Ten Facts About the Human Genome

1. Of the 3.2 billion base pairs in the human genome, less than 2% code for proteins. 98% of the genome is not coding for proteins. There are 24000 genes in a human. Rice, for example, has 35000 genes. What is going on? I think I’m more complex than a rice plant.
   
   
2. 99% of the human genome is identical in all people.
   
   
3. The functions of many of the 24000 genes in the human genome are not yet known.
   
   
4. Genome sequencing is getting faster and cheaper. In 2007, the genomes of James Watson and Craig Venter were made public. It took those genomes two months each to get sequenced, with a cost of about 1 million dollars each. The price is going down and down. The objective is to reach the 1000$ genome by the next decade.
   
   
5. Genome sequencing of individuals is useful for: screening for possible diseases, genetic research and origins research.
   
   
6. We have fewer genes than a rice plant. There are three possible explanations for this, but the basic one is that we can do many things with each gene.
   
   
7. Genes are interrupted in their information sequence by non-coding sequences, called introns. Introns are kind of nonsense. Every gene has so many introns that the coding regions can be mixed and matched together. Each human gene gets translated into about 5 proteins.
   
   
8. After a protein is made, it folds into its three-dimensional shape, but other things can happen to it. Sugars can be put on to proteins and change their functions. We can have a set of genes that add sugars to various proteins. These modifications add to the diversity of proteins that can be made.
   
   
9. There is a big chunk of the human genome that makes RNA’s that don’t get out of the nucleus, that don’t end up getting translated into protein. These are very small RNA’s called micro RNA’s (mRNA). They were very recently discovered. In fact, they aren’t even in most textbooks. In the human genome, these small RNA’s may be involved in gene regulation (turning a gene on or off). We’re not quite sure what these mRNA’s are doing, but humans have a lot of them.
   
   
10. Scientists used to say that 98% of the human genome that doesn’t code for protein is junk. It looks like this junk has a valuable function. The junk does have some gems there, the mRNA’s.