chap456,161718 MICROEXAM STUDY
BIOL2420 – Chapter 4,5,6 Study Guide
Ch.4
1.What are symbiotic relationships?
Symbiotic relationships are interactions between organisms of different species. Microbes tend to live in communities with other microbes and exhibit a variety of symbiotic relationships.
Define:
Mutualism: In this interaction both organisms benefit.
Amensalism: In this interaction one organism is harmed and the other is unaffected.
Commensalism: In this interaction one organism benefits and the other is unaffected.
Neutralism: In this interaction both organisms are unaffected.
Parasitism: In this interaction one organism benefits and the other is harmed.
2. What is the microbiome?
The microbiome is the collection of microbes, and their genetic material, that inhabit a specific organism or environment.
For example, the gut microbiome refers to all microbes that reside in the lower intestine of a human.
3. What are the main categories of prokaryotes and their characteristics? (fill out the table)
Categories | Main Characteristics | Examples |
Proteobacteria | Gram-negative; Subdivided into 5 groups, many from microbiome and some pathogens. | Neisseria spp – cause gonorrhea and meningitis
Escherichia spp. – includes E.coli
Vibrio spp. – cause cholera |
Non-proteobacteria | Gram-negative bacteria that are very different from the Proteobacteria group. | Chlamydia spp. – cause trachoma and sexually transmitted infections
Fusobacterium spp. – cause biofilms and gum disease |
Gram-positive Bacteria | Gram-positive; Subdivided by GC% content | Mycobacterium spp. – high GC content; cause tuberculosis and leprosy
Clostridium spp. – low GC content; cause botulism and tetanus |
Deeply Branching Bacteria | Evolutionary distinct from most other bacteria. Many exhibit tolerances to a wide variety of environments. | Deinococcus spp. – exotic microbe that is highly resistant to radiation |
Archaea | These are the oldest microbes and fundamentally different than all other microbes. Not typically found in other organisms. | Many have larger genomes.
Cell membranes are made of different biomolecules.
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Ch.5
1.What are the main categories of eukaryotic microbes and their characteristics? (fill out table)
Categories | Main Characteristics | Examples |
Unicellular Parasites | AKA Protists; Single-celled organisms with more specialized structures | Paramecium – uses cilia for locomotion
Amoeba - has pseudopodia for locomotion
Euglena - uses flagella for locomotion |
Parasitic Helminths | Multi-cellular worms that are parasitic. Most lay eggs or larvae. | Nematodes – roundworms
Platyhelminths – flatworms
Tapeworms |
Fungi | Diverse group that with cell walls that contain chitin and can be unicellular or multi-cellular | Yeast – single-celled fungus
Molds – multi-cellular composed of hyphae.
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Algae | These are photosynthetic protists that can be unicellular or multi-cellular | Dinoflagellates – single-celled photosynthetic plankton
Kelp – larger plant-like seaweed that is photosynthetic. |
Lichens | A combination of algae and fungus in symbiosis. | Crustose lichens – crust like lichen
Foliose lichens – leaf-like lichens |
Ch.6
1.What are the main characteristics of viruses?
Simple structures composed of genetic material covered in protein. Rely on other organisms to complete lifecycle.
2. What is host range?
Host range refers to the specific organisms a virus can infect; Typically, can be resolved to a specific cell type.
Example: COVID-19 was specific to epithelial cells in the lining of the lungs and nasal cavities of human adults.
Define vector: A vector is an organism that can harbor a virus, usually with no negative effects, and transmit the virus to its host.
3. What is a bacteriophage?
These are viruses that are specific to bacteria. They “eat” bacteria.
What are the common structures of a bacteriophage?
Most bacteriophage have a “lunar lander” appearance consisting of a genome encased by a protein capsid, tail fibers for attaching to cells, and a sheath that enables the penetration of bacteria membranes.
4. What is the difference between naked and enveloped viruses?
Enveloped viruses have an outer layer composed of their host’s cell membrane. If the envelope is destroyed they are less able to infect.
Non-enveloped viruses are “naked” and do not need an outer layer composed of their host’s membrane to infect.
5. How are viruses typically distinguished or classified?
Viruses are typically classified by being enveloped or naked and the type of genome. The genomes can be DNA or RNA, single-stranded or double-stranded, and positive or negative.
Example: Influenza is an enveloped, single-stranded, negative-sense RNA virus.
6. What are the life cycles exhibited by virulent and temperate viruses?
Virulent viruses only undergo the Lytic cycle, where they infect cells, make copies of themselves, and destroy the cell.
Temperate cells can undergo both the Lytic cycle and the Lysogenic cycle, where they infect cells, and integrate their genome into the host’s genome, and reside there until conditions change.