Y chromosome

Y chromosome,

n a sex chromosome that in humans and many other species is present only in the male, appearing singly in the normal male. It is carried as a sex determinant by one half of the male gametes. None of the female gametes contain a Y chromosome.

yawn,

n an involuntary act of opening the oral cavity wide and taking a deep breath. It tends to occur when a person is bored, drowsy, or depressed and may be accompanied by upper body movements to aid chest expansion.

yaws

n a disease caused by
T. pertenue. It occurs in hot regions; raspberry-like excrescences occur on the hands, face, feet, and external genitalia.

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Y chromosome

the chromosome which causes the medulla of the embryonic gonad to form a testis. If there is one other chromosome present and it is X the newborn animal will be a fertile male. If there are two other X chromosomes, giving an XXY configuration, it will be a phenotypic male but sterile. Autosomal genes can have the same effect, creating an intersex newborn in an animal with XX chromosomes.