What are the penguin parts of the body?

For starters, a penguins wings are not big enough to support the body mass of the Penguin, thus not allowing it to fly. These wings do make great flippers, though

In regards to the penguin's skeleton: Unlike the majority of other birds, penguins do not have hollow bones, so are much heavier and harder to support with their small wings. The solid, as opposed to hollow, bones act as ballast to help them dive. Also, being solid, they are less prone to breakage from the stresses of swimming. Some (but not all) flying birds have hollow bones to be lighter.