Chapters 16-18 - Viruses, bacteria, archaea, protists, fungi Flashcards
Are viruses alive? Why or why not?
No
They lack metabolic processes and ability to replicate on their own
What is a virus?
Consists of nucleic acids (either DNA or RNA) enclosed by a capsid
How do viruses replicate?
They need host cells in order to replicate.
Viruses must inject their genetic material into a host cell and used their hosts to make more copies of the virus.
How do viruses enter a host cell?
Some cells have receptors that recognize the virus, and the virus attaches itself to those receptors. It will either:
1. Inject its genetic material into the host cell (if it’s a bacteriophage)
2. Entire the cell completely intact via Endocytosis.
The lytic cycle
When the host cell is destroyed at the end of of the viruses replicative cycle.
Once many copies of the virus is generated the host cell bursts (lyses) and releases the viruses to go infect other cells
The lysogenic cycle
When the host cell is not destroyed at the end of the viruses replicative cycle.
The virus DNA becomes incorporated into the genome of the host cell. The cell can then divided many times with each daughter cell having bits of the viral DNA in them.
(Sometimes the lysogenic cycle turns into the lytic cycle and all daughter cells burst at once)
Viroids
Naked, circular RNA molecules that infect plants, NOT animals
Prion
Infectious protein particles that contain no genome, and infect only animals, NOT plants.
Cause other others in brain cells to bring on disease symptoms
Alzheimer’s and Parkinson’s may be associated.
Virophages
Viruses that infect other viruses
What is an emerging virus?
A virus that appears suddenly, or is new to medical science.
Ex. HIV, Ebola, Covid
What are the 3 processes that contribute to emerging viruses?
- Mutation
- Contact between species
- Spread from isolated populations
How do you catch a cold?
When viruses are inhaled and make contact with the lining of the upper respiratory tract.
(Usually from a rhinovirus)
Can you catch a cold from being cold?
In humans, it was tested that cold people were no more likely to get a virus than warm people.
In other animals, being cold will lower immunity, but not really in humans
Can antibiotics help against viruses?
No, because viruses don’t have a cell wall for the antibiotic to attack.
What is a strep bacteria type?
Strep refers to bacteria which form in chains.
Ex. if you have streptococci, you have chains of round bacteria.
What is a staph bacteria type?
Refers to bacteria which form in clumps.
Ex. Is you have staphylococci, you have clumps of round bacteria
Photoautotrophs
Use energy from the sun to make organic molecules from CO2
Ex. Cyanobacteria
Photoheterotrophs
Get energy from the sun, but carbon from organic sources
Ex. Purple nonsulphur bacteria
Chemoautotrophs
Get energy from inorganic molecules and use carbon from CO2 to make organic molecules.
(Inorganic -> organic)
Ex. Most archaea
Chemoheterotrophs
Get both energy and carbon from organic molecules
Ex. Most bacteria
Microbiome
The collection of all microorganisms that naturally live in our bodies and helps in developing our immune system.
Dysbiosis
A microbial imbalance inside of the body
Caused by use of antibiotics, and poor diet choices
Why shouldn’t we use antibacterial soaps?
Most of them contain the antimicrobial Triclosan which will make you more susceptible to become resistant to other antibiotics
Archaea are extremophiles, what does this mean?
They live at temperatures, pressures, or pH levels thy would kill other life forms.
(They live in extreme environments)
Halophiles - live in very salty environments
Thermophiles - live in very hot environments (usually near volcanoes)
Symbiosis
A physically close association between organisms of two or more species.
Mutualism
A relationship in which organisms living in symbiosis both benefit from the relationship.
Protist
A eukaryote that is not a plant, animal, or fungus. They are typically unicellular (but there are exceptions.)
Ex. Amoeba, slime molds, algae
Mycorrhizae
A symbiotic relationship between a fungus and a plant.
The fungus benefits from a supply of sugar from the host plant. In return the fungus increases the plants surface area for nutrient absorption
This occurs in about 80% of plants
Heterokont
A heterokaryotic stage were hyphae of two strains fuse cytoplasm but remain haploid because their nuclei haven’t fused yet.
(Dikaryotic)
