1. CELL STRUCTURE & FUNCTION
Human Biology
CELL STRUCTURE & FUNCTION
Instructor Terry Wiseth

2. CELL MEMBRANE Cell membrane made up of: 1) Phospholipids 2) Sterols
3) Proteins
4) Glycoproteins

3. PHOSPHOLIPIDS cell membrane - semi-permeable lipid bilayer
two layers of Phospholipids

4. STEROLS common sterols of cell membranes Cholesterol (animal cells)
prevent packing of lipid cells in the cell membrane

5. PROTEINS Proteins are embedded into the cell membrane
These proteins serve a variety of cell membrane functions

6. GLYCOPROTEINS proteins are embedded in the bilayer
glycoproteins - sugar-protein combinations
sugars extend out to the extracellular fluid

7. CELL MEMBRANE

8. FLUID MOSAIC MODEL membrane bilayer shows fluid behavior
molecules of the bilayer are in constant motion

9. FLUID MOSAIC MODEL
membrane is composite of molecules allowing a “mosaic description”
cell survival depends on fluidity characteristics of the cell membrane

10. FLUID MOSAIC MODEL
extracellular fluid temperature decreases cause a stiffening of the cell membrane
disrupts membrane protein function

11. CELL THEORY Smallest entity that retains the characteristics of life
1) Complex organization
2) Metabolic activity
3) Reproduction

12. CELL SIZE Most cannot be seen without the aid of a microscope
Larger cells
”Yolk” of bird eggs
Fish eggs “caviar”

13. CELL SIZE
Human eyes able to see about 100 microns

14. LIGHT MICROSCOPE
The light microscope has a limit of resolution of about 200 nm (0.2 microns)

15. TEM
The Transmission Electron Microscope (TEM) has a limit of resolution of about 2 nm

16. SEM The Scanning Electron Microscope (SEM) also has a limit of 2 nm
Sperm & Egg
Bronchiole cilia
WBC engulf bacteria

17. GENERALIZATIONS OF CELL THEORY
Cells vary in size, shape and activities
All cells have:
1) Plasma membrane
2) DNA region
3) Cytoplasm
4) Organelles

18. PLASMA MEMBRANE Outer membrane maintains the integrity of the cell
Membrane does not however isolate the cell

19. PLASMA MEMBRANE Cell membrane “Lipid bilayer”
Boundary that bars free passage of water soluble substances in and out of the cell

20. NUCLEUS
DNA is localized in the cell nucleus

21. CYTOPLASM
Everything enclosed by the plasma membrane except the DNA semi-fluid

22. CYTOPLASMIC STREAMING
Cytoplasm is not stagnant but rather is constantly moving (streaming)

23. ORGANELLES
Organelles--internal sacs which have a specific metabolic function
Essential in keeping chemical reactions in the cytoplasm separate from each other

24. CELL MACHINERY

25. CELL MACHINERY

26. NUCLEUS Nucleus sequesters DNA
1) Separates DNA from chemical reactions in cytoplasm
2) Nuclear membranes control access between nuclear material and cytoplasm

27. NUCLEUS
Nuclear envelope has pores to allow passage of messenger units of nucleic acid

28. NUCLEUS

29. NUCLEOLUS 1) Assembly of RNA and ribosomes
2) Storage of RNA and ribosomes

30. DNA Instructions for building proteins (enzymes) are contained in DNA
Instructions of heredity are distributed in several DNA molecules of various lengths
Humans = 46 DNA molecules

31. DNA
DNA is threadlike
prior to cell division the DNA molecules duplicate

32. CHROMOSOMES
DNA folds and twists into condensed structures called chromosomes

33. CYTOMEMBRANE SYSTEM
Series of organelles through which lipids and proteins, produced on cytoplasmic ribosomes, pass through in becoming packaged for export

34. CYTOMEMBRANE SYSTEM 1) Endoplasmic reticulum (ER) 2) Golgi bodies
3) Vesicles
4) Lysosomes

35. ENDOPLASMIC RETICULUM
1) Rough endoplasmic reticulum
Ribbon like structure with ribosomes attached
Arranged as flat, stacked sacs

36. ENDOPLASMIC RETICULUM

37. RIBOSOMES Ribosomes are small spherical shaped structures
Serve as the “working table” for assembling proteins

38. RIBOSOMES

39. ENDOPLASMIC RETICULUM
2) Smooth endoplasmic reticulum
Lacks ribosomes

40. SMOOTH ENDOPLASMIC RETICULUM
Appears like a system of pipes
1) Lipid synthesis
Ex: endocrine glands produce steroid hormones
2) Inactivate harmful by-products of metabolism and drugs
Ex: liver cells

41. GOLGI BODIES
Resemble stacks of pancakes

42. GOLGI BODIES
Flattened sacs in which lipids and protein molecules are modified

43. GOLGI BODIES
Modifications allow for sorting and packaging for transport

44. GOLGI MODIFICATIONS

45. GOLGI MODIFICATIONS

46. VESICLES Sacs which transport or store enzymes, lipids and proteins
1) Peroxisomes
2) Lysosomes (microbodies)

47. VESICLES 1) Peroxisomes
Contain enzymes to break down fatty acids and amino acids

48. VESICLES 2) Lysosomes Vesicles of intracellular digestion
Contain enzymes which can break down any polysaccharide, protein, nucleic acid and some lipids

49. LYSOSOMES
Important in proper function of white blood cells (immunity)

50. LYSOSOMES

51. CYTOMEMBRANE SYSTEM
Raw materials (amino acids and lipids) are dissolved in the cytoplasm

52. CYTOMEMBRANE SYSTEM
Under the instructions of the DNA molecule polypeptide chains of proteins are assembled from the dissolved raw materials

53. CYTOMEMBRANE SYSTEM

54. MITOCHONDRIA
Contains a series of inner membranes folded repeatedly (cristae)
Increases the total surface area available for reactions

55. MITOCHONDRIA
Use oxygen to assist in liberating energy stored in sugars (aerobic respiration)

56. MITOCHONDRIA
Energy is used to form ATP molecules which is used for protein synthesis and transport
ATP-molecule is able to store and transport energy for short periods of time

57. MITOCHONDRIA Most numerous in high energy demanding cells
Ex: muscles, liver

58. MITOCHONDRIA

59. CYTOSKELETON
Interconnected system of bundled fibers, threads and lattices

60. CYTOSKELETON
Extend from the cell membranes, organelles and nucleus

61. CYTOSKELETON
Supply internal organization, shape, ability to move, reinforce the cell membrane and hold proteins in place

62. CELL SURFACE SPECIALIZATIONS
Gap Junctions
channels of exchange in animal cells
ex: liver, heart

63. CELL SURFACE SPECIALIZATIONS
Junction Proteins
hold cells together in forming tissues

64. END Cell