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Genotype
- organism's DNA (collection of genes)
- represents that organism's potential properties
- (soem properties are there, but are not developed or expressed)
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Chromosome
neatly packaged DNA molecule
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Chromosome of a Prokaryote
- the chromosome is referred to as the nucleoid
- DNA is not bund with histone proteins
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Bacterial Chromosome
- most contain a circular DNA
- not wound around histone proteins to form nucleosomes
- few thousand unique genes
- structural gene sequences make up the largest part of bacterial DNA
- one origin of replication to initiate DNA replication
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The Gene
- unit of heredity
- segments of DNA that code to make a particular protein or functional product
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Process of making proteins begins with...
Transcription
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Transcription
- process of making proteins
- begins with transcription
- happens-->1. RNA is copied from DNA
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2 step
2. mRNA will carry the coded info or instr for assembling the polypeptides from DNA to the ribosomes where the polypeptides will be made
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building of polypeptides is called....
Translation
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Translation
- actual building of polypeptides
- deciphering of nucleic acid info and converting that info into a language cell can understand
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replication transcription translation diagram
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Operon Model
how transcription of mRNA is regulated
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Repression
- inhibits gene expression and decreases the synthesis of enzymes
- 1. Repressors
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Repressors
- proteins
- stop the ability of RNA polymerase to initiate transcription from repressed genes
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Induction
- activates transcription by
- producing an inducer (chemical that induces transcription)
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Operon
- functional unit
- include:
- 1. Structural genes
- 2. Regulatory genes
- 3. Control genes
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Regulator
gene that codes for a protein capable of repressing the operon (a repressor)
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Control locus
- (promoter and operator)
- sequence where transcription of the structural genes is initiated
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Structural locus
- three genes
- each coding for a diff enzyme need to catabolize a substance
- catabolize (make a substance undergo catabolism)
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Example of The Operon Model
- ex: Lactose
- when lactose is present, E. Coli synthesizes enzymes needed to break down lactose
- Lactose is an inducer molecule
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If lactose is absent (The Operon Model)
a regulator gene produces a repressor molecule that binds to a control region called the operator site, preventing the structural genes from encoding the enzyme for lactose digestion
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If Lactose is present (The Operon Model)
- it bidns to the repressor at the operator site
- structural genes are released and produce their lactose digesting enzymes
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Genes and enzymes
- genes contain instr for enzymes
- if inducer molecules are present
- bacteria are able to express their genes if this particular nutrient is in the environment
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Transformation (gene 2008)
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Mutation (def.)
permanent change in the DNA sequence
(make certain microorg resistant to antibiotics or increase tehir pathogenicity)
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Mutation effects
- 1. some have an expressive effect
- gene mutates, the enzyme encoded by the gene can become less active or inactive bc the sequence of the enzyme amino acids may have changed
- 2. can be harmful or fatal change to the cell, or it can be beneficial especially if it creates a new metabolic activity
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Types of Mutations
- 1. Point mutation
- 2. Missence mutation
- 3. Nonsense mutation
- 4. Frame Shift mutation
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1. Point Mutation
- (substitution)
- substitution for a normal base
- causing alteration of the genetic code, which then can be replicated
- most common type of mutation
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2. Missence mutation
a new amino acid is substituted in the final protein by the mRNA during translation
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3. Nonsense mutation
- terminator codon in the mRNA appears in the middle of a generic message instead of at the end of the message
- causes premature termination of protein synthesis
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4. Frame Shift mutation
nucleotides are either added or inserted into the DNA strand
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Mechanisms of DNA transfer
- 1. Conjugation
- 2. Transformation
- 3. Transduction
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1. Conjugation
- mechanism of DNA transfer
- plasmid (or other genetic material) is transferred from one bacterium to another throgh a sex pilus
- can share plasmids that are known as resistance plasmids which bear genes that make bacteria resistant to some antibiotics
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2. Transformation
- the acceptance of small fragments of DNA from the surrounding environment by a bacterial cell
- facilitated by competent cells
bacteria can acquire genes for structural components like capsules and fimbriae; or for antibiotic resistance
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3. Transduction
- process by which a bacteriophage serves as a carrier for the transfer of DNA from one bacterium to another
- occurs generally only among bacteria of the same species
- Virulent strains of C. diphtheriae, Clostridium and Streptococcus pyogenes acquire their ability to produce toxins through transduction

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Table of Intermicrobial Exchange
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Sterilization
- destruction of ALL microorganisms, viruses, and endospores
- used in cultured media and prepared food
- performed by:
- 1. Autoclave
- 2. Incineration
- 3. Sterilizing gas (ethylene oxide)
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Autoclave Sterilization
- cylindrical metal container that has a metal tight door to hold one end with racks to holds materials
- complex network of valves
- temperature and pressure gauges
- duct for regulating and measuring pressure and conducting steam into the chamber
- best results is at 15 PSI at 121 temp
- superior choice to sterilize heat resistant mareial such as:
- glassware, cloth, rubber, gloves, metallic equipment, liquids, paper and some heat resistant plastic
- NOT: substances that repel water (wax, oils, powders)

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2. Incineration
- 1. flame of electric heating coil
- 2. Bunsen burners 1870oC
- 3. Incinerators 800-6500oC
- hospital & research labs
- destruction of infectious substances, animal carcasses, and pathology samples
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3. Sterilizing Gases (Ethylene Oxide)
- chemiclaves are automatic ethylene oxide sterilizers
- has gas canisters containing ethylene oxide
- Ethylene's oxide effective insterilizing surgical devices, syringes, and disposable Petri plates
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gases
- Glutaraldehyde- a sterilant for materials usually damaged by heat-respiratory therapy equipment, fiber optic endoscopes, kidney dialysis equipment, alternative vaccine preservative, sanitizer for poultry carcasses.
- Ethylene Oxide-heat sensitive plastics and delicate instruments in hospitals and industries Chlorine dioxide –air and surface sterilant
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Ionizing Radiation
- •Ionizing radiation can penetrate a solid barrier, enter it, and dislodge electrons from it. Breakage of DNA creates massive mutations
- •Completed by gamma rays, X rays, and cathode rays
- •Ionizing radiation can be used on flour, meats, fruits and vegetables
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UV Radiation (Disinfection, not Sterilization)
- UV radiation (nonionizing) excites atoms by raising them to a higher energy state, but does not ionize the. Pyrimidine dimers are formed instead
- Nonionizing radiation can be used for disinfection, but not sterilization
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Antisepsis
- rediction of pathogenic microoragnisms and viruses on living rissue
- any practice that prevents the entry of infectious agents into sterile tissues preventing infection
- Treatment: chemical antimicrobials (iodine, alcohol)
- ex: handwashing, flame sterilization of equipment, and preparing surgical equipment and instruments
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Aseptic (def.)
free of pathogenic contaminants
ex: proper hand washing, flame sterilization equip etc
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Sepsis (def.)
growth of microorganisms or the presence of microbial toxins in the body, blood, and other tissues
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Disinfection (def.)
- destruction or killing of microorganisms and viruses on nonliving tissue by the use of chemical or physical agents
- destroy vegetative forms of pathogens not endospores
- ex: phenols, alcohols, aldehydes, and surfactants
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Halogens
- non mettalic, highly chemical elements which are effective against vegetative cells, fungal cells, fungal spores, protozoan cysts, and many viruses
- inhibit protein function
- ex: Iodine- surgery, campers to disinfect water
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Degermination (def.)
- removal of microorganisms by mechanical means
- ex: cleaning the site of an injection
- using an alcohol wipe
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Pasteurization (def.)
uses heat to kill pathogens and reduce the number of food spoilage microorganisms in food and beverages
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Sanitation (def)
treatment to remove or lower microbial counts on objects such as eating and drinking utensils to meet public health standards
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cide or cidal (def)
death or destruction of an organism
- ex: bacteriocides, fungicides, germicides
- bactericide- agent destroys bacteria but not endospores
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static or statis (def.)
inhibition of growth
- ex: refrigeration, freezing, dissection, and some chemicals
- Bacteriostatic- agent that prevents stops, or inhibits the growth of bacteria
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Iodine
antiseptic prep for surgery and injection, surgical hand scrubs and water treatment
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Phenol
- strongly microbiocidal and destroy vegetative bacterial, fungi, and viruses
- ex: Lysol spray, Triclosan in soaps cosmetics and medications
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