This is a debatable issue. Some argue that it is a distinct sound while others argue that it is not. But many agree that it has the function of lengthening the vowel preceding it. The difference between the members of the pairs such as ‘ada-ağda’, ‘tura-tuğra’, ‘yama-yağma’, etc., is the length of the vowels preceding ‘ğ ’. Thus, ‘ğ’ is not treated as a distinct consonant here.