Males have how many chromosomes

So, mitochondrial DNA is always inherited from the female parent. In humans, a few conditions, including some forms of hearing impairment and diabetes, have been associated with DNA found in the mitochondria. Yes, they differ in a pair of chromosomes known as the sex chromosomes. Females have two X chromosomes in their cells, while males have one X and one Y chromosome.

Inheriting too many or not enough copies of sex chromosomes can lead to serious problems. For example, females who have extra copies of the X chromosome are usually taller than average and some have mental retardation. Males with more than one X chromosome have Klinefelter syndrome, which is a condition characterized by tall stature and, often, impaired fertility.

Another syndrome caused by imbalance in the number of sex chromosomes is Turner syndrome. Women with Turner have one X chromosome only. They are very short, usually do not undergo puberty and some may have kidney or heart problems. Scientists looking at cells under the microscope first observed chromosomes in the late s. However, at the time, the nature and function of these cell structures were unclear. Researchers gained a much better understanding of chromosomes in the early s through Thomas Hunt Morgan's pioneering studies.

Morgan made the link between chromosomes and inherited traits by demonstrating that the X chromosome is related to gender and eye color in fruit flies. Chromosomes Fact Sheet. What is a chromosome? What do chromosomes do? Do all living things have the same types of chromosomes? What are centromeres? What are telomeres? How many chromosomes do humans have? Humans have 23 pairs of chromosomes, for a total of 46 chromosomes. How are chromosomes inherited? Do males have different chromosomes than females?

The twenty third pair is called the sex chromosomes, while the rest of the 22 pairs are called autosomes. Typically, biologically male individuals have one X and one Y chromosome XY while those who are biologically female have two X chromosomes.

However, there are exceptions to this rule. The sex chromosomes determine the sex of offspring. The father can contribute an X or a Y chromosome, while the mother always contributes an X. The Y chromosome is one-third the size of the X chromosome and contains about 55 genes while the X chromosome has about genes.

In genealogy, the male lineage is often traced using the Y chromosome because it is only passed down from the father. All individuals carrying a Y chromosome are related through a single XY ancestor who likely lived around , years ago.

The X chromosome is significantly longer than the Y chromosome and contains hundreds more genes. Because the additional genes in the X chromosome have no counterpart in the Y chromosome, the X genes are dominant. This means that almost any gene on the X, even if it is recessive in the female, will be expressed in males.

These are referred to as X-linked genes. Genes found only on the Y chromosome are referred to as Y-linked genes, and expressed only in males. Genes on either sex chromosome can be called sex-linked genes. There are approximately 1, X-linked genes, though most of them are not for female anatomical characteristics.

In fact, many are linked to disorders such as hemophilia, Duchenne muscular dystrophy, fragile-X syndrome and several others. They are responsible for red-green color blindness, considered the most common genetic disorder and found most often in males. The non-sex feature X-linked genes are also responsible for male pattern baldness. In contrast to the large X chromosome, the Y chromosome contains only 26 genes. Sixteen of these genes are responsible for cell maintenance.

Nine are involved in sperm production, and if some are missing or defective, low sperm counts or infertility may occur. One gene, called the SRY gene, is responsible for male sexual traits. The SRY gene triggers the activation and regulation of another gene, found on a non-sex chromosome, called the Sox9. The Sox9 triggers the development of non-sexed gonads into testes instead of ovaries. Abnormalities in the sex chromosome combination can result in a variety of gender-specific conditions that are rarely lethal.