Micro Test 3 Ch 17

Front 1

Bacteriophage growth

Back 1

- must be inside cell to reproduce
- one step growth curve
+viral progeny made and released at same time

Front 2

-Eclipse period
-Latent period
-Rise period
-Burst size

Back 2

-no intact virons exist
-no viral progeny released yet
-viral progeny released
-# of viruses produced per infected cell

Front 3

Plaque

Back 3

-zone of bacterial or cell lysis due to infection by a single viron
-Only formed by viable virus particles
-Plaque Forming Units(number of colonies)
-can be used to obtain pure viral cultures

Front 4

Bacteriophage Repoduction Cycle

Back 4

A)Lytic Infection
-cell lysis during virus release
-Virulent Phages
B)Latent Infection
-incorp into host cells chrom
-later reactivated to cause lytic infection
-Temperate phages

Front 5

Virulent Phage Reproduction

Back 5

1)Attachment
2)Penetration & Uncoating
3)Replication of Viral NA
4)Synthesis of Viral coat proteins
5)Assembly of Virons
6)Release of Viral Progeny

Front 6

1) Attachment

Back 6

-Phages bind to specific receptor sites
-Receptor sites vary among phages
-No receptor no attachment

Front 7

2) Penetration & Uncoating

Back 7

-Penetration of viral DNA, and loss of empty capsid

Front 8

3) Replication of viral nucleic acid

Back 8

-Virus stops reproduction of cell DNA, RNA, Proteins
-Activation and transcription of early genes
-3 types of early genes
1) enzymes to degrade bacterial DNA
2) enzymes to aid in synthesis of viral DNA
3) Proteins involved in inhibiting bacterial mechs

Front 9

Synthesis of T4 DNA

Back 9

-Contains hydroxymethylcytosine (HMC) instead of cytosine
-After DNA synth HMC is glycosylated, protecting the DNA

Front 10

Replication of ssDNA

Back 10

-must generate a dsDNA replicative form before replication or transcription can occur

Front 11

4)Synthesis of Viral Coat Proteins

Back 11

- Virus-encoded sigma factor directs the reading of the late genes by the cell's RNA polymerse
- Late- transcribed after the phage nucleic acid is replicated

Front 12

3 Catergories of Late Genes

Back 12

1)Phage structural proteins
2)Proteins that aid in phage assembly
3)Proteins involved in cell lysis and release of phages

Front 13

5)Assembly of Virons

Back 13

-Spontaneous self assembly
1)Head
-Proteins assembled in prohead
-DNA packed into head
2)Tail
-attached to head at collar
3)Tail fibers made & attach to baseplate
-Ends eclipse period

Front 14

6)Release of Viral Progeny

Back 14

-Lysis usually
-T4 proteins
+Endolysin (attacks petidoglycan)
+Holin (lesions in cell membrane)
-latent period is 22 mins after infection

Front 15

B)Temperate Bacteriophages

Back 15

-Specialized transduction
-Lysogeny
+Non-lytic relationship btwn phage and host
+Intergration of phage genome into host DNA (prophage)
+Lysogens(infected bacterial host)

Front 16

Lambda repressor

Back 16

-cI gene product
-Activated= lambda remains prophage
-Inactivated= prophage excises and becomes virulent
+Repair mechs for DNA directly inactivates repressor protein

Front 17

Cro Protein

Back 17

-Cro gene product
-Regulates lytic cycle genes
-Blocks synthesis of lambda repressor

Front 18

Induction

Back 18

-Activation and excision of prophage
-Triggered by drop in Lambda Repressor
-Virus then enters lytic replication cycle

Front 19

1)Inductase
2)Excisionase

Back 19

1)Viral enzyme that catalyzes induction of lamba genome into cell's genome
2)Enzyme that reverses intergration process by binding to integrase