DNA - Biotechnology

Cloning Create a new organisms using existing DNA; makes a brand new organism with the same copy of DNA as another organism Identical twins are natural clones To make a clone, place existing DNA sample into an egg cell that has had the original nucleus removed; it will grow into a genetically identical copy of the donor cell (essentially creating a twin)

Cloning

Cloning Why? Farmers can clone livestock to create more of the exact same “perfect” specimen Scientists can learn a lot about DNA through cloning or possibly even bring back an extinct species like the Wooly Mammoth to study Doctors can clone single organs, single cells, or even single genes to use as treatments to replace cells that are unhealthy or damaged (instant transplant options or cancer treatments?) Companies can make a lot of money cloning pets

Restriction Enzymes Proteins that cut DNA at specific sequences Discovered in bacteria, these proteins evolved as a defense against viral/invading DNA. When they see DNA that they recognize as not belonging to their bacteria (by recognizing their specific sequence), they cut the DNA at that sequence to “kill” it Some cut straight across (­­­­­­­­­­­­­­­­blunt ends) while others cut in a zig zag pattern that leaves base pairs exposed (sticky ends). Sticky ends can be reconnected theoretically. Used as DNA “scissors” and “glue” in applications like recombinant DNA and DNA fingerprinting

Restriction Enzymes

Restriction Enzymes

Recombinant DNA/Transgenic Organisms/Genetically Modified Organisms (GMOs) “Cut and paste” genes; remove a gene from one organism and place it into the genome of a totally different species Genes are cut out using restriction enzymes that create sticky ends. Both the donor DNA and the receiver DNA is cut with the same sticky end. The two matching sticky ends can then be reconnected through base pairing and ligase (final enzyme from DNA replication) will fully connect and proofread them.

Recombinant DNA/Transgenic Organisms/Genetically Modified Organisms (GMOs) Requires a vector to move the DNA from the donor to the receiver. Vectors are usually viruses for eukaryote cells and plasmids for bacterial cells. Viruses are natural vectors that infect cells by injecting their own DNA into a healthy cell and taking over the cell. By removing the viral DNA and replacing with the desired DNA, the new DNA can be “injected” into the cell. Plasmids are circular pieces of DNA that bacteria recognize as safe. Usually plasmids are formed when another bacteria is killed and its DNA is spilled into the environment. Bacteria will naturally pick up any plasmid it encounters in the hopes of gaining new DNA that may be helpful. Engineering a plasmid and exposing the bacteria to it quickly allows the new gene to enter the bacteria cell.

Recombinant DNA/Transgenic Organisms/Genetically Modified Organisms (GMOs)

Recombinant DNA/Transgenic Organisms/Genetically Modified Organisms (GMOs) Why GMOs? Created the industry of “pharming” where we put human genes into bacteria so we can quickly and cheaply produce needed medical hormones such as insulin for diabetics Farmers use GMOs to grow stronger and better crops; GMOs are in just about everything you eat these days Create “designer” pets and plants, such as trees that glow in the dark to replace street lamps or glow fish to work as night lights Controversial because they are so new; not sure if absolutely safe yet, but only time will tell

DNA Fingerprinting Since every person’s DNA is unique, different DNA will be cut by restriction enzymes in different ways. By treating two different samples of DNA with the same restriction enzyme, you end up with a different number of pieces of varying lengths. Gel electrophoresis uses electricity to separate the pieces by size. This creates a unique pattern for each person’s DNA that can be used to identify unknown DNA samples. If banding patterns have similarities, they may be related. If banding pattern is identical, then it is the same DNA

DNA Fingerprinting To perform a DNA fingerprint, cut each DNA sample with the same restriction enzyme to create segments of various lengths. Segments are then separated using gel electrophoresis to create a unique banding pattern. Compare the bands to identify the unknown DNA. Only identical twins will have the same banding pattern. Any other matching band pattern signifies the same DNA. Used for identifying missing persons, crime scene investigation, and paternity testing

DNA Fingerprinting Gel Electrophoresis

DNA Fingerprinting Crime Scene Investigation

DNA Fingerprinting Paternity Testing

The Human Genome Project Although DNA is unique enough to use as an identifier, in general all human DNA genes are very similar. The HGP set out to sequence all of the nucleotides found in human DNA. It took decades and collaboration between seven different countries to complete because we have a LOT of DNA! Used to begin identifying the location and function of specific gene sequences and possibly could lead to therapy for genetic disorders and birth defects once thought untreatable.

The Human Genome Project