Reproducing DNA Quanities
Polymerase chain reactors can be used to amplify the amount of a specific sequence of DNA. This is useful because in forensic investigations there often isn't enough DNA to help investigators.
How does it work? There are three main steps: Denaturation, annealing and elongation! Denaturation is when the DNA strands are heated to the point that the two strands separate from each other. Annealing is when DNA primers attach themselves onto the end of the strands. Finally, elongation is when another DNA heat resistant primer is added onto the strands. Its job is to replicate the strands. |
DNA Profiling
Massive amounts of DNA on their own isn't very useful. However, with gel electrophoresis investigators can discover many things relating to murder or paternity cases.
During electrophoresis, fragments of DNA are separated according to their size.
During electrophoresis, fragments of DNA are separated according to their size.
The fragments are placed in the wells of an agarose gel, which is placed in a buffering solution. An electric current is passed across the gel. Since DNA is negatively charged, it moves to the anode which is positive.
Small fragments travel faster than larger fragments thus the fragments are separated according to size.
How is this helpful?
In DNA profiling, people are identified by the basis of their DNA profiles which can be seen with electrophoresis.
All humans have segments, or satellites, of DNA that don't code. They are made up of something called Short Tandem Repeats (STR). The STRs are repeating elements and each individual has a different number of repeats. The STRs are excised to form fragments, which can occur by cutting the DNA with various restriction nuceleases. Thus, when they are placed in the electrophoresis tanks, each individual will have a unique profile.
This technique can be used in paternity tests to determine who is the father of a child. In addition, this technique can be used in murder cases to identify suspects or victims.
Small fragments travel faster than larger fragments thus the fragments are separated according to size.
How is this helpful?
In DNA profiling, people are identified by the basis of their DNA profiles which can be seen with electrophoresis.
All humans have segments, or satellites, of DNA that don't code. They are made up of something called Short Tandem Repeats (STR). The STRs are repeating elements and each individual has a different number of repeats. The STRs are excised to form fragments, which can occur by cutting the DNA with various restriction nuceleases. Thus, when they are placed in the electrophoresis tanks, each individual will have a unique profile.
This technique can be used in paternity tests to determine who is the father of a child. In addition, this technique can be used in murder cases to identify suspects or victims.
Human Genome
The Human Genome Project was started in 1990 and was finally completed in 2003. From the project we learned that humans had roughly 25,000 genes though that number has been reduced to roughly 20,000 since. It was also discovered that humans have 3 billion base pairs.
Due to the project we have a better understanding of DNA mapping which is the number and position of specific genes. The project has also allowed us to:
Learn more about our ancestry and origins
Identify genetic disorders in individuals by creating gene probes to screen for a specific malady.
Use the new proteins we have discovered to develop better medicine
Due to the project we have a better understanding of DNA mapping which is the number and position of specific genes. The project has also allowed us to:
Learn more about our ancestry and origins
Identify genetic disorders in individuals by creating gene probes to screen for a specific malady.
Use the new proteins we have discovered to develop better medicine
Gene Transfers
1. Extract DNA
Remove a plasmid (circular DNA in prokaryotes) from an organism. Then remove the desired gene from the plasmid. Amplify both the gene and plasmid by using polymerase chain reactors
2. Digestion and Litigation
Cut the plasmid with restriction enzymes. This will usually create "sticky ends" which are short sequences that hang on the end of the DNA strands and allow the strands to connect with each other. The desired gene and plasmid are then spliced together by DNA ligase to create a recombinant plasmid.
3. Transfection and Expression
The recombinant plasmid is then inserted into the desired host cells and hopefully the desired trait will express itself.
Remove a plasmid (circular DNA in prokaryotes) from an organism. Then remove the desired gene from the plasmid. Amplify both the gene and plasmid by using polymerase chain reactors
2. Digestion and Litigation
Cut the plasmid with restriction enzymes. This will usually create "sticky ends" which are short sequences that hang on the end of the DNA strands and allow the strands to connect with each other. The desired gene and plasmid are then spliced together by DNA ligase to create a recombinant plasmid.
3. Transfection and Expression
The recombinant plasmid is then inserted into the desired host cells and hopefully the desired trait will express itself.
Genetically Modified Organisms
Crops and animals can be genetically engineered or modified with both positive and negative results. Look at our GMO documentary for more details.
Clones
A clone is a genetically identical organism or a group of cells that is derived from a single parent cell. It has many uses.
In somatic cell nuclear transfer (SCNT) female animals are treated with hormones to stimulate the development of eggs. Then the nucleus from the egg is removed. The egg is then fused with the somatic cell of another organism, making the egg a diploid. An electric shock is given to the egg to allow it to divide and once this has happened the egg is then placed inside the uterus of a surrogate mother which will produce the clone. The clone will have the same genetic info as the organism that contributed the diploid nucleus.
In somatic cell nuclear transfer (SCNT) female animals are treated with hormones to stimulate the development of eggs. Then the nucleus from the egg is removed. The egg is then fused with the somatic cell of another organism, making the egg a diploid. An electric shock is given to the egg to allow it to divide and once this has happened the egg is then placed inside the uterus of a surrogate mother which will produce the clone. The clone will have the same genetic info as the organism that contributed the diploid nucleus.
Uses of Cloning
Embryos aren't used now so there isn't much of a debate against therapeutic cloning anymore since no embryo has to be wasted.