DNA Extraction 1510

DNA Extraction 1510 - Extraction of DNA Introduction All...

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Extraction of DNA Introduction All living organisms are composed of cells that contain DNA (deoxyribonucleic acid) and RNA (ribonucleic acid): nucleic acids , the fourth kind of biomolecule. Nucleic acids contain the hereditary information of the cell. In eukaryote cells, like humans, spinach and mushrooms, DNA forms discrete chromosomes contained within a membrane-bound nucleus . In prokaryotic cells, like bacteria, DNA is in a circular form and there is no nucleus. Each species has a known number of chromosomes, for example humans have 46 (23 pairs), dogs have 78, cats 38, horses 64, wheat 42, rye 14 and cauliflower 18. Paired chromosomes are called diploid (2N), 1 chromosome comes from each parent during fertilization. The parental gametes contain only half of the chromosome content of the zygote and are called haploid (1N). Many plants, though, don’t always follow the haploid/diploid rule. Most wild strawberries have 14 chromosomes (1N = 7). Throughout centuries scientists and gardeners have cultivated new species and hybrids of existing species. These species include tetraploids (4N), hexaploids (6N) octaploids (8N) and decaploids (10N). In general these polyploidy species are more robust plants with larger fruits, one of the primary reasons they have been selected for. Why grow tiny plants when you can grow bigger, healthier ones in the same space? And gigantic strawberries will surely sell for more at the grocery store! The most common cultivated strawberry, Fragaria ananassa , is an octoploid , 112 chromosomes. It is propagated through asexual reproduction, cuttings and runners, to maintain the continuity of its DNA. Although it can undergo sexual reproduction, thus the seeds (actually achenes) that are found on the outside of the berry, strawberry farmers want to maintain the exact genetic makeup from one generation to the next. Kiwi fruit ( Actinidia ) also contain a lot of DNA, but it is due to a large haploid chromosome number (29). Recent research to increase the size (and marketability) of kiwi fruit has resulted in the observation of tetraploids (116 chromosomes) and hexaploids (174 chromosomes). Biochemistry of DNA
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DNA Extraction 1510 - Extraction of DNA Introduction All...

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