biology virus test
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biology virus test
biology 9th grade
when were viruses discovered ?
seen in 1935
what is the basic structure of a virus?
nucleic acid , capsid , tail sheath , bacteriaphage
why are viruses not living ?
-cannot reproduce without a host cell
-not made of cells
-do not require energy
-do not grow and develope
why do some think that they are alive ?
they can evolve
what are the possible shapes of viruses
viruses capsids allow them to -
attach only to specific cells
What are some common viruses?
What is the lytic cycle?
-get in , take over, destroy the cell
What are the steps in the lytic cycle ?
1. attachment ( attaches to the cell)
2. injection(DNA is incerted into the cell )
3. Take over(enzymes chop up the host)
4.Manufacture (cell produces viral capsid & DNA)
6. Release (an enzyme opens cell membrane then virus comes out)
What is the lysogenic cycle ?
you get it you have it forever
What are the steps in the lysogenic cycle?
3.provirus fromation (viral DNA attaches to the host cell DNA * cell carries on normal functions
4.Host cell Reproduction ( copies virus DNA into all new daughter cells)
5. Activation(a trigger causes the virus DNA to activate)
6. Take over
ex : HIV, Herpes, Hepititus, Chicken Pox
What are retroviruses ?
* RNA-> DNA
reverse transcriptase enzyme
How can you prevent viral infections ?
* produce memory cells
produced by infected cells - signals uninfected cells to set up a protective barrier
* white blood cells
What are the two kingdoms of bacteria?
What are the general characteristics of bacteria
prokaryotic / unicellular / cell walls
peptidoglycan (protein / sugar)
Modern Bacteria - infect us
what is the structure of DNA ?
Flagella, cilia, cell membrane, pilus ( reproduction) cell wall, Capsule, Ribosomes, DNA (circular) plasmids (small pieces of DNA)
What are some bacterial shapes?
Bacillus ( rod shaped)
Spyrilla ( spiral )
Example of coccus bacteria
example of Bacillus
example of spyrilla
what are the life processes?
movement , gas exchange, nutrition, reproduction
what does obligate mean ?
must be ...
what does faculative mean ?
how do bacteria move?
contact transfer - cilia-flagella-gliding
Types of Gas exchange...
aerobic- requires oxygen
anaerobic- doesnot require oxygen
photosynthetic autotroph - uses light and co
chemosynthetic autotrophs - nuses chemical and co
ex thermal vent bacteria
heterotrophic- eat things for energy
types of reproduction :
asexually - binary fission
sexual - transfer of plasmids
*utalizes a pilus to transfer plasmids
What are endospores?
- a protective "structure" cantaining DNA and a protein coat
when are endospores produced?
when the bacteria is in harsh conditions- too hot or cold- too dry- no food
whats is an autoclave ?
a pressure cooker to destroy bacteria - medical use
What are the benefits of bacteria?
help digest food and produce vitamins-intestines- Decomposers- saprophites- Nitrogen Fixation , Food flavoring , antibiotics,transgenic bacteria
-soil bacteria that convert n2 to no3
what are the characteristics of archae bacteria ?`
thrive in very harsh conditions- have cell walls made of psedomurine
what is psedomurine
carbohydrate / protein
bacteia that lives in digestive systems of large mammals
what are some harmful effects of bacteria?
howdo you control bacteria?
wash well need food moisture appeophate tempretures