ch. 20 -- viruses test (biology)

Question 1

What is a virus?

Answer 1

A virus is a nonliving particle made of proteins, nucleic acids, DNA or RNA, and sometimes lipids

Question 2

Describe the basic structure of a virus.

Answer 2

there is a capsid surrounding the virus, an additional membrane that surrounds that capsid, RNA or DNA. Comes in all different shapes and sizes. Proteins on the outside (act as identifiers)

Question 3

What surrounds all viruses and what is it made of?

Answer 3

A capsid surrounds all viruses. It is made of proteins

Question 4

What does a virus have inside that has the instructions for making copies of the virus?

Answer 4

DNA or RNA (never both)

Question 5

True/False? Viruses only come in THREE shapes, THREE sizes, and TWO structures?

Answer 5

false (many different shapes, sizes, and structures)

Question 6

what is on the outside of a virus that acts as identifiers?

Answer 6

proteins

Question 7

What do specific proteins on the outside of a virus do? Why do they do this?

Answer 7

They act as identifiers. They do this to recognize and bind to specific receptors on a cell.

Question 8

Most viruses infect a ____________ cell.

Answer 8

specific type of

Question 9

What are viruses that only infect bacteria called?

Answer 9

bacteriophages

Question 10

Why are viruses not living?

Answer 10

they cannot reproduce on their own

Question 11

what are the two types of viral infections?

Answer 11

lytic and lysogenic infections

Question 12

what does it mean to lyse the cell?

Answer 12

the cell bursts open

Question 13

what of the two viruses automatically begins chopping up the host cell’s DNA?

Answer 13

lytic

Question 14

What viral infection never leaves your body? Why?

Answer 14

Lysogenic viral infection. Places the DNA or RNA into the host cell DNA

Question 15

what is prophage?

Answer 15

Viral DNA that is incorporated into host DNA

Question 16

What are the two ways a virus can cause disease?

Answer 16

directly destroying living cells or by affecting cellular processes in ways that upset homeostasis

Question 17

be able to label the head, tail fibers, sheath, and DNA of a bacteriophage

Question 18

What are 2 ways we can prevent viruses? Explain both in detail.

Answer 18

1. Vaccinations – injection of a vaccine (a weakened or a similar, but less dangerous pathogen (virus)) to help the body produce immunity
2. Personal hygiene – (2 examples needed on test) – wash your hands, it dislodges the viruses off the surface. Don’t share drink or food, not sharing food or drink prevents ingestion of the virus or come in contact with a virus

Question 19

What treatments do we have for viruses? Explain what is used and what they do.

Answer 19

Antiviral drugs – they’re drugs that attack specific viral enzymes that the virus has and the host does not. They are used to speed recovery from the viral infections or stop activation of the viral infections in other cells (Tamiflu, HIV)

Question 20

What does a virus have to have to survive? Why?

Answer 20

A virus has to have a living host. It hijacks the cellular processes and if the host is not living it will not divide and replicate the virus

Question 21

Explain the lytic cycle:

Answer 21

a bacteriophage attaches to the host cell and injects its DNA
bacteria is chopped up and new capsid proteins are made
DNA is copied
the viral DNA assembles together
the cell lyses and the T4 travels out and infects other cells

Question 22

explain the lysogenic cycle:

Answer 22

a daughter cell with a prophage
prophage integrates into the bacterial chromosome, becoming a prophage
the bacterium reproduces normally, copies the prophage and transmits it to daughter cells