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DNA- The "Stuff" of Life Its simplistic and elegant, structure.

DNA is the longest molecule in cells, yet its structure is simple. This article explores the composition and organization of DNA, including the nucleotides, backbone, base pairing, and directionality.

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DNA- The "Stuff" of Life Its simplistic and elegant, structure.

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  1. DNA- The "Stuff" of Life Its simplistic and elegant, structure.

  2. DNA DNA is the longest molecule found in the cell, yet its structure is quite simple. The human cell contains 5-6 feet of DNA in every cell autosomal cell. The basic building block of nucleic acids are the nucleotides. There are 3 billion base pairs or 6 billion nucleotides in a human cell.

  3. A nucleotide consist of: 1. A pentose sugar: Deoxyribose for DNA and Ribose for RNA 2. Phosphate group- This is what makes the nucleic acid, acidic 3. Nitrogenous base- DNA- AGCT RNA- AGCU

  4. Nitrogenous bases

  5. How is DNA analogous to a ladder? DNA is double stranded and analogous to a ladder. The sides of the ladder are composed of alternating sugars (deoxyribose) and phosphate groups that run antiparallel (opposite direction) to one another. On the left side the first carbon found on the strand is #5 and the last carbon is carbon #3. This side is said to be 5'-3'.

  6. What types of molecules make up the backbone of the DNA molecule made of?

  7. Why is the other side of the DNA molecule is upside down! The opposite side is upside down compared to the left side. On the right side, the first carbon found on the strand is #3 and moving on down the last carbon is carbon # 5. This side is said to be 3'-5'.

  8. Why do the two sides run in opposite directions?

  9. What makes up the “rungs” of the DNA molecule? The nitrogenous bases form the rungs of the ladder. A pyrimidine always base pairs with a purine. Thyamine will base pair with adenine on the opposite side. This is a double ring paired with a single ring. This will form 2 hydrogen bonds. Nitrogen bonding forms weak hydrogen bonds. Hydrogen bonds are weak but millions of them together will keep the two strands together.

  10. What type of bond is between adenine and thymine? How many bonds between adenine and thymine?

  11. Guanine pairs with? How many bonds between this complementary base pair? Guanine will base pair with cytosine on the opposite side. This is a single ring paired with a double ring. This will form 3 instead of 2 hydrogen bonds.

  12. Notice the direction of the nucleotides on each side of the DNA molecule.

  13. This will continue for billions of base pairings forming a molecule of DNA.

  14. What is the direction of the left side of the sugar phosphate back bone? What is the direction of the right side? What does this mean?

  15. This is how the molecule may be represented in a book. Notice the shapes of the nitrogenous base pairs.

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