I've done that my whole life - I've taken the way people think and turned it on its head.

I had to grow up, reach a certain age where I see people do have something to show me.

I do something to make things nature never made but which is useful to humans.

I care about this beautiful planet that we all share. This is a home that we have to leave in good shape for the next generations.

Nature's made much more dangerous things than I ever will.

Pittsburgh was a wonderful place to grow up - diverse and complex, one could go from one culture to a completely different one in just a few blocks. It was a whole world in one city.

I learned how to navigate the world, and life's potholes, in Pittsburgh.

I meet so many young people who want to plan out their lives and want a recipe. They want me to tell them how to succeed. I didn't follow a recipe. I followed my instincts.

Most innovative things are not obvious to other people at the time. You have to believe in yourself. If you've got a good idea, follow it even though others tell you it's not.

Doing science at the highest level is hard for anyone. It's hard for women, and it's hard for the men. And we need to have supportive mentors and role models we can look up to.

For me, I was always the only woman in my cohort, first as a mechanical engineering undergraduate student, then as a chemical engineering graduate student. There were very few women getting degrees in those fields at the time. My role models were men - great men role models.

What I want to do is demonstrate that biology can learn how to make a vast array of molecules that people thought were outside the realm of biology.

My feeling is that we can genetically encode almost any kind of chemistry. We just have to learn how to do that.

Engineering the biological world was even more interesting than engineering the mechanical world.

Enzymes catalyze all the reactions of life. They're what allow you to extract materials and energy from your environment and turn that into muscle and tissue and fat. That's all done by enzymes. They're pretty remarkable chemists - they're even better than Caltech chemists.

I wanted to make enzymes that would solve human problems, not just problems for a cell that makes them.

The code of life is like a Beethoven symphony. We have not yet learned how to write music like that. But evolution does it very well. I am learning how to use evolution to compose new music.

Microbes such as bacteria and yeast use enzymes to make fuels from biomass. We use directed evolution to perfect those enzymes and make new fuels efficiently.

Evolution is good for optimising and that is well understood. But evolution also creates things that no one knew were even possible.

In the test tube, I can make any DNA I want, recombining it from monkeys, worms, anywhere. So I can explore new rules of breeding with molecules.

I took mechanical drawing, geometry and typing at high school, the latter because that is what they did with smart girls in those days!

I wanted to rewrite the code of life, to make new molecular machines that would solve human problems.

Bemoaning your fate is not going to solve the problem.

Human beings have been manipulating the biological world for thousands of years without understanding how DNA codes function.

I love what I do, and I'm grateful for every day I can do it.

I know how to do science. I know how to make things. I don't know how to run a company. Now that's a really tough job.

I'm interested in using evolution to move forward into the future, to get biology to do a lot of new chemistry for us.

We all need friends, and friends are there to hold you up when nothing else can.

Isobutanol is not a natural product, but we evolved an enzyme that makes it possible to convert plant sugars to this precursor to jet fuel.

Evolution, to me, is the best designer of all time.

I tried lots of things and never stopped learning.

I was used to being the only woman in everything... I didn't even think about it. Men were my role models - there's nothing wrong with that.

For some reason, there are political forces that somehow feel threatened by honest inquiry. How can you be threatened by wanting to know the facts?

Only engineers would do something like random mutagenesis.

Cellulose has physical and chemical properties that make it difficult to access and difficult to break down.

Using the power of protein engineering and evolution, we can convince enzymes to take what they do poorly and do it really well.

This innovation machine that's evolution, we can use it to do all sorts of interesting things.

Silicon is all around but it's tied up in rocks... with these very strong silicon-oxygen bonds that living systems would have to break in order to use silicon.

I'd like to see what fraction of things that chemists have figured out we could actually teach nature to do. Then we really could replace chemical factories with bacteria.

What I find most interesting is what nature can do if you only ask.

The real frontier is making these hybrid systems where you expand the capabilities of biology with chemistry.

Inside of a living cell there are thousands of proteins that enable it to make more of itself and make your malaria drug, for instance. We don't understand those. We don't understand how they work together.

We're seeing a move toward making things that either chemistry cannot make or can't make efficiently but biology does.

My whole interest is, how do you use evolution as an innovation engine? How does evolution solve new problems that life faces? And to have a system that can create a whole new chemical bond that biology hasn't done before, to me, demonstrates the power of nature to innovate.

People are really interested in these fundamental questions: Why is life based on carbon and not silicon?

Silicon-based life on Earth doesn't make sense, but perhaps it would in some totally different environment.

Enzymes are masters of chemistry. They evolved over billions of years to perform specific biological functions. They make complex materials with virtually no waste.

In the universe of possibilities that exist for life, we've shown that it is a very easy possibility for life as we know it to include silicon in organic molecules. And once you can do it somewhere in the universe, it's probably being done.

My laboratory uses evolution to design new enzymes. No one really knows how to design them - they are tremendously complicated. But we are learning how to use evolution to make new ones, just as nature does.

The biological world always seems poised to innovate.