Summary of "¿Qué es el ADN y cuáles son sus FUNCIONES? Doble hélice, nucleótidos, bases"

What DNA is and where it is found

DNA (deoxyribonucleic acid) is the biomolecule that constitutes the genome of living organisms and some viruses. It contains the information required for organism development and functioning.
Genome: the complete set of DNA molecules in a cell.
- Eukaryotes: mainly nuclear DNA (linear chromosomes) plus small amounts of DNA in mitochondria and, in plants and algae, chloroplasts.
- Prokaryotes: DNA is typically located in the nucleoid region (often a circular chromosome) and may include additional extrachromosomal plasmids.
Genes are defined segments of the genome that serve as the molecular “blueprints” for producing proteins.

Heredity: DNA is faithfully replicated and transmitted between generations.
Information storage and encoding: DNA stores genetic instructions that are decoded into proteins through transcription and translation.
Enabling cellular structure and function: encoded proteins act as enzymes, structural components, regulators of gene activity, and mediators of cell movement, signaling, growth, reproduction and life-cycle processes.
Source of variation: mutations alter DNA sequences, providing variation on which natural selection acts; some mutations cause disease.
Non-coding DNA: besides protein-coding sequences, non-coding regions have functional roles (an analogy is that coding sequences are words while non-coding regions provide spacing, punctuation and regulatory context).

DNA is a biopolymer assembled from repeating monomers called nucleotides.
Each nucleotide comprises three parts:
1. a five‑carbon sugar (deoxyribose)
2. a phosphate group
3. a nitrogenous base (adenine, thymine, guanine, cytosine)
Backbone and connectivity:
- Nucleotides connect linearly via phosphodiester bonds that link the 5’ carbon of one sugar to the 3’ carbon of the next, giving strand polarity (5’ → 3’).
Double helix and base pairing:
- DNA is typically two complementary nucleotide chains forming a double helix.
- Complementary base pairing via hydrogen bonds: adenine (A) pairs with thymine (T); guanine (G) pairs with cytosine (C).
- Chemical classification: purines (adenine, guanine) and pyrimidines (thymine, cytosine).
Higher-order organization:
- In eukaryotes, linear DNA associates with histone proteins to form chromatin and chromosomes.
- In many prokaryotes, DNA is circular and may associate with proteins; plasmids are extra-chromosomal DNA molecules.

Replication: faithful copying of DNA for inheritance.
Transcription and translation: reading (decoding) DNA sequences to produce the peptide/protein sequences specified by genes.
Mutation and DNA damage: changes to DNA can lead to biological consequences such as variation, speciation, or disease.

The chemical nature of nucleic acids was identified in the 19th century (Friedrich Miescher isolated “nuclein” in 1869).
The double-helix structure of DNA was elucidated in the 1950s; key contributors include James Watson, Francis Crick, and Rosalind Franklin.

The auto-generated subtitles contained several inaccuracies and garbled phrases. Corrections include:

The 1869 discoverer of “nuclein” was Friedrich Miescher, not Friedrich Nietzsche.
The sugar in DNA is deoxyribose (not ribose).
The correct bond linking nucleotides is a phosphodiester bond (not “phosphodiesterase bond”).
Complementary bases are held together by hydrogen bonds (not “de novovalent” bonds).
Descriptions of prokaryotic vs. eukaryotic DNA organization and histones were imprecise: histones compact DNA in eukaryotes; many bacteria lack canonical histones.