Basic Unit of Life: The Cell

1. Chapter 3 Basic Unit of Life: The Cell

2. All Organisms are made up of cells Eukaryotes- Moth Juniper Protozoans Ciliates in water on plant Prokaryotes Bacteria in insect gut and on surface of insect and tree

3. Cell theory • All living organisms are made up of cells • All cells come from other cells Theory refers to the body of knowledge that has been developed through scientific inquiry

4. Two Cell Categories Prokaryote Eukaryote • Cell membrane • Cytoplasm • DNA (in a loop) • Ribosomes (for creating proteins) • Cell wall • Very small • DNA is loose in cytoplasm • Cell membrane • Cytoplasm • DNA (in strands) • Ribosomes • Many other organelles • Cell wall in plants • Variable size – larger than prokaryotes • Nucleus holds DNA

5. The organisms that cause colors in the hot springs of Yellowstone are single celled and have been around since the beginning of life on this planet. Would these organisms be prokaryotes or eukaryotes? Would their cells have a nucleus? A. Prokaryotes, yes B. Prokaryotes, no C. Eukaryotes, yes D. Eukaryotes, no http://serc.carleton.edu/microbelife/extreme/extremeheat/yellowstone.html

6. Basic Cell Structures • Cell Membrane • Nuclear double membrane around nucleus • Mitochondria for energy • Processing and packaging organelles • Lysosomes – digestion • Cytoskeleton - support

7. Plasma Membranes

8. Bilayer Structure

9. Molecules Found in the cell Membrane Cholesterol increases membrane flexibility

10. Types of Membrane Proteins 1. Receptor proteins – • Bind to external molecules which cause reactions in cell • Ex. Target cells can detect hormones in blood – regulate development of secondary sexual characteristics 2. Recognition proteins • Typically have attached carbohydrate chains • Give the cell identity – other cells can recognize them • Ex. During development cells interact & work together to develop structures. Recognition is essential. • Ex. Autoimmune disease = faulty self-recognition

11. Visual examples Receptor proteins Recognition proteins

12. Types of Membrane Proteins 3. Transport proteins • Move other molecules across the cell membrane • Transmembrane proteins only • Ex. Nerve cell fire – Na ions moved across 4. Enzymatic proteins • Increase rate of chemical reactions associated with the cell membrane • Ex. cAMP formation regulated – internal messenger created

13. Visual Examples Transport proteins Enzymatic proteins

14. Why is the cell membrane considered a fluid mosaic? • It’s primarily made up of water with dispersed fats and proteins in a mosaic pattern • Proteins move back and forth through the membrane from inside to outside of the cell and back in a fluid mosaic pattern. • It’s made up of several different types of molecules, like a mosaic, and many of those molecules float around in the lipid bilayer.

15. Cell Structure and Function • Cells are factories • Need raw materials to enter the cell • Need to eliminate wastes • Need to export products produced in the cell • Need to keep up-to-date on needs of surrounding cells and tissues

16. Endocytosis

18. Exocytosis

19. Animation of endocytosis and exocytosis http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio02.swf::Endocytosis%20and%20Exocytosis

20. Other means of movement Passive Transport Active Transport • Requires no input of energy • Diffusion • Osmosis (diffusion of water across a membrane) • Requires energy input to move molecules across the cell membrane or around in the cell • Primary – uses ATP • Secondary

21. Diffusion Key: Molecules tend to move from an area of high concentration to an area of low concentration When moving across a membrane – diffusion may be facilitated by a transport protein

22. Osmosis

23. Irrigation problems • Irrigation can lead to a build up of soil salinity • If soil develops a similar (or higher) salt content than the plant cells, water doesn’t flow as easily into plant roots. • Soil salt concentrations make plants and soil more alike in fluid concentration (isotonic) - so water doesn’t flow across the cell membranes into the plant roots. • Soil salinity creates drought like conditions in which plants can’t get water

24. PassiveTransport

25. Active Transport

26. The object depicted in the figure: A) is a bacterial cell.B) could be either a plant or an animal cell.C) is a ribosome. D) is an animal cell.E) is a plant cell.

27. Cell Wall Not found in animals A major component of the cell wall is the complex carbohydrate, Cellulose

28. If the concentrations of a particular molecule are equal on both sides of the membrane, facilitated diffusion will: A) insure that the molecule becomes concentrated outside the cell.B) insure that the molecule stays impermeable to the membrane.C) insure that the molecule becomes concentrated inside the cell.D) insure that the concentrations inside and outside the cell are both increased.E) be ineffective.

29. Connections Between Cells:1. Tight Junctions> hold cells in place> keep fluids from passing around edges of cells blood brain barrier lining of gut

30. Connections Between Cells:2. Desmosomes>throughout body

31. Connections Between Cells:3. Gap Junctions>Allows small molecules, but not large proteins and organelles to move between cells.

32. Cell Size • Chicken egg = 40-60 mm • (1mm = 1/1000 m) • Paramecium caudatum = 60X 230 um • (1 um = 1/1000 mm) • Red blood cell = 1.9-7.5 um • Bacteria 0.5-2 um • Why not bigger?

33. What limits the size of cells? • Much of what occurs in a cell depends on the movement of materials in and out of the cell through the plasma membrane • Rate of production and waste removal is dependent on cell volume • Rate of movement across the membrane depends on surface area of cell • As cell size increases, volume increases as a cubed unit while surface area as a square unit.

34. Surface to volume ratio

35. Nucleus and chromosomes

36. Cytoskeleton Made up of protein fibers that can expand, contract, move past one another.

38. Microfilaments underlie the cell membrane and cytoskeletal elements can break down and reform to allow changing shape in Amoeba.

39. Cell locomotion:

40. Mitochondria – have own DNA!

41. Mitochondria con’t • Number in a cell may vary • Cells with high energy demands like muscles have more than other cells • Process known as aerobic respiration (Kreb cycle & electron transport phosphorylation) takes place here. • Sugar (C6H12O6) + 6H2O + 6O2 => 6 CO2 + 12 water (H2O) + Energy • Breaks down sugar to release the energy in the chemical bonds • Oxygen is used and Carbon dioxide is a waste biproduct.

42. Chloroplasts Only in Plant Cells and Single-celled Algae Have own DNA! Similar in some ways to bacteria that do photosynthesis – especially DNA

43. Evolution of Eukaryote Cells

44. Lysosomes – Waste removal Up to 50 different types of enzymes!

45. Endoplasmic Reticulum

46. Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum

47. Golgi Apparatus

49. Vacuoles