Studying the Genome: DNA Technology

Chromosomes DNA is packaged together into chromosomes. Human cells hold 23 different pairs of chromosomes (46 total) in their nuclei that contain thousands of genes.

Chromosomes The complete set of chromosomes with all of an organism’s DNA is known as its genome. The first printout of the human genome to be presented as a series of books.

Essentially, a karyotype is a picture of the chromosomes. A karyotype shows the number and appearance of the chromosomes in the nucleus. Essentially, a karyotype is a picture of the chromosomes.

Karyotype Chromosomes can be stained to show specific banding patterns. This also allows them to be placed into homologous pairs.

Fluorescence In Situ Hybridization (FISH) = Chromosome Painting Fluorescent markers can also be used to dye chromosomes or label specific genes. This is known as chromosome painting, and it is very useful in the study of chromosomes.

Chromosome Painting The entire chromosome can be painted, or doctors can look for specific genes. This can help diagnose patients with genetic disorders.

Chromosome Painting FISH techniques can also be used to compare the genomes of different species. This technique can be used to study how different species are related to each other on the genetic level. Somatic chromosome karyotyping of 14 corn lines probed with the FISH mixture.

Using chromosome painting techniques, doctors and scientists can identify chromosomal mutations in a patient that could results in medical issues.

Gel Electrophoresis Another technique used to study the genome is called gel electrophoresis. The first step in this process is to cut up DNA into smaller pieces using restriction enzymes.

Gel Electrophoresis The DNA is then placed into wells at the end of a gel and separated based on the size and charge of each fragment.

When it is finished, it creates a DNA fingerprint When it is finished, it creates a DNA fingerprint. Because everyone’s DNA is unique, the pattern of fragments is unique just like a fingerprint.

DNA fingerprints can be used to test for paternity because ½ a child’s DNA comes from the father. They can also be used to link DNA evidence from a crime to a suspect.

Recombinant DNA GloFishTM are genetically modified fish which contain fluorescent proteins from sea coral. Photo courtesy of www.glofish.com DNA which contains genes from more than one source is known as recombinant DNA. The DNA has been recombined into a new arrangement. These sections of DNA can even be from completely different species!

Recombinant DNA Once again, the first step creating a strand of recombinant DNA is to cut out the desired gene using restriction enzymes. Then the target strand of DNA is cut apart and the new segment is spliced in. The process of joining together fragments of DNA is called gene splicing.

Recombinant DNA This is known as the genetic code. Genes from one organism can be placed into another because ALL living things use the same four nitrogen bases (A,T,G and C) in their DNA to code for the same amino acids. Tobacco Plant producing the green fluorescent protein of a jellyfish. This is known as the genetic code.

The Genetic Code is common to all… From the snakes on their bellies, To the trees so tall! From the snakes on their bellies, Photo by Patrick Haney

This technology can be used to produce plants that are resistant to disease and produce their own pesticides and insecticides. The plant on bottom produces a protein that makes it resistant to attack from insect larvae.

Recombinant DNA Human genes can even be placed into bacteria! The bacteria can then make the protein that would be needed by humans. Bacteria and plants which have had the gene for making insulin inserted into their DNA make the drugs taken by diabetics!

Knockouts Gene knockouts are organisms that have had one of their genes intentionally broken or “knocked out.”

The left mouse has had a gene for hair growth knocked out. Knockout Mice The left mouse has had a gene for hair growth knocked out. The mouse on the left has had a gene knocked out that affects obesity in the mice. Knockouts help scientists understand the purpose of genes that have been sequenced but are still not fully understood. By making the gene inactive, scientists can determine what the role of the gene is inside the animal.