DNA
Technology / Applied Genetics
Cloning:
A clone is an organism that has exactly the same genes as the organism from which it was produced.
Clones do exist naturally: for example, many plants will grow a new plant from a leaf cutting.
Cloning an animal is difficult:
§ Take a body cell from the animal and an egg cell; remove the nucleus from the egg cell.
§ Remove the nucleus from the body cell and put it into the egg cell.
§ Trigger the egg cell to begin developing into a new organism.
What is cloning?
Click and clone (a mouse)
Cloning myths
Is it cloning? Online quiz
DNA Forensics:
DNA fingerprinting is a way to determine if DNA from a sample matches the DNA from a certain person. It can also tell if two people are related. It is often used in police work (“forensics”).
How it works is that certain enzymes cut up DNA at certain base sequences, such as GAATTC. Since everyone’s DNA is a little different, cutting it up will result in pieces of slightly different sizes. Scientists separate the small pieces from the larger pieces, and all of the different DNA fragment sizes make up that person’s “DNA fingerprint.”
Crime scenes:
Genetic disorders:
Some genetic disorders are caused by
a problem in the number of chromosomes.
A karyotype
will show this (example: three copies of
chromosome #21 is Down Syndrome)
Other genetic disorders are caused by
DNA mutations in one or more genes.
There are tests for certain genetic disorders to determine if a person
has the diseased form of a gene (example: a DNA probe. If the person’s base pairs match up to the
base pairs in the probe, they will bond and you can see that the person has the
diseased form of the gene.)
Sometimes we don’t know if a disease is genetic, so a pedigree can be
constructed to see if the disease has been passed down in a family. The pedigree can be analyzed to see if it is
most likely due to a recessive, dominant, or X-linked gene, for example. (Does it skip generations? Is it more common
in boys? etc.)
Try making karyotypes and diagnosing
them at this web site:
(Click on “Patient Histories” at the bottom of the
page and use the buttons at the bottom of the pages to switch between Patient
A, Patient B, and Patient C.)
Learn about testing for a genetic
disorder here:
(Click on “Inherited Disease” and watch the
video. Then it will ask you to find the
mutation in the sequence of bases. Click
“Find it for me” each time. Afterwards,
watch the second video.)
Genes can be inserted into plasmids,
which are circular pieces of DNA found in bacteria and viruses. Plasmids made by scientists are called “recombinant
DNA.”
Scientists can make plasmids containing certain genes and then insert the
plasmid into a bacterium. The bacterium
will then divide many times, creating many bacteria that contain the gene. The will all read the gene and make the
protein. Medicines such as insulin and
antibiotics can be made this way.
Scientists can also make plasmids and put them into viruses. Viruses have the ability to invade the cells
of plants, animals, and/or humans (things that can do this are called
“vectors”) and put its DNA into their cells.
Scientists have used this method to make food crops that are able to
survive pests or cold weather, as well as crops that contain more vitamins.
(Look
for the box called “Gallery of Genetic Modifications” and click “Learn more.”)
Making insulin:
(Click on “Production” and then “Putting it
together.” Then you can find out how insulin is made using bacteria as well as
using yeast.)
Gene therapy:
(Look at Figure 16 on page 160 in the book!)
Genes can be inserted into plasmids,
which are circular pieces of DNA found in bacteria and viruses. Plasmids made by scientists are called “recombinant
DNA.”
Scientists can make plasmids and put them into viruses. Viruses are “vectors” – this means they have
the ability to invade our cells (this is how they make us sick). By removing the viral DNA, the virus no
longer makes us sick. Instead, it can
put the plasmid genes into the cells.
Scientists are working on ways to use plasmids and viruses to put good
copies of a gene into the cells of people with certain genetic disorders. This is called gene therapy.
For example,
cystic fibrosis is a disorder in which the person has a defective version of a
certain gene and can’t make the protein.
Gene therapy would put a good copy of the gene into the cells, so that
they would be able to make the missing protein.
(Look for the “Gene Therapy” box and click on “Learn
more.”)
Try to design gene therapy for cystic
fibrosis here:
Further
explorations:
(If the plug-in works on these computers, watch parts 1, 2,
4, and others if interested)
No comments:
Post a Comment