This video shows the growth and reproduction of a mustard plant, Brassica rapa, sped up 12,000 times. The seeds of flowering plants contain a young embryo and stored food to fuel the early stages of growth. In Brassica rapa seeds, the food is stored in two cotyledons, or "seed leaves," which emerge first from the ground and quickly become photosynthetic. As growth progresses, the stem elongates and more leaves are produced. The appearance of flower buds signifies that the plant is about to engage in sexual reproduction. Meiosis produces two types of spores within the flower: microspores are produced in the anther sacs, and megaspores are formed in structures called ovules. Ovules are found inside the base of the carpel in a region called the ovary. Both the microspores and megaspores undergo mitotic cell divisions to produce small, multicellular organisms called gametophytes. The microspores develop into pollen grains, each containing a male gametophyte, whereas the megaspores develop into female gametophytes. At maturity the male gametophyte produces two sperm cells, and the female gametophyte produces one egg cell. Pollination occurs when some agent moves pollen grains from the anther to the stigma. In this video, a small black brush is the pollinator. Now the sperm from a pollen grain can reach the egg cell through a pollen tube that is produced by the pollen grain, allowing double fertilization to occur. One sperm combines with two nuclei called the polar nuclei in the female gametophyte, forming a triploid nucleus that gives rise to a transient storage tissue in the seed called the endosperm. In Brassica rapa, the developing embryo of the maturing seed consumes nearly all of the energy stored in the endosperm. The other sperm combines with the egg cell of the female gametophyte, forming a zygote that in turn will form the seed embryo by mitosis. As the seeds develop, the ovary enlarges to form a fruit that protects the developing seeds. During fruit enlargement, the petals fall off and the stamens wither. In annual plants, such as Brassica rapa, the energy of the entire plant is diverted to the developing fruits and seeds, and the plant turns brown. After the fruits turn brown and dry out, they split open and release the seeds. Credit: Courtesy of Graham R. Kent and Rebecca L. Turner, Smith College.
Table of contents
- 1. Introduction to Biology2h 40m
- 2. Chemistry3h 40m
- 3. Water1h 26m
- 4. Biomolecules2h 23m
- 5. Cell Components2h 26m
- 6. The Membrane2h 31m
- 7. Energy and Metabolism2h 0m
- 8. Respiration2h 40m
- 9. Photosynthesis2h 49m
- 10. Cell Signaling59m
- 11. Cell Division2h 47m
- 12. Meiosis2h 0m
- 13. Mendelian Genetics4h 41m
- Introduction to Mendel's Experiments7m
- Genotype vs. Phenotype17m
- Punnett Squares13m
- Mendel's Experiments26m
- Mendel's Laws18m
- Monohybrid Crosses16m
- Test Crosses14m
- Dihybrid Crosses20m
- Punnett Square Probability26m
- Incomplete Dominance vs. Codominance20m
- Epistasis7m
- Non-Mendelian Genetics12m
- Pedigrees6m
- Autosomal Inheritance21m
- Sex-Linked Inheritance43m
- X-Inactivation9m
- 14. DNA Synthesis2h 27m
- 15. Gene Expression3h 20m
- 16. Regulation of Expression3h 31m
- Introduction to Regulation of Gene Expression13m
- Prokaryotic Gene Regulation via Operons27m
- The Lac Operon21m
- Glucose's Impact on Lac Operon25m
- The Trp Operon20m
- Review of the Lac Operon & Trp Operon11m
- Introduction to Eukaryotic Gene Regulation9m
- Eukaryotic Chromatin Modifications16m
- Eukaryotic Transcriptional Control22m
- Eukaryotic Post-Transcriptional Regulation28m
- Eukaryotic Post-Translational Regulation13m
- 17. Viruses37m
- 18. Biotechnology2h 58m
- 19. Genomics17m
- 20. Development1h 5m
- 21. Evolution3h 1m
- 22. Evolution of Populations3h 52m
- 23. Speciation1h 37m
- 24. History of Life on Earth2h 6m
- 25. Phylogeny2h 31m
- 26. Prokaryotes4h 59m
- 27. Protists1h 12m
- 28. Plants1h 22m
- 29. Fungi36m
- 30. Overview of Animals34m
- 31. Invertebrates1h 2m
- 32. Vertebrates50m
- 33. Plant Anatomy1h 3m
- 34. Vascular Plant Transport2m
- 35. Soil37m
- 36. Plant Reproduction47m
- 37. Plant Sensation and Response1h 9m
- 38. Animal Form and Function1h 19m
- 39. Digestive System10m
- 40. Circulatory System1h 57m
- 41. Immune System1h 12m
- 42. Osmoregulation and Excretion50m
- 43. Endocrine System4m
- 44. Animal Reproduction2m
- 45. Nervous System55m
- 46. Sensory Systems46m
- 47. Muscle Systems23m
- 48. Ecology3h 11m
- Introduction to Ecology20m
- Biogeography14m
- Earth's Climate Patterns50m
- Introduction to Terrestrial Biomes10m
- Terrestrial Biomes: Near Equator13m
- Terrestrial Biomes: Temperate Regions10m
- Terrestrial Biomes: Northern Regions15m
- Introduction to Aquatic Biomes27m
- Freshwater Aquatic Biomes14m
- Marine Aquatic Biomes13m
- 49. Animal Behavior28m
- 50. Population Ecology3h 41m
- Introduction to Population Ecology28m
- Population Sampling Methods23m
- Life History12m
- Population Demography17m
- Factors Limiting Population Growth14m
- Introduction to Population Growth Models22m
- Linear Population Growth6m
- Exponential Population Growth29m
- Logistic Population Growth32m
- r/K Selection10m
- The Human Population22m
- 51. Community Ecology2h 46m
- Introduction to Community Ecology2m
- Introduction to Community Interactions9m
- Community Interactions: Competition (-/-)38m
- Community Interactions: Exploitation (+/-)23m
- Community Interactions: Mutualism (+/+) & Commensalism (+/0)9m
- Community Structure35m
- Community Dynamics26m
- Geographic Impact on Communities21m
- 52. Ecosystems2h 36m
- 53. Conservation Biology24m
27. Protists
Protist Life Cycles
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