Chapter
Objectives
- Describe the contributions
of A. Mayer, D. Ivanowsky, M. Beijerinck, and W. Stanley to
the discovery of viruses
- List and describe the
structural components of viruses
- Explain why viruses
are obligate parasites
- Describe 3 patterns
of viral genome replication
- Explain the role of
reverse transcriptase in retroviruses
- Describe how viruses
recognize host cells
- Distinguish between
lytic and lysogenic reproductive cycles using phage T4
and phage λ as examples.
- Outline the procedure
for measuring phage concentration in a liquid medium
- Describe several defenses
bacteria have against phage infection
- Using viruses with envelopes
and RNA viruses as examples, describe variations in replication
cycles of animal viruses
- Explain how viruses
may cause disease symptoms and describe some medical weapons
used to fight viral infections
- List some viruses that
have been implicated in human cancers and explain how tumor
viruses transform cells
- Distinguish between
horizontal and veritcal routes of viral transmission in plants
- List some characteristics
that viruses share with living organisms and explain why viruses
do not fit our usual definition of life
- Provide evidence that
viruses probably evolved from fragments of cellular nucleic
acid
- Describe the structure
of a bacterial chromosome
- Describe the process
of binary fission in bacteria and explain why replication
of the bacterial chromosome is considered to be semiconservative
- List and describe the
3 natural processes of genetic recomgination in bacteria
- Distinguish between
general transduction and specialized transduction
- Explain how the F plasmid
controls conjugation in bacteria
- Explain how bacterial
conjugation differs from sexual reporduction in eukaryotic
organisms
- For donor and recipient
bacterial cells, predict the consequences of conjugation between
the following
- F+ and
F - cell
- HFr and F -
cell
- Define transposon and
describe 2 essential types of nucleotide sequences found in
transposon DNA
- Distinguish between
an inseretion sequence and a complex transposon
- Describe the role of
transponases and DNA polymerase in the process of transposition
- Explain how transposons
can generate genetic diversity
- Briefly describe the
2 main strategies cells use to control metabolism
- Explain why grouping
genes into an operan can be advantageiojs
- using the trp
operon as an example, explain the concept of an operon and
the functionof the operator, repressor, and corepressor
- Distinguish between
structural and regulatory genes
- Describe how th lac
operon functions and explain the role of the inducer allolactose
- Explain how repressible
and inducible enzymes differ and how these differences reflect
differences in the pathwyas they control
- Distinguish between
positive and negative control and give examples of each from
the lac operon
- Expalin how CAP is affect
glucose concentration
- 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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- Compare the organization
of prokaryotic and eukaryotic genomes
- Describe the current
model for progressive levels of DNA packing
- Explain how histones
influence folding in eukaryotic DNA
- Distinguish between
heterochromatin and euchromatin
- Using the Barr body
as an example, describe the function of heterochromatin in
interphase cells
- Describe where satellite
DNA is found and what role it may play in the cell
- Describe the role of
telomeres in solving the end-replication problem with thelagging
DNA strand
- Using the genes for
rRNA as an example, explain how multigene families of identical
genes can be advantageous for a cell
- Using α-globin
and β-globin genes as examples, describe how multigene
families of nonidentical genes probably evolve, including
the role of transposition
- Explain the potential
role that pormoters and enhancers play in transcriptional
control
- Explain why the nuclear
envelope in eukaryotes offers a level of post-trascriptional
control beyond that found in prokaryotes
- Explain why the ability
to rapidly degrade mRNA can be an adaptive advantage for prokaryotes
- Describe the importance
of mRNA degradation in eukaryotes and describe how it can
be prevented
- Explain how gene expression
may be controlled at the translational and post-translational
level
- Compare the arrangement
of coordinately controlled genes in prokaryotes and eukaryotes
- Explain how eukaryotic
genes can be coorinately expressed and give some examples
of coorinate gene expression eukaryotes
- 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
- Describe the key steps
of steroid hormone action on gene expression in vertebrates
- In general terms, explain
how genome plasticity can influence gene expression
- Describe the effects
of gene amplification, selective gene loss, and DNA methylation
- Explain how rearrangements
in the genome can activate or inactivate genes
- Explain the genetic
basis for antibody diversity
- Explain how DNA methylation
may be a cellular mechanism for long-term control of gene
expression andhow it can influence early development
- Describe the normal
control mechanisms that can convert proto-oncogenes to oncogenes
- Explain how changes
in tumor-suppressor genes can be involved int ransforming
normal cells into cancerous cells
- Explain how oncogenes
are involved in virus-induced cancers
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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 |
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Chapter
Outline Framework
- The Genetics of Viruses
- Researchers discovered
viruses by studying a plant disease
- A virus is a genome
enclosed in a protective coat
- Viruses can reproduce
only within a host cell
- Phages reproduce using
lytic or lysogenic cycles
- Animal viruses are
diverse in their modes of infection and replication
- Plant viruse are serious
agricultural pests
- Viruses may have evolved
from other mobile genetic elements
- The Genetics of Bacteria
- The short generation
span of bacteria facilitates their evolutionary adaptation
to changing environments
- Genetic recombination
produces new bacterial strains
- The control of gene
expression enables individual bacteria to adjust their metabolism
to environmental change
- The Structure of Chromatin
- Chromatin structure
is based on successive levels of DNA packing
- Genome Organization
at the DNA Level
- Repetitive DNA and
othe noncoding sequences account for much of a eukaryotic
genome
- Gene families have
evolved by duplication of ancestral genes
- gene amplification,
loss, or rearrangement can alter a cell's genome
- The Control of Gene
Expression
- Each cell of a multicellular
eukaryote expresses only a small fraction of its genome
- The control fo gene
expression can occur at any step in the pathway from gene
to functional protein
- Chromatin modifications
affect the availability of genes for transcription
- Transcription initiation
is controlled by proteins that interact with DNA and with
each other
- Post-transcriptional
mechanisms play supporting roles in the control fo gene
expression
- The Molecular Biology
of Cancer
- Cancer results from
genetic changes that affect the cell cycle
- Oncogene proteins
and faulty tumor-suppressor proteins
- Multiple mutations
underlie the development of cancer
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