Viruses And Bacteria Flashcards
What is a virus
A virus is a particle that causes disease in organisms and consists of a core of nucleic acids surrounded by a protein coating
How do viruses differ from unicellulaire organisms
Viruses do not have a nucleus, complex inner membrane, or organelles like mitochondria or endoplasmic reticulum
Describe the structure of a virus
Viruses have a core of nucleic acids ( DNA or RNA, not both ). They have a capsid [protein coat surrounding the nucleic acid and protect it]. Some viruses also have an envelope [protective protein coating seen in some viruses. Some are covered with spikes or carbs and proteins which allow viruses to chemically recognize and attach to the cell they infect].
What is ‘specificity of viruses’
Specificity of viruses describes how the viruses can infect so many different kinds of organisms
Eg. Plant viruses only infect plants
Many viruses infect just one host
What is host range
The number of host species a virus can infect
Viruses are dependent of living cells. Outside of living cells, viruses cannot ____, ____, ____, or ____ on their own.
Viruses are dependent of living cells. Outside of living cells, viruses cannot move, grow, reproduce, or respire on their own.
Viruses are obligate intracellular parasites. What did this mean?
A virus can only reproduce inside a host cell
Any hypothesis about viral origins must explain 4 observations. What are these?
- Viruses depend on totally on living organisms for survival
- Most viruses infect only a few hosts
- Families of viruses have genetic material that is more similar to host than other viruses
- Some viral genes are almost identical to genes of their host
Explain viral replication in the lyric cycle
This viral replication rapidly kills a host cell and makes the host cell lyse (burst).
Explain the lyric cycle in detail
The nucleic acid of a virus takes control of host cell’s activity and directs it to make more copies of the virus. When done, it kills the host cell, thus releasing new virus cells to infect more hosts.
What is a virulent phage
A phage that replicates only by a lyrics cycle
Describe the lysogenic cycle
A viral replication process in which a virus does not immediately kill a host cell. It may lay dormant, waiting to pop up when conditions are right (eg. Low immune system).
Describe the lysogenic cycle
A viral replication process in which a virus does not immediately kill a host cell. It may lay dormant, waiting to pop up when conditions are right (eg. Low immune system).
What is a prophage
The viral nucleic acid attaches to the host cell’s chromosomes. The prophage reproduces every time the chromosome reproduces until a stimulus causes it to attack the host and go through the lytic cycle.
What are two methods of defense bacteria have against phages
- Natural selection favors bacterial mutants with surface proteins that can’t be recognized
- They can identify foreign DNA and cut it up by using restriction enzymes (bacterial DNA is methylated so it isn’t cut accidentally)
What is a viral envelope
It is derived from a host cell’s plasma membrane that binds to specific receptors
What is a viral envelope
It is derived from a host cell’s plasma membrane that binds to specific receptors
What is the RNA genome
i. Retroviruses use reverse transcriptase to copy their RNA to DNA (eg. HIV)
ii. The viral DNA in the host virus genome is called a provirus
iii. Proviruses remain permanent residents of host cells
What is a retrovirus
Dangerous viruses that replicate nucleic acids in the reverse of the standard way. Rather than using DNA to make RNA, retroviruses use RNA to make DNA
What are viroids and prions
Viroids are tiny particles of pure RNA that cause disease in plants
Prions are particles of proteins that cause some diseases in animals
These are not viruses because
1. Viroids do not have protein capsids protecting the nucleic acids
2. Prions do not have nucleic acids
All members of kingdom monera are prokaryotic. What are 5 common characteristics of all prokaryots
- They do not have a nucleus
- They do not have membrane bound organelles
- They have different ribosomes than those found in eukaryots
- Almost all proks. are smaller than the smallest euks.
- Most prokaryots are single cell organisms
There are 2 groups under kingdom monera: eubacteria and archaebacteria. Give a short description of the two
Archaebacteria live in unusually harsh environments. They have different cell walls, membranes, and ribosomes than other monerans.
Eubacteria are known as the true bacteria. They have strong cell wallsto maintain shape, protect the cell, and prevent bursting in hypotonic environments
What are methanogens
Methanogens produce CH4 and live in oxygen-free environments. (Found in swamps, marshes, mammals). Used industrially to treat sewage and purify water
What are thermoacidiphiles
These live in extremely hot (60°-250°C) and acidic waters. Colonies of these glisten the edges of near boiling hot springs
What are chemosynthesizers
These use inorganic compounds as an energy source. They flourish in the deep-sea hot springs formed by volcanic vents on the ocean floor
What are extreme halophiles
These live in extremely salty conditions. They grow in water 9× saltier than sea water
What are gram-positive bacteria
These have thick walls made of protein sugars (peptidoglycans) that take on a purple color during gram staining.
[Found in yogurt, buttermilk, antibiotics, toxins]
What are gram negative bacteria
These have less peptidoglycans but an outer membrane that has an extra lipid layer (lipopolysaccharides) outside the cell wall and look pink after gram staining
[Some cause infections, some perform N2 fixation]
What are cyanobacteria
There are gram negative monerans that perform photosynthesis and release oxygen
(Much larger than most proks and provide food for other organisms)
Eubacteria are typically aerobic
Define the following:
Obligate aerobe
Obligate anaerobe
Facultative anaerobe
Obligate aerobe = organisms that cannot survive without oxygen
Obligate anaerobe = organisms that cannot survive in the presence of oxygen
Facultative anaerobes = organisms with the ability to function in the absence of oxygen but prefer oxygen
What is binary fission
A method of reproduction in which DNA of monerans replicates after which the cell divides producing two identical cells
(asexual reproduction under normal conditions)
What is conjugation
What are pili
This is the process of exchange genetic material through cell-to-cell contact. During this, the DNA moves from one bacteria to another and as a result, the DNA in the cells changes and increases the diversity of the generations that follow (sexual reproduction under harsh conditions)
Pili are the hair like structures that help bacteria attach together
What is transformation
This is the process by which bacterial cells pick up and incorporate DNA from dead bacterial cells of some closely related species
What is transduction
Using a bacteriophage to transfer DNA from one bacterial cell to another
What is transduction
Using a bacteriophage to transfer DNA from one bacterial cell to another
What are endospores
Some bacteria have a special means of surviving difficult conditions. When living conditions become unfavorable, some bacteria form dehydrated cells (endospores) that are thick walls that resist heat, drought, radiation, etc.
What are some uses of bacteria
E. Coli in the colon metabolized fecal material and allows animals to absorb minerals / vitamin k
Bacteria can be used to make Proteins like hormones and insulin for medical uses
What are the three groups of protists
- Protozoans - unicellulaire animal-like protists that are heterotrophes
- Algae - plant-like protists that are autotrophes that lack cell walls/ can swim
- Slime molds - fungus-like protists that are decomposes which have different cell walls
What are protozoans
The resemble animals in that they
1. Eat other organisms for food
2. Move around
They only differ in that they are unicellular
What are sarcodinians
They are amoebas that move by extending lobes of cytoplasm (aka pseudopods) and eat bacteria/smaller organisms.
They have calcium carbonate or silica shells with pores for the pseudopods to get in and out
What are zooflagellates
Protozoans with flagella
Mainly live in fresh H2O and have symbiotic or parasitic relationships
What are ciliaphorans
(Largest protozoan group)
Covered in cilia for movement through water
What are paramecium
Ciliaphorans that use cilia. Once the food enters oral groove and pinches off to form food vacuoles, after nutrients are extracted from food the waste is ejected thru anal pore
What are trichocysts
Tiny toxic darts paramecium use to capture prey
All protozoans have _______ which pump out excess _____.
Contractile vacuoles, water
Paramecium have two different nuclei: the micro and macro. Describe each
Macronucleus - controles ongoing functions of cell/asexual reproduction(b.f.)
Micronucleus - involved in genetic exchange
What are sporozoans
Spore-forming parasitic protozoans with no structure for movement and are parasites on animals
(Conjugation and b.f.)
What are dinoflagellates
Unicellular algae with
-2 flagella
-covered in cellulose
-some have symbiotic relationships with animals that live near coral reefs
What are diatoms
Unicellular algae that
-lack cilia and flagella
-glass like silica walls
-(2 halves tgh, like petri dish)
What are eugenoids
Unicellular algae also like protozoans
-no rigid cell wall
-they have pellicles (flexible protein covering)
What does thallus mean in terms of algae
The multicellular body of an algae that does not have a specific name (like stem, flower)
What are chlorophyta
Multicellular green algae either
- filaments with cells liked at ends or
-flat sheets of cells
Live in fresh water or moist soil
What are lichens
Lichens are symbiotic relationships between fungi and algae
What are rhodophyta
Multicellular red algae
-have varying pigments to trap sunlight for photosynthesis
Live in warm saltwater
What are phaeophyta
Multicellular brown algae
-have hold fasts that anchor to rocks and
-air bladders that act as balloons which help leaf structures to float to surface for photosynthesis
Lives in cool saltwater (what we have)
What is alternation of generations
Brown algae lifestyle where they go through diploid, sporeproducing phase and haploid gamete producing phase
What are phytoplankton
Algae in plankton that perform photosynthesis
What are plasmodial slime molds
These alternate between an amoeboid form and a spore producing fruiting body
If slime molds cannot find enough food, it will stop feeding and form fruiting body that produces spores which can spread and remain dormant until conditions are favorable
What is a plasmodium
Mass of cytoplasm formed by slime molds when feeding
What are cellular slime molds
These alternate the same way as plasmodial slime molds except when there is no food availible near by, cells clump together (pseudoplasmoid)
What is a watermold
This group of fungus like protists is decomposes (parasites), typically grow in fresh water on decaying plants and animals
What is the name of spherical bacteria
Coccus
What is the name of rod shaped bacteria
Bacillus
What is the name of spiral bacteria
Spirillum
What is the name of a pair of bacteria? A cube of 8?
Diplo
Sarcina
What is the name of a chain of bacteria? A cluster?
Strepto
Staphylo
What is the name of a chain of bacteria? A cluster?
Strepto
Staphylo
