ability of an organism to move by itself. in microorganisms, fimbriae, pili, & flagella are structures that aid in motility. Motility is used to move towards nutrients and away from toxins, or simply to respond to changes in the environment.
