1. Cells The smallest unit of life

2. Discovering the Cell 1665 - Robert Hooke

3. Anton van Leeuwenhoek - late 17th, early 18th centuries

4. 1839 – Cell Theory is proposed independently by Theodore Schwann and Matthias Jakob Schleiden.

5. Cell Theory: The cell is the fundamental structure of all living things. All living things are made of cells. Cells arise from pre-existing cells through cell division.

6. Ernst Ruska - 1938

7. Light micrograph Scanning electron micrograph Paramecium

8. Cell Membrane Transmission electron micrograph Scanning electron micrograph

9. Prokaryotic Cells

11. Prokaryotic Features No membrane-bound organelles, such as a nucleus. DNA in one large ring-shaped chromosome An enormous variety of metabolic pathways. Highly successful and adaptable.

12. External structure Coccus (spherical) Spirillus (spiral)Bacillus (rod-shaped)

13. Internal Structure Figure 4-20a Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. chromosome (nucleoid region) plasmid (DNA) cytosol plasma membrane cell wall capsule or slime layer prokaryotic flagellum food granule ribosomes pili

14. Viruses A virus is usually not considered living. A virus consists only of a protein coat (sometimes with a lipid outer layer) and a piece of genetic material (DNA or RNA).

15. Bacteria vs. Virus FeaturesBacteriaVirus Reproduces independently? Has genetic material? Has cell membrane? Has metabolism? Living?

16. Eukaryotic Cells

17. Eukaryotic Features Cells contain membrane-bound organelles. Nucleus holds multiple strands of DNA, which condense into chromosomes during cell division. May be single-celled or multi-cellular organisms.

18. Figure 4-3 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. smooth endoplasmic reticulum mitochondrion cytosol lysosome ribosomes on rough ER centriole Golgi apparatus vesicle nuclear pore nuclear envelope chromatin (DNA) nucleolus plasma membrane rough endoplasmic reticulum free ribosome nucleus Animal cell

19. Plant Cell - same organelles as an animal cell, plus a few more ribosomesfree ribosome nuclear pore nuclear envelope chromatin (DNA) nucleolus nucleus smooth endoplasmic reticulum vesicle rough endoplasmic reticulum Golgi apparatus choloroplast mitochondrionplastid plasma membrane plasmodesma cell wall central vacuole cytosol

20. Things we will see in cells First let’s focus on things we can see using a light microscope and ordinary stains: Cell nucleus Cell membrane Cell wall Plastids (Chloroplast, amyloplast, chromoplast) Plant cell vacuole

21. Figure 4-9a Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. nuclear pores nuclear envelope chromatin nucleolus Nucleus

22. Cell Wall secondary cell wall middle lamella plasma membrane primary cell wall

23. Chloroplast thylakoid outer membrane inner membrane channel interconnecting thylakoids 1 micrometer stroma granum (stack of thylakoids)

24. Amyloplasts and other plastids starch globules 0.5 micrometer plastid

25. Protein-making Machinery Information for making proteins is in DNA, stored in the nucleus. An RNA copy is made in the nucleus and sent out to the rough Endoplasmic Reticulum (ER). Proteins leave the ER and are finished and packaged in the Golgi apparatus.

26. Figure 4-12 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. vesicles rough ER smooth ER ribosomes Endoplasmic Reticulum

27. Figure 4-13 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. Protein-carrying vesicles from ER merge with Golgi apparatus Golgi apparatus Vesicles carrying modified protein leave Golgi apparatus Golgi Apparatus

28. Figure 4-14 Biology: Life on Earth 8/e ©2008 Pearson Prentice Hall, Inc. 1 A protein is synthesized in the rough ER. 5 Vesicles merge with the plasma membrane and release protein by exocytosis. 4 Completed protein is packaged into vesicles. 3 Vesicles fuse with Golgi. The protein may be altered and finished. 2 Protein is packaged into vesicles and travels to Golgi apparatus. ER and Golgi function

29. Organelles in Cell Energy Chloroplasts capture energy from the sun and use that energy to manufacture sugars (chemical energy storage). Mitochondria break the bonds in sugars and release the energy that was stored there.

30. Mitochondrion cristae outer membrane inner membrane intermembrane compartment 0.2 micrometer matrix

31. Chloroplast thylakoid outer membrane inner membrane channel interconnecting thylakoids 1 micrometer stroma granum (stack of thylakoids)

32. Single-Celled Organisms Single-celled organisms carry out the same functions that our multicellular bodies do, but all within a single cell. How do they do it?

33. One-celled Eukaryotic organisms have unique challenges. A Paramecium must: ingest food excrete waste sense and respond to the environment

34. (a) Cilium (b) Flagellum propulsion of fluid return strokepower stroke plasma membrane direction of locomotionpropulsion of fluid continuous propulsion

35. cilium Paramecium 0.1 micrometer protein "arms" central pair of microtubules section of cilium (transmission EM) basal body plasma membrane

36. contractile vacuole full reservoir contracted reservoir

37. pore collecting ducts central reservoir Reservoir contracts, expelling water through pore. Water enters collecting ducts, fills central reservoir.

38. Recap Prokaryotic cells have no membrane- bound organelles. Eukaryotic cells have membrane-bound organelles, which compartmentalize processes for better efficiency. ALL cells have a cell membrane and DNA.