Micro Test 1: Lectures 1-7, 11 – Flashcards
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Unlock answersEarly Microbiology attributed disease to: |
Evil spirits
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Anton Van Leeuwenhoek |
invented first microscope
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Abiogenesis |
Live from Non-life
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Louis Pasteur |
Pasteurization of wine/milk/juice
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Robert Koch |
ID cause of anthrax; B. anthracis ; |
Koch Postulates |
The cause of the disease must be: ;
; |
Ignaz Semmelweis |
Handwashing |
Joseph Lister surgical technique ; Edward Genner ; Alexander Fleming |
Aseptic technique using phenol on surgical wounds Cowpox used for protection against small pox Pencillin discovery (1928) |
Why Classify bacteria?; |
; Communication ; |
Three Domain System |
Archae ; ; ; ; ; ; ;Eukaryota ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;;;;; ;; ;;;;;; ;; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;;;; Bacteria ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;; ; ;;;;;;;;;;;;;;;;; ;; ; ;; ;; ; ; ; ;Archae and Eukaryota more closely related |
Naming species |
Genus species or Genus species |
Bacteria storing |
Lyophilized (freeze-dried) Frozen at -80;C Liquid N2 (-196;C) for long term |
Taxonomic Scheme Classical |
**Requires growth of organism ; observation used to classify microorgansims** structure/morphology biochemical/physiological cell surface GC composition |
structure/morphology |
physical characteristics:; shape/size of colony/cell arrangement external features ; |
Biochemical/Physiological |
physiological characteristics: growth factors metabolic end products antibiotic sensitivites |
Cell surface |
Serological; ex. capsule Phage typing (detecting single strains of bacteria) ; |
Guanine-Cytosine content |
Determine percent GC content by: melting DNA; (higher GC content=higher mp) ; |
Genetic Scheme |
Phylogeny: changes in DNA gene sequence over time; evolution ; *Not always necessary to culture organism |
Guidelines of which gene is used |
Universal. All bacteria should have the gene Identical function Easy to work with ; 16S or 23S in prokaryotes |
Three methods of Genetic Scheming |
Nucleic Acid Hybridization Nucleic Acid Sequencing DNA fingerprinting (not used as much) |
Nucleic Acid Hybridization |
Flourescent tagged probes of complimentary DNA that hybridize with the complimentary rRNA of the bacteria. Viewed with a Flouresence Microscope |
Nucleic Acid Sequencing |
Extract gene for interest (rRNA) Polymerase chain reaction (amplify) use computer to align sequences (compares squence to known organisms) |
Endosymbiotic Hypothesis |
Bacterial endosymbiont of eukaryote lost ability to live independently ; DNA/Ribosomes similar to bacteria |
Common bacteria used in lab |
Gram Positive ;cocci: ex. S. aureus ; ;;streptococcus ;;; ;;staphylococcus ;;; ;bacilli Gram Negative ;Bacilli ;;Lactose + (E. coli;) ;;Lactose - |
Gram positive stain |
Thick peptidoglycan layer 2 membranes polysaccharide capsule flagella: 2 support rings stains: dark purple S-layer attached to petidoglycan if present sporulate teichoic acid/lipoids form lipoteichoic acid; |
Gram Negative |
Cytoplasmic Membrane Thin peptidoglycan layer stains: light pink porins (pores) flagella (4 support rings) s-layer attached directly to outer layer do not sporulate Lipopolysaccharide outer layer
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Three Domain Characteristics |
Archae: single-celled, no nucleus/organelles Bacteria: large single-celled, prokaryotic Eukaryota: multicellular ; |
Magnification vs. Resolution |
Magnification: how big Resolution: distinguish fine detail (smaller wave length |
Light Microscopy |
View living specimens at 1000x-1500x Types:; Brightfield: specimen is dark, field is light (heat-fixed and stained specimens) Phase Contrast: Best for unstained, living specimens Flourescent: uses UV light (smaller wave length=greater resolution) |
Structure comparisons Prokaryote vs. Eukaryote |
Cytoplasmic membrane: BOTH Membrane-bound nucleus: Eukaryote Ribosomes: prokaryote (70S)/ eukaryote (80S) Cell Wall: petidoglycan(P)/ cellulose(E) Internal membrane-bound organelles: Eukaryote Flagella: flagellin(P)/ Microtubules(E) Cytoskeleton: **Actin(P);/ eukaryotes Cell Size: .3-3 microns(P)/ ;3 microns(E) |
Bacterial Cell Structures |
Cocci Bacilli Spirilla Stalked Sheathed Pleomorphic |
External Cell Structure;Types |
Capsule: slime S-layer: protein surface layer; protection pili: adhesion/conjugation flagella: motility chemotaxis: ability to move toward attractant (positive) or away from repellent (negative) |
Capsule, Glycolax or slime |
protection hydrated polysaccharide or polypetide can be thicker than bacteria Creates immune response: antigenic reaction (ex. K-antigen) |
Cell Envelope Peptidoglycan |
NAG-NAM structural component functions: maintain cell shape, resist osmotic stress Contain Teichoic Acid in Gram POSITIVE Lysozyme breaks down PG ; |
NAG-NAM |
dissacharides bonded in rows/columns by polypeptides (sugars linked with proteins) ; Pentaglycine bridge is Gram positive |
Gram Negative Cell Wall |
2 layers: 1) Thin layer of Peptido Glycan 2) Surrounded by outer membrane linked by lipoproteins |
Cell Membrane Properties |
membrane fluidity: short tails and double bonds (enables growth at lower temps) ; lack of fluidity (growth at higher temps) |
Cytoplasmic membrane Function |
distinguishes self from environment site of ATP synthesis entry/exit control synthesis site for cell wall and surface components maintains proton motive force |
Membrane Protein Function |
Proteins*20 amino acids connected by peptide bonds that fold into 3D structures* synthesis of cell wall components respiratory enzyme/ATP synthesis Transport across membrane |
Protein Transport functions diffusion, facilitated diffusion, active transport, group translocation, secretion |
Diffusion: molecules move freely energy independent (hi;low) Facilitated Diffusion: carrier protein, requires concentration gradient (hi;low)
Active Transport: works against concentration gradient, requires energy (ATP;ADP) Group Translocation: Phosphorolation (molecule chemically modified by phospho group), requires energy Secretion: multiple pathways |
Are all Cellular Membranes the same? |
No. Phosopholipids: fatty acid composition, molecule attached to phosphate ; Differences used for classification |
Nucleoid |
one circular chromosome in the;cytoplasm containing supercoiled DNA that is not membrane bound, additional DNA present as plasmids ; |
Endospores (spores) |
Gram positive most resistant biological structure known Resting Stage; non reproductive |
Flagella Types |
Polar: one flagella at one end of rod Bipolar: 2 flagella, on opposite ends Peritrichous: 4 flagella Lophotrichous: multiple flagella at one end *H-antigens |
Cell Membrane Structure |
Phospholipids: polar head, nonpolar tail Amphiphatic: assembles into bilayers |
Archael Membranes ; |
No peptidoglycan ; |
Cytoplasm ; |
rudimentary cytoskeleton contains ribosomes |
DNA replication |
semiconservative: each strand is a template for DNA ; Initiation Elongation Termination |
DNA replication (E. coli): Initiation |
Origin: ori;C (Adenine/Thymine rich) DnaA (initiator protein) binds and unwinds DNA at;ori C uses energy (ATP;ADP), forms replication bubble Helicase seperates unwound DNA into leading strand (3'→5') and lagging strand (5'→3') ; |
Important Elongation Polymerases |
DNA Pol I: reads fragments, replaces RNA nucleotides with DNA nucleotides DNA Pol III: Needs DNA template, Nucleotides, Primer |
DNA replication Elongation |
Template strand (leading) always 3'-5' DNA pol III adds DNA on template strand in 5'-3' direction following RNA pol Okazaki fragments synthesize short pieces in the 5'-3' direction on lagging strand |
Elongation cont'd |
DNA pol III falls off DNA pol I cuts of RNA nucleotides and replaces with DNA nucleotides Finally DNA ligase seals gaps |
DNA replication Termination |
2 ways: Tus protein recognize ter sites
Bacteria have a cyclic chromosome |
Post-Replication Events |
DNA is methylated (protection): masks DNA to not destroy good DNA
Methylation proteins recognize new strand (unmethylated) and old strand (methylated) and repairs errors
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Plasmids |
*DNA not located on the chromosome replicates like DNA with pol, but on smaller level
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Replisome |
Starts new round of replication to speed the replication process |
Replication Summary |
Must be rapid and efficient Semiconservative DNA synthesis occurs in the 5'-3' direction Methylation protects/aids mutation recognition Multiple rounds of replication |
Plasmids |
Conjugation: bacterial sex; plasmids copied and transferred to another bacterium by sex pilus Selective advantage: Can spread genes Types: transmittance: F plasmids, fertility Antibiotic resistance: R plasmids Xenobiotic degradation: oil eaters Virulent
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Plasmids cont'd |
Plasmids can be isolated and studied At higher temperatures, plasmids can be 'cured' from the organism, then see if the trait is lost Curing: growing bacteria at a higher temperature so it throws plasmid out because it's not necessary
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Polymerase Chain Reaction (PCR) |
Amplifies specific regions of DNA in vitro (out of cell) replication of target DNA Needs: DNA, Taq polymerase, dNTP, DNA primers 1) Heating: Melt H-bonds 2) Annealing: primers find complimentary bases 3) Elongation: DNA polymerase |
Recombination Types |
Recombination: trade chromosomes Homologous Recombination: Rec proteins help incorporate new DNA Non-Homologous Recombination: rare in bacteria, 2 random ends of DNA glued by ligase |
Transpons |
Mobile element or "jumping gene" Jumps to a different place on the chromosome and copies itself Plasmids can spread with transpons |
Types of Media |
Solid/Liquid defined media: uses pure chemicals in known concentrations complex media: ingredients present, but not chemically defined |
Classification of Media |
General Purpose: complex, nutrient agar/broth; general growth Differentiation: blood agar; bacteria lyse RBCs Selective: MacConkey agar; selective for Gram negative, first step in ID of bacteria Enrichment: contains components that promote growth; *defined medium
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Growth Curve |
X-axis: Time Y-axis: log #of visible cells phase 1: lag phase Phase 2: log phase (exponential phase) Phase 3: stationary phase Phase 4: Death phase |
Nutrient Limitation Adaptation Strategies |
*organisms in nature are usually stressed Dormacy: spore formation in bacteria Reproduction: spore reproduction in molds Habitat Selection: most important (food!) Alter Metabolism: shut down non-essential proteins, induce proteins that aquire nutrients Adhesion
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Metabolism |
Chemical reactions occuring within an organism |
Catabolism |
Metabolic break down **Releases energy** |
Anabolism |
Biosynthesis: Synthesis of necessary cell components for growth; building up **Requires energy** |
Metabolism is tightly controlled |
Specific enzymes and Regulated enzymes Nutrients, Energy & Reducing Power: Required for survival Metabolic energy is stored as membrane potential (ATP) Reducing power stored as NADH or FADH2 |
Polymers→Monomer→End products (building blocks) |
polymers are insoluble and broken down by secreted enzymes then the monomers are transported by active transport/group location
eg. Cellulose (insoluble) → Cellubiose (soluble)→ Glucose (soluble) |
Monomers |
Once transported inside the cell, they are burned (catabolic) and captured as ATP, NADH, FADH2
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Monomer Pathways |
Glycolysis: catabolic reax, break down glucose and stored; glucose in→pyruvate out Entner Douderoff: Catabolic reax; glucose→ATP, not as effective Pentose Phosphate: Generates Ribose; used for DNA/RNA Kreb's cycle: central hub substrate level phosphorylation: catabolic; coupled directly to ATP production |
Respiration |
Uses electron transport chain (ETC) often implies aerobic catabolism; **not always (anaerobic respiration) |
Biosynthesis of Proteins |
; Polymers formed from Monomers Amino Acids;; Proteins (Transcription) ; |