IB Topic 2

1. IB Topic 2 Cells

2. CELL THEORY TOPICS • Cell theory • Characteristics of life • Multi-cellular organisms • Microscopes and linear magnification • Prokaryotes • Eukaryotes • Cell membranes and transport • Cell size and limitations • Cell divisions • Cancer

3. A. There are 3 main points 1. All living organisms are composed of cells. 2. Cells are the smallest unit of life. 3. All cells come from pre-existing cells Cell Theory

4. A. The discovery of cells is linked to technological advancements (microscopes) B. 1590-Jansen developed the compound microscope (it had two lenses) C. 1665-Robert Hooke discovered the cell 1. Looking at cork 2. Thought the cells looked like chambers 3. Called them ‘cells’, as in jail cells Cell theory: history and evidence

5. D. 1675-Leeuwenhoek discovered unicellular organisms E. 1838-Mathius Schleiden discovered all plants are made of cells F. 1839-Theodore Schwann discovered all animals are made of cells

6. G. 1855-Rudolph Virchow discovers all organisms are made of cells **organism=any living thing

7. 1. Order (organization) – from small to large -Ex: Organelles make up cells. Cell make up tissues. Tissues make up organs. Organs make individuals. 2. Metabolism- organisms take in and release energy 3. Response (to the environment)- response to stimuli Characteristics of Life

8. Cool Picture of Metabolism

9. 4. Growth and development-heritable programs of DNA direct growth and development (change in one’s shape during life) Examples:

10. 5. Homeostasis-organisms have regulatory mechanisms to maintain their internal environments Examples: body temperature blood sugar osmoregulation Which image is probably someone who has hyperthermia?

11. 6. Reproduction-the ability to reproduce ones own kind -This follows the theory of biogenesis (life only comes from life)

12. 7. Evolutionary adaptation-life evolves as a result of interaction between organisms and their environment ***Any organism (single cell or multi-cell) that is considered alive must exhibit all of these characteristics.

13. A. Multicellular organisms show emergent properties B. Emergent properties arise from interaction of the components *The whole is greater than the parts (Ex: a heart cannot function without the whole body) *A single cell can do nothing on its own, but when you put all of the cells together they can perform many functions Multicellular organisms

14. A. Multicellular organisms differentiate to carry out specialized functions B. All cells originated from the same place and all carry the genetic information to perform any function (your toe cell could have been a brain cell) Multicellular organisms and differentiation

15. C. In each cell there is only a small amount of activated genetic material Ex: All cells have the genes for taste. The only cells with activated ‘taste’ genes are on your tongue. D. Cell differentiation is determined by a cells position relative to the others and chemical gradients E. Stem cells retain the capacity to divide and have the ability to differentiate along different pathways

16. Have ability to reproduce and differentiate Embryo cells all start out as stem cells Valuable for scientific research May be able to differentiate stem cells to desired cell type These may replace damaged cells Stem Cells

17. Example of stem cell differentiation

18. Homework-Outline one therapeutic use of stem cells for humans or some other animal. DO NOT USE WIKIPEDIA AS YOUR RESOURCE!! You may use any government or university website. Their websites generally end in .edu or .gov.

19. Viewing Cells 1. Light microscopes allow us to: -see color images -have a larger field of view -prepare samples easily -observe living and non-living material **We cannot see most cell organelles 2. Electron microscopes allow us to: -see more detail because they have a higher resolution

20. Comparing microscopes

21. Microscope Vocabulary 1. Resolution-describes clarity of pictures -higher resolution = more detailed pictures -human unaided resolution= 0.1mm (anything further apart than 0.1 mm is viewed as two objects) 2. Magnification-makes objects larger 3. An increase in magnification may reduce the resolution

22. Calculating Linear Magnification This is the original object. This is the magnified image. Diameter of the image=4cm Diameter of the specimen=2 cm Find the magnification. A. The formula- Magnification = size of image size of specimen B. Example-the object is magnified by two

23. 1 mm C. Scale bars - lines added to micrographs of drawing to help show the actual size of structures Ex. **You must know how to convert between SI Units to perform a magnification problem correctly!! Ex: 1mm = 1 x 10-3 m

24. 1nm (nanometer) = 1 x 10-9 m 1ųm (micrometer) = 1 x 10-6 m 1mm (millimeter) = 1 x 10-3 m 1cm (centimeter) = 1 x 10-2 m 1m (meter) = 1m 1km (kilometer) = 1 x 103 m Common SI Unit Conversions

25. Calculating linear magnification 1. Use a ruler to find the length of the scale bar. 2. Measure the length of the picture using the same unit that you used to measure the scale bar. 3. Divide the length of the picture by the length of the scale bar and multiply by the number in the scale bar. Calculating linear magnification

26. 4. If you did this correctly you should have only one unit left (it should be the unit that was in the scale bar). This is the size of the object in the picture. 6. Once you have the size of the object you can calculate magnification. 7. Divide the measured size of the picture by the actual size of the object and multiply by the scale bar (with units). 8. When you do this be sure your units are the same. When you divide they should cancel out. 9. If you did this correctly, your magnification should not have a unit.

27. Example: Go to p. 169 Figure 10.1-C. Calculate the magnification. 1. Length of scale bar = 0.8 cm 2. Length of picture = 5.7cm 3. 5.7 cm x 10.0 μm = 71.25 μm = actual 0.8 cm size of object (photo) Number given in scale bar of picture

28. 4. To calculate the magnification you must convert the actual size of the object and the measured size of the photo to the same units (meters are usually the easiest). 5. How it looks: a. 5.7 cm= 5.7 x 10-2m or 0.057 m (IMAGE SIZE) b. 71.25ųm = 71.25 x 10-6m or 0.00007125 m (ACTUAL SIZE) *In (a) the decimal was moved to the left two times (x 10-2)and in (b) the decimal was moved to the left six times (x 10-6)

29. 6. Magnification = 0.057 m =800 0.00007125 m 7. The picture is magnified 800 times. Assignment Calculate the magnification for the following images. 1. p. 169 Figures 10.1 d and e 2. p. 860 Figure 43.19 3. p. 921 Figure 46.10 4. p. 114 Figures 7.3 a and b

30. Prokaryotic Cells E. coli

31. Diagram of a typical prokaryote

32. 1. Cell wall-gives the cell structure and strength 2. Plasma membrane-separates the internal features from the outside environment 3. Cytoplasm-holds cell’s organelles and enzymes 4. Pili-help the cell hold on to other structures and aid in movement Prokaryote organelles

33. 5. Flagella-aid in organism movement 6. Ribosomes-make protein from mRNA 7. Nucleoid-area containing naked DNA 8. Slime capsule-a protective barrier around the cell (may help shield it from antibiotics) More prokaryote organelles

34. An electron micrographs of E. coli ** For IB you must be able to identify the structures on a micrograph. http://www.cellsalive.com/index.htm

35. Another diagram of a prokaryote

36. 1. Most prokaryotes divide by binary fission 2. Some reproduce by budding or filamentous growth Prokaryote reproduction http://www.bact.wisc.edu/Microtextbook/index.php?module=Book&func=displayarticle&art_id=112

37. Eukaryote Cells Animal cell

38. 1. All eukaryotes have enclosed nuclei and other membrane bound organelles 2. Eukaryotes are true cells (‘eu’ = true) 3. Eukaryotic cells are present in protists, plants, fungi and animal General Eukaryote Information

39. 1. Draw, label and annotate a diagram of a eukaryotic animal cell Include: free ribosomes rough ER lysosomes Golgi apparatus mitochondria nucleus cytoplasm centrioles cell membrane nucleolus DNA (chromatin) smooth ER Homework

40. 1. Animal cells have a secretory vesicle -It secretes glycoproteins that makeup the extracellular matrix -The extracellular matrix functions in support, adhesion and movement The Secretory Vesicle

41. Diagram of a plant cell

42. 1. Organelles found in plants only: -cell wall -chloroplasts-organelle required for photosynthesis -vacuole-membrane bound sac used for storage of organic compounds Plant Cells

43. 2. More on the cell wall -Found in all plants and some prokaryotes -provides rigid support for the cells -made mostly of cellulose -plays important role in turgor (hardening of cells by the intake of water) -prevents cells from taking in too much water Plant Cells

44. Homework: Outline the roles of extracellular components in plants (cell wall) and animals (extracellular matrix).

45. Summary of differences between eukaryotes and prokaryotes!

46. A. The Fluid Mosaic Model-model of the plasma membrane B. Designed by Singer and Nicolson Cell Membranes

47. C. The model is a mosaic of proteins embedded in a phospholipid bilayer D. The phospholipid bilayer has two layers of amphipathic lipids Hydrophilic heads Hydrophobic tails

48. E. Amphipathic- has a polar head and a non-polar tail F. Hydrophilic=water loving (polar) -found on inner and outer edges of cell membrane G. Hydrophobic=water fearing (non-polar) -found inside the cell membrane Diagram of cell membrane Hydrophilic heads Hydrophobic tails Cytoplasm

50. H. Lipids can move laterally through the cell membrane I. Cholesterol molecules found between the phospholipids may reduce fluidity, but prevent crystallization J. Membranes must be fluid to work