Answer:

The time for suhoor ends with the arrival of dawn. As Allah says in the Qur’an: “Eat and drink until the white thread of dawn becomes distinct from the black thread [of night]. Then complete the fast until nightfall.” (Qur’an 2:187) 

If one wakes up late and misses suhoor, they must still refrain from eating or drinking for the remainder of the day until sunset. Consuming anything during the fasting hours will invalidate the fast.