I have a biology test tomorrow and I'm getting really confused
How can sex cells undergo meiosis if there are no pairs?
And also does each pair of chromosomes in a normal body cell undergo mitosis?
And also are there still 46 chromosomes in sex cells or are there 23? and of these chromosomes are there still sex chromosomes in a pair? And what do the sex chromosomes have to do with the sex cells?
Sorry for all these questions but I'm super confused and any help would be appreciated :)
thanks!
How can sex cells undergo meiosis if there are no pairs?
And also does each pair of chromosomes in a normal body cell undergo mitosis?
And also are there still 46 chromosomes in sex cells or are there 23? and of these chromosomes are there still sex chromosomes in a pair? And what do the sex chromosomes have to do with the sex cells?
Sorry for all these questions but I'm super confused and any help would be appreciated :)
thanks!
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Sex cells are the product of meiosis, therefore, they do not undergo meiosis themselves. A typical body cell carries two copies of each of the 23 human chromosomes, also referred to as a diploid cell, and therefore has 46 total chromosomes (23*2=46). But a sex cell only carries a single copy of each chromosome, which means they only have 23 chromosomes. When two sex cells come together, such as a sperm and an egg, a cell containing 46 chromosomes is created (23 chromosomes from the sperm and 23 chromosomes from the egg).
Chromosomes in body cells do not individually undergo mitosis; cells containing chromosomes do. Instead, 23 pairs of chromosomes (46 total chromosomes) are replicated (copied) and pulled apart in mitosis of body cells, resulting in two daughter cells that each contain 46 chromosomes.
Sex chromosomes have no pairs. Sex cells contain 23 chromosomes, not 46, because they have to join together to form a body cell. When two sex cells fuse, the 23 from one are introduced to the 23 from the other, resulting in the development of a 46 chromosomed body cell.
The only relationship between sex cells and sex chromosomes is that the sex chromosomes are within the sex cells. Sex chromosomes are the X and Y chromosomes that are found in some species. In humans, the sex chromosomes are the 23rd pair of chromosomes. An X chromosome is found in both males and females. But the Y chromosome is only found in males. When an X from one sex cell combines with the X of another sex cell, the result is an XX chromosome pair and the offspring is a female. If the offspring is XY, it is male.
Chromosomes in body cells do not individually undergo mitosis; cells containing chromosomes do. Instead, 23 pairs of chromosomes (46 total chromosomes) are replicated (copied) and pulled apart in mitosis of body cells, resulting in two daughter cells that each contain 46 chromosomes.
Sex chromosomes have no pairs. Sex cells contain 23 chromosomes, not 46, because they have to join together to form a body cell. When two sex cells fuse, the 23 from one are introduced to the 23 from the other, resulting in the development of a 46 chromosomed body cell.
The only relationship between sex cells and sex chromosomes is that the sex chromosomes are within the sex cells. Sex chromosomes are the X and Y chromosomes that are found in some species. In humans, the sex chromosomes are the 23rd pair of chromosomes. An X chromosome is found in both males and females. But the Y chromosome is only found in males. When an X from one sex cell combines with the X of another sex cell, the result is an XX chromosome pair and the offspring is a female. If the offspring is XY, it is male.
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Human sex cells have 23 chromosomes. Male sex cells have either an X or a Y chromosome, female sex cells have an X chromosome. When fertilisation occurs, the resulting (normal) zygote will have either two X (female), or both X and Y (male), chromosomes.
Meiosis is explained in detail here:
http://biology.about.com/od/meiosis/ss/m…
Meiosis is explained in detail here:
http://biology.about.com/od/meiosis/ss/m…