Lesson 3: Viruses Flashcards
What is a virus?
a small, non-living particle
Virus characteristics?
- contains genetic material surrounded by protein called a capsule
- they do not contain cytoplasm
- they are NOT cells and do not grow organelles (do not grow in gen)
- much smaller than any cell
Why are viruses not alive?
- cannot grow or reproduce on their own
- do not produce or use any energy (ex: ATP)
- do not create waste
- they are simple packages of genetic instructions in the form of DNA or RNA
What are the two types of virus replication processes called?
- lytic cycle
- lysogenic cycle
Stages/process of the lytic cycle
- The virus attaches itself onto the cell and injects its DNA/RNA into the cell or gets engulfed into the cell as a whole
- The viral DNA/RNA controls the cell and instructs it to create new virus parts
- The new virus parts assemble to create several new viruses
- The viruses are released from the now infected cell and are now on their way to infect other cells (cell dies in this process)
Stages/process of the lysogenic cycle
- virus infects cell with their DNA/RNA but does not CONTROL the cell
- The viral DNA/RNA becomes a part of the cells DNA
- It is replicated as the cell is replicated (through mitosis)
- Therefore, all new daughter cells now have viral DNA in their DNA
- In this process, the host cell is NOT killed by this cycle
virus may be triggered to re-enter the lytic cycle if stressed
Rhinovirus
- most common viral infection (it is the cause of the common cold)
- among the smallest viruses
- humans dont become “immune” to this virus as there are so many strains (kind of like variants)
HPV
- HPV16 and HPV18 are known to cause around 70% of cervical cancer cases
- HPV6 and HPV11 can cause genital warts
- These are the strains that the Gardasil vaccine can protect you against
Ebola
- contact disease that can infect humans and other primates
- symptoms: fever, sore throat, muscle pain, headaches, vomiting, diarrehea, rash
- you eventually begin to bleed internally and externally and organs will begin to shut down
- the virus spreads through contact with body fluids
HIV
- viral infection that causes acquired immunodeficiency syndrome (AIDS)
- AIDS is a progressive condition which leads to the failture of the immune system
- HIV is passed through the transfer of bodily fluids such as blood, semen, vaginal fluid, pre-ejaculate, or breast milk
Smallpox
- infectious disease caused by 2 strains of the variola virus
- this virus attacks the small blood vessels of the skin and mouth which causes its characteristic rash and blisters
Covid-19
- RNA infection that causes damage to multiple systems in the body such as the respiratory and cardiovascular system
- can be transferred by touch, droplets, and inhalation of airborne viral particles
- this virus uses the spike proteins on its surface to bind proteins on the surface of human cells; this allows the virus to move into the cell and use the machinery within to make more copies of itself, killing the cell in the process (lytic cycle)
Viral infection treatments
needs to be treated with antiviral medications which prevent the following: attachment/entry, nucleic acid replication, virus protein processing, virus maturation
can be prevented with vaccinations (antibiotics dont work against viruses only against infections that are bacterial)
3 types of vaccinations
- live (infectious) attenuated agents; weakened or modified microbes so that they are less virulent
- inactivated (non-infectious) whole agents; modified viruses so that they cannot trigger disease
- subunit preparations; only part of the agent is used to provoke an immune response (protein of the virus or sugar coating of the virus)
How do vaccinations work?
Vaccinations prepare your immune system so that its ready (made enough antibodies) to fight the virus when it invades the body; helps your white blood cells “remember” the virus; when the virus enters the body, your immune system will recognize it and get rid of it before you can become ill (it cannot take control or sneak into the cell like usual)
