Chapter 19 Flashcards Preview

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Flashcards in Chapter 19 Deck (30):
1

What did Beijerinck conclude?

That it needed host to reproduce

2

What are the 2/3 parts of viruses?

1. Genome
2. Capsid
3. Envelope

3

What are the components of a viral envelope and where do they originate from?

Membrane proteins/phospholipids from host cell;
Proteins and glycoproteins of viral origin

4

What are bacteriophages?

Viruses that infect bacteria strictly

5

What does Phage T4 infect?

E. Coli

6

Host range?

Range of types of cells a certain type of virus can infect

7

When does viral infection begin?

When virus binds to host cell

8

What are the 3 mechanisms of genome entry?

1. Injection from tail
2. Endocytosis
3. Fusion of envelopes

9

What is the method of genome entry for phages?

Injection from tail

10

What are capsids made up of?

Capsomeres

11

What type of phage undergoes the lytic cycle?

Virulent phage

12

What type of phage undergoes lysogenic and lytic cycle?

Temperate phage

13

Why haven't phages exterminated all bacterium

1. Natural selection
2. Restriction enzymes
3. Lysogenic cycle

14

What do restriction enzymes do?

Identify foreign DNA and cut it up

15

What joins the prophage and host cell's genome together?

Viral proteins

16

Prophage?

Phage DNA segment in bacteria DNA

17

What triggers lytic mode from lysogenic mode?

Environmental signals (chemical, radiation)

18

How is transcription of prophage genes prevented

Protein coded by prophage prevents its transcription

19

What do nearly all animal viruses have?

Membrane and RNA

20

What are glycoproteins made by?

Ribosomes bound to ER

21

What are the 2 ways of creating a viral envelope?

1. Exocytosis; glycoproteins use host cell membrane
2. Host envelope replaced by Golgi apparatus membrane

22

What are the three types of RNA genomes found in animal viruses?

1. Directly as mRNA
2. Template for mRNA to be transcribed from
3. Retroviruses

23

In retroviruses, what transcribes the RNA to DNA?

Reverse transcriptase

24

HIV contains what?

2 RNA molecules and 2 reverse transcriptase

25

Provirus

DNA (transcribed from RNA) incorporated into host's genome

26

What can the RNA transcribed from a proviral DNA strand do?

1. Serve as mRNA for viral protein synthesis
2. Serve as genome for new viruses

27

What are the 2 DNA molecules viruses are like

Plasmids and transposons

28

What do plasmids do?

They work apart from cell's genome and can tranfer between cells

29

What do transposons do?

DNA segments that can move within cell's genome

30

Difference between provirus and prophage?

Provirus stays permanently in host's genome, prophage can turn lytic