Lecture 19 - Viruses Flashcards Preview

BISC 120 > Lecture 19 - Viruses > Flashcards

Flashcards in Lecture 19 - Viruses Deck (37):
1

What are the 7 characteristics of life?

1. metabolism
2. reproduction
3. cellular organization
4. homeostasis
5. growth
6. adaptation
7. response to stimuli

2

Do viruses have metabolisms? Can they reproduce?

only with help from host cell

3

Do viruses have cellular organization?

no cells, no nuclei, no organelles, no cytoplasm

4

Do viruses have homeostasis?

-generally no
-no cells/cellular components in which to maintain an internal environment

5

Do viruses have growth?

no. built by host cell in fully-formed state

6

Do viruses adapt?

yes, evolutionary change over time in response to selection

7

Do viruses have a response to stimuli?

don't response to touch/sound/light but they can be impaired/killed by antivirals

8

What are the 4 steps of the experiment done with tobacco and sap?

1. extracted sap from tobacco plant with tobacco mosaic disease
2. passed sap through porcelain filter
3. rubbed filtered sap on healthy tobacco plants
4. healthy plants became infected

9

What are viruses?

-not cells
-infectious particles consisting of nucleic acids in a protein shell
-sometimes in a membranous envelop

10

What is a capsid?

protein shell

11

What are possible hosts for a virus?

-archaea, plants, animals, fungi, protists

12

What are possibilities for the genome?

-linear or circular
-one piece or mutliple pieces
-RNA or DNA
-double or single stranded

13

What are 4 major viral groups?

...

14

What is a large virus?

pandoravirus

15

How does replication of viruses work?

-only in host cells
-most use of host's enzymes, ribosomes, tRNA, amino acids, ATP and other molecules

16

What are 2 ways that the phage can reproduce?

-lytic cycle
-lysogenic cycle

17

What is the lytic cycle?

1. virus attach to bacteria
2. inject phage DNA + degrade host DNA
3. synthesize viral genomes/proteins
4. self-assembly of viruses
5. release viruses (destroy host)

18

What is the lysogenic cycle?

1. virus attach to bacteria
2. inject phage DNA
3. integrate into host DNA
4. prophage copied with bacterial chromosome
5. many divisions create many infected bacteria

19

How do animal viruses reproduce?

often involving a viral envelop

20

What is a viral envelope?

-outer membrane
-Protruding
from the outer surface of this envelope are viral glycoproteins
-bind to specific receptor molecules on the surface of a host cell

21

What is a virulent phage?

A phage that replicates only by a lytic cycle.

22

What are the 5 steps to phage assembly?

1. attachment
2. entry of phage DNA and degradation of host DNA
3. synthesis of viral genomes + proteins
4. self-assembly
5. release

23

What is a temperate phage?

-lytic and lysogenic cycles of phage lambda

24

What is reverse transcriptase?

-transcribes an RNA template into DNA,
-providing an RNA S DNA information flow,
-the opposite of the usual direction.
-source of the word retro

25

What is a provirus?

The integrated viral DNA

26

What is herpes simplex type I

oral, cold sores

27

What is herpes simplex type 2

genital

28

What is herpes zoster

chickenpox/shingles

29

What are 4 types of host ranges?

-broad range (EX West Nile)
-species-specific (EX Measles)
-tissue specific (EX human cold)

30

What can recombinant viruses do?

expand host range

31

What are viroids?

-sub-viral pathogens
-circular RNA molecules without protein coats
-mostly infect plants

32

What are prions?

-infection proteins
-cause brain diseases include scrapie in sheep, mad cow disease, Alzheimer's

33

What is the origin of viruses?

-hard to discern due to horizontal gene transfer + lack of fossil record

34

What is a viral shunt?

viruses move more nutrients (and carbon) from other organisms into particulate/dissolved pool

35

Why is HIV hard to treat/

-reverse transcriptase has hight mutation rate

36

What happens when immunity cells are attacked?

T4 helper cells arrive to scene

37

What is the conclusion from the tobacco experiment?

pathogen(virus) is smaller than bacteria