bio exam 2

horizontal transmission of plant viruses

transfer of virus from one plant to another typically through damaged plant tissue (cant just inject bc plants have a cell wall); may come from pollen, another plant, or vectors like insects

vertical transmission of plant viruses

virus is transmitted from the parent plant

symptoms of plant viruses

hyperplasia (abnormal cell proliferation), hypoplasia (decreased growth/vigor), necrosis of plant or tissue (death of cells)

plant viruses

most are ssRNA, but not all; due to hosts cell wall, the virus needs a mechanism for entry (damage, insects, vectors); causes devastating crop loss, affecting food supply; plum pox, tomato spotted wilt virus, zucchini yellow mosaic virus

animal viruses

dont have to penetrate a cell wall to gain access to host cell; associated with a variety of human diseases; causes: acute disease, chronic infections, oncogenic viruses, intermittent symptoms, asymptomatic infection

acute disease

type of animal virus; flu and cold; symptoms get increasingly worse for a short period followed by the elimination of the virus from the body by the immune system

chronic infections

type of animal virus; long term viral infections and can hid from immune systems; hep C

oncogenic viruses

type of animal virus; have the ability to cause cancer; hep C, HPV

intermittent symptoms

type of animal virus; stay in nervous system/brain tissue for months or even years; herpes

asymptomatic infection

type of animal virus; cause productive infections without causing any symptoms; herpes 6 and 7

vaccines

primary method of controlling viral disease; antibiotics aren’t helpful (designed to kill bacteria, not virus); designed to boost immunity; may be prepared using live viruses(attenuation/weakening), killed viruses, or molecular subunits

variola virus

smallpox

antiviral drugs for treatment

designed to kill bacteria, so will not eliminate viruses; sometimes these drugs can be used to treat diseases caused by viruses; can inhibit a virus by blocking the actions of one or more of its proteins- targeted proteins must be encoded by viral genes and these molecules must not be present in a healthy host cell; tamiflu drug

tamiflu

antiviral drug; reduces the duration of flu symptoms by 1 or 2 days but it doesn’t prevent symptoms entirely; inhibits neuraminidase and prevents visions from exiting the cell, so now it cant leave and go infect another cell; prevents virus from detaching from host cell

prions

proteinaceous infectious particles for animals; smaller than viruses; contain neither RNA nor DNA- only proteins; cause fatal neurogenerative diseases: mad cow, creutzfeldt-jakob, scrapie, chronic wasting; not destroyed by cooking

how do prions work

abnormal PrP converts normal PrP into abnormal PrP; normal prions found in brain (PrPc) interact with abnormal (PrPsc- misfolded normal proteins) and all convert into PrPsc ; causes holes in brain tissue

viroids

smaller than prions; smallest; only infects plants; can reproduce only within a host cell; dont manufacture proteins; causes crop failures; potato spindle tuber viroid (PSTV) was the first identified one- infected knives cut healthy potatoes

prokaryotes

first organisms on earth; live on and in every other living organism; most are benign and essential to life; first observed by Leeuwenhoek

who discovered the techniques for pure culture and staining using agar

Robert koch

culture medium

contains all the nutrients needed by the target microorganism; can be liquid (broth) or solid; after incubation time at the right temperature, there should be evidence of microbial growth here

pure culture

a lab culture containing a single species of microorganism

blood agar plates

used to diagnose streptococcus infections

Robert kauch

proposed 4 postulates to prove a causal relationship between a microorganism and an individual; used a diseased animal with suspected pathogen and healthy animal and used a culture sample from both then inoculated (inject) healthy animal with pathogen and it became diseased

koch’s 4 postulates

microorganism must be found in abundance in all organisms suffering from the disease, but shouldn’t be found in healthy organisms ; microorganism must be isolated from a diseased organism and grown in pure culture; cultured microorganism should cause disease when introduced to healthy organism ; microorganism must be reisolated from the inoculated diseased experimental host and be identical to the original specific causative agent

prokaryotic cell size

0.1-5 micrometer in diameter; much smaller than eukaryotes; the predominant organisms of bacteria and archaea

prokaryote shapes

cocci (round), bacilli (rod), spirilli (spiral- syphillis); often occur in pairs, chains, tetras, clusters, etc

chondromyces crocatus- prokaryote

anabaena (cyanobacteria); engulfed by ancestral prokaryotic cell to become chloroplast; prokaryote

staphylococcus; grape like cluster; spherical shape

streptococcus; long chains; spherical; prokaryote

prokaryote structure

all of these types of cells have 4 common structures: plasma membrane, cytoplasm, double-stranded DNA genome, ribosome (no nucleus or microtubules)

plasma membrane in prokaryote structure

found in all prokaryotes; functions as a barrier for the cell and separates the cell from its environment

cytoplasm in prokaryote structure

found in all prokaryotes; complex solution of organic molecules and salts inside the cell

double-stranded DNA genome in prokaryote structure

found in all prokaryotes; the informational archive of the cell

ribosomes in prokaryote structure

found in all prokaryotes; sites of protein synthesis

pilus

found in some prokaryotes; bacteria use this to attach to surfaces; can form sex pilus (bridge) and cause conjugation

capsule

found in some prokaryotes; resists attack from host immune system, making it more pathogenic; outermost of cell wall/plasma membrane; made up of sticky carbs and proteins; glues cells together or to surface

flagellum

found in some prokaryotes; mobility

cell wall in prokaryotes

almost all have this; lies outside plasma membrane; protects and prevents lysis; bacteria has it with peptidoglycan and archaea uses other structural polysaccharides (no PG)

mycoplasma

smallest bacteria that lacks a cell wall

gram positive bacteria

bacteria with thick (90%) PG layer; found by Hans christian gram; stains purple in gram stain

gram stain

reflects cell wall type

gram negative bacteria

bacteria with thinner PG layer AND an outer lipid bilayer membrane; turns pink bc outer lipopolysaccharide layer is often toxic and resists drugs and immune system

nostoc filaments

thread-like chains of photosynthetic cyanobacteria; held together by capsules

taxis in prokaryotes

movement towards or away from stimulus

chemotaxis

movement towards/away from chemical/nutrients

phototaxis

bacteria move towards/away from light source

geo/magneto taxis

movement towards/away from gravity or magnetic field

plasmids

many prokaryotes have this; extra tiny DNA rings with few genes; replicate independently; separate from the bacterial chromosome; not essential for life but add diversity; drug resistance genes

5 key differences between bacteria and archaea

plasma membranes, cell walls, DNA replication, gene expression, 16S rRNA sequence

archaea plasma membrane

has tetra ether polymer which allows extremophiles to withstand high temps; uses ether linkage; formed on glycerol skeleton

bacteria plasma membrane

unbranched; use ester bonds

extremophile

type of prokaryote; bacteria and archaea that are adapted to grow under extreme conditions

acidophile

extremophile; survive acidic conditions

alkaliphiles

extremophile; survive basic conditions

thermophiles

extremophile; survive high temp

hyperthermophile

extremophile; survive extremely high temp

psychrophiles

extremophile; survive icy temps

halophile

extremophile; survive high salt

osmophile

extremophile; survive high sugar concentration

deinococcus radioduran

a prokaryote that can tolerate very high doses of ionizing radiation

polyextremophile

extremophile; survive radiation

prokaryote metabolism

nutrients and energy sources

prokaryote metabolism- macronutrients

nutrients that are needed in large amounts (Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur)

prokaryote metabolism- micronutrients

nutrients that are needed in small amounts (iron- needed for cytochromes which help with electron transport reactions)

prokaryote metabolism- light

energy source; photoautotrophs and photoheterotrophs

prokaryote metabolism- chemical

energy source; chemoheterotrophs and chemolithoautotrophs; can get it from organic or inorganic chemicals (chemo-organo(humans) and chemolitho trophs respectively)

prokaryote ecology

interactions among organisms and roles in ecosystem

prokaryote ecology(relations)- interactions among organisms

symbiosis (2 species living in close relationship), which has 3 types: parasitism, commensalism, mutualism

prokaryote ecology- roles in ecosystem

decomposers, produces O2 (Cyanobacteria), role in carbon cycle, nitrogen cycle

parasitism

symbiosis; prokaryote ecology; getting nutrients from host, making the host sick; includes pathogens which cause disease; anthrax and cholera bacteria

commensalism

symbiosis; prokaryote ecology; one species benefits without any impact on other species; like bacteria living on our skin

mutualism

symbiosis; prokaryote ecology; both organisms benefit from eachother; rhibozium in legume roots get sugar, and provide fixed N for plant

photoautotrophs

type of prokaryote that gets its energy from sunlight and carbon from CO2 (prokaryote metabolism)

photoheterotrophs

type of prokaryote that gets its energy from light, but carbon from organic compounds (prokaryote metabolism)

chemoheterotrophs

type of prokaryote that obtains energy and carbon from chemical sources (prokaryote metabolism); most important decomposers on earth (secreted enzymes hydrolyze dead material/waste); absorptive

chemolithoautotrophs

type of prokaryote that obtain their energy from inorganic compounds and build complex molecules from CO2

free-living prokaryote

not living in symbiosis; not dependent

how old is the earth

4.5 billion years old

ancient atmosphere

anoxic (no molecular oxygen), only anaerobic organisms were able to live

autotrophs

self-feeders that make their own food; primary producers; carbon fixation (CO2 converted to organic molecules) meaning they go through the carbon cycle

heterotroph

must consume other organisms for sustenance

phototrophs

autotrophic; convert solar energy into chemical energy; appeared within 1B years of the earths formation

cyanobacteria

aka blue-green algae; ancestral versions of this began oxygenation of the atmosphere- increase in O2 concentration allowed the evolution of other life forms; evolved from phototrophs; prochlorococcus (marine) is the most abundant photosynthetic organism

carbon cycle

used by many prokaryotes; continuous process by which carbon moves through the Earth’s atmosphere, land, oceans, and living organisms; carbon enters the soil, and microbial respiration and decomposition happens

nitrogen cycle

used by many prokaryotes; nitrogen gas is useless for plants but nitrogen itself is necessary, so nitrogen-fixing bacteria does its job which leads to ammonification

ammonification

used during nitrogen cycle; process by which ammonia is released during the decomposition of nitrogen containing organic compounds

prokaryote reproduction

aesexual via binary fission which doesn’t provide an opportunity for genetic recombination or genetic diversity; 1n results in 2 1n cells

if prokaryote reproduction is aesexual, where does its diversity come from

high rate of cell division allows for many mutations; short generation spans allows for rapid evolution; horizontal gene transfer (transformation, transduction, conjugation)

transformation

cell takes up prokaryotic DNA directly from environment; may remain as a plasmid or incorporated into genome; 2 types: natural and artificial

transduction

bacteriophage injects DNA into the cell; bacterial DNA is inserted into donor cell, enzymes break up the bacterial DNA, then one viral phage capsid houses the bacterial DNA, and it is inserted into the recipient cell

conjugation

DNA is transferred via sex pills that connects the 2 cells; requires presence of F factor in donor (F+ , meaning the cell contains the plasmid), resulting in 2 F+ cells; e coli

natural transformation

DNA is released from a dead cell and picked up by another live cell; proteins involved in transformation are encoded by bacterial chromosome (Griffiths capsule experiment)

artificial transformation

accomplished in the lab; used to transform e.coli for molecular cloning

endospores

some bacteria produce these under stress; survive heat and drought for years; bacillus anthraces (anthrax), clostridium tetanus (tetanus)

domain archaea

major group of prokaryotes; more closely related to eukarya than bacteria; includes extremophiles and methanogens(produce methane) but can also live in normal conditions; no human-disease causing

domain bacteria

5 types: proteobacteria, chlamydias, spirochetes, cyanobacteria, gram + bacteria

domain bacteria: proteobacteria

gram negative; diverse array of metabolism/nutrition; includes many n-fixing and common gastrointestinal pathogens; e coli, salmonella (food poisoning), rhizobium, vibrio cholerae

rhizobium

type of proteobacteria; nitrogen-fixing; found in legume group

domain bacteria: chlamydias

gram negative; all are parasites within animal cells; chlamydia trachomatis