Thipsuda and Georgianna,

Your summary about Alfredo is accurate and informative. I suggest you put the main idea in the first sentence. The main idea is not that he is from Mexico. The main idea is your second sentence, It should be the first sentence.

The sentences are correct except for this one.

"He was unable to provide for his family too like his father and made the decision to head north."

Correct:  He was unable to provide for his family like his father and made the decision to head north.

In the last paragraph, attended should be past tense. 

      Mr. Alfredo Quinones is from Mexico. He is a neurosurgeon  and professor at John Hopkins University, and a researcher who is looking for a breakthrough in the treatment of brain cancer.

      His life started in Mexico. When he was 5 years old he was working at his father 's gas station. When the Mexico's economy collapsed his father could no longer keep food on the table for the family ,but he continued his schooling and became a teacher by the time he was 18; he was unable to provide for his family too like his father and made the decision to head north.

      He hopped a border fence from Mexico into the United States and became a migrant farm-worker. He picked cotton , tomatoes and cantaloupes, and lived in the fields in a broken-down camper. When his cousin told him he would be a farm-worker for the rest of his life , he realized he have to move on.

     He did English classes at a community college and he attend the University of California, Berkeley. At Berkeley he went there with a scholarship. He went on to Harvard Medical School. By that time he received his U.S. citizenship.