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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]
Most mammals, including humans, have an XY sex-determination system: the Y chromosome carries factors responsible for triggering male development. 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]
G-banding, G banding or Giemsa banding is a technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes. It is the most common chromosome banding method. [1] It is useful for identifying genetic diseases (mainly chromosomal abnormalities) through the photographic representation of the entire chromosome ...
The X and Y sex chromosomes are different in shape and size from each other, unlike the rest of the chromosomes , and are sometimes called allosomes. In some species, such as humans, organisms remain sex indifferent for a time during development ( embryogenesis ); in others, however, such as fruit flies, sexual differentiation occurs as soon as ...
Sex linked diseases are passed down through families through one of the X or Y chromosomes. Since usually men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. Men and women can get the X-linked ones since both inherit X chromosomes. [22] An allele is either said to be dominant or recessive. Dominant inheritance occurs ...
The human brain. Differences in male and female brain size are relative to body size. [85] Early research into the differences between male and female brains showed that male brains are, on average, larger than female brains. This research was frequently cited to support the assertion that women are less intelligent than men.
In writing, the term "Determination of sex" peaked in usage around 1910. [5] [6] The term "sex determination" increased in usage after 1900. [7]In the 1960 and early 70's the term "sex assignment" came into prominent use as a colloquially word for "determination of sex" and "sex determination".
This represents the size of a composite genome based on data from multiple individuals but it is a good indication of the typical amount of DNA in a haploid set of chromosomes because the Y chromosome is quite small. [7] Most human cells are diploid so they contain twice as much DNA (~6.2 billion base pairs).