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.

Biology – Kevin Dees

Stem cells

• Controversial, why?

• embryonic stem cells

have greeter potential

for differentiation into

a greater number of

cell types than adult

stem cells

Biology – Kevin Dees

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

Biology – Kevin Dees

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

Biology – Kevin Dees

What are some of the practical

applications of these new

technologies

Biology – Kevin Dees

Diagnosis of disease

• Using DNA technology to recognize

specific sequences that allow for the

identification of disease causing alleles

Biology – Kevin Dees

Human gene therapy

• Using biotechnology to alter an afflicted individual’s genes

• Example – SCID – severe combined immunodeficiency

• Still controversial – Uses retroviruses

– How to regulate??

Biology – Kevin Dees

Pharmaceutical products

• Manufactured insulin and hGH

• Using recombinant DNA and plasmids

from bacteria

Biology – Kevin Dees

Forensic evidence

• DNA fingerprinting

• Uses simple

tandem repeats

(single locus

tandem repeats)

• DNA fragments cut

with restriction

enzymes

Biology – Kevin Dees

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

Biology – Kevin Dees

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!