Chapter 18 Viruses and Prokaryotes

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Virus
An infectious particle made only of a strand of DNA or RNA surrounded by a protein coat.
Viruses and Bacteria both cause infections, but how are they different?
A virus is a particle made only of a strand of DNA or RNA, while bacteria are one-celled microorganisms. This is how they differ. Both can cause infections, which was previously stated in the question.
Pathogen
Any living organism or particle that can cause an infectious disease. It is also called an infectious agent.
How are viruses like living cells?
viruses respond to their environments, have genes, and can reproduce
How are viruses unlike living cells?
viruses, unlike living cells, cannot reproduce on their own
Viroids
Infectious particles that cause disease in plants. They are made of single-stranded RNA without a protein coat, and are passed through seeds or pollen.
How do viroids impact agriculture?
Viroids impact agriculture, because they can stunt the growth of plants.
Prion
An infectious particle made only of proteins that can cause other proteins to fold incorrectly.
How are prions unusual?
Prions are unusual because they are infectious yet have no genetic material.
What types of diseases can prions cause?
mad cow disease, or BSE (when you eat meat from animals that are infected), Creutzfeld-Jakob (another brain disease)
Capsid
The protein shell which surrounds the genetic material of a virion, a signal viral particle.
What are three common viral shapes?
enveloped, helical, polyhedral
What can viruses have either of, but never both?
A virus can have either DNA or RNA, but it can never have both.
Bacteriophages
viruses that infect bacteria
How do viruses that infect Eukaryotes differ from Bacteriophages?
They differ in their methods of entering the host cell.
Describe the two types of infections viruses cause... (Compare the analogy on page 515. Which type of infection is the bad house guest that eats all the food and destroys the house. Which is the type that is more subtle but a permanent house guest?)
The lytic infection is an infection pathway in which the host cell bursts, releasing the new viral offspring into the host's system, where each then infects another cell. (This is the bad house guest that eats all the food and destroys the house.) While, in a lysogenic infection, a phage combines its DNA into the host cell's DNA. (This is the permanent house guest, that destroys the house over time.)
Prophage
The phage DNA inserted into the host cell's DNA. In organisms other than bacteria, this is called a provirus.
In a vertebrate what is the first obstacle a virus must pass to enter its host?
A virus must pass through the skin of a vertebrate in order to enter its host.
What are some common Viral infections?
The common cold, Influenza, SARS, HIV
Epidemic
A rapid outbreak of an infection that affects many people.
Vaccine
A substance that stimulates the body's own immune response against invasion by microbes.
Retro virus
A virus that contains RNA and uses an enzyme called reverse transcriptase to make a DNA copy.
Obligate Anaerobe
Prokaryotes which are actually poisoned by oxygen, therefore, cannot live in the presence of it.
Obligate Aerobes
Prokaryotes which need the presence of oxygen in their environment.
Facultative aerobe
A prokaryote that can survive in an environment that has oxygen or not.
What are the three most common forms of Bacteria?
lactobacilli: rod shaped, Spirochaeta: spiral, and Entercocci: spherical
Plasmid
A small piece of genetic material that can replicate separately from the prokaryote's main chromosome.
Flagellum
A long, whip like structure outside of a cell that is used for movement.
Conjugation
Prokaryotes can exchange parts of their chromosomes through a hollow bridge of pili formed to connect two or more cells. In this process, genetic material transfers between prokaryotes, producing genetic variation. A conjugation bridge forms from the donor cell to a recipient cell
Endospore
A specialized cell with a thick, protective wall.
What are two ways in which pokaryotes that live within our bodies are helpful to us?
Prokaryotes keep away harmful microbes by filling niches that might otherwise be filled with disease causing bacteria, make vitamins and other compounds, and give nutrients.
Describe some ways Prokaryotes play important roles in ecosystems....
* Some, such as cyanobacteria, produce oxygen through photosynthesis.

* Some recycle carbon, nitrogen, hydrogen, and sulfur through the ecosystem.

* The absence of prokaryotes in the environment can disrupt an ecosystem, since other organisms rely on them for their survival.
Bionemediation
A process that uses microbes and other living things to break down pollutants.
Toxin
A poison released by an organism.
What are two ways Bacteria can cause illness to the host?
By invading the tissues and attacking cells or by making poisons, or toxins that can be carried by blood to sites throughout the body.
What are some common bacterial infections?
Tuberculosis, Food Poisoning, Acne, Anthrax, Lyme Disease, Tetanus, Tooth decay
Antibiotics
Chemicals that kill or slow the growth of bacteria.
How can bacteria evolve to resist antibiotics?
Multidrug-resistant bacteria, happens as a result of natural selection, as individuals who are more resistant are more likely to survive and reproduce.