AnswersDrive2nd October 2019
millerandlevine
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What is the difference between a purine and pyrimidine?
Do you know the difference between a Purine and a Pyrimidine? Purines and Pyrimidines are the nitrogen-containing "bases" found in the nucleotides that make up DNA and RNA. As shown in Figure 12-5 from the Dragonfly Book (at right), purines have two rings in their structure, while pyrimidines have just one.
What is purine and pyrimidine?
Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine and cytosine) are pyrimidines.
Is guanine a pyrimidine?
In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus, in DNA, the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively.
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Why do pyrimidines bond with purines on the DNA ladder?
The nitrogenous bases point inward on the ladder and form pairs with bases on the other side, like rungs. Each base pair is formed from two complementary nucleotides (purine with pyrimidine) bound together by hydrogen bonds. The base pairs in DNA are adenine with thymine and cytosine with guanine.
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What are the three major differences between DNA and RNA?
Structurally, DNA and RNA are nearly identical. As mentioned earlier, however, there are three fundamental differences that account for the very different functions of the two molecules. RNA has a ribose sugar instead of a deoxyribose sugar like DNA. RNA nucleotides have a uracil base instead of thymine.
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Why is it called a double helix?
The double helix describes the appearance of double-stranded DNA, which is composed of two linear strands that run opposite to each other, or anti-parallel, and twist together. Each DNA strand within the double helix is a long, linear molecule made of smaller units called nucleotides that form a chain.
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Why is it important that purine Bonds with a pyrimidine?
Notice that each base pair consists of a purine and a pyrimidine. The nucleotides in a base pair are complementary which means their shape allows them to bond together with hydrogen bonds. The A-T pair forms two hydrogen bonds. The hydrogen bonding between complementary bases holds the two strands of DNA together.
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Who was responsible for determining the structure of the DNA molecule and in what year?
Purine has 2 structure rings, which are Guanine and Adenine. Pyrimidine has 1 structure ring, which are thymine and cytosine. Who is responsible for determining the structure if the DNA molecule & in what year was this done? James Watson and Francis Crick & in 1953.
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What is the definition of purine in biology?
One ring has six members, the other has five, and each has two nitrogens. Purines include a number of biologically important compounds, such as adenosine, caffeine, uric acid, and the two bases adenine and guanine, which are components of DNA and RNA.
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Which are pyrimidines?
Thymine (T) Uracil (U) In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus, in DNA, the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively.
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What are the two purines?
They include the nucleobases adenine (2) and guanine (3). In DNA, these bases form hydrogen bonds with their complementary pyrimidines, thymine and cytosine, respectively. This is called complementary base pairing. In RNA, the complement of adenine is uracil instead of thymine.
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What is the difference between purine and pyrimidine bases?
Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine and cytosine) are pyrimidines.
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Is uracil a purine?
In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by thymine. Uracil is a demethylated form of thymine. Uracil is a common and naturally occurring pyrimidine derivative.
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How many base pairs are in a full turn or twist of a DNA molecule?
The variation of energy with the twist of the base pairs about the helix axis shows the straight DNA free in solution is most stable with about 10 1/2 base pairs per turn rather than 10 as observed in the solid state, whereas superhelical DNA in chromatin is most stable with about 10 base pairs per turn.
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How many purines are there?
There are two kinds of nitrogen-containing bases - purines and pyrimidines. Purines consist of a six-membered and a five-membered nitrogen-containing ring, fused together. Pyridmidines have only a six-membered nitrogen-containing ring. There are 4 purines and 4 pyrimidines that are of concern to us.
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What is the difference between ribose and deoxyribose?
Ribose, found in RNA, is a "normal" sugar, with one oxygen atom attached to each carbon atom. Deoxyribose, found in DNA, is a modified sugar, lacking one oxygen atom (hence the name "deoxy"). Notice the difference between ribose and deoxyribose in the figure above.
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Why is adenine always pairs with thymine?
So, "A" pairs with "T", and "C" pairs with "G." So the question asks why does A pair with T. This is due to the chemical structure of each base. Adenine and Thymine establish two hydrogen bonds between them. Guanine and Cytosine establish three hydrogen bonds between them.
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What is the name of the sugar in the DNA backbone?
The backbone of DNA is based on a repeated pattern of a sugar group and a phosphate group. The full name of DNA, deoxyribonucleic acid, gives you the name of the sugar present - deoxyribose. Deoxyribose is a modified form of another sugar called ribose.
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How many rings does a purine have pyrimidine have?
Below is a picture showing how the bases pair. You will see that a purine with two rings always pairs with a pyrimidine with one ring. In this way the width of the DNA molecule stays the same.
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Which base does adenine pair with in RNA?
The base pairing of guanine (G) and cytosine (C) is just the same in DNA and RNA. So in RNA the important base pairs are: adenine (A) pairs with uracil (U); guanine (G) pairs with cytosine (C).
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What are the molecules that form the sides of DNA?
It has an alternating chemical phosphate and sugar backbone, making the 'sides' of the ladder. (Deoxyribose is the name of the sugar found in the backbone of DNA.) In between the two sides of this sugar-phosphate backbone are four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
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What happens in the replication of DNA?
In both cases, replication occurs so quickly because multiple polymerases can synthesize two new strands at the same time by using each unwound strand from the original DNA double helix as a template. One of these original strands is called the leading strand, whereas the other is called the lagging strand.