In this video, we're going to talk about the second step of transcription, which is the elongation of transcription. Elongation is really just a word that means to elongate or make something longer, and the 'something' that's being made longer is the RNA itself. Elongation is the process where the RNA polymerase enzyme is building, synthesizing, or elongating an RNA molecule. It does this by base pairing free RNA nucleotides that are floating around in the cell with the DNA template. By the end of the process, the RNA molecule that's being built will carry the message that's encoded by the DNA. The RNA polymerase enzyme, which is the primary enzyme involved in transcription, will continue to move across the gene, unwinding the DNA as it moves and building the RNA in the 5' to 3' direction of the RNA. If we look at our image below at the elongation of transcription, the RNA polymerase has unwound the DNA. You can see that the DNA on the inside is unwound, and it's beginning to elongate or build that RNA molecule. By pairing free RNA nucleotides, these little squares floating in the cell, the RNA polymerase incorporates them into this growing RNA strand by pairing these RNA nucleotides with the DNA template strand. The RNA polymerase is transcribing in the direction towards the right. It will continue to transcribe the coding sequence, representing the process of elongation. During this process, the mRNA molecule is growing; it is elongating from its 5' end to its 3' end. The RNA polymerase will continue to elongate in this direction, transcribing the gene until it reaches the terminator sequence at the end. We will talk more about this termination process in our next video. It is important to note that in eukaryotic organisms, the RNA that is first transcribed is not the final RNA. Instead, it's a premature RNA or just a pre-mRNA. We will discuss pre-mRNA later in our course. It is also interesting to note that a single gene can actually be transcribed simultaneously by several RNA polymerases to make more RNA if needed. While this mRNA is being built by this RNA polymerase, it is possible for a second RNA polymerase to come and bind to the promoter and transcribe this gene simultaneously where there are multiple RNA molecules being built simultaneously from the same gene. This concludes our brief introduction to the elongation of transcription. In our next video, we'll talk about the third and final step of transcription, which is the termination of transcription. I'll see you all there.
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
15. Gene Expression
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