Content Objective: Understand the key evidence supporting the endosymbiotic origin of mitochondria and chloroplasts, including the presence of 70S ribosomes, circular DNA, and independent replication. Explore how multicellularity evolved, focusing on its advantages, such as cell specialization and increased organism size.
Language Objective: Create detailed and labeled sketch notes to visually represent the key concepts of the endosymbiotic theory and the evolution of multicellularity. Use precise scientific terminology such as "70S ribosomes," "circular DNA," "cell specialization," and "multicellularity" to explain these concepts clearly in both visual and written descriptions.
Syllabus Details:
A2.2.12 - Origin of eukaryotic cells by endosymbiosis - "Evidence suggests that all eukaryotes evolved from a common unicellular ancestor that had a nucleus and reproduced sexually. Mitochondria then evolved by endosymbiosis. In some eukaryotes, chloroplasts subsequently also had an endosymbiotic origin. Evidence should include the presence in mitochondria and chloroplasts of 70S ribosomes, naked circular DNA and the ability to replicate."
A2.2.13 (HL) - Cell differentiation as the process for developing specialized tissues in multicellular organisms - "Students should be aware that the basis for differentiation is different patterns of gene expression often triggered by changes in the environment."
A2.2.14 (HL) - Evolution of multicellularity - "Students should be aware that multicellularity has evolved repeatedly. Many fungi and eukaryotic algae and all plants and animals are multicellular. Multicellularity has the advantages of allowing larger body size and cell specialization."
Activity 1 - Endosymbiotic Hypothesis (SL only)
Activity 2 - Evolution of Multicellularity -
Video 1 - The momentous transition to multicellular life may not have been so hard after all
How does this video help explain the importance of genes in the development of multicellularity?
How do the experiments show the possibility of multicellularity?
Video 2 - How Did Multicellularity Evolve?
a. What are some of the advantages of multicellularity?
b. Cell specialization is a vital part of multicellularity. Use examples from the video to explain why.
Activity 3 : Sketch Notes of Evolution of Multicellularity
Create hand-drawn sketch notes using the reading and videos as support.
*SL only needs to consider the Endosymbiotic Hypothesis
A. Strengthen Your Skills
A good reading on the Endosymbiotic Hypothesis
B. Expand Your Knowledge
What Do We Mean by Multicellularity? The Evolutionary Transitions Framework Provides Answers
https://www.youtube.com/watch?v=-ksYl2VvIHc
https://www.mpg.de/8738984/evolution-of-multicellularity