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PART 3. GAMETOGENESIS and FERTILIZATION IN FLOWERING tree

Flower structure

As you know from researching plant life cycles, gamete production and also fertilization in flowering tree is quite various from those processes in animals. Us will begin with a quick look at flowers, the website of tree reproductive organs. Remember the flowers are component of the sporophyte generation and also will create spores by the process of meiosis.

You are watching: How do the sperm nuclei in a pollen grain reach the egg nucleus in an ovule

Review the structure of a typical flower and also be certain that you recognize the duty of each flower part. Observe the demonstrate of a huge flower and identify the sepals, petals, stamens, and also pistil.

Working in pairs, take it an Astromerias flower to your table and note that it has actually the exact same parts; castle are simply smaller. Then closely remove a stamen and also the pistil. Location them under the flex camera and capture an image. Label the anther that the stamen. Label the stigma and ovary the the pistil. Send to WebAssign because that question 15. After you have actually your picture, usage a razor blade to reduced open the ovary and also observe the small ovules within it.

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As you examine this flower, note that the reminder of the stamens are dubbed anthers (where pollen is produced), and the pointer of the pistil is referred to as a stigma (where pollen grains land prior to fertilization). The pollen grains then kind tubes that grow down the pistil and also enter the ovary. 2 haploid (sperm) nuclei move down the the tube to reach the ovules within the ovary wherein fertilization occurs. If fertilized, the ovules build into seeds.

Pollen grains and fertilization

At the start of the class, her TA put some pollen seed in a sugar solution to see if castle would grow pollen tubes. Check the demonstration regularly to see if pollen tubes room growing.

Observe these scanning electron micrographs because that a high magnification watch of genuine pollen grains. Keep in mind the differences in surface framework which permits the plant types to be identified. Maturation pollen grains space released come the surface of the anther wherein they space picked increase by pollinators (mainly insects) or by the wind. If a pollen serial lands on the stigma the a flower, a pollen tube forms, grows down the pistil, and enters an ovule. Watch these measures in the micrographs and video below.


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Anthers bearing mature pollen grains difficult stigma of a pistil where pollen grains will certainly land Pollen tube (aqua) cultivation into ovaries to reach the ovules within

video - growth of the pollen tube

Now that you have actually seen examples of pollen grains and pollen tubes, check out the following slide. Capture picture at ideal magnification and label a pollen grain, pollen tube, and also sperm nucleus. Submit your labeled image to WebAssign for inquiry 16.

slide - pollen regarded by digital microscopy when a pollen pipe reaches the ovule, that delivers the two sperm nuclei, one of which will fertilize the egg nucleus of the embryo sac within the ovule. The various other sperm nucleus will certainly fuse through the" polar nuclei" that the embryo sac to kind the endosperm nucleus i beg your pardon is triploid. Check out the following animation which illustrates this process.

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animation - double fertilization

After fertilization has occurred, the fertilized egg nucleus (zygote) establishes into one embryo, the endosperm grows and also stores food because that future use by the embryo, and the coverings that the ovule end up being the seed coat. For this reason the ovule develops into a seed after double fertilization occurs.


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Each ovule in ~ the ovary of this flower has a zygote i beg your pardon will develop into one embryo. Endosperm cell within the ovule will certainly accumulate nutrients for use by the embryo together it grows. Once nutrient warehouse is complete, a fibrous coat will form around each ovule. The ovules will then it is in seeds.

Meanwhile, the surrounding ovary creates into a fruit i m sorry aids in seeds dispersal. When you know the whole story the gametogenesis and also fertilization in flowering plants, prize question 17.