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Unit 5 Test Review
Ch. 19 & 20
| Term | Definition |
|---|---|
| Viruses: | - very small - nucleic acid + capsid - limited host range - reproduce quickly within host cells - can mutate easily |
| Capsid: | protein cell |
| Nucleic Acid: | DNA or RNA (double or single-stranded) |
| Viral Envelopes: | surround capsid |
| Entry of Viruses: | attach to host cell membrane receptors through capsid proteins or glycoproteins on viral envelope (animal) |
| RNA viruses: | no error-checking mechanisms |
| Lytic Cycle: | use host machinery to replicate, assemble, and release copies of virus |
| Virulent phages: | cells die through lysis or apoptosis |
| Lysogenic (Latent) Cycle: | DNA incorporated into host DNA and replicated along with it |
| Bacteriophage DNA: | prophage |
| Animal virus DNA | provirus |
| UV radiation, chemicals: | lysogenic -> lytic cycle |
| Temperate Phage: | uses both methods of replication |
| Bacteriophage: | virus that infects bacterial cells |
| Animal viruses... | - have a membranous envelope - host membrane forms around exiting virus - difficult for host immune system to detect virus |
| Retrovirus: | RNA virus that uses reverse transcriptase |
| Reverse Transcriptase: | RNA -> DNA |
| Provirus: | newly made viral DNA inserted into chromosome of host - host transcribes provirus to make new virus parts |
| HIV: | infects white blood cells (helper T) |
| HIV+: | - provirus (DNA inserted) - latent |
| AIDS: | - <200 WBC count - opportunistic infections |
| Emerging Viruses | mutation of existing viruses |
| Pandemic: | global epidemic |
| Zika Virus: | - spread by Aedes mosquitoes (Aedes aegypti) - major outbreak in Brazil and Latin America - linked to birth defects (microcephaly) |
| Vaccine: | weakened virus or part of pathogen that triggers immune system response to prevent infection |
| Antiviral Drugs: | block viral replication after infection |
| Viroids: | small, circular RNA molecules that infect plants & cause errors in regulatory systems that control plant growth |
| Prions: | misfolded, infectious proteins that cause misfolding of normal proteins |
| Diseases caused by prions: | - prions act slowly – incubation period of at least 10 years before symptoms develop - prions are virtually indestructible (cannot be denatured by heating) - no known cure for prion diseases |
| Prion Neurodegenerative Diseases: | - Alzheimer's - Parkinson's |
| Genetic Diversity in Prokaryotes | 1. Rapid reproduction (binary fission) 2. Mutations – errors in replication 3. Genetic recombination |
| Transformation: | uptake of foreign DNA from surroundings - observed by Griffith (bacteria & mice) |
| Transduction: | viruses transfer genes between prokaryotes - recombine DNA of donor and recipient cell - viruses (bacteriophages) carry bacterial genes from one host cell to another |
| Conjugation: | DNA transferred from one to another - one cell donates DNA to another - donors cell extends a sex pilus (“mating bridge”) through which DNA is transferred - requires the presence of a piece of DNA called the F factor to produce the pilus |
| Plasmids | small ring of DNA that carries a few genes - replicates separately from bacterial chromosome - can carry genes for antibiotic resistance (R plasmids) - used frequently in genetic engineering for gene cloning |
Created by:
tessamcelrone
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