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Genomics, Proteomics and
Genetic Engineering
Genomics and Proteomics
• The field of genomics deals with the DNA sequence,
organization, function, and evolution of genomes
• Proteomics aims to identify all the proteins in a cell or
organism including any posttranslationally modified
forms, as well as their cellular localization, functions,
and interactions
• Genomics was made possible by the invention of
techniques of recombinant DNA, also known as gene
cloning or genetic engineering
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Genetic Engineering
• In genetic engineering, the immediate goal of an
experiment is to insert a particular fragment of
chromosomal DNA into a plasmid or a viral DNA
molecule
• This is accomplished by breaking DNA molecules at
specific sites and isolating particular DNA fragments
• DNA fragments are usually obtained by the treatment of
DNA samples with restriction enzymes
• Cloning from mRNA molecules depends on an unusual
polymerase, reverse transcriptase, which can use a
single-stranded RNA molecule as a template and
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synthesize a complementary DNA (cDNA)
cDNA Cloning
• The resulting full-length cDNA contains an
uninterrupted by introns coding sequence for the
protein of interest
• If DNA sequence is known at both ends of the
cDNA for design of appropriate primers,
amplification of the cDNA produced by reverse
transcriptase is possible by reverse transcriptase
PCR (RT-PCR)
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Bioinformatics
• Rapid automated DNA sequencing was instrumental in the
success of the Human Genome Project, an international
effort begun in 1990 to sequence the human genome and
that of a number of organisms
• However, a genomic sequence is like a book using an
alphabet of only four letters, without spaces or punctuation.
Identifying genes and their functions is a major challenge
• The annotation of genomic sequences at this level is one
aspect of bioinformatics, defined broadly as the use of
computers in the interpretation and management of
biological data
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Functional Genomics
• Genomic sequencing has made possible a new approach to genetics
called functional genomics, which focuses on genome-wide patterns of
gene expression and the mechanisms by which gene expression is
coordinated
• DNA microarray (or chip) - a flat surface about the size of a postage
stamp with up to 100,000 distinct spots, each containing a different
immobilized DNA sequence suitable for hybridization with DNA or RNA
isolated from cells growing under different conditions
• DNA microarrays are used to estimate the relative level of gene
expression of each gene in the genome
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Fig. 10.13
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Reverse Genetics
• Mutation has traditionally provided the raw material
needed for genetic analysis. The customary procedure
has been to use a mutant phenotype to recognize a
mutant gene and then to identify the wildtype allele
and its normal function
• Recombinant DNA technology has made possible
another approach, often called reverse genetics, in
which wildtype genes are cloned, intentionally mutated
in specific ways, and introduced back into the
organism to study the phenotypic effects of the
mutations
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People that are unable
to remove UV-induced
DNA lesions
are sensitive to
sunlight
E. coli that are unable
to remove UV-induced
DNA lesions
are also sensitive to
sunlight
UV dose
WT uvrA uvrB uvrC
J/m2
0
5
10
20
40
80
120
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Gene Targeting
• The procedure for introducing mutations into specific
genes is called gene targeting
• Gene targeting in embryonic stem cells involves
homologous recombination between target gene in vector
and target gene in genome
• Target gene in vector contains unrelated DNA so that
recombination disrupts function of targeted gene
• Cells with targeted gene mutations can be selected by
including an selectable marker in the sequences that are
incorporated into the genome
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Transgenic Animals
• Germ-line transformation
involves the insertion of
genes into the
reproductive cells of an
organism, which
permanently alters the
genetic content of the
individual and all offspring
= transgenic animals
• Transgenic animals are
used to study the functions
of specific genes in
development or disease
processes
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Applied Genetic Engineering
• Crop plants with
improved nutritional
qualities can be
created
• Animal growth rate can
be genetically
engineered
• Engineered microbes
can help degrade toxic
waste
• The production of
useful proteins is a
primary impetus for
recombinant DNA
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Biomedical Applications
• Recombinant DNA technology is used to produce large
amounts of medically important proteins
• Animal viruses such as retroviruses may prove useful
vectors for gene therapy to treat single gene disorders
• Recombinant DNA probes detect mutant genes in
hereditary disease
• A major breakthrough in disease prevention would
come through the development of synthetic vaccines
produced by recombinant DNA
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