When you think of nucleotides what comes to mind? My first thought would be DNA. But what are they? Nucleotides are the building blocks for compounds for compounds such as DNA and RNA (nucleic acids). One can also think of nucleotides as phosphoric acid ester of nucleosides (2-deoxy-ribofuranose). They are organic compounds made of a sugar and phosphate backbone and nitrogenous base segments.

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FIG1: SHOWING A TYPICAL NUCLEOTIDE.

Let’s take a closer look at the sugar as this is what is characteristic of the DNA and RNA.

As their name may suggest, DNA or Deoxyribonucleic acid and RNA or Ribonucleic acid are composed of the deoxyribose and ribose sugars respectively.

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FIG2: SHOWING THE DIFFERENCE BETWEEN RIBOSE AND DEOXYRIBOSE SUGARS.

Deoxyribose is formed from the removal of oxygen at the second carbon.

PURINES VERSUS PYRIMIDINE

FEATURE

PURINE

PYRIMIDINE

TYPE OF COMPOUND

Heterocyclic aromatic organic compounds

Heterocyclic aromatic organic compounds

STRUCTURE

2 carbon-nitrogen rings with four nitrogen’s. An imidazole ring fused to a pyrimidine ring.

A carbon-nitrogen rings with two nitrogen’s.

NUCLEOBASES

Adenine, Guanine

Cytosine, Thymine, Uracil

FUNCTION

Produces RNA and DNA, proteins and starch.

Produces RNA and DNA, proteins and starch.

TABLE1: SHOWING THE FEATURES OF PURINE AND PYRIMIDINE.

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FIG3: SHOWING THE STRUCTURES OF PURINE AND PYRIMIDINE.

WAIT! There is something you should note about these two groups.

ü  Thymine is ONLY found in DNA structures

ü  In RNA Uracil takes the over the position of Thymine but they are similar in structure.

ü  Cytosine and Uracil are the pyrimidines of RNA.

 

DNA!!!!

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FIG4: SHOWING THE MAGIC OF DNA

DNA can do some amazing things don’t you agree? Have you ever wondered why people tell you that you resemble someone such as your parents or relative? You should look like yourself don’t you think? Take a look at your parents when they were younger around your age now. For some, that may be a mirror image, for others slightly different. This is the work of your DNA. For those of you that your parents say you’re ugly like my dad does with me, just turn around and tell them I’m your child. Who’s laughing now huh?

DNA is such a big business in this world now and what better way other than sticking your ear in and learning a little something here and there.

DNA, held in the nucleus of eukaryotic cells creates the platform for everyday functioning. DNA is composed of nucleic acids formed from nucleotides with its characteristic deoxyribose sugar backbone. Each nucleotide has its attached base pair which is needed to form the double helix of the DNA strand. This double strand feature was suggested by two individuals which today is referred to was the Watson – Crick Model.

These guys basically wanted to know more about DNA down it its structural level. The level of thinking that they took on is simply amazing. Using previous research results from x-rays and so on they came to the conclusion. They proposed that each DNA strand has alternating bases and these bases were hydrogen bonded to an antiparallel chain of their complementary bases forming the double helix we know today. I believe that they deserved that prize for their research. Props to them both on their amazing work. But what were these complementary bases?

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FIG6: SHOWING THE COMPLEMENTAERY BASE PAIRS AND ITS YDROGEN BONDING.

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FIG7: SHOWING THE NUMBER OF BONDS BETWEEN BASES.

From these images we can see each base and its complement and between them are two to three hydrogen bonds. Bonding between bases therefore is in a particular order for DNA ONLY. REMEMBER- (A-T AND G-C), adenine-thymine and guanine- cytosine. RNA has a different pair where the thymine is replaced by the uracil.

 

Here is a video which goes through how DNA is formed and the bonding involved.

 

http://www.youtube.com/watch?v=uH8RIur8jkM

NUCLEOTIDES AND DNA!

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