Chapter 21

Question 1

Capsid

Answer 1

The protein shell of a virus that contains its genetic material

Question 2

What is Reverse Transcriptase and what does it do?

Answer 2

Reverse Transcriptase is a “RNA-dependent, DNA polymerase”, which means it reads RNA but makes (polymerizes) DNA.

Question 3

Where is Reverse Transcriptase mainly found?

Answer 3

In retroviruses

Question 4

How are viruses classified?

Answer 4

By their genome, their size, and their host

Question 5

Why is there a “cold and flu” season?

Answer 5

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

Question 6

Each virion has…

Answer 6

1. Nucleic Acid (might be DNA or RNA)
2. Protein capsid
   *some also have an “envelope” that is similar to a cell membrane

Question 7

When is an envelope usually made?

Answer 7

Enveloped Viruses possess a membrane that surrounds its capsid and is acquired in the late stages of virus assembly AKA budding

Question 8

Bacteriophage

Answer 8

Question 9

What do bacteriophages do?

Answer 9

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.

Question 10

Adenovirus

Answer 10

Infects the human respiratory tract and is non-enveloped

Question 11

What is a retrovirus?

Answer 11

A virus that can reverse transcribe it’s RNA genome into DNA form (HIV!!)

Question 12

A virus can either contain…

Answer 12

DNA or RNA but not both! It may be single or double stranded, circular or linear, in one piece or multiple!

Question 13

What are the benefits of having a viral envelope (for the virus)?

Answer 13

Question 14

HIV

Answer 14

• A Retrovirus!
• Enveloped
• infects helper T-cells
• uses GP120 to attach to the CD4 receptor (like a key!)

Question 15

Apoptosis

Answer 15

Programmed cell death (If something is wrong with a cell our body will just kill it)

Question 16

Steps of Virus Infections

Answer 16

1. Attachment
2. Entry (through envelope or host receptors)
3. Replication and Assembly
4. Egress (Release)- Often times resulting in a host cell lysis

Question 17

Corona Virus (Covid-19)

Answer 17

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.

Question 18

Fomite

Answer 18

Inanimate infected surfaces

Question 19

Budding

Answer 19

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

Question 20

Plaque

Answer 20

Region where viruses are killing bacteria

Question 21

How do viruses go from being latent to active?

Answer 21

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!!