Term
| All viruses have a nucleocapsid. What 2 components do all viruses have in their nucleocapsid? |
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Definition
| Nucleic acid (viral genome) and Capsid |
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Term
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Definition
| The protein coating around the genome, determines the shape of the virus |
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Term
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Definition
| Repeating or identical protein subunits that make up the capsid |
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Term
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Definition
| Classification of viruses based on genome |
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Term
| Primary vs. Secondary characteristics of viruses |
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Definition
Primary~ Genome (how they make mRNA)
Secondary~ Envelope & Shape |
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Term
| Naked vs. Enveloped viruses |
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Definition
Naked viruses~ only nucleocapsid
Enveloped viruses~ nucleocapsid enclosed by lipid bilayer |
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Term
| Naked vs. Enveloped viruses |
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Definition
Naked viruses~ only nucleocapsid
Enveloped viruses~ nucleocapsid enclosed by lipid bilayer |
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Term
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Definition
| Protein layer connecting envelope to nucleocapsid |
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Term
| Why are naked viruses more resistant to disinfectants than enveloped viruses? |
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Definition
| Disinfectants destroy the lipid bilayer of enveloped viruses, which are necessary for attachment to the host cell. Naked viruses are not affected and can still attach to host cells. |
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Term
| Viral attachment proteins def. |
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Definition
| Surface proteins of viruses that determine host range and tissue tropism. They are recognized by the immune system, and viral identification |
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Term
| 3 types of viral attachment proteins & def. |
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Definition
Spike proteins~ glycoproteins on envelopes
Tail fibers~ on a complex phage
Fiber proteins~ on capsid of naked viruses |
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Term
| 4 common shapes for viruses |
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Definition
Icosahedral ~ radial symmetry
Helical/Filamentous ~ flexible
Complex/Amorphous ~ no symmetry
Complex-tailed |
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Term
| 3 parts of complex-tailed bacteriophages |
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Definition
Head~ icosahedral, contains genome
Tail~ injects genome into host cell
Tail fibers~ attachment to host cell |
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Term
| 5 steps of viral replication |
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Definition
1. Host Cell Recognition & Attachment
2. Genome Entry
3. Biosynthesis
4. Assembly/Maturation
5. Release & Transmission |
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Term
| Productive vs. Latent phage growth |
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Definition
Productive~ more virions produced and released
Latent (lysogenic)~ viral genome replicates or integrates as circular DNA, no virions produced |
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Term
| Lytic vs. Temperate phage |
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Definition
Lytic (virulent)~ produced by productive growth
Temperate~ produced by lytic growth, can switch to productive growth |
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Term
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Definition
| A non-cellular particle containing a genome that can replicate only inside the host cell |
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Term
| Bacteriophage (phage) def. |
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Definition
| A virus that infects bacteria |
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Term
| 4 Acellular agents of viruses |
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Definition
-No plasma (cell) membrane
-No binary fission
-No way to generate ATP
-No way to synthesize proteins |
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Term
| What 3 things do Obligate Intracellular Parasites do? |
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Definition
-Uses host cell for energy and substrates
-Hijack the host cell's replication machinery
-Direct host cell to express viral genes and proteins |
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Term
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Definition
| A complete virus particle, not broken down |
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Term
| What is a lysozyme used for in the genome entry step for a complex phage? |
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Definition
| Making a hole in the cell wall to inject the viral genome and not the capsid |
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Term
| Where do viral attachment proteins attach to the cell membrane/wall |
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Definition
| On "receptors" (e.g., LPS, porin, pili) |
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Term
| Early vs. Late genes/proteins |
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Definition
Early genes/proteins~ modify or alter the host's replication or transcription
Late genes/proteins~ rebuild the virus (in complex phage; phage-tail, capsomeres, etc...) |
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Term
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Definition
| The number of virions released from a host cell (usually in the hundreds) |
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Term
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Definition
| Clearing on a lawn of bacteria on an agar plate that shows phage infection occurred (lysis or no growth) |
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Term
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Definition
| A temperate phage that integrates its genome into the host bacterial cell. |
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Term
| What do prophages do to the host cell? |
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Definition
| They give the host cell new properties (phenotypes) |
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Term
| 2 types of bacterial defense against phage & how they work |
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Definition
Restriction enzymes~ recognize short DNA sequences and cut foreign DNA (uses methylation)
CRISPR~ crRNA is transcribed from integrated phage sequences in their own genome, CAS proteins cleave DNA, and bacteria target the invading phage DNA sequence. |
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Term
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Definition
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Term
| 2 types of genome entry that often involve the entire nucleocapsid |
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Definition
Endocytosis (by host)~ virus-host attachment triggers endosome formation, the only option for naked viruses
Fusion~ envelope fused with host plasma membrane |
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Term
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Definition
| Capsid is broken down to release the genome once inside the host |
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Term
| Biosynthesis makes what 2 things? |
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Definition
| Viral genome and virus proteins, mechanisms depend on the viral genome |
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Term
| DNA Polymerase template & product |
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Definition
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Term
| RNA Polymerase template & product |
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Definition
| DNA -> RNA (transcription) |
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Term
| Replicase template & product |
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Definition
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Term
| Reverse Transcriptase template & product |
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Definition
| RNA -> DNA (reverse transcription) |
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Term
| Of the 4 polymerases of biosynthesis, which 2 are unique to viruses? |
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Definition
| Replicase and Reverse transcriptase |
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Term
| How are viral genomes more efficient than other genomes? (3 ways) |
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Definition
| Viral genomes can have overlapping reading frames, polycistronic mRNA can encode several proteins, and viral proteins are often translated as one large polypeptide and then cleaved |
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Term
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Definition
| Use DNA and RNA polymerase, and can use either host enzymes in the nucleus or use their own enzymes in the cytoplasm |
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Term
| Why do some DNA viruses replicate in the cytoplasm instead of the nucleus? |
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Definition
| They do not have to rely on the host's cell cycle. |
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Term
| What do proviruses do to a host cell's cell division? |
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Definition
| Increased or unregulated cell division |
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Term
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Definition
| Genes on a provirus that increase cell division and cause host tumor formation |
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Term
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Definition
| Uses replicase to go from +RNA -> -RNA -> +RNA, often happens in the cytoplasm |
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Term
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Definition
| mRNA, can be directly translated |
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Term
| -RNA & dsRNA viruses & what they have prepackaged |
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Definition
| Uses replicase to go from -RNA -> +RNA -> -RNA, often happens in the cytoplasm. Host ribosome cannot synthesize -RNA, so replicase protein is prepackaged |
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Term
| Reverse transcribing viruses |
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Definition
| Uses reverse transcriptase to go from RNA -> DNA and RNA polymerase to go from DNA -> RNA, DNA copy integrates into host genome, and provirus is created |
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Term
| Antigenic Drift vs. Antigenic Shift |
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Definition
Antigenic Drift~ slow, small changes in the virus. Mistakes during replication cause mutations and new strains. Replicase and reverse transcriptase are more error-prone
Antigenic Shift~ a large, rapid change. Recombination and reassortment. New strains or subtypes are very foreign to immune system |
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Term
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Definition
| Antigenetic shift, 2 viruses share a cell and create a subtype |
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Term
| Enveloped vs. Naked virus assembly/maturation |
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Definition
Enveloped virus~ envelope proteins need to use host cell ER and Golgi system
Naked virus~ fully assemble before release (host dies) |
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Term
| Enveloped vs. Naked virus release |
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Definition
Enveloped virus~ use exocytosis (golgi membrane) or budding (cell membrane)
Naked virus~ often use Apoptosis (kills host cell) and sometimes vesicles |
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Term
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Definition
| A latent virus turns productive, new disease symptoms, more contagious |
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Term
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Definition
| Virus-like infectious agent made entirely of RNA, most infect plants |
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Term
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Definition
| Infectious agents made of only protein, very stable-resistant to heat, UV, and proteases |
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Term
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Definition
| Destruction of all living cells, spores, and/or viruses |
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Term
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Definition
| Removal or elimination of most pathogens from inanimate surfaces |
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Term
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Definition
| Removal or elimination of most pathogens from living tissues |
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Term
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Definition
| Reducing microbe numbers to "safe" levels to meet an accepted health standard |
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Term
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Definition
| Chemical agents or methods that kill microbes |
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Term
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Definition
| Chemical agents or methods that slow/stop microbe growth or reproduction |
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Term
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Definition
| Delaying spoilage of foods or perishables |
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Term
| 4 Situational Considerations |
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Definition
1. Type of microbe~ highly resistant requires more rigorous treatment
2. Number of Microbes~ the more cells, the longer time needed for treatment
3. Risk of Infection~ personal vs. public spaces, immunocompromised people, immune barrier
4. Object being sterilized/disinfected~ is it sensitive, living tissue, ect... |
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Term
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Definition
| The time it takes to kill 90% (1 log reduction) of cells at a particular temp. |
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Term
| 2 types of dry heat physical agents |
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Definition
1. Incineration can sterilize
2. Dry ovens can sterilize |
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Term
| 3 types of moist heat physical agents |
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Definition
1. Boiling
2. Pressured steam (Autoclave) can sterilize
3. Pasteurization |
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Term
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Definition
| Filteration through a pore size of 0.2 micrometers removes bacteria, a pore size of >0.2 micrometers is needed to remove viruses, can sterilize |
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Term
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Definition
1. Ultraviolet~ only good for surface penetration
2. Ionizing radiation~ gamma rays, electron beams, x-rays, can sterilize |
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Term
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Definition
| Chemical that kills or inhibits microbes (includes disinfectants, sterilants, antiseptics, and Antimicrobial Drugs) |
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Term
| Levels of CDC classification |
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Definition
High~ Aldehydes, Ethylene, Proxygenes (Mostly sterilants)
Intermediate~ Halogens (Mostly disinfectants)
Phenolics and Bisphenols
Easy~ Alcohols and Quats |
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Term
| What classes of the CDC classification have issues with resistance? |
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Definition
| Phenolics and Bisphenols, and Quats |
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Term
| How do catatonic detergents kill bacteria? |
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Definition
| Positive attraction binds strongly to negatively charged bacterial membranes and causes cell lysis |
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Term
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Definition
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Term
| Narrow vs. Broad spectrum |
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Definition
Narrow spectrum~ targets one or just a few groups of bacteria, useful when pathogen is known
Broad spectrum~ targets many groups of bacteria, useful when pathogen is unknown, can cause dysbiosis |
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Term
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Definition
| Disruption of the normal microbiota |
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Term
| Antagonistic vs. Synergistic effects |
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Definition
Antagonistic effects~ one drug inhibits the function of another
Synergistic effects~ two drugs that work better together |
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Term
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Definition
Drug harms the pathogen, not the host, measured by the chemotherapeutic index
High therapeutic index = less toxic to host |
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Term
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Definition
| The area around a drug that inhibits growth of bacteria |
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Term
| What do Beta-lactams target and do? |
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Definition
| They target the cell wall by inhibiting transpeptidase and penicillin-binding proteins |
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Term
| What do semisynthetic chemical derivatives do? |
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Definition
-Increase stability
-More active/fewer doses needed
-Increased spectrum of activity
-Overcome resistance |
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Term
| What 2 kinds of antibiotics target bacterial membranes? |
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Definition
Gramicidin~ targets gram-positives, forms ion channels in the membrane
Polymyxins~ targets gram-negatives, high affinity for the LPS |
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Term
| What 2 kinds of antibiotics target DNA or RNA synthesis? |
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Definition
Quinoloes~ inhibit DNA replication; (DNA gyrase; supercoiling)
Rifampin~ targets and inhibits RNA polymerase directly |
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Term
| What kind of antibiotic targets protein synthesis? |
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Definition
| Macrolides~ target the ribosome |
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Term
| What kind of antibiotic targets metabolism/biosynthesis? |
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Definition
| Sulfonamides "Sulfa Drugs"~ synthetic drug that inhibits folic acid synthesis by posing as a substrate |
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Term
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Definition
-Blocking attachment or fusion
-Biosynthesis
-Maturation and release |
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Term
| Antifungal and Antiprotozoal common target |
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Definition
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Term
| 4 ways bacteria resist drugs |
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Definition
1. Prevent drug entry~ destroy antibiotic before it enters the cell, or decrease membrane permeability
2. Prevent drug-target binding~ alter the target, or modify the antibiotic
3. Dislodge the antibiotic
4. Pump the antibiotic out (efflux pumps) |
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Term
| Innate vs. Acquired resistance |
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Definition
Innate resistance~ due to inherent characteristics of an organism
Acquired resistance~ developed through genetic changes: mutation or HGT |
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Term
| How does misuse of antibiotics cause resistance? |
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Definition
| Not taking a full dose causes selective pressure, promoting survival of resistant/fitter strains |
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Term
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Definition
| Any bacteria, virus, fungus, protozoan, or helminth that causes disease in humans |
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Term
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Definition
| The ability of an organism to cause a disease |
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Term
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Definition
| Microbes that cause harm-inducing infections |
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Term
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Definition
Ectoparasites~ parasites that infect externally
Endoparasites~ parasites that infect internally |
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Term
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Definition
| Any disruption of the normal structure or function of the body that can be recognized by a set of characteristic symptoms or signs |
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Term
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Definition
| A disease caused by a pathogen that can be transferred from one host to another |
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Term
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Definition
| The study of when or where diseases occur and how they are transmitted in a population |
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Term
| What are 3 founders of epidemiology? |
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Definition
1. John Snow~ Cholera outbreaks in London
2. Ignaz Semmelweis~ Maternal death by puerperal sepsis in 2 maternity clinics
3. Florence Nightingale~ Typhus epidemic in english civilian and military population |
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Term
| Descriptive vs. Analytical epidemiology |
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Definition
Descriptive epidemiology~ data that describes occurrences (person, place, and time)
Analytical epidemiology~ uses descriptive epidemiology to form a hypothesis (can be experimental or observational) |
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Term
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Definition
| Pathogen enters host and begins to grow |
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Term
| Acute vs. Chronic infection |
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Definition
Acute infection~ symptoms develop and resolve rapidly
Chronic infection~ involves symptoms that develop gradually and resolve slowly, if at all |
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Term
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Definition
Symptoms~ subjective changes, things you tell your doctor (ex. nausea, fatigue, pain)
Signs~ objective changes, things the doctor sees or can measure (ex. swelling, redness, temp.) |
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Term
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Definition
| Signs and symptoms are caused by the host's response to the infection |
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Term
| 4 key characteristic stages of an acute disease |
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Definition
1. Incubation~ initial infection
2. Prodromal~ first symptoms, don't know you are sick yet
3. Illness~ obvious sickness
4. Decline~ immune response 'kicks in' |
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Term
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Definition
| Always present in a population, predictable rate @ low numbers |
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Term
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Definition
| Number of cases rises above a certain endemic threshold |
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Term
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Definition
| Disease acquired by many people in a short time, geographic area widens |
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Term
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Definition
| Epidemic over a wide geographical area |
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Term
| Index case/Patient zero def. |
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Definition
| The first person with a disease |
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Term
| 3 steps of contact tracing |
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Definition
1. Find the index case
2. Identify who has come in contact with the index case
3. Quarantine individuals |
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Term
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Definition
| Total number of active cases of a disease in a given location |
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Term
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Definition
| Number of new cases of a disease in a given location over a specific period |
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Term
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Definition
| Rate of illness due to a disease |
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Term
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Definition
| Rate of death due to a disease |
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Term
| 4 parts of the chain of infection |
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Definition
1. Organism
2. Reservoir
3. Transmission
4. Susceptible host |
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Term
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Definition
| Scientific method for linking pathogen to a disease, microbe must be found in all cases of disease, and absent from healthy individuals |
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Term
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Definition
| Likely to cause disease after infection in a healthy host |
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Term
| Opportunistic pathogens def. |
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Definition
| Unlikely to cause disease in a healthy host, low pathogenicity |
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Term
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Definition
| How easily an organism causes disease |
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Term
| Lethal dose 50% (LD50) def. |
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Definition
| Number of bacteria or virus particles required to kill 50% of an experimental group of animal hosts |
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Term
| Infectious dose 50% (ID50) def. |
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Definition
| Number of bacteria or virus particles required to infect 50% of an experimental group of animal hosts |
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Term
| 3 characteristics of pathogenicity |
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Definition
1. Attachment to host
2. Avoid host immune system
3. Stealing nutrients from the host |
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Term
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Definition
| The animals a pathogen can infect and produce disease in |
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Term
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Definition
Narrow~ Infects only one or a couple animals
Broad~ Infects many animals |
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Term
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Definition
| An animal or an environment that normally harbors the pathogen |
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Term
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Definition
| An animal that harbors the pathogen, but does not have the disease |
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Term
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Definition
| Infections of animals that can be transmitted to humans |
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Term
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Definition
| Route of transmission, can be simple or complex |
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Term
|
Definition
1. Vertical~ parent to offspring
2. Direct~ person to person
3. Indirect ~ through and intermediary
-Airborne
-Vehicle
-Vectors |
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Term
| How is ID50 related to infectivity? |
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Definition
| They are inversely related; the lower the ID 50 means the fewer microbes needed to cause infection in 50% of a population, high virulence |
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Term
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Definition
| Inanimate objects used for indirect (vehicular) transmission |
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Term
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Definition
| Mosquitos or ticks that carry disease from point A to point B, but do not experience the disease, a type of indirect transmission |
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Term
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Definition
Portal of exit~ how a pathogen gets out of a reservoir
Portal of entry~ how a pathogen enters a susceptible host |
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