Zygotes are the basis of new developing organisms, and they play an important role in the reproductive process. The zygote is formed by the union of two gametes. It is the first cell that begins to divide and specialize to create an offspring. Whether in plants or animals, the zygote serves the same function and develops in a similar manner.
How Zygotes Form
The zygote that forms after fertilization contains two sets of chromosomes, each of which comes from one of its two parents. This cell is also called a diploid, and is represented by a distinct diploid number. The diploid number indicates the number of chromosomes the cell has. For example, a pea contains 14 chromosomes and has the diploid number 14. A potato's diploid number is 24. The diploid number of corn is 20.
New Cell Creation
The zygote exists within a dormant seed, which will grow when soil, water and light conditions trigger cell division. The single-celled zygote quickly divides to form two new cells, each an equal copy of the other. The nuclei of each new cell contains the same number of chromosomes. These two cells each divide again, creating four identical cells. The process of cell division continues and the zygote becomes a plant embryo, which continues to transform as it breaks free from the seed coat and grows toward adulthood.
Growing Into a Fully Develooped Plant
As the embryonic plant develops, its cells begin to adopt specialized functions. This process is known as differentiation, and is responsible for creating the different parts of the plant as it grows. The development of roots, a stem, leaves and the xylem and phloem cells, which act as the plant's circulatory system, occurs during this time. Throughout this process, the plant's cells all contain the same number of chromosomes as did the original zygote. In the case of the pea plant, there are 14 chromosomes derived equally from each parent.
The Creation of New Zygotes
Adult male plants germinate pollen grains, which are then transported by wind or animals to other plants. During pollination, the male sex germ from the pollen grain comes into contact with the female ovule, where its genetic material combines with the female sex germ. This results in fertilization, which creates new zygotes. Each new zygote gets half of its genetic material from each parent and, within the seed casing, is then disbursed into the environment to begin the cycle again.