Regulation of Gene Expression and...
Transcript of Regulation of Gene Expression and...
Biology – Kevin Dees
Chapters 18 & 20
Regulation of Gene Expression
and Biotechnology
Biology – Kevin Dees
Organization of DNA
• Double helix
• DNA wrapped around
histone proteins to
form nucleosomes
• Strings of
nucleosomes coil to
form chromatin
• During prophase,
chromatin condenses
by looping onto a
protein scaffold
folding to begin to form
chromosomes
• Metaphase, replicated
chromosome
Biology – Kevin Dees
• During normal cell activity, when the majority of gene expression occurs, the DNA must be carefully unwound to allow for transcription to occur
• To accomplish this, histone acetylation occurs; the addition acetyl groups (-COCH3) to the tails of the histones causes the chromatin to become less compact
Biology – Kevin Dees
• Recall that only about 1-5 % of
DNA actually is organized into
gene that can be expressed to
produce proteins
• The process of gene
expression is carefully
regulated at many different
levels
• So, if all cells in our bodies
contain the same genome
what causes cell
differentiation?
• Differential gene expression
– expression of different genes
in different cells as determined
by one or more of these
regulatory mechanisms
Biology – Kevin Dees
It is understanding the concepts of differential
gene expression and DNA’s organization that
holds many keys to the future of:
• Biotechnology –
– Daily there is some news regarding the use of
DNA technology
Biology – Kevin Dees
Cloning technology
• Gene cloning – uses bacteria (E. coli) to serve as a factory to express desired gene
• Plasmid
• Gene inserted into plasmid using restriction enzymes – cut DNA at specific sequences
• Recombinant bacterium
• Reproduce rapidly
• Lots of applications
Cloning of “Dolly”
• Notice how genetically,
Dolly is identical to the
sheep that supplied the
nucleus; not the egg cell
donor; not the surrogate
mother.
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Stem cells
• Controversial, why?
• embryonic stem cells
have greeter potential
for differentiation into
a greater number of
cell types than adult
stem cells
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Biology – Kevin Dees
Polymerase chain reaction, PCR
• Used to amplify DNA to make large
quantities of specific genes or other DNA
pieces
• Heats (to denature DNA) and then cools
(to allow hydrogen bonding) to make
multiple copies of DNA
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Restriction enzymes can also be used to cut DNA into
fragments that can be analyzed with respect to their size.
• Restriction fragment analysis techniques are used to provide
comparative information about DNA sequences
• Gel electrophoresis is one techniques that filters these fragments
• DNA – negative charge
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What are some of the practical
applications of these new
technologies
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Diagnosis of disease
• Using DNA technology to recognize
specific sequences that allow for the
identification of disease causing alleles
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Human gene therapy
• Using biotechnology to alter an afflicted individual’s genes
• Example – SCID – severe combined immunodeficiency
• Still controversial – Uses retroviruses
– How to regulate??
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Pharmaceutical products
• Manufactured insulin and hGH
• Using recombinant DNA and plasmids
from bacteria
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Forensic evidence
• DNA fingerprinting
• Uses simple
tandem repeats
(single locus
tandem repeats)
• DNA fragments cut
with restriction
enzymes
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Environmental cleanup
• Engineering microbes to
– extract heavy metals
• Copper
• Lead
• Nickel
– Cleanup toxic waste
– Clean wastewater
– Clean oil/chemical spills
Biology – Kevin Dees
Transgenic organisms • Genes form one organism are incorporated into another.
• Used to promote desired traits in livestock – Better wool
– Leaner beef
• As pharmaceutical factories – Desired genes placed in “pharm” animals to build essential proteins
• Clotting factors in sheep milk used to treat cystic fibrosis
• controversial
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Ethics of genetic manipulation
• Creation of super bugs – viruses or
microbes that are out of control
• Super weeds with chemical resistance
• Consumption of genetically modified (GM)
organisms and health consequences??
• Should a person’s genes be a factor in job
eligibility or insurance??
Biology – Kevin Dees
BIOL 1406
The End!