Can haploid daughter cells divide again

Cell division

When cells divide, both daughter cells should contain exactly the same genetic information as the mother cell. In order for this to work, the chromosomes must first be doubled.

We have seen that only certain bases can pair with each other in a double strand of DNA. Even if only one strand of DNA is known, this tells us what the opposite strand should look like. It is precisely this fact that is important in the duplication (replication) of the DNA. It begins with the separation of the double strand into two individual strands.

Now enzymes can attach exactly the right bases and thus create two new double strands. Whenever the enzymes recognize adenine, they add thymine on the opposite side. With cytosine, on the other hand, guanine is built in, and so on. The two strands of DNA that are created in this way are called sister chromatids. Actually, they are even "Siaemesian twin chromatids" because they are like one egg to another and are even connected to one another at the centromere. The phase of the cell cycle when DNA is duplicated becomes Interphase Mitosis - make two out of one


Mitosis - make two out of one

Mitosis, the actual division of the nucleus, follows the interphase. So that the long DNA threads do not break, they are first condensed (compressed). The chromosomes can then be seen under the microscope as x-shaped structures. The center of the X is the centromere. Next, the chromosomes accumulate in the equatorial plane, i.e. in the middle of the cell nucleus. Long thin threads, called spindle fibers, attack the centromeres and tear the sister chromatids apart. One chromatid from each chromosome is drawn to one of the cell poles. There the chromosomes are decondensed (unpacked) again and a new nuclear membrane is formed. The cell then divides.


Meiosis - a special type of cell division

In the case of sexual reproduction, the parents pass on genetic information (chromosomes) to their children. So that the number of chromosomes does not double with each new generation, germ cells are formed that only have half the chromosome set. Most organisms are diploid and their germ cells are therefore haploid. The process of germ cell formation is called meiosis.

In meiosis, the condensed chromosomes arrange themselves in pairs in the equatorial plane. One paternal and one maternal chromosome are next to each other. As in mitosis, spindle fibers attack the centromeres. Instead of individual chromatids, whole chromosomes are drawn to the two cell poles. Cell division then takes place as described above.

Only after the first division are the chromosomes broken down into their two sister chromatids and the cells divide again. Four haploid germ cells have developed from one diploid cell, the genetic information of which happens to be composed of maternal and paternal components.