What was the main difference between miasma theory and germ theory?
Miasma theory blamed “bad air,” while germ theory recognised microorganisms cause disease.
Germ theory became widely accepted in the second half of the 19th century.
When did germ theory become widely accepted?
In the second half of the 19th century.
This period marked significant advancements in understanding disease causation.
What did Max von Pettenkofer advocate for?
- Clean water
- Sewage systems
- Fresh air
- Hygienic food production
- Reduced overcrowding
His work laid the foundation for public health practices.
What discipline did Pettenkofer establish?
Hygiene as a research discipline.
His contributions were pivotal in the field of public health.
Who is considered one of the fathers of microbiology?
Robert Koch
Other notable figures include Pasteur and Leeuwenhoek.
What key achievement is Koch known for?
Cultivating bacteria in a lab.
This was crucial for the development of microbiology.
Which viruses are more stable: enveloped or non-enveloped?
Non-enveloped viruses.
Their structure makes them more resistant to environmental factors.
Who discovered the first human virus and when?
Ivanovsky in 1892.
This discovery was based on a plant virus filtrate.
Why are viruses considered non-living?
They lack metabolism and use host cells to replicate.
This characteristic differentiates them from living organisms.
What is the smallest type of virus?
Circular RNAs (250–430 nt).
Their size contributes to their unique replication strategies.
What is the largest known virus?
Megaklothovirus (2.5–3.1 μm).
Its size challenges traditional definitions of viruses.
What are the three hypotheses of virus origin?
- Regressive hypothesis
- Cellular origin hypothesis
- Co-evolution hypothesis
These hypotheses explore how viruses may have evolved.
When did many infectious diseases first begin spreading to humans?
Around 6500 BC when farming developed.
This transition marked significant changes in human health.
Give an example of a virus with a broad host range.
Influenza virus.
Its ability to infect multiple species contributes to its prevalence.
Give examples of human-specific viruses.
- Smallpox virus
- Poliovirus
These viruses have evolved to infect only humans.
What are the 6 typical steps of viral replication?
- Attachment
- Entry
- Uncoating
- Synthesis
- Assembly
- Release
Understanding these steps is crucial for developing antiviral strategies.
What determines viral attachment?
Viral proteins binding host cell receptors.
This specificity is key to viral infectivity.
What is viral tropism?
The range of host cells a virus can infect.
It influences the spread and impact of viral infections.
What entry method is used by non-enveloped viruses?
Direct penetration via capsid pore formation.
This method allows them to enter host cells efficiently.
What entry method is used by enveloped viruses?
Membrane fusion.
This process is facilitated by the viral envelope.
What does receptor-mediated endocytosis require?
Virus attachment that triggers endocytosis.
This mechanism is crucial for many viruses to enter host cells.
How do dsDNA viruses normally replicate?
Similar to host cells, using host DNA & RNA polymerases.
This replication strategy allows them to efficiently produce new viral particles.
What is the major exception among dsDNA viruses?
Orthopoxviruses replicate in the cytosol using their own polymerases.
This unique feature distinguishes them from other dsDNA viruses.
How do ssDNA viruses replicate their genome?
Host DNA polymerase makes complementary strand → dsDNA intermediate.
This process is essential for their replication.
