48 terms

Chapter 20 Pearson Biology Viruses

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virus
a non living particle made of proteins, nucleic acids, and sometimes lipids; can only reproduce and grow by infecting living cells
DNA or RNA
what makes up the core of a typical virus
capsid
outer protein coat of a virus
bacteriophage
viruses that infect bacteria, means "bacteria eaters"
viruses enter living cells and, once inside, use the machinery of the infected cell to produce more viruses
how does a virus infect bacteria
lytic infection and lysogenic infection
two methods viruses use to infect host cells
lytic Infection
virus enters a bacterial cell, makes copies of itself, and causes the cell to burst or "lyse," which releases new virus particles that can attack other cells
viral DNA
in bacteriophage T4, directs the synthesis of new viruses using materials in the cell
lysogenic infection
host cell is not immediately taken over; virus DNA (called a prophage) is inserted into the host cells' DNA where it is copied along with the host DNA without damaging the host; viral DNA multiplies as the host cells multiply
prophage
bacteriophage DNA that becomes embedded in the bacterial hosts cell's DNA and then removes itself from the host cell DNA ~part of the lysogenic infection cycle -
retrovirus
Its genetic information is copied from RNA to DNA instead of the usual DNA to RNA
prokaryotes
the smallest and most common microorganisms - unicellular organisms that lack a nucleus and store there DNA inside the cytoplasm
a cell membrane surrounding the cytoplasm
what is inside the cell wall of a prokaryote
they are classified in either domain Bacteria or domain Archaea
how are prokaryotes classified
Archaea look similar to bacteria but are genetically closer to eukaryotes
are Archaea similar to bacteria
Archaea lack peptidoglycan and have different membrane lipids than Bacteria
give two ways in which archaea are different than bacteria
by characteristics such as shape, the chemical nature of cell walls, the way they move and obtain energy
how are prokaryotes identified
bacillus
rod shaped prokaryotes
coccus
spherical prokaryotes
spirillum
spiral and corkscrew shaped prokaryotes
heterotrophs
Are most (but not all) prokaryotes heterotrophs or autotrophs
asexually by binary fission
do prokaryotes reproduce sexually or asexually
binary fission
prokaryote doubles in size, replicates its DNA then divides in half to produce 2 identical daughter cells
endosphere
a thick internal wall that encloses DNA and a portion of the cytoplasm ~ this will form in prokaryotes when growth conditions become unfavorable and they want to protect their DNA
conjugation
how prokaryotes exchange genetic information, hollow bridge forms between 2 bacterial cells, and genetic material, usually in the from of a plasmid, moves from one cell to the other.
1) decomposers that break down dead matter
2) producers that carry out photosynthesis
3) convert natural nitrogen gas into a form plants can use during nitrogen fixation;
4) used in industry and food production
why are prokaryotes vital to maintaining the ecological balance of the living world - list four things they do
pathogens
disease causing microorganisms, commonly come from bacteria and viruses
two general ways: destroy living cells and tissues diirectly or cause an immune response that destroys tissues
how do bacterial pathogens produce diseases that affect humans and other animals
by breaking down the cells for host
how do bacterial pathogens damage cells and tissues directly
yes - they release toxins/poisons that travel throughout the body and interfere with the normal activity of the host
do bacterial pathogens release toxins
washing; using disinfectants like bleach; preparing and storing foods safely; sterilize exposed items (use heat to kill bacteria)
how can you control bacterial pathogens
prevent with vaccine; treat with antibiotics
how can you prevent or treat bacterial diseases
Vaccine
what is a preparation of a weakened or killed pathogen or inactivated toxin that stimulates the body to produce immunity to the disease.
natural way of killing pathogens
what is a body's immunity
antibiotics
what is a drug used to attack a bacterial infection when it occurs
they are compounds that block the growth and reproduction of bacteria
how do antibiotics work
emerging disease
an unknown disease that appears in a population for the first time, or a well-known disease that suddenly becomes harder to control
Why are pathogens threatening to human health?
human populations have little or no resistance to pathogens, methods of control aren't developed
How do Prokaryotes differ?
In size, shape, in the way they move, and in the way they obtain and release energy
What are the methods used to protect food?
heating, freezing, sterilization by heat NOT vaccination
retrovirus
What type of virus causes the disease AIDs?
common cold, influenza, AIDS, chicken pox and measles
What are examples of viral diseases in humans?
yes
Do viruses produce serious diseases in animals and plants?
hygiene or vaccination
What are two ways to protect agains viral diseases?
yes
Are there antiviral drugs that help reduce the symptoms of specific virures?
due to increase in worldwide travel and food shipments; also scientists are struggling to keep up with the evolution of bacteria and viruses
Why are emerging diseases spreading?
overuse of antibiotics
What has led to the emergence of resistant strains of bacteria?
How does a virus get into a cell?
Most viruses have surface proteins that bind receptors on the cell and trick the cell into taking it in.