Genetic Engineering and Other Aspects of Biotechnology

lowlytoolboxBiotechnology

Oct 22, 2013 (3 years and 8 months ago)

62 views

Outcomes
• 4.4.1 Outline the use of polymerase chain reaction (PCR) to copy and amplify
minute quantities of DNA.
• 4.4.2 State that, in gel electrophoresis, fragments of DNA move in an electric
field and are separated according to their size.
• 4.4.3 State that gel electrophoresis of DNA is used in DNA profiling.
• 4.4.4 Describe the application of DNA profiling to determine paternity and also
in forensic investigations.
• 4.4.5 Analyse DNA profiles to draw conclusions about paternity or forensic
Genetic Engineering and Other
investigations.
• 4.4.6 Outline three outcomes of the sequencing of the complete human genome.
• 4.4.7 State that, when genes are transferred between species, the amino acid
Aspects of Biotechnology
sequence of polypeptides translated from them is unchanged because the genetic
code is universal.
IB Biology
• 4.4.8 Outline a basic technique used for gene transfer involving plasmids, a host
cell (bacterium, yeast or other cell), restriction enzymes (endonucleases) and
DNA ligase.
• 4.4.9 State two examples of the current uses of genetically modified crops or
animals.
• 4.4.10 Discuss the potential benefits and possible harmful effects of one example
of genetic modification.
• 4.4.11 Define clone.
• 4.4.12 Outline a technique for cloning using differentiated animal cells.
• 4.4.13 Discuss the ethical issues of therapeutic cloning in humans.
• DNA from very small samples such as semen,
blood, tissues, or even from specimens that have
Copying and Amplifying DNA
been dead for a long time can be amplified using
PCR.
• PCR or polymerase chain reaction is a method
used by scientists to produce millions of copies
of a sequence DNA.
• This can be
completed in two
hours and means
that scientist do
not have to use
bacteria to amplify
DNA.
Gel Electrophoresis
PCR Funny Videos
• Gel electrophoresis is used to separate mixtures
of proteins, DNA, or other molecules that have a
• http://www.youtube.com/watch?v=x5yPkxCLad
charge.
s
• Enzymes are used to chop DNA into smaller
• http://www.youtube.com/watch?v=CQEaX3Mi
fragments and the DNA fragments are placed on
Dow
a thin sample of gel and an electrical charge is
applied to both ends of the gel.
• This is done by placing a positive electrode on
one end of the gel and a negative electrode on
the other end.• The result is a picture of “bands” of DNA.
• The particles will move based on their charge
towards one electrode or the other.
• The rate at which the DNA particles move is
dependent upon the size and charge of the DNA
molecule.
• The smaller and highly charged molecules will
move farther and faster than larger, less charged
molecules.
DNA Profiling
• The process of gel electrophoresis produces a
DNA profile of the organism which can be used
to compare and contrast DNA sequences.
• The process of matching the unknown sample of
DNA with a known sample is called DNA
profiling.
• The pattern of bands
produced is specific
to the individual involved
and it is highly unlikely to
be the same for any two individuals.
• DNA profiling can also be used in criminal
investigations (murder or rape) when there is
DNA Profiling
DNA left at the scene of the crime.
• A DNA sample
• DNA profiles can be used in paternity suits
can be taken from
where there is an unknown parent.
the suspect,
• By comparing the
profiled and
DNA profiles created
compared to the
through gel
DNA found at the
electrophoresis
scene.
parentage can be
proved.Problems... How else is it used?
• One difficulty of DNA profiling can be that cross • DNA profiling is also used to identify
relationships between organisms to see which
contamination
individuals are related.
of the DNA
• Ecologists use DNA profiling to help establish an
sample could
understanding of
alter the results.
social relationships,
migrating patterns
and nesting habits.
Similar DNA?
• Sequencing the human genome will make it
easier to study how human development is
The Human Genome Project
affected by genes.
• The human genome project launched in 1990
and it has been a worldwide collaborative effort
to sequence the entire human genome.
• The project succeeded in 2003 and now
scientists are attempting to which sequences
represent genes and what those genes do. • Knowing the human genome could allow for
easier identification and treatment of genetic
• Drugs to treat disease in humans could be
diseases.
manufactured based on the DNA base sequence
of
genes or the
structure of the
proteins coded
for by those
genes.
• The Human Genome project will also give us
new information about the origins, evolution,
and migrations of the human species.
Universal Genetic Code
• Gene transfer involves the removal of a gene
from one organism and placing it into another.
• The genetic code is universal which means it is
the same for all living things.
• In other words, a gene codes for the same
polypeptide whether it is a human cell, bacterial
cell, or any other type of cell.• One technique often used in gene technology is
the cloning of DNA inside a bacterium, most
Gene Transfer
often E. coli.
• This can be done because the genetic code is
• Gene transfer is a process often called genetic
universal therefore it can be transferred from
modification and any organism that has had
one
genes transferred to them are referred to organism to another.
as genetically • The following
diagram shows an
modified
overview of gene
organisms (GMO)
cloning using a
or transgenic
bacterium plasmid.
organisms.
• Tomato plants have been genetically modified to
Genetically Modified Crops & Animals
become more tolerant of salt in the soil.
• Plants and animals that have been genetically
• There is hardly anything that farmers can plant
modified are known as GMO’s.
that tolerates salt so it gives farmers a crop to
plant in their soil with a higher salt content.• Some tomato plants (cherry tomatoes) have also
been genetically modified to delay the ripening
Resistance to Herbicides
process which allows them to survive the
harvesting and shipping period and ripen
• Some plants have had genes introduced to them
reaching full flavor in time for sale.
that allow them to thrive even when they are
exposed to herbicides meant to kill weeds.
Animals
• Some animals can be used as a “pharmaceutical
factory” to produce large amounts of rare
biological substances needed for medicinal
purposes.
• Sheep are often used to carry a gene for a
human blood protein needed for blood
clotting. The sheep secrete the factor IX in their
milk which can then be purified.
Pros and Cons of Gene
Modification
• Gene transfer can be regarded as potentially
harmful.
• There is a lot of concern surrounding the release
of the GMO’s into the environment.
• They could spread and compete with or
potentially wipe out the naturally occurring
varieties.
• There is also concern that the engineered genes
could cross species barriers.• One benefit of gene modification is that it
provides more specific or less random breeding
Example
than that of the more traditional methods.
• Maize crops (corn) is a good example of gene
modification that has many potential benefits
and harmful effects.
• The crops are often damaged by corn borer
insects so a gene from a bacterium has been
transferred into the maize.
• This gene codes for a bacterial protein called Bt
toxin that kills corn borers who feed on the
maize.
Possible Benefits Possible Harmful
Effects
Less pest damage would lead to higher The Bt toxin or the bacterial DNA found
crop yields. This could help reduce food in the genetically modified maize could
shortages. be harmful to humans or animals.
Higher crop yields means less land Insects other than the corn borers could
needs to be used. Some land could be killed. The toxin is found in maize
then become wildlife conservation pollen which is blown onto plants
areas. surrounding the crops. Any insects that
feed on the wild plants could be harmed.
The gene transfer would reduce the The spread of the pollen containing the
amount of insecticide sprays which are Bt gene could potentially change the
expensive and harmful to farmers and wild plants in the surrounding
wildlife. area. Cross pollination in some plants
but no others means that there would be
a struggle for the plants without the Bt
toxin to survive.
Clones
• Clones are a group of genetically identical Cloning using differentiated cells
organisms or a group of cells artificially derived
from a single parent cell that has already
differentiated.
• 3 naturally occurring examples of clones:
Monozygotic twins, Plant cuttings, Asexual
reproduction.Arguments for cloning in Arguments against cloning
Cloning Humans? Click and Clone Game
humans in humans
Already happens naturally when There could be psychological problems
• http://learn.genetics.utah.edu/content/tech/clo
identical twins are formed; not a new of identity or individuality among clones.
ning/clickandclone/
phenomenon.
When screening for genetic diseases the There is a lot of potential for suffering
cloning of embryos would make the because cloning using differentiated
process easier. cells carries a high risk of fetal
abnormalities and a high rate of
miscarriage.
Couples who cannot have children on Due to the fact that the DNA extracted
their own could increase their chances of from the differentiated cells has already
success with IVF if their embryos are begun the ageing process the cloned
cloned human may grow older faster than usual.
What do you think about cloning
humans?