Monday, May 9, 2016

Smallest Cell

This headline and link are from the Washington Post. The article describes the smallest cell to which the scientists were able to reduce, and it turns out it is twice as big as they thought it would be:

This man-made cell has the smallest genome ever — but a third of its genes are a mystery:

https://www.washingtonpost.com/news/speaking-of-science/wp/2016/03/24/the-creators-of-the-first-synthetic-life-made-a-cell-with-just-enough-genes-to-survive/ .

The news is from J. Craig Venter Institute. They had previously been known for putting together a synthetic combination of DNA which survived in a cell and was capable of reproduction. Link here:

http://science.sciencemag.org/content/329/5987/52 .

DNA is the molecule that forms our genes. These are used for coding proteins, which do the work of our cells. Cells are the basic unit of biology. DNA is also needed for reproduction, to pass the information to offspring. Humans have trillions of cells, and most of them contain their own set of DNA. Some organisms, like bacteria, have only one cell, but still need DNA to make protein and for reproduction. As you have probably seen, but if you want you can see in the picture in the link below, DNA looks like a twisted ladder. Each step of the ladder has a smaller molecule that acts, in sequence with the other steps, as a code for the protein so it can be made correctly. There are 4 types of steps which are called bases and in bacteria it takes about 1000 bases per gene. And as the WP article points out, “to build a DNA code that will support life, you need to be pretty much error-free.”

Picture from www.creationwiki.org :

http://www.creationwiki.org/Deoxyribonucleic_acid .

Scientists have been trying to determine what is the least number of genes a single cell, such as a bacterium, can have and still stay alive. This is not a fully-functional cell in the sense it would have to be given nutrients that it could not produce itself. Scientists had thought the number would be in the vicinity of 250, but have found, at least in this approach, that more genes are needed than they thought. They came up with 473. (There are 32% they don’t know their function.) The organism needs over 531,000 base pairs in order for it to function (in Press Release here).

An abstract of the new scientific paper is here:

http://science.sciencemag.org/content/351/6280/aad6253 .

Eugene Koonin, the director of comparative genetics at NIH, estimated a fully functional cell would need about 1000 genes. These would be fully self-functional, not needing supplements fed to them. At 1000 bases per gene, that would be one million bases in exact order. The article which contains his estimate can be found here:

http://nar.oxfordjournals.org/content/36/21/6688.full .

What are the chances that even half of that, an exact sequence of 500,000 bases, could have randomly come together to start life, composing a complete genome which codes for life processes (even if there were nutrients in the environment) such as breakdown of sugar to make the structures of the proteins, reproduction and other functions, and organize all of it in tiny cells? This could not have happened by chance even in billions of years.

Praise God for His Creation.

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