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Biomolecules - Nucleic Acid

This video provides a detailed explanation of nucleic acids, primarily focusing on DNA and RNA. The video breaks down the components of nucleic acids (0:18-1:04): Nucleic acids (DNA and RNA) are made of nucleotides. Nucleotides are composed of a nucleoside and a phosphate ion (0:36-0:49). Nucleosides are formed from a pentose sugar and a nitrogenous base (0:56-1:04). Key details about these components include: Pentose Sugars (1:11-1:46): Can be ribose (C5H10O5) or deoxyribose (C5H10O4), with the key difference being the absence of an OH group on the second carbon in deoxyribose. Nitrogenous Bases (1:48-2:54): Categorized into purines (adenine (A), guanine (G)) and pyrimidines (thymine (T), cytosine (C), uracil (U)). Uracil is found only in RNA. Base Pairing (2:55-3:31): Adenine pairs with thymine (or uracil in RNA) via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds. Ring Structures (3:33-4:51): Purines have two heterocyclic rings with four nitrogen atoms in the ring, while pyrimidines have one ring with two nitrogen atoms. The video also details the total number of nitrogen atoms in each specific base. Nucleoside and Nucleotide Naming (6:07-6:49): The video provides the specific names for nucleosides and nucleotides based on their nitrogenous base (e.g., adenine forms adenosine (nucleoside) and adenylic acid (nucleotide)). The video further explains the bonding within these structures (7:15-8:56): Glycosidic bond (7:27-7:35): Connects the nitrogenous base to the pentose sugar's first carbon. Phosphoester bond (7:40-7:45): Connects the phosphate group to the pentose sugar's fifth carbon. Phosphodiester bond (8:37-8:45): Forms between two nucleotides, linking the phosphate group of one to the third carbon of another pentose sugar, creating a polynucleotide chain. The DNA structure (9:10-13:00) is described as: A double helical structure, given by Watson and Crick (9:52-10:07). Anti-parallel strands (10:07-10:40): One strand runs 5' to 3', and the other runs 3' to 5'. Major and Minor Grooves (10:48-10:59): Distinct features of the DNA helix. Pitch Length (11:09-11:29): One complete turn (pitch) of the helix is 34 angstroms (3.4 nanometers) and contains 10 base pairs (20 nucleotides). The turn angle between two base pairs is 36 degrees. The video also touches upon different types of DNA (13:11-13:45) (A, B, C, Z DNA) based on base pairs per pitch, with B-DNA being the most common, and discusses Chargaff's Rule (14:06-16:21), stating that in DNA, purines (A+G) equal pyrimidines (T+C), and thus A=T and G=C. This rule does not apply to single-stranded RNA. Finally, the video briefly mentions types of RNA: mRNA, rRNA, and tRNA (15:33-15:39).