DNA Technology Notes

Recombinant DNA (rDNA): Artificially constructed DNA by combining two different DNA strands.
Genetic scientists use techniques to create unique DNA strands for various purposes.

DNA containing the desired gene is removed from a cell.
Enzymes cut out the desired gene.
Enzymes insert the gene into a DNA vector (e.g., a plasmid from a bacterium).
The DNA vector is taken from a bacterium.
Bacteria reproduce, creating a large number of bacteria with the new characteristic.
Applications: Production of drugs/enzymes and pest-resistant plants.

An organism that has undergone a recombinant DNA procedure.
Involves the transfer of genetic material from one organism to another (plant or animal).
Also termed transgenic organisms due to gene transfer.

A clone is a genetically identical copy of an organism, either naturally occurring or created in a lab.
Asexual reproduction in organisms like bacteria and some plants results in offspring genetically identical to the parent.

A donor cell is taken from a sheep's udder (contains the DNA to be cloned).
An egg cell is taken from an adult female sheep.
The nucleus of the egg cell is removed (enucleated).
The donor nucleus and the enucleated egg cell are fused using an electric shock.
The fused cell begins dividing normally.
The embryo develops normally.
The embryo is placed in the uterus of a foster mother.
**A cloned lamb (Dolly) is born.

Cells with the potential to develop into many different types of cells in the body, serving as a repair system.
Two main types: embryonic stem cells and adult stem cells.

They can divide and renew themselves over a long time.
They are unspecialized and cannot perform specific functions in the body in their undifferentiated state.
They have the potential to become specialized cells, such as muscle cells, blood cells, and brain cells.

Totipotent stem cells: Can differentiate into embryonic and extraembryonic cell types, capable of constructing a complete, viable organism. Produced from the fusion of an egg and sperm cell, and cells from the first few divisions of the fertilized egg.
Pluripotent stem cells: Descendants of totipotent cells that can differentiate into nearly all cells, i.e., cells derived from any of the three germ layers.
Multipotent stem cells: Can differentiate into a number of cell types, but only those of a closely related family of cells.
Unipotent stem cells: Can only differentiate into one cell type.

An egg is fertilized or cloned to form an embryo.
The embryo divides multiple times to form a sphere called a blastocyst (1-5 days).
**Embryonic stem cells are visible (5-7 days) and capable of developing into any tissue in the body.
**The cells are removed and grown in a Petri dish to create a stem cell line.
**Scientists use various nutrients and factors to turn stem cells into different types of tissues (tissue production).

Stem cells are extracted from the patient's bone marrow.
They are placed in a Petri dish with nutrients and growth factors.
The cells multiply and can be stored indefinitely under the right conditions.
When ready, the stem cells are injected back into the patient's heart to repair damaged tissue.

Pancreatic islet cells: Could provide a cure for diabetes.
Muscle cells: Could repair or replace a damaged heart.
Nerve cells: Could be used to treat Alzheimer's and Parkinson's diseases and repair spinal cord injuries.

A technique used in the lab to make millions of copies of a particular section of DNA.
First developed in the 1980s.

Denaturation: Original DNA is heated to 94-96°C to separate the double strands.
Annealing: Primers are added and bind (anneal) to the single-stranded DNA at a specific temperature (e.g., ~68°C).
Elongation: DNA polymerase extends the primers and replicates the DNA sequence at approximately 72°C.

**RNA or DNA is extracted from a sample that may contain pathogenic DNA.
**PCR is performed.
**If PCR is positive (Yes PCR), a pathogen is present.
Solution passes through gel and filter to paper towels
DNA transferred to filter
**Hybridize with unique $^{32}P$ -labeled nucleic acid probe specific to a pathogen.
Remove unbound probe
Expose X-ray film to filter for autoradiogram

A laboratory technique used to establish a link between biological evidence and a suspect in a criminal investigation.
A DNA sample from a crime scene is compared with a DNA sample from a suspect.
If the two DNA profiles match, the evidence likely came from that suspect.

A DNA sample is obtained from the subject (blood sample or a swab of tissue from the inside of the mouth; blood sample is usually preferred).

Establish a blood relationship between two people.
Determine whether two people are a good genetic match for medical reasons.
Determine whether a particular individual's DNA matches DNA at a crime scene.
Identify a body.

**Blood sample is collected.
**DNA is extracted from blood cells.
**DNA is cut into fragments by a restriction enzyme.
**The DNA fragments are separated into bands during electrophoresis in an agarose gel.
**The DNA band pattern in the gel is transferred to a nylon membrane by Southern blotting.
**A radioactive DNA probe is prepared.
**The DNA probe binds to specific DNA sequences on the membrane.
**Excess DNA probe is washed off.
**The radioactive probe is bound to the DNA pattern on the membrane.
**X-ray film is placed next to the membrane to detect the radioactive pattern.
**The X-ray film is developed to make visible the pattern of bands, which is known as a DNA fingerprint.