In order to answer this question, it is clear that you need to work out what Skloot is trying to establish in Part 1 of this book, where she focuses on the life of Henrietta Lacks and her suffering from the cancer that eventually killed her. Skloot gives this information to paint the human story of the disembodied cancer cells that have revolutionised medical science in so many ways. Having herself, as a medical student, only come across the cells by their name of HeLa cells, she desires to make the reader cognisant of the life behind those cells and the suffering and deprivation that Henrietta Lacks suffered. This is why the first section of the novel contains information that deliberately seek to make us feel sympathy towards Henrietta Lacks and the cruel cancer that robbed her life, and her children of their mother. Note for example, the following quote from Emmett:
She was sick like I never seen. Sweetest girl you ever wanna meet, and prettier than anything. But them cells, boy, them cells of hers is somethin else. No wonder they never could kill them... That cancer was a terrible thing.
This, following a description of the physical pain that Henrietta must have endured, seeks to engage the reader's sympathy for the human cost of something that has benefited us all so greatly. A good thesis statement would therefore be:
In Part 1 of The Immortal Life of Henrietta Lacks, Skloot seeks to engage the reader's sympathy for Henrietta Lacks and her family by describing her background and her death from cancer.
This thesis statement would allow you to explore this aspect of the book and develop the ways in which Skloot seeks to present Henrietta's life in ways that will allow us to feel sympathy for her as a human, rather than just a bunch of disembodied cancer cells. In many ways this first part of the book is the most important, as Skloot uses it to reclaim Henrietta Lacks as a warm-blooded human just like us.