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Micro Test notes 2


Necessary for growth, primary component of cell structure. Water
Types of environments? Hypotonic, Isotonic, and Hypertonic
Water flows into the cell and cell eventually explodes Hypotonic environment
Water flows out of the cell and cell shrinks and dies Hypertonic environment
microbes are able to live/adapt to mildly hypertonic environments osmotolerant
Microbes require extreme hypertonic environments to survive osmophilic
Microbes living in the dead sea, great salt lake and adapt by using salts as necessary integral components of cell structure. Halophiles (osmophilic)
A measure of Hydrogen ion concentration pH 0-14
pH 0-5.5, fungi, algae, helicobacter pylori, acidic environment, use active transport to pump out excess hydrogen ions, create acid shock proteins that help prevent denaturation if cytoplasm is to acidic. Acidophites
High pH alkaline, basic, low hydrogen concentration
Low pH Acidic, high hydrogen concentration
pH 5.5 to 8.5, most microbes, hydrogen ions flow evenly by facilitated diffusion Neutrophiles
pH 8.5 to 14, only bacteria, alkaline environment, use active transport to pump hydrogen ions back into the cell. Alkalophiles
Poikilotherms (varied irregular heat), temp varies with environment Temperative
Cardinal Temps a minimum temp for growth. a optimum temp for growth. a maximum temp for growth.
Classes of Microbes by Temp Psychophiles, Psychrotrophs, Mesophiles, Thermophiles, Hyperthermophiles.
microbes found living on glaciers and snowfields, Chlamydomonas nivalis (watermelon snow), not human pathogens, have and increased concentration of unsaturated fatty acids in plasma membrane. Psychophiles
Main cause of food spoilage in the fridge, cause off color, smell, bad taste etc. not significant human pathogens Psychrotrophs
Most microbes are in this group including human pathogens. Mesophiles
Found in hot water springs, pipes, hot springs, compost piles, not human pathogens, important in biotechnology, heat stable enzymes, TAQ polymerase used to copy DNA in PCR(Polymerase chain reaction). Thermophiles
Found in deep sea hydrothermal vents, volcanic springs, pyrococcus abyss, adapt by increase concentration of saturated fatty acids in plasma membrane. Hyperthermophiles
With oxygen Aerobic
Without oxygen Anaerobic
Use aerobic respiration for growth, growth is quicker but creates free radicals which must be destroyed by creation of enzymes, to prevent cell damage. Aerobic cells
Use anaerobic respiration or fermentation for growth, although growth is slower, no free radicals to worry about Anaerobic cells
Classes of Microbes by Oxygen Obligate aerobes, Facultative anaerobes, Aero-tolerant anaerobes, Microaerophiles.
Microbes will die if oxygen not present. Top of tube. Obligate aerobes
If oxygen present microbes will use it and grow most quickly if oxygen is not present growth is slower. Microbes throughout tube although more prominent at top. Facultative anaerobes
Do not use oxygen grow equally well with or without oxygen. Evenly throughout tube. Aero-tolerant anaerobes
Require oxygen but at reduced concentration 2-10% atm. Bacteroides gingivalis. Fine line of microbial growth somewhere near top of tube. Microaerophiles
Microbes are able to survive and grow up to a max of about 400 atm but grow more quickly at lower pressure. Barotolerant
Thriving under high environmental pressure Barophilic
Expose food to rapid changes in pressure to control growth of pathogens in food. High Pressure Pasteurization (HPP)
Three basic nutritional requirements for microbial growth? Source of nutrients, energy and electrons or hydrogen atoms that donate electrons.
MIcrobes that create every compound for growth, assuming 3 basic nutritional requirements are available. Prototrophs
Cannot create every compound for growth, need growth factors. Auxothrops
Vitamins, amino acids, purines, pyramidines. Growth factors
Has the ability to store information, information can be copied/replicated and passed to offspring. DNA (deoxyribose neucleic acid)
The subunits that compose DNA? Nucleotides
Each nucleotide has three components. 5 carbon sugar (in DNA deoxyribose)(in RNA ribose), phosphate group, and nitrogenous group.
In DNA nucleotides 4 possible nitrogenous bases? adenine, guanine, thymine, cytosine.
Purine Double ring, adenine+guanine
Pyrimidine Single ring, Thymine+Cytosine
In RNA 4 possible nitrogenous bases? adenine, guanine, cytosine, uracil.
DNA is like a ladder side rails? Alternating phosphate and sugars
DNA is like a ladder rungs? Nitrogenous bases
Adenine+Thymine 2 H bonds
Cytosine+Guanine 3 H bonds
The entire sequence of DNA in an organism? Genome
Genome is divided into 2 general regions? Gene, and Non transcribed region.
Region of DNA that is transcribed into single messenger RNA and translated into a polypeptide (protein product) Gene
Includes many regions with currently unknown functions and promoters= non transcribed region of DNA that control gene expression (how often a gene gets used). Non transcribed region
The synthesis of RNA under the direction of DNA. DNA template to create a mRNA (complementary)of the DNA. Transcription
Use mRNA to create the appropriate polypeptide. Translation
In translation mRNA is read in blocks of nucleotides. Codons, each codon specifies codes for a particular amino acid.
Two basic mechanisms to generate genetic diversity. Mutation, and genetic recombination
A stable heritable change in DNA sequence. Mutation
One sequence is altered does not change back. Stable mutation
Change in DNA sequence are passed to offspring Heritable mutation
A change in DNA sequence that is harmful or adverse for the organism. (e.g. mutation inhibits/blocks ability to create glycocalyx) Negative mutation
Change in DNA sequence that neither harms or benefits the organism. Could result from redundancy in genetic code. Silent mutation
Change in DNA sequence that alters a structural feature of the organism (e.g. cell shape, size, cell wall). Morphological mutation
Change in DNA sequence that alters a biosynthetic or other enzymatic pathway (e.g. microbe loses the ability to create folic acid a vitamin required for growth). Could cause a prototroph to become axotroph. Biochemical mutation
Change in DNA sequence that only effects the microbe in specific environments. (e.g. ability to create penicillinase). Only beneficial with penicillin present. Conditional mutation
Change in DNA sequence that alters the identity of one or more nucleotide base pairs does not alter total number of nucleotides. Base substitution
A base substitution in DNA may lead to changes in the polypeptide product. Missense mutation, nonsense mutation, silent mutation, frameshift mutation.
Change in DNA sequence that alters the identity of one or more amino acids in the polypeptide product. Missense mutation
Change in DNA sequence that eliminates the start codon or creates a premature stop codon. Nonsense mutation
Change in DNA sequence that does not alter the polypeptide product (due to redundancy). Silent mutation
Occurrence of linearly arranged, largely identical, repeated sequences of DNA. Redundancy
Change in DNA sequence in which one or more nucleotide base pairs are inserted into or deleted from the sequence also alters the total number of nucleotides. Could lead to missence mutation, nonsense mutation, or silent mutation. Frameshift
Two cause of mutation? Spontaneous mutation and induced mutation
A change in DNA sequence that occurs during DNA replication due to error by the polymerase. Relatively rare 1 in 1,000,000 genes copied Spontaneous mutation
Enzyme that copies the DNA during transcription. Polymerase
A change in DNA sequence caused by exposure to a mutagen (any chemical or physical factor that alters the DNA sequence). Nitrous acid causes base substitution, and benzpyrene causes frameshifts. Higher frequency 1 in 1000 genes copied. Induced mutation
Genetic diversity is created by? mutation or genetic recombination
In Eukaryotes genetic recombination occurs by? Sexual reproduction
The process by which a strand of genetic material (usually DNA; but can also be RNA) is broken and then joined to a different DNA molecule. Genetic recombination
In prokaryotes genetic recombination occurs by? One way transfer of DNA from a donor to a recipient cell.
3 mechanisms of one way transfer. Conjugation, transformation, and transduction
One way transfer of DNA between two cells in temporary physical contact, physical contact created by the sex pilus. Conjugation
First evidence of conjugation 1946 Lederberg and Tantum
The uptake of naked DNA by a competent cell. Uptake by modified sex pillus. Transformation
First evidence of transformation. 1928 injection of mice with S. Pneum. with capsule mouse dies, without capsule mouse lives,with capsule killed by heat mouse lives.
One way transfer of DNA from donor to recipient by a bacteriaphage (a virus that infects bacteria). Transduction
A process that removes or destroys all vegetative cells (dormant, bacteria, fungi, algae, protozoans), endospores and viruses. Sterilization
A process that removes destroys or inhibits the growth of disease causing (pathogenic) microbes. Disinfection
A process that reduces microbial number to a level considered safe by the public health standards. Sanitation
A process that removes destroys or inhibits the growth of pathogenic microbes on living tissues. Not as strong as disinfectants would not damage skin. Antiseptics
Anti-microbial agents vary Range in action, and strength of action.
Strength of action may be cidal or static.
Agent kills the target microbes Cidal
Agent inhibits the growth of the target microbes (e.g. germ static vs. fungicidal) Static
Factors that affect efficiency of antimicrobial agents. Duration of exposure, Presence of organic debris, and surface features, temperature, concentration, population size, population composition.
Chemical anti-microbial agents capable of sterilization. Aldehydes and Sterilizing gases.
2 main types of antimicrobial agents. Chemical agents and physical agents
Most are capable of sterilization most can only disinfect. Chemical agents
Most are capable of sterilization Physical agents
Physical antimicrobial agents Heat, Autoclaving, Boiling water, Fractional steam sterilization, dry heat sterilization, Pasteurization, Filtration, and radiation.
How would you know if autoclave is working properly? Autoclave tape, growth check, endospore strip.
3 day process that kills all endospores Fractional steam sterilization
Commonly used for items such as metal or glass that would corrode from moist heat. Typical run 160-170 degrees celsius for 2-3 hrs. Without moisture both time and temp required to sterilize increase. Dry heat sterilization
Goal is to destroy pathogenic microbes and microbes that would spoil the food without altering taste, texture, nutritional quality of the food. Pasteurization
Used for heat sensitive liquids. Filtration
Types of Filtration Depth filtration, and Membrane filtration
Composed of fibrous or granular materials compacted into a thick layer. Depth Filtration
Composed of a thin layer with holes of a defined size. Membrane filter traps any microbe larger that the pore size (e.g. fecal coli forms) Membrane Filtration
HEPA filters pore size 0.45 nm
Smallest filter pore size 0.01 nm
Use to sterilize heat sensitive plastics, suture material, tubing, hormone solutions, vaccinations, medical waste, surgical instruments. Energy disrupts chemical bonds and causes denaturation. Radiation
Relatively lox energy poor penetration, but can cause lethal DNA mutations. Microbes must be directly exposed to cause damage. Ultra Violet Radiation (UV)
Uses an electron accelerator to shoot a stream of electrons at items to be sterilized. Higher energy than UV penetration about 2 inches, currently used to sterilize medical and clinical supplies and water. E-Beams (electron)
Created using electron accelerator to create photons (no mass). Higher energy than E-Beams, also used to sterilize clinical supplies. X-Rays
Photons given off from the decay of certain radioactive elements (e.g. cobalt 60). Highest energy best penetration for sterilization. Gamma Rays
Created by: Hector1006