Chapters 18~19: Genetics of Viruses and Bacteria and Eukaryotic Genomes
AP Biology
Stoneleigh-Burnham School
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Judith S. de Nuño
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Chapter Objectives

    1. Describe the contributions of A. Mayer, D. Ivanowsky, M. Beijerinck, and W. Stanley to the discovery of viruses
    2. List and describe the structural components of viruses
    3. Explain why viruses are obligate parasites
    4. Describe 3 patterns of viral genome replication
    5. Explain the role of reverse transcriptase in retroviruses
    6. Describe how viruses recognize host cells
    7. Distinguish between lytic and lysogenic reproductive cycles using phage T4 and phage λ as examples.
    8. Outline the procedure for measuring phage concentration in a liquid medium
    9. Describe several defenses bacteria have against phage infection
    10. Using viruses with envelopes and RNA viruses as examples, describe variations in replication cycles of animal viruses
    11. Explain how viruses may cause disease symptoms and describe some medical weapons used to fight viral infections
    12. List some viruses that have been implicated in human cancers and explain how tumor viruses transform cells
    13. Distinguish between horizontal and veritcal routes of viral transmission in plants
    14. List some characteristics that viruses share with living organisms and explain why viruses do not fit our usual definition of life
    15. Provide evidence that viruses probably evolved from fragments of cellular nucleic acid
    16. Describe the structure of a bacterial chromosome
    17. Describe the process of binary fission in bacteria and explain why replication of the bacterial chromosome is considered to be semiconservative
    18. List and describe the 3 natural processes of genetic recomgination in bacteria
    19. Distinguish between general transduction and specialized transduction
    20. Explain how the F plasmid controls conjugation in bacteria
    21. Explain how bacterial conjugation differs from sexual reporduction in eukaryotic organisms
    22. For donor and recipient bacterial cells, predict the consequences of conjugation between the following
      1. F+ and F - cell
      2. HFr and F - cell
    23. Define transposon and describe 2 essential types of nucleotide sequences found in transposon DNA
    24. Distinguish between an inseretion sequence and a complex transposon
    25. Describe the role of transponases and DNA polymerase in the process of transposition
    26. Explain how transposons can generate genetic diversity
    27. Briefly describe the 2 main strategies cells use to control metabolism
    28. Explain why grouping genes into an operan can be advantageiojs
    29. using the trp operon as an example, explain the concept of an operon and the functionof the operator, repressor, and corepressor
    30. Distinguish between structural and regulatory genes
    31. Describe how th lac operon functions and explain the role of the inducer allolactose
    32. Explain how repressible and inducible enzymes differ and how these differences reflect differences in the pathwyas they control
    33. Distinguish between positive and negative control and give examples of each from the lac operon
    34. Expalin how CAP is affect glucose concentration
    35. Describe how E. coli uses the negative and positive controls of the lac operon to economize on RNA and protein synthesis

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    1. Compare the organization of prokaryotic and eukaryotic genomes
    2. Describe the current model for progressive levels of DNA packing
    3. Explain how histones influence folding in eukaryotic DNA
    4. Distinguish between heterochromatin and euchromatin
    5. Using the Barr body as an example, describe the function of heterochromatin in interphase cells
    6. Describe where satellite DNA is found and what role it may play in the cell
    7. Describe the role of telomeres in solving the end-replication problem with thelagging DNA strand
    8. Using the genes for rRNA as an example, explain how multigene families of identical genes can be advantageous for a cell
    9. Using α-globin and β-globin genes as examples, describe how multigene families of nonidentical genes probably evolve, including the role of transposition
    10. Explain the potential role that pormoters and enhancers play in transcriptional control
    11. Explain why the nuclear envelope in eukaryotes offers a level of post-trascriptional control beyond that found in prokaryotes
    12. Explain why the ability to rapidly degrade mRNA can be an adaptive advantage for prokaryotes
    13. Describe the importance of mRNA degradation in eukaryotes and describe how it can be prevented
    14. Explain how gene expression may be controlled at the translational and post-translational level
    15. Compare the arrangement of coordinately controlled genes in prokaryotes and eukaryotes
    16. Explain how eukaryotic genes can be coorinately expressed and give some examples of coorinate gene expression eukaryotes
    17. Provide evidence from studies of polygene chromosomes that eukaryotic gene expression is controlled at transcription and that gene regulation repsonds to chemical signals such as steroid hormones
    18. Describe the key steps of steroid hormone action on gene expression in vertebrates
    19. In general terms, explain how genome plasticity can influence gene expression
    20. Describe the effects of gene amplification, selective gene loss, and DNA methylation
    21. Explain how rearrangements in the genome can activate or inactivate genes
    22. Explain the genetic basis for antibody diversity
    23. Explain how DNA methylation may be a cellular mechanism for long-term control of gene expression andhow it can influence early development
    24. Describe the normal control mechanisms that can convert proto-oncogenes to oncogenes
    25. Explain how changes in tumor-suppressor genes can be involved int ransforming normal cells into cancerous cells
    26. Explain how oncogenes are involved in virus-induced cancers

Chapter Terms:

Chapter 18 Terms

capsid

viral envelope

bacteriophage (phage)

host range

lytic cycle

virulent virus

lysogenic cycle

temperate virus

prophage

provirus

retrovirus

 

reverse transcriptase

HIV

AIDS

vaccine

virion

prion

nucleoid

transformation

transduction

conjugation

 

F factor

episome

F plasmid

R plasmid

transposon insertion sequence

operator

operon

repressor

regulatory gene

corepressor

inducer

 

Chapter 19 Terms

histones

nucleosome

heterochromatin

euchromatin

repetitive DNA

satellite DNA

Alu elements

multigene family

pseudogene

gene amplification

retrotransposons

immunoglobulins

differentiation

DNA methylation

genomic imprinting

histone acetylation

control elements

enhancers

activator

DNA-binding domain

alternative splilcing

proteasomes

oncogenes

proto-oncogenes

tumor-suppressor genes

ras gene

p53 gene

 

Chapter Outline Framework

  1. The Genetics of Viruses
    1. Researchers discovered viruses by studying a plant disease
    2. A virus is a genome enclosed in a protective coat
    3. Viruses can reproduce only within a host cell
    4. Phages reproduce using lytic or lysogenic cycles
    5. Animal viruses are diverse in their modes of infection and replication
    6. Plant viruse are serious agricultural pests
    7. Viruses may have evolved from other mobile genetic elements
  2. The Genetics of Bacteria
    1. The short generation span of bacteria facilitates their evolutionary adaptation to changing environments
    2. Genetic recombination produces new bacterial strains
    3. The control of gene expression enables individual bacteria to adjust their metabolism to environmental change
  3. The Structure of Chromatin
    1. Chromatin structure is based on successive levels of DNA packing
  4. Genome Organization at the DNA Level
    1. Repetitive DNA and othe noncoding sequences account for much of a eukaryotic genome
    2. Gene families have evolved by duplication of ancestral genes
    3. gene amplification, loss, or rearrangement can alter a cell's genome
  5. The Control of Gene Expression
    1. Each cell of a multicellular eukaryote expresses only a small fraction of its genome
    2. The control fo gene expression can occur at any step in the pathway from gene to functional protein
    3. Chromatin modifications affect the availability of genes for transcription
    4. Transcription initiation is controlled by proteins that interact with DNA and with each other
    5. Post-transcriptional mechanisms play supporting roles in the control fo gene expression
  6. The Molecular Biology of Cancer
    1. Cancer results from genetic changes that affect the cell cycle
    2. Oncogene proteins and faulty tumor-suppressor proteins
    3. Multiple mutations underlie the development of cancer

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