Isotoon explains biology by animating the process you are stuck on, such as cellular respiration, meiosis or gene expression, as a short video or a 3D model of the cell you can turn. Ask in your own words and watch each step happen in order, with its sources listed.
Follows one cell down two paths: mitosis makes two identical diploid copies (2n to 2n), while in meiosis homologous chromosomes pair up and cross over, the pairs split in meiosis I, and the cell ends as four genetically unique haploid gametes (2n to n).
Scenes, in order:
A recording of a 3D scene of DNA replication: the double helix, its 5′ and 3′ ends marked, turns as helicase and topoisomerase arrive at the replication fork and the parent strands are pulled apart, then primase lands on each separated strand.
Labeled in the scene:
Biology is full of processes that are hard to picture from a diagram: what moves where, in what order, and why. Ask about the step that is not clicking and watch it happen.
Mitosis copies a cell: one diploid (2n) cell divides once into two identical diploid cells, which is how the body grows and repairs tissue. Meiosis makes gametes. Homologous chromosomes pair up and swap segments (crossing over), the pairs separate in meiosis I, and the sister chromatids separate in meiosis II. The result is four haploid (n) cells, each genetically different, which is why siblings are not identical.
Cellular respiration releases the energy in glucose in three stages: glycolysis, the Krebs cycle and the electron transport chain. Most ATP is made in the last stage, where electrons pass along proteins in the inner mitochondrial membrane and pump protons across it; the protons flow back through ATP synthase. Oxygen is the final electron acceptor. Without it the electrons back up, the chain stops, and the cell falls back on fermentation, which makes far less ATP.
A gene is a stretch of DNA. In transcription, RNA polymerase copies it into messenger RNA. In translation, a ribosome reads the mRNA three bases (one codon) at a time while transfer RNAs bring the matching amino acids, which are joined into a chain that folds into a protein. Changing one base can change one amino acid, change nothing (several codons code for the same amino acid) or stop the protein early.
The ones marked 3D become a model you can turn, step through and tap.
Every claim is checked before anything is drawn, and every video lists its sources. See plans