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Structure and Function of the Cell. Cells make up all living things.

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Presentation on theme: "Structure and Function of the Cell. Cells make up all living things."— Presentation transcript:

1 Structure and Function of the Cell

2 Cells make up all living things

3 Cells are the basic unit of life Cells Tissues Organ systems Organs 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 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 nonpolar But 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


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

48 Think of it as molecules spreading out!

49 Progression of Liquid Diffusion

50 High Conc. Low Conc. ?

51 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


53 Osmosis – A Passive Process where water moves across a cell membrane from an area that is hypotonic (lots of water, little solute) to an area that is hypertonic (little water, lots of solute)

54 think of the water as trying to dilute the concentrated side to make the concentration even Weak Iced TeaStrong Iced Tea Move water until you get Two perfect Iced teas

55 Tonicity – term used to compare the concentration of one solution to another - will determine where water goes 3 Conditions Hypotonic Isotonic Hypertonic

56 The solution with the higher concentration is called Hypertonic. The solution with the lower concentration is called Hypotonic If the concentrations are equal, they are called isotonic

57 20% Salt Solution 10% Salt Solution Which is Hypertonic?

58 Inside is Hypertonic

59 10% Salt Solution 20% Salt Solution Which is hypertonic?

60 ? Outside is Hypertonic

61 20% Salt Solution Isotonic:

62 Isotonic

63 Crenation Cytolysis Comparing Cell types chart

64 Plasmolysis Vs. Turgidity in Plant cells - Turgor pressure: Pressure that the water INSIDE the cell puts on the cell wall. Supports plant

65 A B A B

66 Active Transport Cell must use energy to force molecules to move across the membrane from a low concentration to a high concentration. Usually used to move ion and since ions can not go through the phospholipids requires a transport protein

67 Active TransportActive Transport:

68 Vesicle Transport Vesicle transport is different from Diffusion, Osmosis, facilitate diffusion and active transport in that we are moving large quantities (many molecules) rather than individual molecules. The cell must package the material in a vesicle and bring it in or out of the cell depending on the goal.

69 Making a vesicle requires the cell to exert energy in the form of ATP, but we don’t have to concern ourselves with concentration differences. The two types of vesicle transport depend on direction - Moving materials into a cell in a vesicle is called endocytosis. Moving materials out of a cell is called exocytosis.

70 Bulk transport into cell Endocytosis Phagocytosis Pinocytosis (SOLIDS) (LIQUIDS)

71 Phagocytosis: “cell eating” large proteins, dead cells, bacteria  substances WAY too big for even a protein; Making/moving a vesicle requires energy  ATP

72 Pinocytosis: Cell drinking; bulk ingestion of liquids Particularly important in kidney and intestinal cells

73 Exocytosis Exocytosis – Bulk Transport out of cell Way of releasing large quantities of stuff from the cell including : Hormones, mucus and cell wastes NEEDS ATP


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