If poly A is added to poly U, to form a double or triple helix, the combination is inactive.

It seems likely that most if not all the genetic information in any organism is carried by nucleic acid - usually by DNA, although certain small viruses use RNA as their genetic material.

It is one of the more striking generalizations of biochemistry - which surprisingly is hardly ever mentioned in the biochemical textbooks - that the twenty amino acids and the four bases, are, with minor reservations, the same throughout Nature.

We are sometimes asked what the result would be if we put four +'s in one gene. To answer this my colleagues have recently put together not merely four but six +'s.

The balance of evidence both from the cell-free system and from the study of mutation, suggests that this does not occur at random, and that triplets coding the same amino acid may well be rather similar.

If, for example, all the codons are triplets, then in addition to the correct reading of the message, there are two incorrect readings which we shall obtain if we do not start the grouping into sets of three at the right place.

If poly A is added to poly U, to form a double or triple helix, the combination is inactive.

For simplicity one can think of the + class as having one extra base at some point or other in the genetic message and the - class as having one too few.

If the code does indeed have some logical foundation then it is legitimate to consider all the evidence, both good and bad, in any attempt to deduce it.

We've discovered the secret of life.

A final proof of our ideas can only be obtained by detailed studies on the alterations produced in the amino acid sequence of a protein by mutations of the type discussed here.

It now seems certain that the amino acid sequence of any protein is determined by the sequence of bases in some region of a particular nucleic acid molecule.

How is the base sequence, divided into codons? There is nothing in the backbone of the nucleic acid, which is perfectly regular, to show us how to group the bases into codons.

It would appear that the number of nonsense triplets is rather low, since we only occasionally come across them. However this conclusion is less secure than our other deductions about the general nature of the genetic code.

Moreover the incorporation requires the same components needed for protein synthesis, and is inhibited by the same inhibitors. Thus the system is most unlikely to be a complete artefact and is very probably closely related to genuine protein synthesis.

Attempts have been made from a study of the changes produced by mutation to obtain the relative order of the bases within various triplets, but my own view is that these are premature until there is more extensive and more reliable data on the composition of the triplets.

Do codons overlap? In other words, as we read along the genetic message do we find a base which is a member of two or more codons? It now seems fairly certain that codons do not overlap.

Unfortunately it makes the unambiguous determination of triplets by these methods much more difficult than would be the case if there were only one triplet for each amino acid.

It has yet to be shown by direct biochemical methods, as opposed to the indirect genetic evidence mentioned earlier, that the code is indeed a triplet code.

This seems highly likely, especially as it has been shown that in several systems mutations affecting the same amino acid are extremely near together on the genetic map.

It now seems very likely that many of the 64 triplets, possibly most of them, may code one amino acid or another, and that in general several distinct triplets may code one amino acid.

The meaning of this observation is unclear, but it raises the unfortunate possibility of ambiguous triplets; that is, triplets which may code more than one amino acid. However one would certainly expect such triplets to be in a minority.

A comparison between the triplets tentatively deduced by these methods with the changes in amino acid sequence produced by mutation shows a fair measure of agreement.

The job of theorists especially in biology is to suggest new experiments. A good theory makes not only predictions but surprising predictions that then turn out to be true.

The ultimate aim of the modern movement in biology is in fact to explain all biology in terms of physics and chemistry.

We used to flock to watch gladiators, public torture and executions. In more recent times, our appetite for mortal violence has been sublimated in sports, photorealistic video games, film and literature.

Metal isnt necessarily aggressive. Theres metal thats contemplative theres metal thats sad and theres metal thats exuberant. No genre is limited in what it can express.

I think the best thing that you can do with your kids is to talk to them like they're human beings, not like they're children and they don't know what they're doing.

I like to look put together without trying too hard. I don't want to look as if God's made another rainbow - I prefer muted, autumnal colours, like most fading redheads.

Poetical appreciation is only newly bursting on me.

My dreams for the future are simple: work, a happy, healthy family, a lovely long motorcycle ride, and continuing the struggle to awaken people to the need for serious human rights reform.

I know that everyone wants to know about 'Downton Abbey,' but the truth is that it was only a few days out of my life. Still, you play a distinctive part on a hit series, and everyone suddenly knows who you are. Isn't it crazy how this business works?

Every time you think the problem is 'out there,' that very thought is the problem.

Very rarely is there a spike in news-stand sales.

I'm not very experienced with boys or the whole dating thingy.

When I graduated from high school, it was during the Depression and we had no money.

I didn't even know I could sing or write songs. I didn't have that education. But people shouldn't think they can look down on someone like me, because I've had the same success as others, sold the same amount of records, if not more. They shouldn't think that because I'm just from 'The X Factor,' I'm not credible or respected as much.

I'm a workaholic. I would not pretend to be anything else. I rarely go to bed before one o'clock in the morning. I might kind of have a spa between half-past twelve and one and relax, and that's when I do my thinking, or my non-thinking. That's when I have a bit of space for myself.

I conceived in art college at the age of 20, near the end of term.

Now the first step has to be taken, the step towards democracy. This step is full of risks, and requires trust on all sides. We don't know where it will lead. But if we just stand still, we will have no chance of escaping the violence.

When I fell for Johnny Galecki, we both knew immediately that we had this connection, and that was it.

No matter how counter-intuitive it may seem, basic research has proven over and over to be the lifeline of practical advances in medicine.

As a director, there is nothing more fun than seeing an audience screaming and jumping. You are the ultimate puppet master, controlling the emotions of the audience.

The most powerful symptom of love is a tenderness which becomes at times almost insupportable.

I just think that most of the people are very close minded.

I don't see any absolute biological limit on human age.

Communism possesses a language which every people can understand its elements are hunger envy and death.

England in the late 1940s was famously grim. As I remember it, London back then was a very dirty place, from coal dust and smoke, from the grit stirred up every day by the jackhammers still clearing out rubble from the Blitz.

I grew up loving actresses or actors who were very classy but who seemed a little bit mysterious because you couldn't grasp what they're really thinking.