Chapter 16 - 18 Viruses, Bacteria, Archaeae, Protists, Fungi Flashcards
What types of living things can get viruses?
All things can get viruses
What is a virus?
“genes in a box”
An infectious particle of nucleic acid (DNA or RNA) wrapped in a protein coat. Come in many different shapes.
Are viruses alive? Why or why not?
No, because viruses lack the metabolic processes and enzymatic machinery of cells to replicate.
What is a capsid?
The protein coat of a virus. It comes in different shapes and sizes, depending on the virus.
Can viruses replicate on their own?
No. On their own, they cannot grow or replicate.
How do viruses replicate?
They must inject their genetic material into a host cell. The host cells transcribe and translate the viral nucleic acid to make more copies of the virus.
What is a bacteriophage?
Viruses that infect bacteria. They kinda look like mini spiders.
phage = eat (bacterial eaters).
How do viruses enter cells?
The virus attaches to a cell’s receptor proteins. Then it injects its genetic material or the entire virus can enter eukaryotic cells via endocytosis.
Why are many viruses specific to certain species or cells?
The cells must have receptor proteins that recognize the virus for the virus to attach to.
How do viruses exit cells (3 ways)?
- They can cause the cell to rupture (lysis/lytic cycle).
- They can “insert” DNA into the host’s DNA (lysogenic cycle). The cell divides as normal, but new cells contains the viral DNA as well.
- In eukaryotic cells viruses can exit via exocytosis, without killing the host.
What is the lytic cycle? What is the lysogenic cycle?
The cycles of viral reproduction.
Lytic ruptures the host cell to release new viruses.
Lyso allows the host to continue dividing but with the viral DNA embedded in the host’s DNA.
Can viruses infect viruses?
Yes!
APMV mimivirus, the largest known virus, can become infected with a tiny virus named Sputnik. But neither virus can reproduce without a host.
What are virophages?
Viruses that infect viruses. They can prevent their virus hosts from operating normally and replicate together with their host viruses in the same eukaryotic cells.
What are retroviruses?
Special viruses that contain an enzyme called reverse transcriptase. This transcribes an RNA template into DNA, which is the opposite of normal transcription.
What is a viroid?
An infectious acellular particle. A naked circular RNA molecules that infect plants but not animals
What is a prion?
An infectious acellular particle. A misfolded form of a protein normally present in brain cells (no genome at all). It converts normal proteins to misfolded prion versions. Only infects animals, not plants.
Which diseases may be related to prions?
Brain diseases like Alzheimer’s and Parkinson’s diseases, chronic wasting disease in deer, mad cow disease, Creutzfeldt-Jakob disease.
What is an emerging virus and some examples? What contributes to their creation (3)?
A virus that appears suddenly or is new to medical science. i.e. HIV, ebola, SARS, ✨Covid-19✨.
Mutation of viruses, contact between species, and spread from isolated populations.
Why are emerging viruses a greater threat than known viruses?
They can spread quickly, before vaccines can be developed.
Can you catch a cold from being cold? Where does this concept come from?
No.
Experiments showed that chilling animals can lower their immunity, but in humans it has the opposite effect.
Why do we tend to get more colds in the winter when it is cold?
We stay indoors more and congregate with people which increases our exposure to viruses.
Also maybe vitamin D deficiencies.
Can antibiotics help against viruses?
No, antibiotics are used to treat bacterial infections. Viruses don’t have cell walls that can be attacked by antibiotics.
Where are bacteria found?
Bacteria are everywhere, in air, water, soil, and YOU.
Are bacteria prokaryotic or eukaryotic?
All bacterial cells are prokaryotic and are much smaller and simpler than eukaryotic cells.
What are bacteria cell walls made of? How can we use this to our advantage?
Peptidoglycan (protein-sugar) which is different from human cell walls. Antibiotics often target the cell wall to kill bacteria without hurting us.
How do bacteria replicate?
Asexually via binary fission (but they can also exchange genetic material between each other).
What are the basic types/shapes of bacteria (5)?
- Round = cocci (coccus, singular);
- Rods = bacilli (bacillus, singular);
- Spiral = spirochaetes;
- Strep = chains (i.e. streptococci or streptobacilli);
- Staph = clump (i.e. staphylococci).
Many rod/spiral have flagella.
How does the size of bacteria compare to other forms of life?
Bacteria are the smallest forms of life
What is gram staining?
A way to identify bacteria.
Some hold the stain well (these look purple, called Gram + bacteria) and some do not (pink, Gram - bacteria).
For bacteria, what are the different means of feeding/getting energy?
Being photoautotrophic, photoheterotrophic, chemoautotrophic, or chemoheterotrophic (most common).
What does it mean to be photoautotrophic?
These organisms make their own food out of sunlight and CO2 using photosynthesis. i.e. cyanobacteria.
What does it mean to be photoheterotrophic?
These organisms get energy from sunlight but carbon from organic sources (not common).
What does it mean to be chemoautotrophic?
These organisms get energy from inorganic chemicals and use CO2 to make organic molecules. i.e. many Archaea living in extreme env.
What does it mean to be chemoheterotrophic?
These organisms get both energy and carbon from organic molecules. i.e. humans and most bacteria.
What is the human microbiome?
All the little microorganisms that live in and on your body, including lots and lots of bacteria. It is VERY important to our health.
The microbiome plays an important role in our developing ____________ systems.
Immune
What two factors can impact an infant’s microbiome?
Vaginal delivery and breastfeeding can contribute to a healthy microbiome.
What is dysbiosis?
A microbial imbalance on or inside a body. Poor diets and use of antibiotics can lead to this.
Why shouldn’t we use antibacterial soaps?
Plain soap and proper hand washing works just as well without the risk of leading to antibiotic resistant bacteria. Also Triclosan (antibacterial agent) is highly toxic to fish.
Are archaea prokaryotic or eukaryotic?
They are prokaryotic.
Which is more closely related to eukaryotic cells, bacteria or archaea?
Archaea are closer to eukaryotes than bacteria are. but archaea are still prokaryotic.
Archaea tend to be extremophiles – what is that?
They live at temperatures, pressures, or pH levels that would kill other life forms.
What are extreme halophiles and extreme thermophiles?
They live in very salty and very hot environments respectively.
What adaptation allows archaea to live in extreme environments?
Important adaptations in their cell walls which can be made of inorganic components or have an outer mono-layer of lipids.
Eukaryotic life likely evolved from _____________ via _________________.
Prokaryotes, Endosymbiosis
What is endosymbiosis?
A theory for how smaller prokaryotic organisms merged with larger ones, and developed a symbiotic relationship (like mitochondria and chloroplasts). A theory for the origin of eukaryotic life.
What is symbiosis?
A physically close association between organisms of two or more species.
What is mutualism?
A relationship in which organisms living in symbiosis both benefit from the relationship.
What is a protist? Are they prokaryotic or eukaryotic?
Predominantly unicellular, simple eukaryotic organisms, though some may be colonial or multicellular.
A eukaryote that is not a plant, animal or fungus.
What forms do protists take? What’s the biggest protist?
They have a very wide variety of shapes and sizes (algae, paramecia, amoebas). Many are microscopic.
Giant kelp can reach up to 30 m tall.
For protists, what are the different means of feeding/getting energy?
Photoautotrophic, heterotrophic or both = mixotrophs.
Do protists reproduce sexually or asexually?
Asexually, sexually, or both. They’re wild, it varies.
What are amoebozoans? Are they protists?
Many species of free living amoeoba, some parasitic amoebas and the slime moulds. They are protists.
What’s some cool stuff about slime moulds and how they behave?
They are a SINGLE multinucleated CELL! It moves via pseudopodia and engulfs food via phagocytosis.
What are fungi and some examples?
Heterotrophs that absorb food through their cells after breaking down macromolecules with enzymes. Mushrooms, fuzzy mould, or yeasts.
What are hyphae?
A network of threadlike filaments that extend through the visible reproductive structure of a fungus and below ground.
What are mycelium?
A mass of branching hyphae underground.
What kind of cell wall do fungi have? Are they closer to plants or animals?
Their cell wall is made of chitin.
Are fungi more closely related to plants or animals?
Despite having cell walls like plants, they’re more closely related to animals.
What is the internal structure hyphae like?
Usually a chains of cells separated by cross-walls with large pores. Some lack cross-walls and have many nuclei within the same mass of cytoplasm.
Why are hyphae so skinny?
They rapidly grow longer without getting thicker creating a very large surface area for nutrient absorption.
Are spores and adult fungi haploid or diploid?
Haploid.
What is the only diploid stage of a fungi?
When sexual reproduction does occur, the zygote is the only diploid phase and undergoes meiosis before forming haploid spores.
Do fungi reproduce sexually or asexually?
Either.
What are imperfect fungi?
Species where asexual reproduction is the only means of spore formation. i.e. moulds and yeasts.
What is a heterokaryotic stage?
In fungi when hyphae of two strains fuse cytoplasms, but may remain haploid for a period of time
Why are fungi important to ecosystems?
They breakdown organic matter and “restock” the environment with essential nutrients. Also tons of plants have mutualistic relationships with fungi to absorb more nutrients.
What are mycorrhiza?
The mutualistic relationship between fungi and plant roots. Fungus gets sugar from the host plant. Fungi increases surface area for water and nutrient uptake for the plant, secrets growth factors and antibiotics.
What event in evolutionary history was mycorrhiza essential for?
The successful colonization of land by plants.
Why are mycorrhiza important for trees? How big can they be?
Evidence shows that trees communicate and share nutrients through this network.
They can be huge.
What was thought to be the largest organism on earth until recently?
People thought may be a humungous fungus in a forest in Oregon until they discovered a giant patch of sea grass.
Are forests simply collections of individual trees?
No, they are complex, interconnected networks of living things that share information and nutrients and rely on each other.
What was Dr. Suzanne Simard’s experiment and what did she discover?
She isolated 3 tree species with plastic bags and exposed them to different Carbon isotopes.
Result: Birch and fir exchanged C with their shared mycorrhizal system. But cedar had a separate system.
