how many different nitrogen bases are found in dna

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Question:How many different nitrogen bases are there (including those found in DNA and RNA)? I thought it was only 5(Apparently I'm wrong) cytosine, thymine, adenine, and guanine (DNA) and (RNA)-Uracil a. 20 b. 26 c. 5 d. 2 e. 4

Answers:There are 5 commonly-occurring bases: Adenine, Cytosine, and Guanine are found in both DNA and RNA. Thymine is found only in DNA, and Uracil only in RNA. Note that there *are* many other kinds of nucleotide bases, which perform functions in tRNA and rRNA, such as structural functions in tRNA loops. These do not perform any coding function, however.

Question:(a.) 2 (b.) 4 (c.) 3 (d.) 20 (e.) thousands of different kinds

Answers:There are base PAIRS in DNA--so there have to be an even number (rules out c). Your textbook lists the names of the nucleotides--count them.

Question:

Answers:because the arrangement of these bases is what maters most....they are called genes...3 base pairs coded together make a gene and there are thousands of possibilities for these genes

Question:A double-stranded DNA molecule is 1 cm long, and the percentage of adenine is 15%. How many cytosines would be ound int he DNA molecule?

Answers:In double stranded DNA, there are always an equal number of Adenine (A) and Thymine (T) since they form pairs. Likewise there will always be an equal number of Cytosine(C) and Guanine(G). The total AT and CG pairs always add up to 100%. Since there is 15% A, there must be 15% T. Since there is 60% left, there is 30% G and 30% C. Now since you have 1cm of DNA, and the average base pair takes up 3.4 Angstroms (3.4 10^-8 centimeters). 1cm/(3.4 10^-8 centimeters/base pair)*2 bases/base pair = 58823529.4 base pairs. 30% of this is 17647058.8 Cytosines, or 1.76*10^7 Cytosines (If my math is right!)

From Youtube

DNA Structure & Testing : What Are the Four Nitrogenous Bases of DNA? :The four nitrogenous bases of DNA are adenine, thymine, cytosine and guanine, each of which pairs with different bases to form a rung on the DNA double helix ladder. Understand the basic construction of DNA withinformation from a biology teacher in this free video on science. Expert: Janice Crenetti Contact: WeAreHDTV.com Bio: Janice Creneti has a Bachelor of Science in secondary science education and a Bachelor of Art in biology from Boston University. Filmmaker: Christopher Rokosz