Viruses Flashcards
(24 cards)
Cells are measured in _______
micrometers (um)
Viruses are measured in _______
nanometers (nm)
What are the two structures that all viruses have?
Nucleic acid and protein coat (capsid)
Give an example of a virus with DNA as its nucleic acid core.
bacteriophage
Give an example of a virus with RNA as its nucleic acid core.
HIV (human immunodeficiency virus)
What is the structure of a bacteriophage
Name two structures of the bacteriophage made of protein
The head and the contractile sheath
These structures are essential for the bacteriophage’s function and interaction with host cells.
What type of cell does a bacteriophage infect?
Bacterial cells
Bacteriophages are viruses that specifically target bacteria.
What does the DNA code for?
The production of new bacteriophage proteins that form the capsid (head)
This process is crucial for the assembly of new bacteriophage particles.
What is the role of the tail fibres?
The tail fibres are important in attaching the virus to bacterial cells
This attachment is the first step in the infection process.
What does a bacteriophage do after it infects a bacterial cell?
Produces bacteriophage proteins from the DNA (for new bacterial coats)
Replicates the DNA
Packages new DNA into the new protein coats
Bacterial cell is destroyed as it ruptures when relating new viruses
This involves several steps including replication of DNA and packaging into new protein coats.
Fill in the blank: After infecting a bacterial cell, a bacteriophage _______ the DNA.
Replicates
This replication is essential for creating new bacteriophage particles.
Fill in the blank: The bacteriophage _______ the new DNA into the new protein coats.
Packages
This step is crucial for the formation of new virions.
True or False: A bacterial cell is destroyed as it ruptures when releasing the new viruses.
True
This lysis of the bacterial cell is a common outcome of bacteriophage infection.
What is the structure of HIV
What is the additional layer that surrounds the protein coat in HIV?
A lipid bilayer containing glycoprotein
This lipid bilayer is crucial for the virus’s ability to infect host cells.
Where is the lipid bilayer obtained from?
The phospholipid bilayer is obtained from the human cells infected before the release of the virus.
This process allows HIV to mimic the host cell membrane.
Why does HIV deliver the enzyme reverse transcriptase into the host cell?
The reverse transcriptase catalyses the synthesis of DNA from RNA.
This DNA is then used to synthesize new protein coats and viral RNA.
Why is reverse transcriptase not required in bacteriophages?
DNA is already present
Bacteriophages typically contain DNA, negating the need for reverse transcription.
What type of human cells does HIV invade?
A type of lymphocyte called helper T-cells
These cells are essential for the immune response.
What is AIDS?
AIDS is a medical condition in which the immune system is critically compromised as progressively more T-cells are destroyed by the HIV virus.
This condition makes the body vulnerable to opportunistic infections.
Why are viruses not true cells?
No cytoplasm, no organelles, inert without access to a living cell
These characteristics differentiate viruses from cellular organisms.
State 2 similarities between HIV and bacteriophages.
- Genetic material within a protein coat
- very small
Both are types of viruses but have different structures and mechanisms.
State 5 differences between bacteriophages and HIV.
- In HIV, the protein coat (head/capsid) is within a phospholipid bilayer
- There is no lipid bilayer in phages
- Glycoproteins are present in HIV, not in phages
- Bacteriophages normally contain DNA, while HIV contains RNA
- HIV contains reverse transcriptase (no reverse transcriptase in phages)
*different shapes
*only phage have tail fibres attached to a base plate
## Footnote
These differences highlight the distinct biological roles and structures of these viruses.
