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SBI4UC Unit 3 Key Questions Hi! If you see a ‘y’ it is the same as a checkmark .. an 'x' means incorrect.28.4/6 a)Watson and Crick had an initial approach in which they created cardboard models of nucleotides and tried to assemble them in various configurations in order to narrow down the possible shape of DNA. Based on x-ray diffraction images of DNA taken by other researchers, Rosalind Franklin and Maurice Wilkins, Watson and Crick reworked their model into a twisted double helix structure of two nucleotides running anti-parallel to each other. The Watson and Crick model also revealed complementary base pairing between Adenine & Thymine and Cytosine & Guanine which aligned with Erwin Chargaff's discovery that the amount of Adenine is equal to the amount of Thymine and the amount of Cytosine is equal to the amount of Guanine in a nucleotide chain.you also need to discuss sugar phosphate bondingto nucleotides3/3 b)The work of Phoebus Levene was crucial in the development of the Watson and Crick model. Levene identified the components of nucleotides and proved that those components linked together to form phosphate-sugar-base units. Without information on the various components of nucleotides and basic idea of how they link together, Watson and Crick would have been unable to piece together those components in what would ultimately become the correct model of DNA structure.2/2 29.Hershey and Chase were able to track the movement of the DNA and proteins in a bacteriophage (as it infected a bacterial cell) separately using radioactive isotopes of Sulfur and Phosphorous. DNA contains Phosphorous but not Sulfur and protein contains Sulfur but not Phosphorous, so the DNA was tagged with a radioactive Phosphorous isotope and the protein with a radioactive Sulfur isotope. The results of Hershey and Chase's experiments showed that only the DNA from the bacteriophage was being inserted into the bacterial cell, proving that DNA alone is responsible for carrying genetic information.
4/4 30.After the strawberry was mashed up to break open its cells, a lysis solution of salt, water, and dishwashing liquid was used to break down the cellular and nuclear membranes to separate the DNA from the other cell parts.The strawberry and lysis mixture was then filtered and rinsed with water to wash the water-soluble DNA through the filter paper. Ice Cold isopropyl alcohol is then slowly added to the poured in to precipitate the DNA from the solution.2/2 31.3'-ATGCCCGGGAATCGAAAT-5'2.5/3 32.The DNA code is the same in every somatic cell in the human body. Humans start out as a single cell and the DNA from that single cell is replicated to create all other cells that make up the human body. Somaticcells, which make up the vast majority of cells in the body, are diploid and have the full amount of genetic information as opposed to reproductive cells which are haploid and have only half the genetic information. how does mitosis ensure this ?