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UD / Biology / BISC 300 / Who created the swan neck flask?

Who created the swan neck flask?

Who created the swan neck flask?


School: University of Delaware
Department: Biology
Course: Microbiology
Professor: Carlton cooper
Term: Summer 2015
Cost: 25
Name: Week 2 of BISC 300
Description: these are lecture notes from this week as well as notes from chapter 3 of the textbook (except the last 2 pages, sorry)
Uploaded: 02/20/2016
15 Pages 150 Views 3 Unlocks

Morgan Grimes DDS (Rating: )

Almost no time left on the clock and my grade on the line. Where else would I go? Jj has the best notes period!

Wednesday Notes

Who created the swan neck flask?

• 1673, Anton Van Leuwenhoek made first and simplest microscope o discovered single-celled organisms in pond water (Animalcules) • People believed Spontaneous Generation- living organisms come from non living matter

o Ie/ dead bodies --> maggots

o Grain + sweaty clothes --> mice

• John Needham boiled mutton to “kill all organisms”, let it cool and waited for  microbes to form

o Claimed the microbes were proof of spontaneous generation o Mutton was exposed to air though

• Spallazani repeated experiment but covered mutton

o No microbes formed

What are the basic structures of bacteria?

o Concluded microbes came from air

• Redi used gauze to cover meat in jar to prove flies cause maggots o Gauze caught fly eggs and maggots grew from those If you want to learn more check out How much of the earth is magnetic field?

o Flies could smell meat through gauze

o 3rd jar was sealed with lid, no eggs, no maggots

• Louis Pasteur created flask that let air in but no microbes to prove  spontaneous generation, broth never grew microbes though

• Essential bacterial structures (all have them) Don't forget about the age old question of What is a double bond in chemistry?

o Cell wall, cell membrane, cytoplasm, nuclear material

• Accessory structure (some have them)

o Capsule, flagella, pili, spore,  

What does a gram stain tell you?

• Spore has a compound, heat shock proteins (hold proteins together) and a  dehydrating agent to keep heat (boiling) from destroying bacteria’s proteins  (?? NOT 100% SURE ABOUT THIS)

• Gram stain developed in 1884 by Hans Christian Gram We also discuss several other topics like What is are descriptive statistics?

o Looked at lung that had pneumonia, saw certain bacteria had certain  color (????)

• 2 groups for bacteria Don't forget about the age old question of What is the negative portrayal of different categories of people?

o Gram + (thick cell wall) stains purple

o Gram – (thin cell wall) stains pink

• Bacteria also divided into groups by shape

Friday Notes

• Gram stain:

o Crystal violet (all purple cells) ???? iodine (all purple) ???? alcohol (G+ =  purple G- = no color) ???? safranin ( G+ = purple G- = red)

• Color dependent on cell wall

o Bacterial cell wall made of peptidoglycan

• For G-: The iodine forms a complex, the alcohol dehydrates the cell, dye gets  trapped in plasma membrane, makes cell colorless (?? NOT 100% SURE  ABOUT THIS)

• G + bacterium:

o NAG and NAM peptidoglycans alternate in cell wall (this happens in  G– too)

o Have “chaperone proteins” called Teichoic acid, support the large cell  wall

o Lipoteichoic acid attaches cell wall to plasma membrane

• G – bacterium:

o Has outer membrane

o Lipoproteins connect cell wall to outer membrane

• Outer membrane- lipoproteins, phospholipid bilayer, lipopolysaccharides  (toxic to humans, cause inflammation)

• Sight of selectivity is in plasma membrane Don't forget about the age old question of Why is directional solidification important?

• Cell wall provides structure and shape

o Survival in hypotonic environment too

▪ Ie/ penicillin kills bacteria by destroying cell wall. Bacteria lyse • Prokaryotes:

o Outer membrane protects from antibodies

• Bacteria can be good in one part of the body and bad in another o Ie/ E. Coli Don't forget about the age old question of How many planets would we need to sustain life?

• G – have pili and flagella, G + just flagella

• Capsule and slime layers made of polysaccharides and/or polypeptides o Capsules are organized and attached securely to cell wall

o Slime layers are unorganized and not as securely attached

• Pili are hair-like proteins on cell for movement and genetic exchange  (conjugation)

o Gives them toxin production and antibiotic resistance

• To see if something is a pathogen:

o Take microorganism from dead animal

o Grow it in pure culture and identify it

o Inject it into healthy animal

o If it dies remove the microorganism and see if it’s the same one that  killed the first animal

Chapter 3 Textbook Notes

• Variety of shapes and sizes in bacteria  

o Cocci- spherical

▪ Single or characteristic arrangement (ie/ Diplococci- divided  cocci remain together to form pairs)

o Rod/ Bacilli- rod shaped

▪ Various ones differ in length-to-width ratio

▪ Single or in chains

o Vibrius- comma shaped

o Spirilla- rigid, spiral

▪ May have tufts or flagella at one or both ends  

o Spirochets- flexible, spiral

▪ Unique, internal flagella arrangement

• Pleomorphic- variable in shape and lacking a single, characteristic form • Range in bacteria size: .3 um – 7 um (???)

• Small size utilizes large surface area to volume ratio

o Bacteria can be large if it maximizes this ration (ie/ convolutions in  plasma membrane)

• Cell envelope- plasma membrane, cell wall, capsule/slime layer • Bacteria don’t have membrane bound organelles, interior morphology is  simple

• Genetic material in nucleoid region

• Ribosomes and larger masses are called inclusions 

• Flagella fro locomotion

• Plasma membrane selectively permeable  

• Respiration, photosynthesis, and synthesis of lipids and cell wall parts occur  in plasma membrane

• Model for membrane is Fluid Mosaic Model 

o Lipid bilayer, proteins float within

• Membrane lipids are amphipathic (polar and non- polar ends) • Peripheral membrane proteins- loosely connected to membrane and soluble  in aqueous solution

• Integral membrane proteins- insoluble in aqueous solution, amphipathic  (hydrophobic regions are buried within bilayer)

o Ie/ transport proteins or electron transport chain

• Membrane is actually a patchwork of different lipidmicrodomains

• Lipid composition of bacterial membrane varies with temperature o Lower temp = more unsaturated fatty acids

o Higher temp = more saturated fatty acids

• Bacterial membranes lack sterols but have hopanoids- sterol-like molecules  made from same precursors as steroids, stabilize the membrane • Macroelements- C, O, H, N, S, and P. Found in macromolecules o Also K, Ca, Mg, and Fe

• Micronutrients/ Trace elements- Mn, Zn, Cb, Cu, nickel

• Growth Factor- molecules needed for survival, obtained from the  environment  

o Amino acids, purines and pyrimidines, vitamins

• Bacteria take in dissolved materials up the concentration gradient • Passive Diffusion- (simple diffusion) molecules move from higher to lower  concentration (down the gradient)

o Large gradient needed for good uptake

o If not used up, rate of nutrient absorption decreases as more nutrients  accumulate in cell

o Small, non-polar substances

• Large and/or polar ones move through transport proteins o Channels- proteins for pores for substances  

o Carriers- proteins carry nutrients across membrane

• Facilitated Diffusion- movement across membrane with help from channels  or carriers

o Rate of diffusion increases more rapidly at lower molecule  concentration than passive

o With carrier the rate reaches a limit, all carriers saturated  o No energy required

o Not major uptake method for bacteria, live in nutrient low  environments

• Energy dependent transport more important uptake

• Active Transport- molecules move from lower to higher concentrations  through input of energy

o Primary- uses carriers called primary active transporters. Energy  comes from ATP hydrolysis

▪ Uniporters move single molecule (ie/ ATP-binding cassete  (ABC) transporters)

o Secondary- uses potential energy of ion gradients to transport  ▪ Cotransporters, 2 substances move simultaneously

▪ Symport- same direction

▪ Antiport- different directions (ie/ electron transport and  oxidative phosphorylation)

• Usually have more than 1 transport system for a nutrient

• Group translocation- molecule is chemically modified when brought into cell • Siderophores- organic, bind to ferric iron and bring it into cell o Bacteria secrete them to gain iron when iron is scarce in environment

• Cell wall can protect cell from toxins and pathogens as well as give a bacteria  pathogenicity  

• Not all bacteria fit the model of being typical Gram + or Gram – • Gram + and – bacteria have different Periplasmic space (space between the  plasma membrane and the outer one (for G -) or the space between the  plasma membrane and cell wall (G +)

• Peptidoglycan has many identical subunits, each contain 2 sugar derivatives  (N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)) and amino  acids

• Peptidoglycans form peptidoglycan sacculus by linking the sugars in their  subunits together, making strands that can be covalently bonded to other  strands

• Sacculus strong but elastic, responds to osmotic pressure

o Also porous

• Gram + have more cross-linking of strands than Gram –

• Teichoic acids are polymers of glycerol or ribotol bonded together by  phosphate groups

o Covalently bonded to peptidoglycan

• Lipoteichoic acids covalently bind to plasma membrane

• Teichoic acids have negative charge, make cell wall negative • May make up 50% of cell wall mass

• Exoenzymes-degrade polymeric nutrients that are too large to pass across  plasma membrane

• Gram – cell walls much more complex

• Much larger periplasmic space, much thinner peptidoglycan layer • Outer membrane linked to cell by Braun’s lipoprotein

• Lipopolysaccharides (LPS) have lipid and carbohydrate: lipid A, core  polysaccharide, and O side chain

• Lipid A has 2 glucosamine sugar derivatives, each has 3 fatty acids and a  phosphate or pyrophosphate

o Can act as a toxin (endotoxin)

• Fatty acids embed in outer membrane, rest of LPS is on membrane surface • Core polysaccharide has 10 sugars

• O side chain (O antigen) is polysaccharide chain that extends from core o Causes immune response in host to produce antibodies that will  respond to that chain, then the bacteria may change the antigenic  nature of the O chain

• LPS gives negative charge to bacteria’s surface, stabilizes outer membrane,  creates permeability barrier, and protects from pathogenic bacteria  • Outer membrane more permeable than plasma

o Because of Porin proteins- form a trimer in the membrane • Bacteria without cell walls stain Gram –

• Crystal violet dye in staining is positive and attracted to negative cell  • The iodine interacts with the crystal violet to make an insoluble complex so  the dye is retained

• The alcohol shrinks the pores of Gram + peptidoglycan to prevent dye loss

o Dye is lost from Gram –

• Safranin stains the colorless cells

• Penicillin inhibits the enzyme that makes cross-links between peptidoglycan  strands

• Protoplasts have lost their cell wall (Gram +), spheroplasts have lost the  peptidoglycan sacculus (Gram -)

o Osmotically sensitive  

• Only bacteria synthesizes peptidoglycan

• Capsules help bacteria resist phagocytosis by phagocytes  • Slime layers have been seen to allow some bacteria to glide, facilitating  mobility

• Both capsules and slime layers are glycocalyx because they consist of a  network of polysaccharides that extend from the cell

o Allows attachment to solid surfaces (ie/ tissue)

• S-layer- composed of protein or glycoprotein

o Adheres to outer membrane in Gram -, peptidoglycan in Gram + o Protect against changing pH, osmotic stress, enzymes and other  bacteria

o Maintain shape and envelope rigidity and may give adhesion • Protoplast-plasma membrane and everything within

• Homologues of eukaryotic actin and intermediate filaments and  microtubules have been found in bacteria

• Bacterial cytoskeleton are involved in cell division, localizing proteins, cell  shape

• Bacteria also has some unique cytoskeletal proteins

o FtsZ, MreB, and CreS (crescentin)

o FtsZ like tubulin, forms ring in center of dividing cell to separate  daughter cells

o MreB determines cell shape in rods

o CreS promotes curved shape, is similar to lamin and keratin • Some bacteria have internal membranous structures

o Photosynthetic bacteria or bacteria with high respiratory activity o Ie/ thylakoids in photosynthetic cyanobacteria  

• These structures could be spherical vesicles, flat vesicle, or tubular  membranes  

• Connected to plasma membrane

• Functions are to serve larger membrane surface in metabolism • Inclusions are formed by aggregation of substances (ie/ granules, crystals,  globules)

o Often used for storage or to reduce osmotic pressure

• Glycogen inclusions, polyhydroxyalkonate granules, sulfur globules, and  polyphosphate granules are the most common storage ones • Polyphosphate granules store phosphate needed for synthesis of important  cell molecules (ie/ nucleic acids)

• Some inclusions are microcompartments (large polyhedrons, consist of one  or more different proteins, hold enzymes)

o Ie/ Carboxysomes- in cyanobacteria, polyhedral coat has 6 different  proteins, 100nm in diameter, holds enzyme carbonic anhydrase to  make carbonic acid into CO2, holds RubisCO to turn CO2 into sugar • Some inclusions used for bacterial movement

o Gas vacuoles give buoyancy, have small and hollow gas vesiacles o Magnetosomes orient themselves in Earths magnetic field • Bacterial cytoplasm packed with ribosomes, or has them loosely attached to  membrane

o Membrane ribosomes make proteins for envelope, free ones make  proteins fro cytoplasm

• Ribosomes of the three domains are similar

• Bacterial ones are 70S, made of 50S and 30S subunits

o S = Svedberg unit (measure of sedimentation velocity in a centrifuge,  faster a particle travels=higher Svedberg)

o Related to particle’s molecular weight, volume and shape: heavier and  compact have larger S

• Most bacteria have singular circular chromosome

• They are longer than length of cell, must be tightly packed o Nucleoid-associated proteins (NAP) cause chromosome to bend anf  fold

o Condensins further compact it during cell division

• A few bacteria have membrane enclosed DNA regions, most do not • Some bacteria have plasmids-small, double stranded DNA molecules that can  exist independently of the chromosome, most are circular  

o Usually less than 30 genes, not essential, usually contain a selective  advantage

o Replication not linked to cell cycle

• Episomes- plasmids that have integrated into the chromosome • Plasmids not always equally divided during cell division

• Curing-loss of a plasmid

• Fimbriae and Pili- slender tubes composed of protein subunits , are 3-10 nm  in diameter and up to several micrometers long  

o Attach cells to solid surface

• Sex pili are larger (diameter 9-10nm), genetically determined by conjugative  plasmids, required for conjugation  

• Many bacteria use flagella to move, they can also use them to attach to  surfaces

o Are slender, rigid, 20nm wide, 20 um long

• Monotrichous-one flagellum (polar if on an end)

• Amphitrichous-one flagellum at each pole

• Lopotrichous- cluster of flagella at one or both ends

• Peritrichous- flagella evenly spread over whole surface

• Flagellum has 3 parts

o Filament extends from cell surface to tip, composed of flagellin, is an  example of self assembly

o Basal body is embedded in cell envelope, most complex part o Hook connects filament to basal body  

• Chemotaxis- movement toward chemical attractants and away from  repellants

o Also thermotaxis, phototaxis, aerotaxis, and osmotaxis

• Swimming is done with flagella, rotates (a run is a smooth swimming  movement, a tumble reorients the cell)  

o Direction of rotations determines whether run or tumble happens  o The flagellar motor has a rotor and stator

o Power supplied by difference is charge and pH across plasma  membrane (proton motive force PMF) speed proportional to PMF o Bacteria can swim from 20-90 um per second

• Most swarming bacteria (bacteria that move in unison across surface) have  peritrichous flagella  

• Spirochetes have multiple flagella on each side of the cell that intertwine and  wrap around the cell and remain in the periplasmic space (periplasmic  flagella)

o Rotate to cause cork-screw shaped outer membrane and rotate to  move

• Twitching and gliding involve IV pili and/or slime, the pili are on one or both  poles

• Twitching motility- short, intermittent jerking. Pili extend and retract pulling  cell forward. Powered by ATP hydrolysis

• Gliding motility is smooth and could be 2-600um per second, more than one  mechanism for it exists

• Social (S) motility-large groups of cells move together and coordinately , uses  IV pili

• Adventurous (A) motility- single cell moving independently  • Chemical attractants and repellants are detected by chemoreceptors o In plasma membrane in Gram –

• Concentrations of attractants and repellants dictate bacteria motion • Endospores are resistant to heat, UV, gamma, chemical disinfectants and  desiccation  

o core has ribosomes and nucleoid etc. but lower water content, then  inner membrane, core wall, cortex (peptidoglycan), outermembrane,  and the coat and exosporium

o all these layers prevent DNA damage

• Bacteria that form endospores are pathogenic

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