"I am a German and a Turk."
Translation:Ich bin Deutscher und Türke.
In German language a male German is "Deutscher" and a male Turk (or as you said Turkish) is "Türke". This is only part of the word and not a declination. A Turkish woman is a "Türkin". Also, the country is one of the few countries that has a definite article: "die Türkei"