MICR 3050- Majors Final Exam Unit 4

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What is a virus?
Genetic elements that replicate independently of a cell's chromosome but requires a living host in order to replicate
What makes up a virion?
Nucleic acid surrounded by a protein coat
2 types of symmetry for viruses
Helical Icosahedral
Symmetry for a Bacteriophage
Positive Sense ssRNA Virus
Genome and mRNA are the same
Negative Sense ssRNA Virus
Genome and mRNA and complentary
6 basic steps to viral replication
1. Attachment 2. Entry 3. Uncoating of the Genome 4. Synthesis 5. Assembly 6. Release
Characteristics of the Lytic Cycle
Mulitplication begins immediately after entering the host Bacterial cell lyses to release bacteriophages Ex: T4
Characteristics of the Lysogenic Cycle
Can reproduce as virulent phages OR can remain in cell without destruction Ex: Lambda
What is the process that converts the lysogenic cycle to the lytic cycle?
Nonlytic relationship between a phagee and the host
Where does a prophage always integrate?
Between the galactose and biotin operons
What is the process called when a prophage could change the phenotype of its host?
Lysogenic Conversion
What triggers induction of the lytic cycle?
A drop in the lambda repressor levels
Are animal viruses naked or enveloped?
Virulent Viruses
Follows the lytic cycle Virions are made and the cell lyses
Cancer Viruses
Virus incorporates and mutates the chromosome Series of events must take place in order for the cancer to appear
Latent Viral Infections
Virus stops producing and remains dormant Symptoms/antibodies/virus is no detectable Ex: Herpes Simplex, Varicella
Persistent Viral Infection
Virus is detectable Clinical symptoms can be mild or absent for periods of time Ex: Hepatitis B, HIV
RNA virus that replicates through a DNA intermediate Enveloped Use reverse transcriptase
Location of chromosom and associated proteins in bacteria
Extra chromosomal DNA Usually small, closed, circular DNA Contain non-essential genes Exist and replicate independently
Detecting mutants via observation
Selectable Mutations
Confer some type of advantage to the organisms that possess them
Placing organisms under conditions where the growth of those with a particular genotype will be favored
Homologous Recombination Steps
1. DNA is nicked 2. SSB and Rec A protein complex formed 3. Recipient DNA invaded 4. Crossover
Uptake of naked DNA by a competent cell followed by the incorporation of DNA in the recipient cell's genome
Generalized Transduction
1. Normal lytic cycle 2. Transducing particle with donor DNA and normal phages produced 3. Transducing particle attaches to host cell and injects DNA 4. Homologous recombination
Specialized Transduction
*Carried out by temperate phages and occurs when prophage is excised incorrectly 1. Induction into lytic phase 2. Phage DNA become circular and detaches from host genome 3. Detached DNA replicates 4. Cell lyses
Bacterial Conjugation
Use of a sex pilus between 2 cells to transfer one strand of F+ cell to F- cell where synthesis of a complentary strand takes place
Synthesizes large quantities of a DNA fragment
What are the 4 things required for PCR?
Target DNA Primers Thermostable DNA polymerase Deoxyribonucleotide triphosphates
3 repeated steps of PCR
Denaturing Annealing Extension
3 main steps of molecular cloning
Isolation/Fragmentation of source DNA Insertion of DNA into cloning vector Introduction of cloned DNA into host
What type of ends are better when it comes to restriction endonucleases?
Single Strand Sticky Ends
6 Benefits to using plasmids as cloning vectors
Small Size Easy to Purify Independent ORI Multiple Copy Number Presence of selectable markers Unique Cloning sites
Microbes regularly found at an anatomical site Associated with healthy body-tissue
When does the microflora relationship begin?
At birth
3 microenvironments of the skin
Dry Moist Sebaceous
Characteristics of bacteria of the skin
Low water activity Acid-tolerant Salt-tolerant
Example of commonly found bacteria of the skin
Propionibacterium acnes
Characteristics of the Mouth
Moist Nutrient Rich Neutral pH Ambient Temp
Example of commonly found bacteria of the mouth
Streptococcus spp.
Characteristics of the Stomach
pH of 2 <10 bacteria/mL per person
Bacteria commonly found to survive in the stomach
Heliocobacter pylori
Characteristics of the small intestine
Increasing pH and the number of bacteria as you progress through the small intestines
Bacteria commonly found in the small intestine
Enterococcus faecalis Lactobacilli
Characteristics of the colon
Largest microbial population of the body Most microbes are obligate anaerobes
Bacteria found most commonly in the colon
Bacteroides Clostridium
Bacteria make up what amount of weight of fecal matter?
Bacteria commonly found in the upper respiratory tract
Staphylococci Streptococci
3 benefits of the relationship between the microbiota and host
Colonization Resistance Development of the immune system Produces vitamins, amino acids, and organic acids
Microbes in the host that do not harm the host's tissue
Microbes that develop toxicity or invasiveness and contrinutes to the damage of host tissues
Innate Immunity
1st line of defense Body's ability to recognize and destroy pathogens or their products Lacks memory
Adaptive Immunity
2nd line of defense Body's ability to recognize pathogens based on their antigens Has memory Has the ability to self-recognize