Why do we need to study molecular biology? What is the application of cell biology and genetics?

Question

anonymous · Answer

Imagine two cells on their "cell phones." What would they "talk" about? They might chat about how things were growing, or what they did at the gene pool last night, or how their new metabolism diet was going. Molecular biology is all about how organisms function and communicate at the cellular level. Chains of molecules regulate everything a cell does, from how it behaves to how it responds to stimuli and grows. 
Genetics and cell biology is the science of heredity. It is studied at the level of whole organisms (classical or transmission genetics), the DNA itself (molecular genetics), or whole populations (population and evolutionary genetics).
Geneticists use molecular approaches to investigate how genes determine physical traits, including susceptibility to diseases and inherited disorders. Cell biology focuses on the structure and function of the components of living cells (such as the cell membrane, the flagella responsible for cell movements, cell differentiation in developing organisms, abnormal cell division, and metabolic interactions between cell compartments).

anonymous · Answer

then how does molecular biology related to epigenetics and genome wide association studies?

anonymous · Answer

Epigenetics gives our bodies the ability to influence which genes will be turned on - or expressed - or off, or partially on, depending on our immediate environment. GWAS examinines common genetic variations. All of these relate to microbiology in the factbthat everything happens in the cell then is expressed outward. From what our body chooses to take in or process, happens on a molecular level and its what shows that is our genetics

anonymous · Answer

Then, is genetics related to molecular biology?