The following is the detailed summary of the Grey’s Anatomy episode Can’t Fight Biology, the 4th episode from season 7. If you want to find about what happened in episodes 1,2 and 3, you can read the articles  and Grey's Anatomy Season 7 - Joint Summary of Episodes 1 and 2 and Grey's Anatomy Season 7 Episode 3 - Summary.

Episode 4

The Cases

A woman has crashed her car into a launderette and now she is in the emergency room with her husband and a young woman. The woman is upset that any serious injury can cause her to delay her vacation to Brazil. She has Huntington’s, a genetic disease that once the symptoms start, many physical and mental disabilities will occur and eventually lead to death. Meredith (Ellen Pompeo) relates to this woman’s sense of urgency and the desire to take as much from life as possible before the disease takes over. This also makes her think about her own mother, whose final years were completely ruled by Alzheimer’s.

Dr. Bailey (Chandra Wilson) needs to take care of a patient (Christian Clemenson - Boston Legal’s Jerry Espensen) who is some sort of a scientist working to cure asthma. Unfortunately, his research involves swallowing worms. Now he has severe problems and needs surgery. However to both Bailey and Christina (Sandra Oh)’s surprise, he seems more attached to his worms than his health.

Alex Karev (Justin Chambers) is helping out Torres (Sara Ramirez) and Arizona (Jessica Capshaw) with a dancer teenager. He has cancer and the absolute solution is to amputate his leg. However dancing is his own life, and he is more than determined to show both to Karev and others that he needs to dance.

The Relationships

Meredith and Derek (Patrick Dempsey) see a doctor about their fertility. Meredith is not happy that the doctor found her uterus hostile.

Christina and Owen (Kevin McKidd) are apartment hunting. Owen is more than happy at the possibility of buying a place that used to be a fire department station, complete with the pole. She is less than enthusiastic.

In the meantime, Meredith’s apartment is more like a hostel with Lexie (Chyler Leigh), April (Sarah Drew), Alex (Justin Chambers) and Jackson (Jesse Williams) all staying with Derek and Meredith. Lexie is annoyed Meredith seems to be sharing more with April than her. April also seems to be taking Izzie (Katherine Heigl)’s old room while Lexie is living in the attic, which also pisses Lexie off.

Torres is disappointed that Arizona doesn’t like Mark (Eric Dane) and that she isn’t putting any effort to warm up to him.

Chief Webber (James Pickens Jr.) is up to his usual ways, going overbroad while trying to promote the hospital. Neither Meredith nor Bailey is too happy about it.

Jackson tries to charm his way into Teddy (Kim Raver)’s operations.

The End

As it turns out, Meredith never meant to keeps stuff from Lexie but April already knew about Meredith’s doctor appointment because she was there when Meredith lost her baby. Lexie makes peace with both April and Meredith.

The woman with the Huntington’s disease has started showing symptoms. Meredith persuades her to see her doctor when she comes back from Brazil and in return gives her medication to help her out. She also asks Christina to take her blood so that she can test herself for Alzheimer’s.

The man with the worms is saved but is upset that his research is lost. Christina is inspired by his dedication to the thing that he loves so much. And as the audience expects her to go back to operating, she buys the former fire department flat for Owen to make him happy.

Teddy tests whether Jackson is indeed just a pretty face or a knowledgeable doctor. When he passes her test, she warns him that if he ever tries to flirt for his job, she will go to the Chief.

Arizona, Torres and Karev manage to save the boy without cutting his leg. Arizona also decides to hang out with Mark alone, and make an effort to like him.

Meredith and Derek decide to just keep having sex and forget about scientific solutions to make a baby- Derek makes it clear that he is happy with Meredith and will be with her whether they have a baby or not and whether she develops Alzheimer’s or not.

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