Division of Labor

1. Division of Labor How a multicellular organism gets from single cell to millions of highly specialized cells

2. Emergent Properties • Each table should have pile of images and several statements or quotes. • The term “emergent properties” basically means that the whole is greater than the sum of the parts. Looking at the images and statements/quotes, work together to explain what “emergent properties” means in terms of the molecules, cells, tissues, etc. in our body.

3. Emergent Properties • Multicellular organisms show emergent properties. For example: cells form tissues, tissues form organs, organs form organ systems and organ systems form multicellular organisms. The idea is that the whole is greater than the composition of its parts. The cells by themselves aren’t much use. It is the many cells working as a unit that allow tissues, organs, and organisms to perform their function. • Emergence is the way complex systems and patterns arise out of a collection of relatively simple interactions. • Examples?

4. Meiosis or Mitosis?

5. Meiosis or Mitosis? • Things to think about… • Is this a process of making gametes (sex cells)? Or do some of these cells become something other than gametes? • Do all of these cells contain the same genetic information?

6. Meiosis or Mitosis? • How do we go from gametes to a “full-fledged” organism? • Fertilization (egg + sperm meet) = zygote. • Many rounds of cell division (we do need more than one cell to perform all our many functions, after all!). This cell division is called MITOSIS. • Cells become specialized.

7. Egg + Sperm… • Let’s watch what happens…

8. Early stages of embryogenesis • Zygote: single fertilized egg to ball of less than 16 cells. • Morula: dense ball of (at least) 16 cells. • Blastula: hollow ball of cells. • Blastocyst • Gastrula: hollow ball of cells with different “cavities” inside. • Neurula: “ with neural tube. • ….

9. Early stages of embryogenesis • Blastocyst (follows blastula stage in mammals): Hollow ball of cells with “inner cell mass.” • Trophoblast: outer layer cells of blastocyst that become the placenta in mammals. • Inner cell mass core of cells inside trophoblast; becomes the fetus.

10. What’s next? • What needs to happen to get from this… • To this?

11. Take a moment… • Think of any type of organism.

12. Organisms are defined in part by their shape • Morphology: the form and structure of an organism. • _____________: The process of forming the shape and structure of an organism and its parts.

13. Organisms are defined in part by their shape • Morphology: the form and structure of an organism. • Morphogenesis: The process of forming the shape and structure of an organism and its parts.

14. Morphogenesis in the context of embryology Egg to fetus

15. What determines morphology? About 7 weeks post-conception About 12 weeks post-conception

16. What determines morphology? • Morphogenesis is controlled by a process called cell differentiation.

17. What determines morphology? • Morphogenesis is controlled by a process called cell differentiation. • What do you think “cell differentiation” means? Think - Pair - Share

18. What determines morphology? • Morphogenesis is controlled by a process called cell differentiation. • Cell differentiation: process of a cell taking on its mature form and role for an organism. • A cell becomes differentiated by producing specific proteins from the DNA template that allow it to develop into its mature form. • Differentiation results in cells taking on their mature form and function, which are all related to that cell’s structure.

19. Cell Morphology (Shape) Cell Differentiation Morphogenesis

20. Cell Signaling • In order to differentiate, cells must somehow “talk” with each other to decide which cells become what.

21. Apoptosis: Example of Cell Signaling • Apoptosis: Programmed cell death • Controlled by cell signals • Extracellularly: hormones • Intracellularly: due to cell stress, such as binding of nuclear receptors by viruses. • Important for morphology of organism… can you think why this might be?

22. Apoptosis: Example of Cell Signaling • Apoptosis: Programmed cell death • Controlled by cell signals • Extracellularly: hormones • Intracellularly: due to cell stress, such as binding of nuclear receptors by viruses. • Important for morphology of organism… can you think why this might be? Think - Pair - Share

23. Apoptosis About 7 weeks post-conception About 12 weeks post-conception

24. Induction • Induction: the initiation or cause of a change/process • Happens via cell communication (cell signaling) • Results in different genes being turned on or off.

25. Regulatory Cascades SIGNAL Gene 1 Gene 1 activates expression of Gene 2 Gene 2 Gene 2 activates expression of Gene 3 And so on… Gene 3

26. Cell Differentiation • Cells in a developing embryo begin to differentiate when they are induced to do so by various signals.

27. Genes and function • Chromosome • Gene • Intron • Exon • Protein • Gene regulation • Differentiation • Morphogenesis

28. Example of induction and differentiation at work! • The pressing question… meiosis or mitosis?

29. Meiosis or Mitosis? • How do we go from gametes to a “full-fledged” organism? • Fertilization (egg + sperm meet) = zygote. • Many rounds of cell division (we do need more than one cell to perform all our many functions, after all!). This cell division is called MITOSIS. • Cells become specialized.

30. Meiosis or Mitosis? • How do we go from gametes to a “full-fledged” organism? • Fertilization (egg + sperm meet) = zygote. • Many rounds of cell division (we do need more than one cell to perform all our many functions, after all!). This cell division is called MITOSIS. • Cells become specialized.

31. Meiosis or Mitosis? • How do we go from gametes to a “full-fledged” organism? • Fertilization (egg + sperm meet) = zygote. • Many rounds of cell division (we do need more than one cell to perform all our many functions, after all!). This cell division is called MITOSIS. • Cells become specialized. • Note: Up through the BLASTULA stage, cells are UNDIFFERENTIATED Write this down!!!

32. How do “sex cells” become “sex cells?” • A germ cell is a cell that gives rise to sex cells. The very first germ cells are called “primordial germ cells” and are initially located outside of the sex organs. (Primordial means “original” or “the first”). Migrate to sex organs. Divide while migrating. Primordial germ cells Germ cells Meiosis (diploid) (diploid) Gametes (haploid)

33. How do “sex cells” become “sex cells?” • Primordial germ cells originate near the cells in the developing embryo that eventually become the gut. Endoderm (gut)

34. How do “sex cells” become “sex cells?” • What determines which cells become primordial germ cells in the early embryo? • Asymmetrical cell division (in animals other than mammals and birds) • Induction by neighboring cells (in mammals and birds)

35. How do “sex cells” become “sex cells?” 1. Asymmetric cell division = “sex cell molecule”

36. How do “sex cells” become “sex cells?” 1. Induction by neighboring cells

37. How do “sex cells” become “sex cells?” 1. Induction by neighboring cells Hey, you guys. Become a sex cell!

38. An Example of Genetic Control of Differentiation

39. Your table has been given a description of a cell type. • Next to the cell type, write the function of that cell and any special structures and shapes (morphology) or organelles that cell might need in order to function the way it does. • How does this morphology relate to the function of the cell? • What genes need to be turned on in this cell?

41. Your table has been given a description of a cell type. • Next to the cell type, write the function of that cell and any special structures and shapes (morphology) or organelles that cell might need in order to function the way it does. • How does this morphology relate to the function of the cell? • What genes need to be turned on in this cell?