75 Questions
What is the tiniest simplest form of life on earth according to the text?
Virus
Why did 15th century Italians call the disease Influenza?
Because they believed it was caused by the influence of stars and plants
What is the term for an organism that must have a cell to replicate?
Virus
Where does a virus become a 'virus particle' with no activity or metabolism?
Outside of the host cell
What process allows a virus to replicate inside an infected cell?
Protein synthesis
Why are viruses considered not cellular organisms?
Because they cannot perform metabolism on their own outside of a cell
What is the key factor that determines the survival of viruses according to the text?
Spreading capacity
'Virus-Host Equilibrium' refers to what concept?
'Virus-Host' relationship maintaining survival balance
What is one of the major reasons why Ebola virus outbreaks are limited to Africa?
Africa has a specific ecological environment that favors the virus.
In what year did Influenza virus of 1919 demonstrate better equilibrium?
1976
Why is Ramesses V's preserved mummy mentioned in the text?
As an illustration of an ancient smallpox infection.
Which characteristic is shared by all cellular life forms according to the text?
Ability to reproduce by division.
Why did Dmitri Iwanowski's work in 1892 open the field called VIROLOGY?
He demonstrated that a small infectious agent smaller than bacteria can transmit disease.
Why are viruses unable to survive on their own in most cases?
Viruses require a host cell for replication and survival.
What major characteristic distinguishes virus particles from cellular organisms?
'DNA must be expressed all the time.'
How did seasonal flu outbreaks differ between 1918 and 1957 according to the text?
'1918 had a higher death rate.'
What is a characteristic of lysogenic viral replication?
Viral genome is incorporated into the host's chromosomes
Which type of RNA viruses have complementary base sequences in their genome compared to viral mRNAs?
Negative-sense RNA viruses
What is the main difference between segmented and non-segmented viruses?
Segmented viruses have their genome divided into many chromosomes
Which phase of viral replication involves the production of viral proteins?
The assembly of new virus particles
What enzyme is required to separate enzymes in a viral infection?
Protease
In which type of RNA virus does the genome contain sequences similar to mRNA?
+ssRNA
What is the initial step in the translation of -ssRNA viruses?
+ssRNA copying
Which cells house viral memory cells that sustain lifelong infections?
White blood cells
'Lytic' and 'Lysogenic' are terms related to which aspect of viral life cycles?
'Lytic' refers to a viral replication cycle, while 'Lysogenic' refers to a dormant state within the host.
'Lyso' in lysogenic is derived from which word, hinting at its nature?
'Lysis'
What did a virologist in the 20th century famously describe a virus as?
A piece of bad news wrapped in a protein
When viruses can sense the presence of the immune system, what action do they typically take?
Reduce replication to avoid immune system detection
In what year did the transfer of smallpox from Europe to the Americas occur?
1519 A.D
Which virus infected about 350 million people worldwide in a chronic way?
Hepatitis B virus
Which virus caused 50-100 million deaths worldwide during the 1918 pandemic?
Spanish Flu virus
Which of the following are common causes of acute infections in humans according to the text?
Viruses
What is a key characteristic of viruses in terms of their presence in the human genome?
Viruses account for the first 8% of our genome
What is a characteristic shared by rabies, Ebola, and smallpox viruses according to the text?
High mortality rates
What is a significant role that viruses like varicella zoster play in human infections according to the text?
Triggering early infections for immunity development
What is the impact of the varicella zoster virus on human infections according to the text?
We need them to infect us early as possible
What significant event occurred in 1519 A.D regarding smallpox?
Transferred from Europe to the Americas
How did Hernando Cortes contribute to the spread of smallpox?
Invaded Mexico and conquered millions of Aztecs
What factors contributed to the defenselessness of the Aztecs in the face of smallpox?
Less than 600 men helped, horses, weapons
What were the major factors that caused significant mortality in the U.S according to the text?
Obesity, tobacco, and alcohol
What is the most common cause of acute infections in humans according to the text?
Viruses
How many total virus infections in the world exceed several billion cases each year in adults?
Several billions
What viruses have high mortality rates according to the text?
Rabies, Ebola, smallpox
Which viruses can lead to long-term disability?
Polio, rubella
What is the key characteristic that distinguishes virus particles from cellular organisms according to the text?
They cannot survive on their own
Explain the historical impact of viruses on human history.
Viruses have caused devastating diseases throughout history, impacting populations like war and natural disasters.
What is the significance of the term 'Influenza' and why did 15th century Italians use it?
The term 'Influenza' was coined by 15th century Italians, who believed it was caused by the influence of stars and planets.
Describe the concept of obligate intracellular parasites in relation to viruses.
Obligate intracellular parasites are viruses that require a host cell to replicate, as they cannot perform metabolism on their own.
Explain the importance of virus-host equilibrium in the survival of viruses.
Virus-host equilibrium is crucial for the survival of viruses, as their natural evolution operates on spreading capacity rather than disease-causing ability.
What is the role of mutants in the survival of viruses?
Viruses produce a large number of mutants to survive, with selection removing non-fittest strains.
Discuss the impact of the death of an infected host on the survival of the infecting virus.
The death of an infected host compromises the survival of the infecting virus, as viruses cannot replicate without a host.
Explain the process of viral replication inside an infected cell.
Inside an infected cell, a virus can replicate to make proteins, enter the nucleus, and produce genome proteins before leaving the cell.
What is the main reason why viruses are considered not cellular organisms?
Viruses are not considered cellular organisms because they lack the ability to perform metabolism on their own outside of a host cell.
Describe the natural evolution process of viruses in terms of spreading capacity.
The natural evolution of viruses operates on their spreading capacity rather than their ability to cause disease.
How do viruses like varicella zoster impact human infections according to the text?
Viruses like varicella zoster play a significant role in causing acute infections in humans.
What is the significance of the hieroglyph from Memphis in 3700BC?
First written record of a virus infection
How did the Influenza virus of 1919 demonstrate better equilibrium?
Killing people but not at the same level as 1918
What disease did Ramesses V die from in 1143 B.C.?
Smallpox
What did Dmitri Iwanowski's work in 1892 lead to in the field of virology?
Birth of the field called VIROLOGY
What is the impact of Ebola virus outbreaks on infected people?
Death up to 90% of infected people shortly after infection
What is the impact of polio infection on most people?
Totally asymptomatic, can spread the virus
How did seasonal flu outbreaks differ between 1918 and 1957?
1918 had a higher death toll
What is the main characteristic of virus particles that distinguishes them from cellular organisms?
Not cellular organism
What is the purpose of a virus solely replicating and infecting other host cells?
To make many copies and infect other host cells
What did Dmitri Iwanowski's discovery reveal about infectious agents in 1892?
Smaller than a bacteria
What is the major distinguishing factor between lytic and lysogenic viral replication cycles?
In lysogenic cycle, viruses are incorporated into the host's chromosome, while in lytic cycle, viruses are released from the host cell after replication.
Explain the impact of HIV infection being lysogenic on human health.
HIV can stay in memory cells for life, leading to lifelong infection and continuous production of new virus particles.
What is the main reason behind viruses like HIV infecting humans for life?
The infection of memory cells by HIV allows the virus to persist in the body indefinitely.
How do segmented viruses, like rotavirus, differ from non-segmented viruses in terms of genome structure?
Segmented viruses have their genome made of many chromosomes, while non-segmented viruses have a single chromosome.
Explain the significance of RNA-dependent RNA polymerase in viral replication.
RNA-dependent RNA polymerase is crucial for copying the viral RNA genome into a form that can be translated and used to produce viral proteins.
What is the primary function of RNA-dependent RNA polymerase in a newly infected cell?
It helps in copying the viral RNA genome into a form suitable for translation into viral proteins.
Describe the role of memory cells in sustaining lifelong infections by viruses like HIV.
Memory cells provide a reservoir for viruses to persist in the body, leading to lifelong infections.
How does the presence of memory cells contribute to the chronicity of certain viral infections?
Memory cells act as a long-term reservoir for viruses, allowing them to continuously produce new virus particles.
What is the significance of viral memory cells in the context of lifelong infections?
Viral memory cells provide a long-term source for continuous production of new virus particles, leading to lifelong infections.
Explain the importance of separating viral enzymes in the infected cell during viral replication.
Separating viral enzymes allows for the activation of specific functions, such as producing structural or processed proteins.
Test your knowledge on basic concepts in human virology with questions about how viruses can sense the immune system, the relationship between viruses and the immune system, and the prevalence of viruses in the environment.
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