Download Applying Our Knowledge of Genetics

Applying Our Knowledge
of Genetics
Selective Breeding
• Selective breeding (domestication) has been going on for
centuries. It is simply the process by which people choose
the animals or plants with the best traits and breed them
together to get offspring that have all of those same traits.
• Animal breeders and farmers do this all the time. The
organisms with the best traits are used to make the next
generation and since most traits are based on your
DNA…You are picking the best DNA to make up the
offspring.
• Positive – You know what you are going to get in your
offspring. Only desired traits show through.
• Negative – You end up with a “monoculture” and
homogeneity…All are the same…Not so good if something
comes along that can kill one of you…It can kill all of you!
Genetic Screening & Counseling
• Genetic screening is a process used by those in
the medical field to see if someone has a
defective or lethal gene in their genetic code.
• This may lead to someone seeing a genetic
counselor.
• Genetic counseling occurs when an expert in the
field of genetics and medicine explains one or
more of the following to a patient that has a
genetic disorder. Items discussed may include:
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–
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Cause of Disorder
Symptoms and/or Treatments
Odds of Passing it on to Children
Clinics and/or Facilities Where Help is Available
Prenatal Diagnosis
• There are a variety of prenatal tests that are performed on
babies while they are still in the womb.
• A prenatal diagnosis involves testing a fetus to check for
possible health-related risks.
• Possible testing procedures include:
– Amniocentesis – A portion of the amniotic fluid is removed
and analyzed. Amniotic fluid surrounds the fetus while in the
womb and contains fetal cells.
– Ultrasound – using sound waves to “see” the fetus.
– Chronic Villus Sampling – Cells surround the fetus are
removed and analyzed. This is only done in high risk cases
because there are risks associated with it.
– Maternal Serum Screening – Mother’s blood is taken and
analyzed for abnormal protein levels that cross from child to
mom. (DNA  RNA  Protein)
Recombinant DNA
• In a recombinant DNA experiment, scientists attempt to
take DNA from one organism and implant it into the DNA of
a second organism.
• We have had success in taking human genes, like the one
for insulin, and inserting them into bacterial cells. The
bacterial cells adopt the gene and make insulin according
to the directions on the human DNA – it is human insulin!
• We use restriction enzymes that cut DNA at specific
sequences (A’s, C’s, G’s, & T’s) and remove the gene from
the human cell’s DNA. It is then put into a bacterial cell
plasmid (DNA) that is cut open using the same restriction
enzyme.
• Some of the plasmids will adopt the gene and when the
bacterial take in the plasmid – they make the proteins that
the plasmid DNA makes – including our insulin!
Recombinant DNA
• Recombinant DNA can
be used to make
transgenic plants and
animals (maybe people
someday) that have
healthy genes inserted
into them to replace or
mask the effects of faulty
genes.
• A transgenic plant may
have the toughness
genes of a desert plant
inserted into a fruitbearing plant in order to
help feed those in harsh
environments such as
those in some third world
countries.
Gene Therapy
• Gene therapy involves the insertion of a properly
working gene into a patient that has a faulty gene in
hopes that the new, healthy gene could be used to
cure the disorder.
• A vector, or DNA delivery system, would need to
be used to insert the “foreign” DNA into the patient’s
cells.
• Some vectors being used are viruses and plasmids.
Stem cells are usually the target cells because they
have not matured yet and will divide and
differentiate after the DNA has been inserted into
them.
• There are some problems…
– Hard to deliver to all cells.
– Immune response of patient to vector.
– Cells do not always divide after they receive the
foreign DNA.
Gene Therapy
Human Genome Project
• The human genome project began in 1990 and
its goal was to map out the “genetic library”. It
would mark the position of 30000-35000 genes
on the chromosomes and then go back and
sequence those genes according to DNA
nucleotide sequence – the A’s, C’s, G’s and T’s.
• The scientists will now know the position and
code associated with each gene in the human
genome.
• It is hoped that this information will be used to
make stronger connections between phenotypes
and genotypes.
(DNA Codes  Observable Traits)
Cloning…Cloning…Cloning…
• Scientists studying reproductive technology are
now using nuclear cloning to create living
organisms that are exact copies (clones) of
previously living organisms.
• Basically, here is what we do…
– Scientists take body cell from creature to be cloned
and an unfertilized egg cell from another individual.
– They remove the DNA from the egg and place the
DNA from the body cell into it.
– The egg now has 46 chromosomes and will be
implanted into a surrogate mother.
– The egg/zygote matures and is given birth to…It
looks exactly like the donor DNA and not the mother!
• No…Humans are not going to give birth to dogs,
horses or sharks…That is crazy talk!
Cloning…Cloning…Cloning…
That’s All I Got…