Science & Math

The Basics of Genetics and DNA

Read, explain, and reason about DNA, genes, and inheritance without falling for the myths most courses teach.

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What you will learn about The Basics of Genetics and DNA

The 7-day sprint
  1. The Molecule and Its Four Letters. DNA is a two-stranded molecule whose four bases pair in a fixed way, so the order of those bases carries the information.
  2. From Thread to Chromosome. A cell packages very long DNA molecules with histone proteins into chromatin, and the packaged form of one DNA molecule is a chromosome.
  3. What a Gene Actually Is. A gene is a segment of DNA that holds instructions for building a particular protein or functional RNA molecule, and much of the rest of the DNA controls when genes are used.
  4. DNA to RNA to Protein. Cells read a gene by transcribing DNA into RNA and, for protein-coding genes, translating that RNA three bases at a time into a chain of amino acids.
  5. Alleles, Genotype, and Phenotype. Because you carry two copies of most genes, the pair of sequence variants you have is your genotype, and the observable result is your phenotype.
  6. How Traits Are Actually Inherited. Simple dominant and recessive patterns are real but rare, and most familiar human traits come from many genes plus environment.
  7. Reading Real Genetics Without Getting Lost. Genomics, reference genomes, and standardized names are the machinery that lets one person's finding be understood by everyone else.
The 80/20: the 6 concepts that matter most
  • Complementary base pairing
  • A gene encodes a protein or a functional RNA
  • Transcription, translation, and the triplet code
  • Two copies, two alleles, genotype versus phenotype
  • Most traits are polygenic and environment sensitive
  • Standard names and reference sequences
The core idea, explained like you are 5

The order of four chemical letters along a DNA molecule is information, and a cell copies that order to pass it on and reads it to build the molecules that do the work.

Then the quiz and the ladder

10 questions that correct you when you are wrong, and beginner, intermediate, advanced levels, each with a practical exercise.

Created Sep 13, 2026. No mistakes have been reported by learners.

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