copyright 2009, The Washington Post WASHINGTON -- Partway through an interview, Carol Greider's cellphone emits the special ring she has set to indicate the caller is one of her two children. Greider, a molecular biologist at Johns Hopkins who this year became one of only 10 women to win the Nobel Prize in medicine, is at her phone in a split second. The caller is her 9-year-old daughter, Gwendolyn, who has gotten out of school. 'How was Spirit Day?' Greider asks. They chat -- a babysitter is at home -- then she rings off. Nearby is a pile of handmade cards from Gwendolyn's fourth-grade class. Twenty-five years ago, as an exceptionally gifted graduate student at the University of California at Berkeley, Greider, now 48, visited her lab to check an experiment, and discovered evidence of an enzyme called telomerase. The enzyme helps maintain telomeres, the caplike structures that protect the ends of chromosomes. The discovery was a breakthrough -- telomerase is implicated in cancer and genetic disease -- the import of which would become clearer over time, as possible therapies emerged. 'I wonder if guys that win the Nobel Prize -- do they send flowers to guys? I didn't think to ask Jack,' she wonders, referring to Jack Szostak, a Harvard scientist who, together with Greider's mentor Elizabeth Blackburn, did groundbreaking work in telomeres; the two shared the Nobel with Greider. She'll ask him next time she sees him. In the meantime, she has sent an e-mail to Gwendolyn's teacher that says, 'I want to come in and say thank you.' It is a rare moment of convergence between her two worlds. For the most part, Greider concentrates on work when at work and on home when at home. She has always had an ability to focus, ever since she was a kid with dyslexia and had to learn to tune out distraction. 'I think to a degree, it was my learning to overcome obstacles early on in my life,' says Greider, a dynamic, down-to-earth woman with rumpled surfer-girl hair. 'That's how I deal with family and work. I focus on one thing. I have colleagues that say, `I called home four times today to see how the kids are doing,' and it's like, really? I never call home. I mean, I try to set things up as safe as I can, and I have my cellphone on and that's it, and I don't even think about it.' You could even say dyslexia was the key to much of Greider's success, including the fact that early on, she resisted getting hung up on the fact that science, historically, often has not been conducive to female achievement. Over the years she has become very aware of the factors that discourage women, but when she was establishing her own career: 'I didn't ever feel like I had been blocked by anything. That could be more a personality thing -- I was pre-selected by being somebody that just ignored barriers.' Dyslexia arguably was responsible for the prize itself -- or at least, for the series of decisions that put Greider on the path to winning. Greider's mother, who died when she was 6, was a biologist; her father was a physicist who encouraged her to find work that engaged her. After college she decided to go to graduate school in molecular biology, but because of her disability she did not test well, and a number of schools rejected her because of poor GRE scores. Just two -- UC Berkeley and Cal Tech -- took note of her stellar grades and invited her for an interview. Accepted by both, she chose Berkeley in part because one of her interviewers was Blackburn. Greider can't say for sure that she gravitated to Blackburn because they are the same gender; it was more that Blackburn was doing intriguing work and spoke about it with infectious passion. But she does think female scientists have a slight affinity for working in the labs of women, and that this accounts in part for the number of women in her own field. Greider calls this a 'founder effect,' an evolutionary term for the fact that traits exhibited by the founders of a population tend to show up in later generations. Because of a male scientist who was unusually encouraging, the field of telomere biology was seeded early on with women, who then attracted more. 'I really think that there are subtle societal factors' at work in science, says Greider. 'It doesn't have to be that the men at the top are saying, `Oh, no, let's not promote women. ... ' I think that there are comfort zones, and a man going to a meeting may feel a little more comfortable introducing his (male) graduate student to his colleagues. ... Those are the kind of mechanisms by which subtle effects can actually affect the outcome.' Her explanation for women's under-representation is at odds with the one infamously suggested by Larry Summers, former president of Harvard, who provoked a uproar in 2005 when he suggested that it might be a problem of 'intrinsic aptitude,' an explanation Greider finds ridiculous. Her own theory takes into account that the difficulty of scientific achievement is not just memorizing formulas and interpreting data; it's surviving in a ferociously competitive culture that depends on strategic alliances. To advance, a young scientist needs to get included on significant projects, preferably with an established mentor. At Berkeley, Greider manifested unusual talent in the lab, a kind of innate genius that has a lot to do with 'the ability to concentrate' and 'not get distracted,' says Titia de Lange, who works in telomere biology and heads a lab at Rockefeller University. 'People have it or don't have it. It's not something that you can teach.' Greider attached herself to a project Blackburn had going; curious why telomeres don't get shorter with cell division, Blackburn suspected there was an enzyme that helped them replicate. Greider spent nine months finding nothing, then decided to change one of the substances in her experiment. When she went in on Christmas Day 1984, to check on it, she looked at an X-ray film and saw a pattern that suggested she had discovered the enzyme Blackburn was looking for. Her mentor, Greider recalls, was 'bowled over.' They did a great deal of testing to make sure they hadn't misinterpreted, then published the results. A major talent had announced itself. Applying for a postdoctoral fellowship at Cold Spring Harbor Laboratory in New York, Greider, who would continue working on telomerase, was offered something better: a three-year independent fellowship designed to nurture young scientists. 'She was probably the most enthusiastic about what she did as a graduate student as anybody I've ever seen,' says Bruce Stillman, now the president of the lab. 'She didn't even last three years; we promoted her to the faculty.' Even as she was advancing, Greider became aware that this was the point at which attrition often occurs, for women. 'The stage at which women tend to drop out is between postdoc and assistant professor, and assistant and associate professor, by far,' she says, a truth that is well established: 'About 50 percent of graduate students (in many scientific fields) are women, and that's not true at the faculty level,' says Stillman. While there she was asked to head a committee to find out what colleagues wanted in a new gymnasium. Instead she encouraged the addition of a child-care center. The facility got built; Greider says there is a photo of her with a shovel at the groundbreaking, nine months pregnant. With the historian of science Nathaniel Comfort, whom she married in 1993, she had a son, Charles, whom they enrolled in the child-care center, and a daughter. Science, argues Greider -- who now runs a lab at Johns Hopkins -- can be made to fit a parent's schedule. 'My job is to be productive. I don't have to be here from 9 to 5, there's not a clock. I will just say I'm going to watch Gwendolyn's play today, and I'll leave. I make sure I say why I'm going. ... I think it's important for people to know that this is OK, (to) send that signal.' Fellow scientists say Greider is as tough-minded as anybody. Her reputation is that of a 'brilliant, hard-working and highly competitive scientist,' says David Keefe, a doctor and scientist who has done work on telomeres and female reproductive aging. Greider says she does not think of herself as competitive, but that competing is hard to avoid. Early on, she says: 'I never really felt like I had to compete. We just started off and were just looking at something that was interesting. And there wasn't anyone else doing it. We could publish it and have the luxury to do the right controls and take our time. 'Now there are many more people in the field,' and so intense is the pressure to be first that if a project is 'something that you really think is going to be hot, you don't say anything about it.' Over the years, Greider has amassed a number of prizes; several years ago she, Blackburn and Szostak were given the Albert Lasker Award for basic medical research, sometimes a precursor to the Nobel. And just as the world of home sometimes intrudes on the world of work, the opposite can also be true. That was the case two weeks ago, when Greider was up, as usual, before 5. As she was folding laundry, the call came. After that, 'I got to send an e-mail and write a sentence that I know has never been written before by a man: Can't make it to spin class. I just won the Nobel Prize.' Several days later, when she heard that President Obama had won the Nobel Peace Prize, she thought to herself, I bet he wasn't folding laundry. 