VIRUSES (lesson three) Flashcards
what is a virus?
a small, non-living particle. (they are simple packages of genetic instructions in the form of DNA or RNA
what is a capsule?
genetic material surrounded by protein in a virus
true or false: A virus contains a cytoplasm and other organelles
false
true or false: viruses don’t grow
true
why are viruses not considered alive
because they cannot grow or reproduce on their own.
do viruses produce energy?
no viruses do not produce or use energy.
true or false: viruses produce waste
false
how are viruses classified?
they’re classified using the taxonomic classification
what are the two types of Virus Replication?
- LYTIC CYCLE
- and the LYSOGENIC CYCLE
what is the difference between of lytic cycle and the lysogenic cycle?
The lytic cycle is fast-paced while the lysogenic cycle is a sleeping-paced (slow)
how many stages does the lytic cycle have?
4 stages
what are the four stages of the lytic cycle?
- Attachment/Entry
- Synthesis
- Assembly
- Release
what happens in the first stage of the lytic cycle (attachment/entry)
virus recognizes the host cell & spike/attachment proteins on the virus then bind to receptors on the cell’s surface, either the whole virus is then engulfed into the cell OR the DNA/RNA is injected into the cell
what happens in the SECOND stage of the lytic cycle
the viral DNA/RNA instructs the cell to produce new virus parts (i.e. new viral DNA & capsids)
what happens in the third stage of the lytic cycle
the new virus parts are brought together and assembled into new viruses
what happens in the fourth stage of the lytic cycle
new viruses are released from the infected cell (via lysis) and the host cell is bursted and killed
what is the lysogenic cycle?
In this cycle, the virus goes into a dormant stage (‘sleeping’); this happens when conditions are favorable to do so
what is the first step of the lysogenic cycle?
The virus injects its DNA/RNA into the host cell but DOES NOT take control of the host cell
what is the second step of the lysogenic cycle?
the viral DNA becomes part of the cell’s DNA
what is the third step of the lysogenic cycle?
It is replicated as the cell is replicated (i.e. via mitosis/meiosis) (Therefore, all new daughter cells contain the virus. The host cell is NOT killed via the lysogenic cycle)
what is the Rhinovirus?
- Rhinovirus is the most common viral infection
- This is the cause of the common cold
- They are among the smallest viruses
what is HPV?
- The human papillomavirus is a DNA virus
- Others are symptomatic including HPV16 and HPV18 which 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
what is Ebola?
- Ebola virus disease or Ebola hemorrhagic fever is a viral fever that can infect humans and other primates
- Symptoms will include fever, sore throat, muscle pain, headaches, vomiting, diarrhea and rash
- Eventually, you begin to bleed internally and externally and organs will begin to shut down
- The virus spreads through contact with body fluids
what is HIV?
- The human immunodeficiency virus (HIV) is a viral infection that causes acquired immunodeficiency syndrome (AIDS)
- AIDS is a progressive condition which leads to the failure of the immune system
- Without treatment the average survival time after infection with HIV is estimated to be 9-11 years
- HIV is passed through the transfer of bodily fluids including blood, semen, vaginal fluid, pre-ejaculate or breast milk
what is Smallpox?
- This virus attacks the small blood vessels of the skin and mouth which causes its characteristic rash and blisters
treatment of viral infections?
Viral infection can only be treated with antiviral medications by preventing the following:
-Attachment/Entry
-Nucleic acid replication
-Virus protein processing
-Virus maturation
what do antibiotics work for?
only work on infections that are bacterial, do not work for viral infections
how can viral infections be prevented
Viral infections can be prevented with vaccinations
what are the 3 types of vaccinations?
- Live (infectious) attenuated agents
- Inactivated (non-infectious) whole agents
- Subunit preparations
what do live attenuated agents do
weakened or modified microbes so that they are less virulent
what do inactivated (non-infectious) whole agents do
modified viruses so that they cannot trigger disease
what do Subunit preparations do
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
To prepare your immune system so that it is ready (has made enough antibodies) to fight when the virus invades the body
benefits of viruses
-They can be used to lower the number of harmful bacteria
-They can be used in something called gene therapy, where viruses are used to insert specific genes or drugs into targeted cells by using viral capsules
