Structure and Function of the Cell

1. Structure and Function of the Cell

2. Cells make up all living things

3. Cells are the basic unit of life Cells Tissues Organs Organ systems Organisms

4. CELL THEORY • 1665 – Robert Hook - Looked at cork, gave the little chambers the name “cells”

5. CELL THEORY 1674 – Anton Van Leeuwenhoek - first to look at living cells - saw “animalcules” or little animals

6. CELL THEORY 1838 – Schleiden - All plants are made of these Cells 1839 – Schwann - All animals are made of these cells 1855 – Virchow • Noticed that Cells make more of themselves.

7. FINAL CELL THEORY • All living things are made up of one or more cells • Cells are the basic unit of structure and function in living things • Cells come from previously existing cells – NO spontaneous generation!

8. Prokaryotes Vs. Eukaryotes Prokaryotes: - literally means “before nucleus” - primitive single celled life, the first! - example: bacteria - still has DNA just not enclosed in a nucleus

10. Prokaryotes Vs. Eukaryotes Eukaryotes: - literally means “true nucleus” - DNA enclosed by the nuclear membrane - Can be single celled like protists (amoebas, paramecium) - Or can be part of a multicellular organism like: plants, animals or fungi

11. Prokaryotes Vs. Eukaryotes Eukaryotes: - significantly larger than prokaryotic cells - have many more organelles than prokaryotic cells

14. How do we study cells? • Microscopy – using a device that magnifies an image of a very small specimen • Magnification: • Resolution:

15. Here’s our specimen, but what’s wrong?

16. Magnify, still no good?

17. Increase resolution

18. Light microscopy • Pros: more affordable • Easier prep • Can observe living cells • Cons: • More limited in terms of Mag/Res

19. Light microscopy

20. Electron microscopy • Pros: • Significantly greater mag/res • Cons: • Specimen Prep is much more involved • Specimen prep will kill specimen, no live observations

21. Electron microscopy *Color is added, EM’s Only see produce black And white images

22. All cells must perform the same few functions to stay alive BUT, since they have different organelles, they might go about it differently

23. I. All cells must control what enters and exits a cell • II. All cells must convert the energy in nutrients to into energy it can use III. All cells must make, modify and ship proteins to where they need to go

24. IV. All cells must be able to store nutrients, digest large molecules and recycle damaged organelles V. All cells must grow and divide VI. All cells have a particular shape and can move IF THEY NEED TO

25. We will be starting with function I

26. Plasma Membrane Phospholipid bilayer that surrounds all cells and certain organelles within the cell

27. Phospholipid Hydrophilic Phosphate head Hydrophobic Fatty acid Tails

28. Remember the Triglycerides?What’s the difference?

29. In water what will happen?

30. Water on outside of cell

31. Water on outside of cell Also Water on Inside of cell

32. Double layer allows: • All hydrophobic parts to be away from water • All hydrophilic parts to be near water

33. Membrane – more than just phospholipids

34. A little more than just phospholipids

35. Plasma membrane contains: Proteins embedded in phospholipid bilayer; Cholesterol tucked between fatty acids Carbohydrate chains

37. Why proteins? • Proteins increase contact with water and act as channels through which certain molecules can pass

38. Why cholesterol? • Cholesterol keeps the membrane fluid and flexible; prevents solidification Why Carbs? Carbohydrate chains act as cell “ID” tags.

39. Fluid Mosaic Model: theory that describes the composition of the membrane - Fluid because it is flexible; p-lipids and proteins can shift position - Mosaic because it is made of many small molecules that work together as a whole

40. Membrane acts as a semi-permeable barrier (think bouncer!) some stuff passes right through the phospholipids: - small, hydrophobic, uncharged

41. some stuff can’t: - ions (Na+, Cl-, K+, Ca++)- polar molecules (Sugars, Amino Acids) - large nonpolarBut don’t we need these?!?! We’re getting there….

42. ? ?

43. There are two general categories of transport: Passive transport: The easy way; no energy required; molecules just flow naturally across Active Transport: the hard way; energy required; molecules need to be pushed or carried across

44. BROWNIAN MOVEMENT Molecules are ALWAYS moving

45. Passive Processes: No energy needed • Diffusion: Movement of solutes from areas of high concentration to areas of low concentration until concentrations are equal. • Concentration Gradient = differences in Concentration

46. Gaseous Diffusion No membrane needed High Conc. Low Conc.

47. Think of it as molecules spreading out!

48. Progression of Liquid Diffusion

49. High Conc. Low Conc. ?

50. Facilitated Diffusion – movement of solute from high concentration to low concentration BUT requires transport protein to move molecule that are too big or polar to get through the bilayer on their own Glucose is too big to fit through phospholipids and will be diffused through a transport protein to get into the cell