Will chromosomes change?

We have learned about chromosomes since we started learning biology in junior high school. In high school, we will know more about the various changes in chromosomes. Many genetic diseases are caused by chromosome changes. Chromosome changes are divided into two types: ploidy and aneuploidy. This distinction mainly depends on whether the organism's cells contain a nucleus. The following article introduces the relevant content about the changes in dyeing characteristics. Those who are interested or do not understand can take a look.

Chromosome changes can be divided into two categories: ploidy changes and aneuploidy changes. The number of chromosomes in various organisms is constant. Except for prokaryotes such as bacteria and cyanobacteria, most eukaryotic organisms undergo "meiosis" when their somatic cells produce reproductive cells (gametes), which is cell division in which the number of chromosomes is halved.

Chromosome changes can be divided into two categories: ploidy changes and aneuploidy changes. The number of chromosomes in various organisms is constant. Except for prokaryotes such as bacteria and cyanobacteria, most eukaryotic organisms undergo "meiosis" when their somatic cells produce reproductive cells (gametes), which is cell division in which the number of chromosomes is halved.

Therefore, the number of chromosomes in the somatic cells of general organisms is twice the number of chromosomes in the reproductive cells, which is called "diploid". In genetics, all the chromosomes contained in reproductive cells are called a "chromosome set." The number of chromosome sets in somatic cells changes, which is called ploidy change. For example, somatic cells contain only one set of chromosomes and are called "haploid".

The drones of honey bees are haploid. For plants, anther culture can be used to obtain haploid plants. The haploid is then treated with colchicine to induce chromosome doubling and become diploid again. Anther culture method is mainly used for offspring cultivation in plant hybrid breeding. The first generation of hybrids is first cultivated into haploids and then induced to double. All of its genes are homozygous, and its offspring no longer undergo Mendelian trait separation. The genetics can be quickly stabilized and become a new variety.

When the chromosomes of a diploid are induced to double, it becomes a "tetraploid". Tetraploid plants generally have thick stems, large leaves, large flowers and large fruits, and are quite valuable in production practice. However, tetraploid plants have few seeds and are not suitable for crops that use seeds (such as cereals).

The hybridization of diploid and tetraploid can produce "triploid". The meiosis of triploids is abnormal and they cannot produce seeds. Seedless watermelon is a triploid obtained by hybridization in this way. Bananas are naturally occurring triploids (their ancestors may also be the result of a hybridization between diploids and tetraploids).

Structural changes in chromosomes include deletions, duplications, inversions, and translocations. As shown in the figure on the right, 1. Deletion (the segment shown in yellow in the middle is missing); 2. Duplication (the segment shown in red in the middle is repeated); 3. Inversion (the segments shown in green and red are inverted 180°); 4. Translocation (the blue segment of the shorter chromosome below is transferred to the longer chromosome above). Many human genetic diseases are caused by structural changes in chromosomes.