highlights from The Gene 🌱

  • DNA (deoxyribonucleic acid)- is just a collection of base pairs (ATGC). Any combination is referred to as DNA. A DNA molecule is in the shape of a double helix
  • 3 base pairs encode an amino acid. But there are only 20 amino acids in total (with 64 possible combinations of the three letter encodings), so some amino acids can be encoded with multiple base pair combinations.
    • Amino acids are the building blocks of proteins
    • 3 nucleotides (base pairs) makes up what’s called a codon
      • So if you have a mutation called a frameshift mutation (deletes or adds a number of nucleotides not divisible by 3, which shifts reading frame), this can be especially bad because they. Imagine we want ACG GGA CTT AGA, but instead we remove GG so we get ACG ACT TAG A. Now the codons following the mutation won’t be the same as they used to be, whereas if you just have a mutation that deletes a bunch of nucleotides that is divisible by 3, this could delete some of the internal structure of the protein, but it may still be partially functioning
  • Chromosome- They are bundles of tightly coiled DNA located within the nucleus of almost every cell in our body. Humans have 23 pairs of chromosomes in each cell, which make up the human genome.
  • Gene- A group of base pairs in DNA make up a gene.
  • Genes are structured like this where each word is a gene: β€œThis………..is…………..the…………….s…….tr………uct……ure…………of………your……….gen…….ome”
  • We have filler base pairs in between genes and within genes
  • Some of this information dictates when/how the gene should be activated or β€œturned on”
  • RNA (ribonucleic acid)- is a collection of base pairs (AUGC) that carry instructions from the DNA for how to build proteins.
  • Different parts of DNA is turned into RNA based on what part of the body the cells are in because the information encoded in the DNA tells proteins which parts of the DNA should be active
  • Scientists were able to identify an enzyme that could convert RNA back to DNA, which allowed them to isolate which genes are β€œturned on” in which situations and parts of the body
  • DNA –> RNA –> proteins. Some of these proteins create chemicals that tell DNA to β€œturn on” some of its other genes and thus create RNA and proteins. This creates a circular structure where DNA makes proteins and then the proteins tell the DNA what to do.
  • Of the millions of biological molecules in the human body (including enzymes, receptors, hormones, etc.), only 250 or 0.025 percent are theraputically modulated by our current pharmacopeia.
  • Mitochondrial DNA is only inherited from the mother and we can trace back the mitochondrial DNA for everyone back to the same single women hundreds of thousands of years ago.
  • Humans have less genetic diversity than apes and most other species (because we are younger)
  • The vast proportion of genetic diversity (85-90%) occurs within so-called races, not between them
  • Genes cannot tell us how to comprehend human diversity; environments, cultures, geographies, and histories can, but what they tell us is meaningless and arbitrary.
    • Dyslexia may have been a useful genetic variant in the past for allowing hunters to focus on multiple targets at once, but now in society it is an illness
  • Some people born with Swyer syndrome have XY chromosomes, but they develop and identify as female. This is because they have mutations in their SRY gene which controls flipping on the genes in the Y chromosome. Inserting extra SRY genes into rats turned their female offspring with XX into males.
  • Author consistently gives arguments and examples that genes (supported by twin studies) govern your propensity to respond or act a certain way (you can think of it as the gradient/first derivative), but not that actual outcome of how you act
  • Environmental impacts on genes can be passed down. For example, famine during WW2 in Netherlands β€œHongerwinter” caused many of these people to be malnourished and the children of those who survived (and their children) were often obese and suffered heart disease later in life because they inherited genes from their parents with these epigenetic markers that allowed the parents to survive the famine.
  • The epigenome is what changes throughout a person’s life. The influence of β€œnurture” is only existing in how it is reflected back in the β€œnature”. The underlying genes are the same over time, but how they are packaged (histones) change

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