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RNA World and the Origin of Life

In 2011  Martin Hanczyc delivered a TED talk in London on the topic of the origin of life, “The Line Between Life and Not-Life” that discussed some of his work with proto-cells. I participated in some online commenting on the TED page including a conversation about the origin of genetic material.

I wanted to point to the talk itself and include some of the posts below.

ImageFrom Ted Mozer III: ” Two questions about life and the origin of same on earth:
Is all know life on earth related and DNA (or even RNA) based?
If life was created on earth (and not from a seed that either arrived via an comet or the like or from an alien visit), why is the creation process a not a contining process. Did the creation process occur and then stop once life awoke? If so, why??”

My Reply: “You’re asking a very good question, Ted.
Think of it this way, imagine that life first originated by self-replicating molecules (probably RNAs) that found a nice safe home in some protocells that were floating around in the neighborhood – it doesn’t matter if this is absolutely true or not, just consider the abstract idea. The ‘food’ that these cells need is more RNA and cell membrane material, right? So, the things that these cells will ‘eat’ are exactly the same stuff that they, themselves, once were. If our new cells are successful, they are probably gobbling up all the other pro to-life material around them.
This does not mean that life could not have happened more than once, but if it’s a rare enough event, then the first things to get there are going to probably stay at the top of the heap.

It would be really cool to find organisms that use different genetic material – this would support multiple origin events, but so far, the universality of DNA argues that it was a one-off thing.”

A Comment by an unknown person: “Self replicating RNA? RNA and its components are difficult to synthesize in a laboratory under the best of conditions, much less out in a primordial mud puddle. This is highly unlikely. Yes, this was a miraculous “one-off thing.””

My Reply: “Yes, I agree, it is difficult to conceive of RNA as a self-replicating genetic material that also acts as an enzyme. Although RNA does currently act as genetic material, this role is restricted to viruses while DNA plays the major role of genetic material in all other organisms (including some viruses). Also, much of the enzymatic work in biological systems is currently carried out by enzyme proteins. However, there are still some RNA enzymes (ribozymes) extant, one of note is the ribosome – a protein / ribozyme complex with deep phylogenetic roots.

The idea of an RNA world as life’s origin has been around for some time, with suggestions of such an origin being proposed by Francis Crick, Alexander Rich and Harold White (among others) in the 1960s and 1970s.

Over the years, data has emerged supporting such a possibility including:

“The system, created by Gerald Joyce and Tracey Lincoln at the Scripps research institute in La Jolla, California, involves a cross-replicating pair of ribozymes (RNA enzymes), each about 70 nucleotides long, which catalyse each other’s synthesis.  So the ‘left’ ribozyme templates the synthesis of the ‘right’, which in turn templates the ‘left’ and so on, building each other via Watson-Crick base pairing. “

discussed in “Chemists edge closer to recreating early life”, Royal Society of Chemistry 2009.

also,

“Clemens Richert and colleagues at the University of Karlsruhe have now shown that, without the use of enzymes, an RNA strand bound to a longer template strand of RNA can grow more than one order of magnitude faster than previously believed. This growth occurs in single nucleotide steps according to the base pairing rules of Watson and Crick.”

-From “Accelerating non-enzymatic RNA replication“, Royal Society of Chemistry 2005.

However, support is not proof. There will never be proof of what actually happened, but, then again, I might just be a brain floating in a jar somewhere…

 
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Posted by on October 13, 2013 in Uncategorized

 

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Visit my Ted Ed flip of the lesson: Myths and Misconceptions about Evolution

ImageTake a look at my new flip of this lesson on Ted Ed:

Myths and Misconceptions about Evolution

http://ed.ted.com/on/HQPBkX36

Then come back here and leave your feedback about what the lesson includes and what you learned or did not learn about. I’d love your feedback on the associated questions and discussion topics so I can edit and optimize them before I show it to my class in the Fall.

 
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Posted by on July 8, 2013 in Uncategorized

 

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A cute video about the beginning of time

From the Ted Ed site:

“How did the universe begin — and how is it expanding? CERN physicist Tom Whyntie shows how cosmologists and particle physicists explore these questions by replicating the heat, energy, and activity of the first few seconds of our universe, from right after the Big Bang.”

Lesson by Tom Whyntie, animation by Hornet Inc

 
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Posted by on June 24, 2013 in Uncategorized

 

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Vaccinated, chapter 10: An Uncertain Future

ImageA lot has been made of the putative link between vaccines and autism since the 1998 publication of ‘Illeal-lymphoid-nodular, non-specific colitis and pervasive developmental disorder in children‘ by Andrew Wakefield. In chapter 10 of Vaccinated, we will be discussing how this article started an epidemic of fear amongst the parents of young children that had a drastic effect on public health.

The author quotes Philip Roth’s The Human Stain as a testimony to the power of suggestion. “To hear the allegation is to believe it. No motive for the perpetrator is necessary, no logic or rationale is required. Only a label is required. The label is the motive. The label is the evidence. The label is the logic.”

In our discussion of this paper we will review the circumstances surrounding its publication, the data presented by the paper, what they mean and don’t mean and what efforts have been made to research the possibility of such a causal link.

A good review of the work done to examine the evidence for any such connections can be found here. We will review the data presented in this article and since that article is a secondary source, we will uncover some of the primary data that this review discusses as see how it compares to the original paper.

In putting this together, I am reminded of an interesting TED talk about how science is done and the necessity for critical examination of data. The talk, by Margaret Heffernan: Dare to disagree is well worth the listen:

 

 
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Posted by on April 2, 2013 in Uncategorized

 

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Science Denialism … A TEDed lesson

Michael Specter, a science journalist at The New Yorker and author of Denialism: How Irrational Thinking Hinders Scientific Progress, Harms the Planet, and Threatens Our Lives gives a remarkably powerful talk on the treatment of science in modern times. He asks, ‘Why do we mistrust scientific authority?’ and encourages us to listen to the data even as we keep our skepticism.

This is a really good talk. I wish I had given it. Follow this link to the TEDed page with this talk and some questions. He mentions Paul Offit, the author of Vaccinated, the book we are reading in Microbiology this semester. Although the mention is brief, it does expose the ugly mob mentality that takes over public discourse sometimes. 

 
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Posted by on March 12, 2013 in Uncategorized

 

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TED Talks, free speech and scientific integrity

Screen Shot 2013-03-07 at 3.15.39 PMThere’s a fascinating, fast-moving discussion join on right now sparked by a recent TEDx talk. If you aren’t aware of TED talks, take some time and check them out, they’re a fascinating group of short talks that cover a variety of ideas. Under the TED umbrella, there are also TEDx talks (TED-liscenced talks that are like the parent, TED talks, but more widespread and under less scrutiny), there are TEDed videos that provide short, educational videos targeting classroom use, etc. I’ve been a big fan of TED because of the caliber or speakers and the quality of their talks.

However, one talk has stood out and has received a lot of attention from the scientific community. This came to my attention recently because I follow Jerry Coyne’s blog and he posted the talk in one of his entries along with a strong critique of the talk. You can check out his post here.

Fortunately, and to the credit of TED, this critique has been taken very seriously and the TED site now has an open comment section where the value of this post is being discussed. If you are interested in thinking about what science is… what evidence is … you might like reading through the extensive comments that have simply exploded. As of right now, there doesn’t appear to be much flaming going on and there are some very good comments being made about what it means to do science.

I’ve had conflicting thoughts about whether to bring this discussion up here, because I think the talk is simply terrible in its treatment of science and I was worried that readers might be mistakenly wooed down the garden path by his wonderful oratory skills, but I think the comments section adds enough balance to the discussion and  the holes in his logic are laid bare.

Happy reading.

 
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Posted by on March 7, 2013 in Uncategorized

 

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First on Land

I found this video on the Ted-ed Site. Since my class is currently reading Your Inner Fish, the story about how the first animals that are direct ancestors of mammals came out of the water, I thought this video on the very first animals to come out of the sea was very appropriate.

Have a look at the video and check out the questions afterwards… you never know, one might show up as extra credit on a quiz…

http://ed.ted.com/on/wAFSbjQj

I hope you enjoy.

 
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Posted by on November 14, 2012 in Uncategorized

 

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