Micro Lecture Exam II (part 2)

• organism's DNA (collection of genes)
• represents that organism's potential properties
• (soem properties are there, but are not developed or expressed)

neatly packaged DNA molecule

• the chromosome is referred to as the nucleoid
• DNA is not bund with histone proteins

• 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

• unit of heredity
• segments of DNA that code to make a particular protein or functional product

Transcription

• process of making proteins
• begins with transcription
• happens-->1.  RNA is copied from DNA

2. mRNA will carry the coded info or instr for assembling the polypeptides from DNA to the ribosomes where the polypeptides will be made

Translation

• actual building of polypeptides
• deciphering of nucleic acid info and converting that info into a language cell can understand

how transcription of mRNA is regulated

• inhibits gene expression and decreases the synthesis of enzymes
• 1. Repressors

• proteins
• stop the ability of RNA polymerase to initiate transcription from repressed genes

• activates transcription by
• producing an inducer (chemical that induces transcription)

• functional unit
• include:
• 1. Structural genes
• 2. Regulatory genes
• 3. Control genes

gene that codes for a protein capable of repressing the operon (a repressor)

• (promoter and operator)
• sequence where transcription of the structural genes is initiated

• three genes
• each coding for a diff enzyme need to catabolize a substance
• catabolize (make a substance undergo catabolism)

• ex: Lactose
• when lactose is present, E. Coli synthesizes enzymes needed to break down lactose
• Lactose is an inducer molecule

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

• it bidns to the repressor at the operator site
• structural genes are released and produce their lactose digesting 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

permanent change in the DNA sequence

(make certain microorg resistant to antibiotics or increase tehir pathogenicity)

• 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

• 1. Point mutation
• 2. Missence mutation
• 3. Nonsense mutation
• 4. Frame Shift mutation

• (substitution)
• substitution for a normal base
• causing alteration of the genetic code, which then can be replicated
• most common type of mutation

a new amino acid is substituted in the final protein by the mRNA during translation

• 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

nucleotides are either added or inserted into the DNA strand

• 1. Conjugation
• 2. Transformation
• 3. Transduction

• 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

• 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

• 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
• 

• 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)

• 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)
• 

• 1. flame of electric heating coil
• 2. Bunsen burners 1870^oC
• 3. Incinerators 800-6500^oC

• hospital & research labs
• destruction of infectious substances, animal carcasses, and pathology samples

• chemiclaves are automatic ethylene oxide sterilizers
• has gas canisters containing ethylene oxide
• Ethylene's oxide effective insterilizing surgical devices, syringes, and disposable Petri plates

• 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

• •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

• 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

• 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 

free of pathogenic contaminants

ex: proper hand washing, flame sterilization equip etc

growth of microorganisms or the presence of microbial toxins in the body, blood, and other tissues

• 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

• 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

• removal of microorganisms by mechanical means
• ex: cleaning the site of an injection
• using an alcohol wipe

uses heat to kill pathogens and reduce the number of food spoilage microorganisms in food and beverages

treatment to remove or lower microbial counts on objects such as eating and drinking utensils to meet public health standards

death or destruction of an organism

• ex: bacteriocides, fungicides, germicides
• bactericide- agent destroys bacteria but not endospores

inhibition of growth

• ex: refrigeration, freezing, dissection, and some chemicals
• Bacteriostatic- agent that prevents stops, or inhibits the growth of bacteria

antiseptic prep for surgery and injection, surgical hand scrubs and water treatment

• strongly microbiocidal and destroy vegetative bacterial, fungi, and viruses
• ex: Lysol spray, Triclosan in soaps cosmetics and medications