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Micro Test 2
| Question | Answer |
|---|---|
| Common additives of Media | Peptone Yeast Extract Chocolate Blood Casein Hydrolysate |
| 6 major types of Media | Defined, Complex, Selective, Differential, Anarobic, Transport |
| Defined Media | Know exacty what is in it |
| complex Media | Less defined |
| Selective Media | Select what to grow. Encourages and Discourages |
| Differential | Differentiated by the way they look |
| Anaerobic | Can't tolerate oxyegen |
| Transport | Clinical Samples |
| Growth Requirements for Bacteria | Nutrients: Carbon, Oxygen, Nitrogen, Hydrogen |
| Characteristics and Uses of Bactriophage | Virus that infects and replicates within bacteria |
| pH at which microbes grow best | 7 (neutral) |
| Purpose of Agar in Nutrient Agar | To customize the media for the specific bacteria so that growth medium is as close as possible to natural environement |
| Types (genera) of bacteria that form spores: | Gram-positive bacteria. Bacillus and clostridium |
| Meaning of Selective Media and examples | Mannitol Salt Agar- Alchol carb utilized by staph and salt that inhiits other bacteriosis Mehtylene Blue: Carbs promote growth of E-coli and gram degative die, inhinit gram positive |
| Meaning of Differential media and example | Macconkey contain lactose, neurtal red and crystal violdet and dye inhibits gram positive |
| Optimal temp for psychrophiles | below 25 C |
| Optimal temp for Mesophiles | Between 25-40 C (this includes hman pathogens |
| Optimal temp for thermophiles | above 40 C |
| Lag phase | preparing for divistion. Grow imn size and meabolically active, but not reproductive |
| Log phase | reproductively active. Increase in number. Symptoms appear due to cell/tissue damage |
| Stationary Phase | equalization; reproductive and death rates are equal; number of living cells are constant; immune system has been activated |
| Death/Decline Phase | cell death; death rate higher than reproductive rate (log decrease) |
| What methods are direct to measure microbial growth? | 1)Viable plate counts 2)Membrane filtration 3)Microscopic counts 4)Electron counters 5)Most probable number |
| What methods are indirect to measure microbial growth? | 1)Metabolic activity 2)Dry weight 3)Turbidity |
| Steps of Viral Replication | -Attachment -Penetration -Biosynthesis -Maturation -Release |
| The structure that all viruses possess | A core of nucleic acid and a protein coat |
| Cytopathic effects that are cytocidal: | refers to degenerative changes in cells, especially in tissue culture, and may be associated with the multiplication of certain viruses |
| Features of oncogenes (genes that transform a cell): First 2/3 | -May provide genetic codes for growth factors to stimulate uncontrolled reproduction -May program development of protein receptors that receive extracellular messages to nucleus at rapid rate |
| Features of oncogenes (genes that transform a cell): 3/3 | -May become incapable of producing substances that turn off cell growth |
| Methods of culturing viruses: | -Animal inoculation -embryonated eggs -tissue culture -organ culture -explant culture -cell culture -primary culture -diploid culture -continuous culture |
| Characteristics of a prophage: | A prophage is a viral genome inserted into the host cell DNA which then either integrates or exists as an extrachromosomal plasmid. They are the main component of viral gene transfer. |
| What is formaldehyde used for? | Formaldehyde is a chemical agent used to inactivate a virus by altering its genome |
| What is meant by a slow viral infection? | A slow viral infection is characterized by a very prolonged incubation period and a prolonged, slowly progressive clinical course. |
| Examples of slow viral infections: | Herpes, shingles from chicken pox |
| When is the cytopathic effect seen? | The cytopathic effect (CPE) is seen when a virus replicates |
| Support for the idea that viruses are nonliving: | Viruses cannot reproduce themselves outside of a host. |
| How bacteriophages contribute to bacterial virulence | By giving a new gene sequence to the host bacteria |
| How and when are viral envelopes acquired? | How: By budding off from a host cell. They gain the envelope from the host's lipid bilayer (cell membrane) When: Envelopes are acquired when a virus leaves a cell |
| Order of assembly of viral components of a cell: | 1. Assembly of the capsid (the capsid is also referred to as a protein capsule) 2. Association with the nucleic acid |
| Factors that regulate the ability of a virus to infect an organism: | A virus can infect any living organism, including plants. |
| Effects of mutagenic agents on bacteria: | always change the genotype (genes) |
| Important genes carried on plasmids | |
| The use of the Ames test: | Used to determine if a substance is mutagenic by testing its ability to induce mutations in bacteria based on the finding that 90% of human carcinogens cause mutations |
| Example of the Ames test | For Example, in bacterial salmonella typhimurium that cannot metabolize histidine is placed on histadine medium and carcinogen is added mutations restoring histidine metabolism occur easily, and colonies grow if substance is carcinogenic |
| Characteristics of plasmids | closed loops separate from the bacterial DNA, Self replicating without help of bacterial DNA, and common in gram negative bacteria. |
| What types of genes exist on plasmids: | |
| How nitrous acid causes mutations: | converts adenine to hypoxanthine, hypoxanthine pairs with cytosine instead of thymine causes mRNA to code for guanine (not adenine). |
| Characteristics of the bacterial chromosome | a.Single double helix in a closed loop b.Not enclosed by a membrane c.Tightly coiled: when unraveled, about 1 mm long. |
| Point mutation- how does it affect gene expression | base substitution; changes a single codon only. |
| Frameshift mutation-how does it affect gene expression | insertion or deletion of a base; changes entire sequence thereafter. |
| Differences between conjugation, transformation and transduction: | Transformation involves acquisition of DNA from the environment, conjugation involves acquisition of DNA directly from another bacterium, and transduction involves acquisition of bacterial DNA via a bacteriophage intermediate. |
| Components of an operon | Inducible operons and Repressible Operons |
| Inducible operons- how and what they regulate | must be activated by inducers, Lactose Operon |
| Repressible Operons - how and what they regulate | transcribed continually until deactivated by repressors, Tryptophan Operon |
| How mutations in overlapping genes may affect protein production: | |
| Use of restriction enzymes: | Specific endonucleases used to cut DNA @ specific sites |
| Uses of genetic engineering and recombinant DNA technology: | Chemical production ( insulin, interferon, human growth hormone, tissue plasminogen activator), animal gene alterations, gene probes |
| Steps used to produce a recombinant vector: First 2/4 | (1) Ligase anneals the fragments to produce a recombinant plasmid (2) After the recombinant plasmid has been inserted in a bacterial cell |
| Steps used to produce a recombinant vector: steps 3 and 4 | (3) the bacteria are grown on a medium containing the antibiotic (4); only those cells that contain the recombinant plasmid (and thus the human growth hormone gene as well) can grow on the medium. |
| what kind of memebranes are used in the Southern Blotting techniques because they are less delicate | Nitrocellulose |
| Purpose of PCR (polymerase chain reaction) | Produce a large number of identical molecules of DNA in vitro |
| Gene library purpose, what it’s used for and what it consists of: | Entire genome of an organism is cut with restriction enzyme (frequent cutter) Ligated into vector (plasmid or phage) Transformed into bacterial cells and store for future use |
| Uses for Southern Blot: | Used to transfer DNA fragments from a gel to a nylon membrane |
| Temperatures used and steps in PCR (polymerase chain reaction) | 1. Denaturation – heat to 94*C 2. Priming – cool to 65*C 3. Extension – 72*C 4. Repeat |
| Effects of mutagenic agents on bacteria | always change the genotype (genes) |
| The use of the ames test | Used to determine if a substance is mutagenic by testing its ability to induce mutations in bacteria based on the finding that 90% of human carcinogens cause mutations |
| Characteristics of plasmids: | closed loops separate from the bacterial DNA, self replicating without the help of bacterial DNA, and common in gram negative bacteria |
| Why types of genes exist on plasmids | R Factors, provide antibiotic resistance |
| How nitrous acids cause mutations | converts adenine to hypoxanthine, hypoxanthine pairs with cytosine instead of thymine and causes mRNA to code for guanine instead of adenine |
| Characteristics of the bacterial chromosome: | A. Single double helix in a closed loop B. Not enclosed by a membrane C. Tightly coiled: when unraveled, about 1mm long |
| Types of mutations and how they affect gene mutation | a. Point mutation: base substitution; changes a single codon only b. Frameshift mutation: insertion or deletion of a base; changes entire sequence thereafter. |
| Differences between conjugation, transformation, and transduction | Transduction involves acquisition of DNA from the environment. Conjugation involves acquisition of DNA directly from another bacterium via a pilus Transduction involves acquisition of bacterial DNA via a bacteriophage intermediate |
| Components of an operon and how and what they regulate | Inducible operons – must be activated by inducers, IE: lactose operon Repressible operons – transcribed continually until deactivated by repressors, IE: tryptophan operon |
| Symbiotic relationship in which one member benefits without significantly affecting the other. | Commensalism |
| Time required for a cell to grow and divide. | Generation Time |
| Microorganism which requires low levels of oxygen | Microaerophile |
| Symbiotic relationship in which both members benefit from their interaction | Mutualism |
| Symbiotic relationship in which one organism derives benefit while harming, or even killing, its host. | Parasitism |
| Microorganism requiring cold temperatures (below 20¦C). | Psychrophile |
| Interplay between drugs that results in efficacy that exceeds the efficacy of either drug alone. | Synergism |
| Microorganism requiring temperatures above 45¦C. | Thermophile |
| Environmentally resistant structure produced by the transformation of a vegetative cell of the Gram-positive genera Bacillus or Clostridium. | Endospore |
| Type of nutation in which a nucleotide base pair is replaced | Substitution |
| A genetic mutation affecting only one or a few base pairs in a genome. Point mutations include substitutions, insertions, and deletions | Point Mutation |
| Type of mutation in which a base pair is inserted into a genetic sequence | Insertion |
| Type of mutation in which a nucleotide base pair is deleted | Deletion |
| A substitution in a nucleotide sequence resulting in a codon that specifies a different amino acid: what is transcribed makes sense, but not the right sense. | Missense mutation |
| A substitution in a nucleotide sequence that causes an amino acid codon to be replaced by a stop codon. | Nonsense Mutation |
| Mutation produced by base-pair substitution that does not change the amino acid sequence due to the redundancy of the genetic code. | Silent Mutation |
| Process by which a protein’s three-dimensional structure is altered, eliminating function. | Denaturation |
| negative feedback) Method of controlling the action of enzymes in which the end-product of a series of reactions inhibits an enzyme in an earlier part of the pathway | Feedback Inhibition |
| The use of recombinant DNA technology to insert a missing gene or repair a defective gene in human cells. | Gene Therapy |
| A small, circular molecule of DNA that replicates independently of the chromosome. Each carries genes for its own replication and often for one or more nonessential functions such as resistance to antibiotics. | Plasmid |
| Enzyme which cuts DNA at specific nucleotide sequences and is used to produce recombinant DNA molecules. | Restriction Enzymes |
| a signaling chemical that bacteria that use quorum sensing produce and secrete | Inducer |
| - a particular DNA sequence is inverted, resulting in an ON to OFF switch and vice versa of the gene located within or next to this switch | Inversion |
| a regulatory protein that binds to an operator and blocks transcription of the genes of an operon | Repressor |
| a single mRNA encoding several different polypeptide chains. | Polycistronic |
| A substance that combines with and activates a genetic repressor, thus preventing gene transcription and inhibiting protein synthesis | Corepressor |
| a chemical analog of one of the purine or the pyrimidine bases normally found in RNA or DNA | Base Analog |
| produced at a steady rate, independent of internal or external stimuli. Said of enzymes, RNA or protein by an organism | Constitutive |
| A Theta structure is an intermediate structure formed during the replication of a circular DNA molecule (prokaryote DNA), two replication forkscan proceed independently around the DNA ring and when viewed from above it resembles the Greek letter "theta" | Theta Structure |
| operon required for the transport and metabolism of lactose in Escherichia coli and some other enteric bacteria. It consists of three adjacent structural genes, lacZ, lacY and lacA | Lactose Operon |
| when something (a protein/transcription factor) binds to the regulatory sequences of a gene (either a promoter or operator) and represses that gene's expression (i.e. makes it so RNA is not produced) | Negative Regulation |
| Genes having nucleotide sequences that may overlap in a way that involves control genes or structural genes | Overlapping Genes |
| An immune system cytokine secreted by macrophages and T cells to kill tumor cells and to regulate immune responses and inflammation. | Tumor Necrosis Factor |
| A protein coat surrounding the nucleic acid core of a virion | Capsid |
| Protein molecules that inhibit the spread of viral infections. | Interferons |
| Mouth lesions characteristic of measles. | Koplik Spots |
| Process of viral replication in which a bacteriophage enters a bacterial cell, inserts into the DNA of the host, and remains inactive. The phage is then replicated every time the host cell replicates its chromosome. Later, the phage may leave the chromoso | Lysogeny (Lysogenic replication cycle) |
| Aggregates of virions in the brains of rabies patients. | Negri bodies |
| Proteinaceous infectious particle that lacks nucleic acids and replicates by converting similar normal proteins into new prions | Prions |
| Any 1ssRNA virus that uses the enzyme reverse transcriptase carried within its capsid to transcribe DNA from its RNA. | Retrovirus |
| (lysogenic phage) Bacteriophage that does not immediately kill its host cell. | Temperate Phage |
| (provirus) An animal virus that remains inactive in a host cell. | Latent Virus |
Created by:
skline1982
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