Double Fertilization Animation

✔ https://HomeworkClinic.com ✔ https://Videos.HomeworkClinic.com ✔ Ask questions here: https://HomeworkClinic.com/Ask Follow us: ▶ Facebook: https://www.facebook.com/HomeworkClinic ▶ Review Us: https://trustpilot.com/review/homeworkclinic.com Flowering plants undergo an Xx unusual reproductive process in which there are two fertilization events, rather than just one. This double fertilization takes place between cells produced in the male reproductive organs (the anthers) and the female reproductive organ (the ovule). The ovule contains a reproductive cell called the megaspore mother cell or megasporocyte. This cell is diploid (2n) and undergoes meiosis to produce four haploid (n) megaspores. In most species, three degenerate, leaving one surviving megaspore. The one surviving mega spore then undergoes three rounds of mitosis to produce eight haploid nuclei. Cytoplasmic divisions do not immediately follow the nuclear divisions, so the eight nuclei initially share the same cytoplasm. This multinucleate structure is called the embryo sac. Within the embryo sac, cell walls form between most of the nuclei. Three cells (antipodal cells) form opposite the micropyle opening of the ovule. Three also form near the micropyle; two are called synergids, and the other is the egg. Finally, two nuclei, called polar nuclei, remain together in one large central cell. The egg cell and the single cell with two polar nuclei will eventually take part in a double fertilization event. Before this can happen, the male gametes the sperm-must travel to these cells within the female's reproductive organs. To reach the embryo sac, a pollen grain that has landed on the stigma begins to germinate, sending a long pollen tube through the style and ovary. A haploid cell, called a generative cell, travels down the pollen tube. The generative cell travels behind the tube nucleus, which is the nucleus of the large cell that makes up the bulk of the pollen tube and grain. The generative cell divides by mitosis to produce two haploid sperm cells. The pollen tube reaches the micropyle of the ovule and digests its way into one of the synergids, releasing the sperm cells. The synergid degenerates as one of the two sperm cells fertilizes the egg cell, producing a diploid (2n) zygote. The second sperm cell fuses with both of the polar nuclei, fertilizing them to produce an unusual triploid (3n) cell. As the zygote develops into an embryo, the triploid cell develops into the endosperm, which serves as the embryo's food supply. Double fertilization, in which a diploid zygote and a triploid endosperm form, is a characteristic unique to angiosperms (flowering plants). Gymnosperms (such as pines), nonseed tracheophytes (such as ferns), and nontracheophytes (such as mosses) lack this double fertilization event. After the endosperm is formed, large amounts of nutrients are moved from other parts of the plant to this tissue, allowing the endosperm to stockpile starch, proteins, and lipids. The endosperm provides the embryo with these nutrients during early development. In many flowering plants, the nutrients of the endosperm are transferred to the developing plant's embryonic leaves, called cotyledons. Either the endosperm or the cotyledons then provide the necessary nutrients to the young plant when it first germinates into a seedling. After germination, the plant's leaves begin photosynthesis, providing the seedling with its own energy source.