Viruses

Question 1

What are viruses

Answer 1

Non living, have to be inside a host to reproduce

Question 2

Explain the structure of viruses

Answer 2

-Have strands of DNA or RNA
-DNA or RNA surrounded by a capsid
-Moveable genes that parasitize cells

Question 3

What is a capsid and what is its use

Answer 3

Protein coat that protects virus from attack by host cell enzymes

Question 4

How are viruses classified

Answer 4

-The disease they cause
-Size and shape
-Nucleic acid structure

Question 5

What are viruses that infect bacterial cells called

Answer 5

bacteriophage

Question 6

What are the different virus shapes

Answer 6

-Polyhedral
-Cylindrical
-Alien shape
-Spherical

Question 7

Which bacteria shape is most dangerous

Answer 7

Spherical

Question 8

What is the difference between RNA and DNA viruses

Answer 8

RNA is the most common type of virus, DNA has less errors and mutations

Question 9

What are the two cycles of reproduction in viruses

Answer 9

Lytic and lysogenic cycle

Question 10

Explain the lytic cycle

Answer 10

1. (Attachment) Virus attaches to host cell, DNA enters the host cell and goes into the DNA of the host cell
2. (Synthesis) Virus DNA replicates its DNA and parts
3. (Assembly) All parts of virus come together to make new virus particles
4. (Release) New virus particles release from infected cell, host cell dies

Question 11

Explain the lysogenic cycle

Answer 11

1. (Attachment) Virus attaches to host cell, DNA enters and goes into host cell DNA
2. (Reproduction) Virus DNA makes copies of itself during mitosis
3. (Cytokenisis) Daughter cells have virus DNA, cycle continues..

(Host cell does not die, virus only goes to lytic cycle when triggered by a change in the environment

Question 12

What are retroviruses

Answer 12

RNA viruses

Question 13

How do retroviruses turn RNA into DNA

Answer 13

Using reverse transcriptase, RNA turns into DNA, becomes RNA again and then becomes proteins

Question 14

HIV (a retrovirus) can alternate between lytic and lysogenic cycle, how?

Answer 14

-HIV has reverse transcriptase, turning RNA into RNA
-Virus chromosomes go in host cell chromosomes
-Virus chromosomes copied when cell divides
-Replication can be a long process

Question 15

Which viral reproduction cycle is most damaging

Answer 15

Lytic cycle because host cell dies

Question 16

How does the alternation of lytic vs lysogenic cycle explain the patterns of many viruses

Answer 16

When host cell is destroyed, most viruses can be noticed because of symptoms, but those symptoms disappear during lysogenic cycle

Question 17

Why are viruses important

Answer 17

-Reponsible for many human diseases
-Can cause epidemics/pandemics
-Some increase risk in cancer
-Kill crops and livestock

Question 18

What are vaccines

Answer 18

A small dead or weakened virus that gets injected into bodies so immune system can build antibodies against it

Question 19

How do vaccines prevent us from getting the virus

Answer 19

because antibodies will already be there to fight it off

Question 20

What is a prion

Answer 20

Proteins that are found in all body tissues, but most on the brain

Question 21

What is unique about prions

Answer 21

Can cause virus but do not have DNA or RNA

Question 22

How can prions cause a virus

Answer 22

When prions are not folded correctly and turn normal shaped proteins into harmful form, can cause bad brain viruses

Question 23

What is an example of a prion disease

Answer 23

Mad cow disease