Structure of nucleid acids

NUCLEIC ACIDS

 A naturally occurring chemical compounds that serve as the primary information-carrying molecules in cells. They play an especially important role in directing protein synthesis. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)  

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Structure of nucleic acids:

Nucleic Acids: DNA and RNA

- Both are nucleic acids, containing carbon, hydrogen, oxygen, nitrogen, and phosphorus.

- Store and carry information to control cell activities and inheritance.

- DNA (Deoxyribonucleic Acid) is a polymer of nucleotides, joined by phosphodiester bonds.

DNA Structure

- Composed of deoxyribonucleotides, each with:

•    Deoxyribose sugar
•    Phosphate group
•    Nitrogenous base (adenine, guanine, cytosine, or thymine)
• Forms polynucleotide chains through condensation reactions.

These are the components:

 The discovery of dna structure:

In the 1940s-1950s, several scientists made significant contributions:

- Erwin Chargaff (USA): Found that DNA from the same species has the same base proportions.

- Rosalind Franklin (UK): Took X-ray diffraction images of DNA.

- James Watson and Francis Crick (UK): Used Franklin's images to create a 3D, double-helical DNA model.

Key Findings

- Sugar-phosphate backbone on the outside

- Complementary bases (A-T, G-C) on the inside, held by hydrogen bonds

- Base pairs are the building blocks of DNA

Watson and Crick's model, published in 1953, revolutionized our understanding of DNA and genetics.

DNA Structure

James Watson and Francis Crick used Rosalind Franklin's X-ray diffraction image to decipher DNA's structure.

Key Features:

- Double helix shape with sugar-phosphate backbone

- Base pairs (A-T, G-C) form cross-bridges, held by hydrogen bonds

- Purines (A, G) face pyrimidines (T, C)

- Antiparallel strands: one runs 5' to 3', the other 3' to 5'

Base Pairing Rule:

- Adenine (A) pairs with Thymine (T), forming 2 hydrogen bonds

- Cytosine (C) pairs with Guanine (G), forming 3 hydrogen bonds

This structure enables accurate DNA replication and transmission during cell division.

Nucleic Acids and Energy

- DNA and RNA are polynucleotides made up of nucleotides.

- Adenosine Triphosphate (ATP) is a nucleotide derivative that serves as a vital energy source for cells.

ATP Structure and Function

- ATP consists of adenine, ribose sugar, and three phosphate groups.

- Energy is released when one phosphate group is removed through hydrolysis, catalyzed by ATPase.

- ATP breaks down into ADP and inorganic phosphate, releasing energy for cellular processes.

Importance of ATP

- ATP is the immediate energy source for most cellular processes.

- The released phosphate group can make other substances more reactive, lowering activation energy for enzyme-catalyzed reactions.