Metaphase 1

In the five phases of prophase 1, initially, the nuclear membrane has disappeared, the chromosomes have become chromosomes; a structure from the network-like structure attains a thin thread-like structure. Now, this phase is known as metaphase 1. A cell is performing different activities during this stage. In metaphase I, a similar type of activity will happen, as in the case of Mitosis. The only difference is in the case of Mitosis, there was a single chromosome. Here two pairs of chromosomes exist in metaphase I. These are known as homologous pairs of the chromosome which includes four chromatids. 

Meiosis 1 – Meiosis is the process of cell division in which four haploid cells are produced following two nuclear divisions of the replicated chromosomes. The haploid condition is called meiocytes. In the process of meiosis, homologous chromosomes undergo genetic recombination. An eye can be put on the process of meiosis I to understand that its generation takes place through crossing over. Meiosis is also called reductional division as it halves its number from diploids 2n to haploids n. 

Meiosis II- Interkinesis can be defined as the time gap that occurs between meiosis I and meiosis II. This phase is considered the short phase of the cell cycle. Aty this stage, no replication of DNA takes place. The synthesis phase is lacking during Meiosis II. During the Prophase I of meiosis I, recombination occurs, leading to the formation of non-identical chromosomes. During Meiosis II, two daughter cells are formed containing the haploid number of chromosomes themselves. 

Metaphase –

Metaphase can be described as the stage of cell division. Usually, the process of cell division takes place by mitosis or meiosis. In the nucleus, chromosomes present individually cannot be observed, but during metaphase, they become condensed by forming a compact, close structure and can be distinguished easily. At this time, they are aligned in the mid of the dividing cells. During karyotyping, the chromosomes present in metaphase are used to diagnose chromosomal abnormalities. Karyotyping can be defined as the process of identifying and observing chromosomes under a microscope. 

A list of pair of chromosomes of various living creatures are given below: 

1. Humans have 23 pairs of chromosomes. 
2. A cow has 30 pairs of chromosomes. 
3. E.coli has 04 pairs of chromosomes. 
4. Chimpanzees have 24 pairs of chromosomes. 

Metaphase I- Metaphase I of the cell cycle have a metaphase plate used for the alignment of four chromatids forming two chromosomes in a bivalent pair. Metaphase I in meiosis is different from the metaphase of mitosis. If we talk about the position in bivalents. It is found to be random means the parental homologs are located at one side, which signifies the daughter’s chances to inherit the 50-50 characters from both the parents (paternal and maternal) in the form of homologous chromosomes. 

Homologous chromosomes are those chromosomes that have the same origin. If we talk about the arrangement of bivalents, then it can be done in four different ways resulting in the differences in chromosome arrangement in the inherited daughter cells. In short, homologous chromosomes follow an independent assortment for the localisation of the metaphase plate. 

Metaphase II- Metaphase II is the phase in the Meiosis II stage. It is the step that highlights the compaction of chromosomes in a dense form, and during this phase, the movement of centrosomes takes place towards the polar regions of a cell. 

Significance of Meiosis and Meiosis-I 

• Production of gametes to carry out sexual reproduction. 
• Production of spores to carry out asexual reproduction in plants.
• Meiosis plays an important role in maintaining the number of chromosomes. 
• Meiosis of cell cycles is open access to the formation of new variations, which is important for improving races of plants and animals. 
• Sometimes abnormalities in meiosis lead to mutations which can be advantageous for living creatures. 
• Meiosis I is responsible for separating homologous chromosomes leading to reductional division. 
• In meiosis, I crossing over can form new combinations of genes. 
• Due to abnormal disjunction meiosis, I can cause mutations in chromosomes. 
• Meiosis I also induces the production of gametes for reproduction. 

Conclusion:

In eukaryotic organisms, the process of transfer of hereditary characteristics occurs through two processes – mitosis in which two daughter cells are formed after the division of the parent cell. After division, the daughter cells receive exact copies of their parental genetic material. It is also called an equational division because both parent and daughter cells contain an equal number of chromosomes and meiosis. Farmer and Moore discovered the term. 

In meiosis in this cell division, the number of chromosomes is reduced to haploid from diploid just after one round of the formation of exact copies of DNA. The process is replication. Meiosis I and Meiosis II are the two divisions of meiosis. After crossing over in meiosis I, a metaphase plate is formed in the centre of the cell during metaphase I.