#biology >Genes are biochemical recipes written in a four-letter alphabet called DNA, recipes for how to make and run a body. A normal human being has two copies of each of 75,000 genes in every cell in his or her body. The total complement of 150,000 human genes is called the "genome," and the genes live on twenty-three pairs of ribbonlike objects called "chromosomes." When a man impregnates a woman, each one of his sperm contains one copy of each gene, 75,000 in all, on twenty-three chromosomes. These are added to the 75,000 single genes on twenty-three chromosomes in the woman's egg to make a complete human embryo with 75,000 pairs twenty-three pairs of chromosomes. ~ [[Biology/Matt Ridley|Ridley]] >Imagine that the genome is a book. There are twenty-three chapters, called CHROMOSOMES. Each chapter contains several thousand stories, called GENES. Each story is made up of paragraphs, called EXONS, which are interrupted by advertisements called INTRONS. Each paragraph is made up of words, called CODONS. Each word is written in letters called BASES. ~ [[Biology/Matt Ridley|Ridley]] # I am among the few animals that have ever lived to have two different genotypes Want to hear something fun? What I will say might be wrong, but seems to be what I understood from the hematologist. **I am among the few animals that have ever lived to have two different genotypes (without better word for it) living within me**, as a result of receiving the bone marrow of X (I would not mention), thus having the genotype of X in my blood, but mine in the rest of my body. As a result I seems to be an interesting use case for science (plus the fact that I have survived in pretty good health, unlike others). # Genes and [[Philosophy/Rationality/Models/Exploration vs exploitation|Exploration vs exploitation]] For sexual species, [[Biology/Sex]] is an [[Optimization|optimization]] method. [[Biology/Evolution/Meiosis]] [[Philosophy/Rationality/Models/Exploration vs exploitation|exploits]] parents existing [[Philosophy/Epistemology/Knowledge|knowledge]] (**genotype**) and [[Philosophy/Rationality/Models/Exploration vs exploitation|explore]] for new features, mutation, add some [[Noise|noise]] to the **genotype**