AP BIOLOGY

Detailed explanation-1: -Often, proto-oncogenes encode proteins that function to stimulate cell division, inhibit cell differentiation, and halt cell death. All of these processes are important for normal human development and for the maintenance of tissues and organs.

Detailed explanation-2: -The central machines that drive cell cycle progression are the cyclin-dependent kinases (CDKs). These are serine/threonine protein kinases that phosphorylate key substrates to promote DNA synthesis and mitotic progression.

Detailed explanation-3: -Proto-oncogenes are normal cellular genes that regulate cell growth and differentiation. They often encode products such as growth factors and their receptors, cell cycle regulators, DNA-binding proteins, transcription factors, protein kinases involved in signal transduction, and others.

Detailed explanation-4: -These normal cellular genes (proto-oncogenes) are involved in the regulation of proliferation and differentiation. However, if mutated, proto-oncogenes have the potential for inducing neoplastic transformation.

Detailed explanation-5: -A mutated (changed) form of a type of gene called a proto-oncogene, which is involved in normal cell growth and division. When a proto-oncogene is changed so that too many copies are made or it becomes more active than normal, it is called an oncogene.