Why do chromosomes become condensed?
Why do chromosomes become condensed?
Heterochromatin is transcriptionally inactive and contains highly repeated DNA sequences, such as those present at centromeres and telomeres. As cells enter mitosis, their chromosomes become highly condensed so that they can be distributed to daughter cells.
Why are chromosomes condensed in mitosis?
Although chromatin changes are already detectable before nuclear envelope breakdown, this leads to further chromatin condensation and allows assembly of the mitotic spindle, which will capture, move and align the individualized chromosomes at the metaphase plate and segregate the disengaged chromatids.
Why does DNA condense into chromosomes during cell division?
Why does the DNA condense into chromosomes during cell division? By condensing DNA into chromosomes, cells can align each chromosome (or during meiosis, each tetrad), along the metaphase plate. The spindle fibers can then pull apart sister chromatids (in Mitosis) or homologous chromosomes (Meiosis I).
What happens with more than 46 chromosomes?
A gain or loss in the number of chromosomes from the normal 46 is called aneuploidy. A common form of aneuploidy is trisomy, or the presence of an extra chromosome in cells. “Tri-” is Greek for “three”; people with trisomy have three copies of a particular chromosome in cells instead of the normal two copies.
What is difference between gene chromosome and DNA?
Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are structures within cells that contain a person’s genes. Genes are contained in chromosomes, which are in the cell nucleus.
Does DNA mean life?
I like to think of DNA as the code for the expression of life. But this definition implies that life is more than what is coded by DNA, so here is a more objective definition: Deoxyribonucleic acid, better known as DNA, is a molecule that encodes all genetic information of life.
Is human DNA a code?
Nearly every cell in a person’s body has the same DNA. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people.