classification quiz: viruses and germ theory 4/17 🦢🎧🧦

what is a virus?

lifeless particles

viruses are non-living because they…

are not made of cells, do not use energy or make proteins, and cannot reproduce on their own

viruses are made of…

a core of genetic material, a protein coat called a capsid that surrounds the genetic material, and an envelope that surrounds the capsid (helps the virus enter the cell)

three common viruses

bacteriophage, tobacco mosaic, influenza

the three methods of viral invasion

* bacteriophages: viruses with DNA-injecting tail fibers that infect bacteria
* plants: viruses enter through tears in the cell wall and damage sites
* animals: viruses enter through endocytosis (cell engulfs material) after attaching to the cell membrane

process of a lysogenic infection

1. a virus fuses its DNA into the DNA of the cell
2. when the cell DNA replicates, the virus DNA replicates too
3. the new cell receives a copy of the virus DNA **(does not produce infection/disease)**

process of a lytic infection

1. the virus attaches to the cell’s membrane
2. the virus inserts its genetic material into the cell
3. the virus takes over cell machinery and makes nucleic acids and capsid proteins (virus DNA + coat proteins = new viruses)
4. the newly assembled viruses burst out of the cell membrane killing the host cell **(produces infection/disease- not good)**

the only defense against viruses

vaccines

what is a vaccine?

a solution containing weakened or killed viruses (pathogens)

when weakened viruses are introduced to the body, the immune system learns how to produce defenses called…

antibodies

vaccines only work against viruses that…

do not change (mutate)

diseases with surface proteins that do not change

smallpox, measles, polio

diseases with surface proteins that mutate often

HIV, cold, influenza

what medications are used to treat viral infections?

antivirals

antivirals cannot cure…

infections

antivirals slow…

viral multiplication

can antivirals inactivate a virus?

no, they cannot kill the virus because it is nonliving

what is a disease?

any change, other than an injury, that disrupts the normal functions of the body

diseases are caused by…

living organisms, materials in the environment, genetics, malfunction of body

the germ theory of diseases says that…

infectious diseases are caused by different types of microorganisms

what is a germ?

a microorganism that can inject diseases

the steps of koch’s postulates

1. observe both normal and sick organisms, take samples from each
2. isolate microbes from one another and characterize the microbes found in the sick organism
3. inject normal organisms with the microbes and observe
4. if an organism displays the same symptoms/signs of the initial disease take samples
5. isolate microbes from one another and characterize the microbes
6. compare the initial isolates with the microbe found in 5, if they are the same, then you have found the cause

how do pathogens cause disease?

* viruses, fungi, bacteria, and some protists destroy cells as they grow
* some bacteria release toxins that harm an organism
* parasitic worms produce sickness by disrupting bodily functions

how do diseases and viruses correlate?

a virus is a small part that can create a larger disease (think like the word virus is smaller than the word disease)

how do diseases spread?

physical contact, contaminated food and water, infected animals that act as vectors

how can we prevent the spread of infectious diseases?

vaccination, disinfectants, pasteurization, refrigeration

ways to fight/cure infectious diseases?

antibiotics, antivirals, antifungals