This entry is a little diversion from the usual pelvic health blogs, but covers a fascinating topic that is at the forefront of medical research.
- Humans have 23 pairs of chromosomes, but apes have 24 pairs. We lost a chromosome during evolution, but gained a thumb…less is more! Noteworthy is that the genetic material of apes is 96% identical to that of humans.
- Our chromosomes contain 20,000 or so genes—only 2000 fewer than worms and less than corn, rice or wheat…in this instance, size doesn’t matter!
- Every cell in our body has identical chromosomes and genes, yet the expression of the genes varies greatly from cell to cell—skin cells are clearly very different than kidney cells, yet share the same genetic blueprint. The nuance, complexity and real mystery of our chromosomes is the orchestration of turning on and turning off certain genes in certain cells at certain times at certain places.
- Our genes can magically shuffle their sequence to make genetic variants to enable fighting off invading pathogens. This dynamic ability allows us to ward off pathogens that are constantly evolving.
- The basic function of genes is to encode for proteins. However, only 2% of the chromosome contains genes that do so. 98% of the genetic material of the chromosome does not encode for proteins and is either located between or within protein-encoding genes and is responsible either for regulating genes or has mysterious functions that are not understood.
- Many of our human genes are actually not human. Embedded within our chromosomes are inactive portions derived from ancient viruses and other non-human sources.
- The ends of chromosomes have “telomeres” that protects the chromosomes from fraying, acting like the plastic pieces at the end of shoelaces.
- The simplicity of the genetic code is well understood: DNA builds RNA, RNA builds proteins, and a triplet of bases of DNA specifies one amino acid of the protein. However, we are clueless about the complexity of the genomic code, with no clear understanding of the coordination of gene expression to build, maintain and repair a human being.
- The Y chromosome determines maleness. It is the only unpaired chromosome, meaning no mate chromosome or duplicate copy, leaving each gene on the chromosome to fend for itself. If a mutation occurs, there is no repairing it by copying it from the intact gene on the sister chromosome. In other words, the Y chromosome has no backup (spare tire) and when a mutation occurs, it spells trouble, being the most vulnerable spot in the human genome. As a consequence, evolutionary forces have transferred important genetic material to less vulnerable chromosomes, whittling the Y chromosome down to being the smallest of all chromosomes. Like risk-taking men, the male chromosome lives dangerously!
- Mitochondria are the “powerhouses” of our cells, responsible for energy and metabolism. All human embryos inherit their mitochondria exclusively from their mothers, as sperm do not contribute mitochondria. If you feel depleted of energy, blame it on your mother!
Much of the information for this entry was derived from an awesome book: The Gene: An Intimate History by Siddhartha Mukherjee, MD, one that we highly suggest that you put on your reading list.