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Bio 112 - Exam 1
Term | Definition |
---|---|
Living things that can be infected by viruses. | Plants, Animals, and Bacteria |
Why viruses are non-living. | They don't metabolize, reproduce on their own, or respond to stimuli. |
What two characteristics do all viruses have? | Genetic information and a protein coat. |
What is host range? | A host range is the type of organisms a virus can infect. |
Explain what determines host range? | Host ranges are determined by the proteins surrounding the virus and the receptors they bond to. |
What are some possible reservoirs for viruses? | Possible reservoirs for viruses include wild birds, rodents, raccoons, and mosquitoes. |
Explain the 5 steps in the lytic cycle. | 1-Attachment: attach to the cell 2-Penetration: DNA is injected into the cell through the hole 3- Synthesis: replication of viral nucleic acid and protein and envelope 4- Assembly: viruses are put together, DNA in capsid 5- Release: usually by lysis |
What is a Virus? | Genes that come wrapped in a protein coat. |
What is a Viroid? | A tightly wound circle of RNA that lacks a protein coat. Basically, its naked RNA that can infect a plant cell. |
What is a Prion? | A normal membrane protein that can exist in multiple three-dimensional shapes, at least one of which is abnormal. When a healthy protein comes into contact with a prion the normal protein switches to the abnormal shape leading to a chain reaction . |
How are viral infections treated and prevented? | Some Viral infections can be treated with antiviral drugs, others are incurable and can only be delayed. Viruses are prevented with vaccines. |
What defines an organism as prokaryotic? | Organisms without membrane bound organelles and a nucleus. |
Name the two prokaryotic domains. | Bacteria and Archaea |
Explain three ways in which the two prokaryotic domains differ in some of their features. | Bacteria cell walls contain peptidoglycan, archaea’s do not. Archaea have different metabolic pathways than bacteria. They also have different membrane lipid bonding. |
Euryarchaeota | Contains the methanogens that live in stagnant water and inside the intestines of animals as well as some of the Halophilic archaea |
Crenarchaeota | Includes the thermophiles and some soil and water microbes that like moderate temps. |
Korarchaeota | Known mostly from genes extracted from their habitats. They seem to be thermophiles |
What is the size range of a prokaryotic cell? | 0.1–5.0 µm in diameter |
Coccus | Round |
Bacillus | Rod shaped |
Spirillum | Spiral or corkscrew |
Strepto- | Chains |
Diplo- | Pairs |
Staphylo- | Clusters |
What is binary fission and what is it used for in prokaryotes? | Binary Fission is a type of asexual reproduction that is used in vertical gene transfer by prokaryotes to pass on their genes. |
Name and explain three ways genes can be transferred between prokaryotes. | Transformation= a dying cell releases DNA as it bursts and other cells absorb this DNA Transduction= Viruses sometimes package up host cell DNA with theirs and pass it on to their next victim Conjugation= two cells use a sex pilus to transfer DNA |
What are the four major roles bacteria play in our environment? | Contributing gases to the atmosphere, recycling organic matter, fixing nitrogen, and living on/in organisms which allows them to function. |
Exotoxins | Toxins that diffuse out of the bacterial cell. Ex: Streptococcus: causes strep throat |
Endotoxins | Specifically the outer membrane of a gram-negative cell wall. Ex: E.coli: causes food poisoning (vomiting and diarrhea) |
Outline the importance of bacteria in the nitrogen cycle. What would happen without them? | Bacteria convert atmospheric nitrogen gas into forms that plants, and from them animals, can use. Nitrogen is part of proteins, DNA, and other organic molecules. Without them plants and animals couldn’t survive. |