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The XX/XY sex-determination system is the most familiar, as it is found in humans. The XX/XY system is found in most other mammals, as well as some insects. In this system, females have two of the same kind of sex chromosome (XX), while males have two distinct sex chromosomes (XY).
In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively. Hormone levels in the male parent affect the sex ratio of sperm in humans. [25]
In the domesticated papaya (Carica papaya), three sex chromosomes are present, denoted as X, Y and Y h. This corresponds with three sexes: females with XX chromosomes, males with XY, and hermaphrodites with XY h. The hermaphrodite sex is estimated to have arisen only 4000 years ago, post-domestication of the plant.
In the absence of a Y chromosome, the fetus will undergo female development. This is because of the presence of the sex-determining region of the Y chromosome, also known as the SRY gene. [5] Thus, male mammals typically have an X and a Y chromosome (XY), while female mammals typically have two X chromosomes (XX).
The degree to which individuals with XX male syndrome develop the male phenotype is variable, even among SRY-positive individuals. [21] Masculinization of SRY-positive XX males is believed to be dependent on which X chromosome is made inactivate. Typical XX females undergo X inactivation during which one copy of the X chromosome is silenced. It ...
When an egg and sperm fuse at fertilization, the two sets of chromosomes come together to form a unique diploid individual with 46 chromosomes. [2] The sex chromosome in a human egg is always an X chromosome since a female only has X sex chromosomes. In sperm, about half the sperm have an X chromosome and half have a Y chromosome. [2]
Individuals can either have sex chromosomes generally linked with being female (XX chromosomes) or usually associated with being a man (XY chromosomes), yet have reproductive organs and genitals ...
XXYY syndrome is a sex chromosome anomaly in which males have two extra chromosomes, one X and one Y chromosome. Human cells usually contain two sex chromosomes, one from the mother and one from the father. Usually, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY).