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Monday, February 04, 2019

What is the dominant view of junk DNA?

I think that about 90% of our genome is junk and I know lots of other scientists who feel the same way. I'm pretty sure that this view is not shared by the majority of scientists but I don't know whether they are convinced that most of our genome is functional or whether they just think the question is unanswerable at the present time. I suspect that the latter view is more common but I'd like to hear your opinion.

Sunday, January 27, 2019

Yeast loses its introns

Baker’s yeast (Saccharomyces cerevisiae) is one of the best studied eukaryotes. Its genome is just slightly larger than the largest bacterial genome and it was the first eukaryotic genome to be sequenced (Mewes at al., 1997). It has about 7000 genes in total and 6,604 of these genes are protein-coding genes but only 280 of these genes contain introns.1 The rest have lost their introns over the course of several hundred million years of evolution (Hooks et al., 2014).

We know that introns have been lost in yeast because the genes of related species have lots of introns. The common ancestor of all fungi undoubtedly had genes with multiple introns because the available evidence indicates that introns invaded eukarotic genes very early in the evolution of eukaryotes. The fact that most introns have been purged from the yeast genome suggests that introns are not essential for gene function. In other words, introns are mostly junk.2

Wednesday, January 23, 2019

What happens when twins get their DNA tested?

The Canadian Broadcastng Company (CBC) has a TV show called Marketplace that promotes itself as an advocate of consumers' rights. It has a history of testing the claims of advertisers and usually shows that these claims are misleading or false. Here's what they say on their website.
On air since 1972, Marketplace is Canada’s consumer watchdog. We get the goods to help you shop smarter and protect yourself from slick scams and misleading marketing claims. We investigate the products and services we all use every day and push companies and government for answers. And we expose the truth on stories that matter to you and your family.

Sunday, January 13, 2019

Most popular Sandwalk posts of 2018

Blogging was light last year because I was busy with other things and because the popularity of blogs is declining rapidly. The most popular post, based on the number of views, garnered only 9229 views, which is more than the most popular post of 2017 but only half as much as the most popular post of 2016. The post with the most comments (53) has almost 10X fewer comments than posts from a few years ago but that's partly because more people are commenting on Facebook and because I'm restricting blog comments in various ways.