AP BIOLOGY

Detailed explanation-1: -Ras activates several pathways, including the RAF-MEK-ERK/MAPK cascade, which transmits signals downstream and results in the transcription of genes involved in controlling several cellular mechanisms. The Ras family members are anchored to the cytoplasmic side of the plasma membrane by carboxyl-terminal farnesylation.

Detailed explanation-2: -GEFs stimulate the GDP for GTP exchange on Ras, which allows Ras to interact with the mitogen-activated protein kinase kinase kinase (MAPKKK) known as Raf, promoting its activation and alleviating its inhibition by 14-3-3 proteins.

Detailed explanation-3: -The MAPK cascades are central signaling pathways that regulate a wide variety of stimulated cellular processes, including proliferation, differentiation, apoptosis and stress response.

Detailed explanation-4: -The RAS/MAP kinase signaling pathway. A growth factor binds to its cognate receptor tyrosine kinase (RTK), along with a transductive complex, which then activates RAS through an exchange of GTP for bound GDP. Active RAS then recruits inactive cytosolic BRAF to the membrane and activates BRAF.