Chapter 21 Flashcards
Capsid
The protein shell of a virus that contains its genetic material
What is Reverse Transcriptase and what does it do?
Reverse Transcriptase is a “RNA-dependent, DNA polymerase”, which means it reads RNA but makes (polymerizes) DNA.
Where is Reverse Transcriptase mainly found?
In retroviruses
How are viruses classified?
By their genome, their size, and their host
Why is there a “cold and flu” season?
1) Humans tend to huddle inside when it’s cold. Great human contact with other humans, door knobs, light switches, etc.)
2) Air gets colder and dryer, human skin cracks. Our skin is our largest organ and this makes it easier for pathogens to enter our bodies
Each virion has…
- Nucleic Acid (might be DNA or RNA)
- Protein capsid
*some also have an “envelope” that is similar to a cell membrane
When is an envelope usually made?
Enveloped Viruses possess a membrane that surrounds its capsid and is acquired in the late stages of virus assembly AKA budding
Bacteriophage
What do bacteriophages do?
They infect bacteria by stealing ATP from a previous host which it will use to contract its central shaft and propel its viral genome into the bacterium.
Adenovirus
Infects the human respiratory tract and is non-enveloped
What is a retrovirus?
A virus that can reverse transcribe it’s RNA genome into DNA form (HIV!!)
A virus can either contain…
DNA or RNA but not both! It may be single or double stranded, circular or linear, in one piece or multiple!
What are the benefits of having a viral envelope (for the virus)?
HIV
- A Retrovirus!
- Enveloped
- infects helper T-cells
- uses GP120 to attach to the CD4 receptor (like a key!)
Apoptosis
Programmed cell death (If something is wrong with a cell our body will just kill it)
Steps of Virus Infections
- Attachment
- Entry (through envelope or host receptors)
- Replication and Assembly
- Egress (Release)- Often times resulting in a host cell lysis
Corona Virus (Covid-19)
Uses spike proteins as the keys to get into cells through their receptors. Vaccines create antibodies that “drape” themself over spike proteins so they can no longer fit with receptor.
Fomite
Inanimate infected surfaces
Budding
When a virus gently eases through the host membrane thus giving it an envelope made of the old host cell membrane. 2 benefits: The host cell doesn’t die, just weakened so it can be reinfected later. The virus is disguised and is harder for the immune system to detect
Plaque
Region where viruses are killing bacteria
How do viruses go from being latent to active?
When a host stresses it creates more cortisol, which if this level is up for a long amount of time it weakens the immune system!!
