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Phenol Coefficient
- Compares how good something is to phenol
- Done in liquid form
- High Number: Kills more bacteria than Phenol
- Low Number: Did worse than Phenol (didn't kill enough)
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Kirby-Bauer Method
- Susceptibility testing
- Taking bacteria and creating a lawn on a plate, then placing an antibiotic disk on it.
- Every hospital in the world does it the same
- Zone if Inhibition: Where cells are being killed around the disk
- Cells that don't have a zone are considered Resistant
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Disc Diffusion
- Very similar to Kirby-Bauer but with chemicals
- Not nearly as standardized
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Mechanisms of Action for Disinfectants
- Denature proteins (changes structure)
- Surfactants on Membrane (makes items soluble, will now wash away with water)
- Alkylating Agents: Nulceic Acids, can replace hydrogen bonds, increasing the pH
- Viruses can be killed easy
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Classes of Disinfectant
- Acids: Change in pH to kill microbes
- Metals: Silver, Mercury, reactive with proteins (Kills Disulfide Bridges), can't become to resistant
- Soaps: Surfactants, Contain Alkali and Sodium, kill bacteria and some viruses
- Halogens: Chlorine (bleach), Iodine (7 electrons in outer shell, breaks down proteins/lipids by stealing electrons
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Alcohols
- Kill bacteria and fungi
- NOT: Endospores, non-enveloped viruses
- Protein denaturation and lipid disruption
- Evaporates, rapidly pulling water with it
- Good for wiping skin
- Bad for wounds (coagulation of a layer of protein leaves bacteria to grow)
- Need water for denaturation reactions
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Hydrogen Peroxide
- 100% used to clean Biosafety rooms
- Kills everything known to man
- R2D2 of death
- Superoxide: bounces around and kills everything
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DNA Structure
- All information necessary for for life is stored in an organisms genetic material - DNA and in some cases RNA
- Anti-parallel, 3' and 5' ends
- Double Stranded
- Double Helix
- Sugar-Phosphate Backbone
- Base Pairs: A/T and G/C
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Heredity
- Transmission of information to the offspring
- Genetics: the study of heredity
- Genome: Genetic information in a cell
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Chromosomes
- Prokaryotes: 1 circular chromosome (vibrios have 2), 1000X longer than the cell (Supercoiling)
- Eukaryotes: Linear, where duplicated, histones to wind up DNA
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Genes
- Basic unit of heredity
- Linear sequence of genetic information
- Usually 1 gene = 1 function
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Locus
Location of the specific gene
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Allele
- Multiple copies
- Genes with different information at the same locus
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Average Gene Size
1000 base pairs/nulceotides
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100K Genome Project
- Based on food born pathogens
- The goal is to create a catalog with 1000 pathogens.
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Genotype
- Information that encodes all the traits of an organism
- Potential properties of the organism
- ALL of the genes
- Mutations change
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Phenotype
- The actual expressed properties of the organism
- Manifestation of the genotype
- Only what is turned on in the cell
- Mutations do not changes
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Central Dogma
- Replication: DNA makes new DNA (daughter cells)
- Transcription: DNA makes RNA as the first step in protein synthesis, new polymer is mRNA (where amino acids are made), can do it backwards for retroviruses
- Translation: RNA codes for amino acids and links them together to form proteins
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DNA Binding
- DNA: A binds to T, and G binds to C
- RNA: A binds to U now (instead of T), and G still binds to C
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Topoisomerase
- DNA Replication
- Unwinds DNA
- Relaxes supercoiling at the end of the replication fork
- Separates DNA circles at the end of replication
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Helicase
- DNA Replication
- Pulls double-stranded DNA apart
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Single Stranded Bind Proteins
- DNA Replication
- Keeps the single strands pulled apart
- Holds replication fork open
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Primase
- DNA Replication
- Creates short double stranded pieces
- Drops in nucleotides
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Polymerase
- Replicates DNA
- Copies of RNA form a DNA template
- Problem: Moves in 3' to 5' direction (only 1 way)
- Attaches and never stops
- Problem: needs double stranded pieces to start
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Ligase
- DNA Replication
- Connects to Okazaki Fragments
- Makes covalent bonds to join DNA strands
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Leading Strand
- Polymerase moves into the replication fork.
- Goes from 3' to 5', to the right
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Lagging Strand
- Moves away from the replication fork
- Still 3' to 5', goes left
- Has Okazaki Fragments
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Okazaki Fragments
- Short pieces of DNA on the lagging strand
- DNA ligase connects them back together
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Semiconservative Replication
Origin of replication of a chromosome
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