What is a gene? What is an allele? What is a genetic trait?

What is a gene? What is an allele? What is a genetic trait?
What is the structure and function of a chromosome?
How does chemotherapy work in treating ALL and what are some common chemotherapy drugs used?
How is DNA structured? What are bases? What is a sequence?
What is the significance of minimal residual disease and guiding ALL treatment decision?
When is a stem cell transplant considered for ALL, and what factors determine that decision?
How is the central nervous system (CNS) protected during ALL treatment?
How do clinical trials contribute to advance ALL treatments and how can patients find clinical trial opportunities?
What are the main treatment phases for ALL and what's the goal of each?