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Dna Structure

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DNA Worksheet

Answer the following in at least 100 words:

1. Describe the structure of DNA. DNA molecules are composed of two strands that form a helical ascending spiral. They fit together like the opposing teeth of a zipper and are held together by weak interactions called hydrogen bonds. These two strands is a long string of subunits called nucleotides, each attached to the one immediately about it and the one immediately below it to form a long chain. Each nucleotide contains a five-carbon sugar. The five-carbon sugar contains a five-membered ring with an oxygen atom as one of the vertices. Each nucleotide also features a phosphate group and a nitrogen-containing base; these bases are typically represented by adenine, cytosine, thymine, and guanine. The base is attached to carbon 1 of the sugar, biologist denote each of the carbons in the sugar using a number from 1 through 5, where 1 represents the carbon to which the base is attached.

2. How does an organism’s genotype determine its phenotype? The genotype of an organism is the sum total of all the genes that it inherits. It is sort of like a blue print that is designed to serve as a guide in the development of the organism, so that it will become the same kind of creature as the parent or parents that it came from. The phenotype, the organism’s physical trait arises from the actions of a wide variety of proteins. For example structural proteins help make up the body of an organism, and enzymes catalyze its metabolic activity. A gene does not build a protein directly, but rather dispatched instructions in the form of RNA, which in turn programs protein synthesis. The molecular chain of command is from DNA in the nucleus to RNA to protein in the cytoplasm.

3. Describe each stage of the flow of information starting with DNA and ending with a trait.…...

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