Chapter 18 Microbial Models: The Genetics of Viruses and Bacteria p. 328

 

Researchers discovered viruses by studying a plant disease p. 328

§         Read this section…have an awareness

A virus is a genome enclosed in a protective coat p. 329

§         Viral Genome consists of….

§         Capsids

§         capsomeres

§          Viral Envelopes

§         Phages (bacteriophages)

§         Figure 18.2 p. 330. Know the viral structures

Viruses can only reproduce within a host cell. 330

§         Host range

§         Receptor sites (lock and key)

§         Viruses of eukaryotes are usually….

§         Viral reproductive cycle

o       Role of DNA polymerase

o       RNA viruses do not use DNA polymerase…why? How do they get around this?

 

 

§         Figure 18.3 p. 331

Phages reproduce using lytic and lysogenic cycles. P. 331

Lytic Cycle p. 331

§         Virulent phages

§         Lytic cycle

§         Figure 18.4 p. 332 ..know the cycle

§         What has kept bacteria from becoming extinct?

§         Role of Natural Selection

§         What are several defenses against destruction by phage infection?

§         Restriction enzymes

 

 

The Lysogenic Cycle p. 332

§         Temperate viruses

§         Lysogenic cycle

§         Prophage

§         Lysogenic cell

§         What switches a virus from a lysogenic to the lytic cycle?

§         Figure 18.5 The Lysogenic and lytic reproductive cycles p. 333… know the cycle

Animal viruses are diverse in their modes of infection and mechanism of replication p. 333

§         Figure 17.6 p. 331…. Know the cycle

§         What are the variables of viral infections and reproduction in animal viruses?

 

 

§         Table 18.1 p. 334

Viral Envelopes p. 334

§         Description of viral envelope

§         How does the virus gain entry into the animal cell?

§         Figure 18.6 p. 334 The reproductive cycle of an enveloped virus

§         Viral envelopes are derived from…..

§         Some viral envelopes (i.e. Herpes) are derived from….

 

RNA as Viral Genetic Material p. 335

§         See Table 18.1 p. 334 

§         Retrovirus

§         Reverse transcriptase

§         Provirus (and example)

§         Vaccines

Causes and Prevention of Viral Diseases in Animals p. 335

§         Link between viral infection and the symptoms

§        Vaccines

§        Role of cowpox

§        Role of antibiotics against bacteria and viruses

§        Figure 18.7 p. 336 HIV, a retrovirus

Emerging Viruses p. 337

§         3 processes that contribute to the emergence of viral diseases

 

 

 

§         Figure 18.8 Emerging Viruses p. 337

Viruses and Cancer p.337

§         Know some examples

§         Carcinogens

 

Plant Viruses are serious agricultural pests p. 338

§        Figure 18.9 p. 338

§        Examples

§        Horizontal transmission

§        Vertical transmission

§        Role of plasmodesmata

 

Viroids and prions are infectious agents even simpler than viruses p. 339

§        Viroids

 

§        Prions

 

 

Viruses may have evolved from other mobile genetic elements p. 339

§        Which came first…. viruses or cells? What is the current thinking and why?

 

 

 

§        Plasmids

 

The short generation span of bacteria helps them adapt to changing environments p. 340

§        Describe the bacterial genome (DNA and plasmid)

§        Nucleoid

§        Mode of reproduction

§        Why are colonies genetically identical?

§        Role of new mutations

 

Genetic recombination and transposition produce new bacterial strains p. 341

§         Detecting genetic recombination in bacteria

§         Figure 18.12 p. 341     

§         Transformation

§         What must a bacterial species posses for the uptake of DNA?

§         Transduction

§         Figure 18.13 p. 342

o       Generalized transduction

 

o       Specialized transduction

 

 

§         Conjugation

§         Role of sex pili

§         F factor

§         Figure 18.14 p. 343

General characteristics of Plasmids p. 343

§         Plasmid

§         Episome

The F plasmid and Conjugation p. 343

§        F plasmids

§        F⁺ vs F^-

§        Hfr

§        Role of the F plasmid…be able to explain how the F plasmid is “contagious”

R plasmids and antibiotic resistance p. 344

§        R plasmids

§        How are R plasmids passed from one bacterium to another?

Transposon p. 345

§        Define

The control of gene expression enables individual bacteria to adjust their metabolism to environmental change. P. 347

Operons: The Basic Concept p. 347

§                     Structural gene

§                     Operator

§                     Operon

§                     Repressor

§                     Regulatory genes

Self Quiz p. 353