Please answer the following question: Answer the following question given this paragraph: Each endocrine hormone affects only certain cells, called target cells. A target cell has proteins on its surface to which a given hormone can bind. Most endocrine hormones are controlled by negative feedback loops. Negative feedback occurs when low levels of a hormone feed back to increase its secretionand vice versa. Q: Each endocrine hormone affects only certain "target" cells, which have molecules of what on the surface that enable binding of a given hormone? Choices: - lipids - rna - gas - protein A:
A:
protein