Lesson Media Objects
DNA and DNA Extraction
Summary - DNA and DNA Extraction
- DNA is a non-living stable molecule. The DNA code is universal allowing it to work the same in all living things. This is a critical fact that makes genetic engineering possible.
- DNA is composed of nucleotides bonded to a sugar-phosphate backbone. Double stranded DNA forms a double helix structure.
- The DNA double helix coils up into compact structures called chromosomes. Small segments of the chromosome that encode a single protein are called genes.
- Chromosomes are microscopic. There are thousands of genes on each chromosome and hundreds of nucleotides in the DNA sequence of each gene.
- The role of DNA is to store and pass on genetic information.
- Proteins are chains of amino acids bonded together and folded into a 3-dimensional structure.
- Proteins do the ’work’ in a cell and function in 3 ways:
- Enzyme=catalyze reactions
- Structure=influence cell shape and tissues
- Regulate=regulate the expression of other genes
- Protein Production
- DNA in the nucleus is copied by RNA polymerase which reads the code and makes a complimentary copy called RNA. (transcription)
- RNA travels from the nucleus to the cytoplasm where amino acids are located.
- The RNA code is read by a ribosome 3 nucleotides (1 codon) at a time linking the appropriate amino acids together into a chain. (translation)
- The amino acid chain (protein) folds up into a 3-dimensional structure able to perform its function in the cell.
- DNA extraction is necessary because genetic engineers need to be able to work with the DNA, cut it, locate and clone a single gene, and modify the gene before they insert it into another organism. The steps in DNA extraction are:
- Plant tissue is crushed to break open the cells and release the DNA.
- Buffered salt solution is added into which the DNA easily dissolves.
- Organic solution is added into which other molecules, such as proteins and fats, easily dissolve purifying the DNA solution.
- The purified DNA solution is separated from the organic waste solution.
- Alcohol is added to the DNA solution causing the DNA to precipitate out into a solid string that can be spooled out with a glass hook and stored indefinitely.
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