1. Atoms to Ecosystems Today: Biological Building Blocks: Our Cells!
Reminders:
Our fist lab is tomorrow, Wednesday. Be sure to bring and prepare your lab notebook!
Our first group quiz is also tomorrow! It’s a “warm-up”, but be sure to review the material we work through today.

2. Your First Challenge:
What sort of key functions will your space station need to support life? What types of structures might accomplish these functions? Form a group and design your space station using the whiteboards!

3. Comparing and Contrasting Prokaryotic and Eukaryotic Cells
Quick “Think, Pair, Share”: Can you come up with three organisms that are made of prokaryotic cells? Three that are made of eukaryotic cells?

4. Prokaryotic Cell Structure

5. Basic Cell Structure: Eukaryotes

6. All Cells: The Plasma Membrane

7. Plasma Membranes: Phospholipids
What do you notice about the structure of this molecule?

8. Plasma Membranes: Structure and Function

9. All Cells: Ribosomes
Ribosomal RNA + Ribosomal Proteins = Ribosomal Subunits
Each Ribosome composed of 2 subunits
Ribosomes synthesize Proteins, may be free or bound

10. Eukaryotic Cells: The Nucleus

11. Eukaryotic Cells: The Nucleus
Double-membrane envelope
Envelope perforated by pores
Pores lined with pore complex proteins
Nuclear Lamina lines the inside of the envelope
Network of filaments, the nuclear matrix, extends through interior

12. Within the Nucleus DNA is organized around proteins to form chromatin
Ribosomal RNA synthesis occurs in the dense nucleolus

13. Eukaryotic Cells: The Endoplasmic Reticulum (ER)
(Part of the Endomembrane System)

14. The Endoplasmic Reticulum
ER is continuous with the nuclear envelope
Composed of a systems of sacs called the cisternae, enclosing the cisternal space
Can be smooth or rough
Has Ribosomes!
Manufactures proteins for excretion in transport vesicles, can serve as membrane factory
No Ribosomes-
Synthesizes lipids, detoxifies, aids in metabolism of carbohydrates, etc.

15. The Endoplasmic Reticulum

16. Eukaryotic Cells: The Golgi Apparatus
(also part of the Endomembrane System)

17. Eukaryotic Cells: The Golgi Apparatus
Vessicles transported to the Golgi after leaving the ER
Composed of a stack of flattened membrane sacs called cisternae
Each stack has two sides, the cis (receiving) face, and the trans (shipping) face
Products labeled and modified while traveling from cis to trans

18. Lysosomes Membrane bound sac of hydrolytic enzymes pH = ~5
Important in Phagocytosis and Autophagy
Also part of the Endomembrane System

19. Eukaryotic Cells: Vacuoles
Any large vessicle may be called a vacuole
Vacuoles are also part of the endo-membrane system

20. The Endomembrane System

21. Eukaryotic Cells: Mitochondria

22. Characteristics:
Enclosed by two membranes: Outer is smooth, inner is folded into cristae
This creates two spaces, the intermembrane space and the mitochondrial matrix
Semi-autonomous! (Divide and reproduce; have their own DNA!)

23. Plant Cells: Chloroplasts
Specialized Plastid containing the green pigment chlorophyll, enzymes, and other molecules for photosynthesis

24. Components & Terminology:
Two membranes, separated by intermembrane space
Internal system of flattened sacs called thylakoids
A stack of thylakoids is called a granum
Thylakoids are surrounded by fluid, the stroma, containing chloroplast DNA, ribosomes, and enzymes!!

25. Explaining the Origins of Mitochondria and Chloroplasts??

26. Explaining the Origins of Mitochondria and Chloroplasts

27. Other Types of Plastids Found in Plants
Chromoplasts
Leucoplasts

28. Peroxisomes Specialized metabolic compartment Single membrane
Transfer hydrogen to oxygen to make peroxide (toxic!)
Peroxide broken down into water

29. Next: The Cytoskeleton
A network of fibers extending through the cytoplasm
Provides structural support, cell motility, and regulation

30. The Cytoskeleton 3 types of fibers: 1. Microtubles (thickest)
2. Microfilaments (thinnest)
3. Intermediate filaments

31. The Cytoskeleton: Microtubules
In cytoplasm of all eukaryotic cells
Hollow rods about 25 nm in diameter
Made of the globular protein, tubulin

32. Functions of Microtubules
Provide shape and support to the cell
Serves as tracks along which motor proteins can move
Help separate chromosomes during cell division
Important components of cilia and flagella

33. Functions of Microtubules

34. Functions of Microtubules

35. Structure of Microtubules

36. Microtubules: Dynein walking in cilia and flagella (Structure and Function!)

37. Origins of Microtubules
Microtubules often grown out from a centrosome (region near the nucleus)
In animal cells, centrioles in the centrosome, give rise to microtubules

38. The Cytoskeleton: Microfilaments (#2)
Also called actin filaments
Solid rods (~7nm) of the globular protein, actin
Each actin chain is twisted into a double chain

39. The Cytoskeleton: Microfilaments (#2)
Structural role: bears tension
Often form a network just inside the plasma membrane, supporting cell shape
Play key roles in microvilli, muscle cell contraction, amoeboid movement, and cytoplasmic streaming

40. Microfilaments in Amoeboid Movement

42. Microfilaments in Cytoplasmic Streaming

43. The Cytoskeleton: Intermediate Filaments (#3)
Diameter = 8-12 nm
Bear tension
Constructed of different types of keratins
More permanent in the cell
Secures nucleus, makes up the nuclear lamina

44. Connections to your Space Station?
Help! We’re running out of coffee…
Connections to your Space Station?
Other Structures or Functions??

45. Next: Cell Surfaces What functions must ALL cell surfaces accomplish?
What structural differences do you notice about these two cell types?

46. The Plant Cell Wall

47. The Cell Surface of Animal Cells
No cell wall!
Have an extracellular matrix (ECM) composed primarily of glycoproteins (esp. collagen)
Another glycoprotein, fibronectin, attaches cells to the ECM by binding at receptor proteins (integrins).
Integrins can transmit signals into the cell!

48. The Cell Surface of Animal Cells

49. Intercellular Junctions in Animal Cells
3 Types:
1. Tight Junctions: membranes fused, preventing leaking across a layer of cells
2. Desmosomes or anchoring junctions: connect cells in strong sheets (like rivets)
3. Gap Junctions: provide channels for small molecules to pass from one cell to the next

50. Intercellular Junctions in Animal Cells

51. The Dynamic Cell Membrane: Setting the Stage
Hmm… I wonder what it’s made of??
In 1895, Charles Overton notices that lipid soluble compounds enter cells more readily.

52. Overton’s Hypothesis Confirmed
Membranes made of lipids and proteins (1915)
1917- artificial membranes made from phospholipids
1925-Gorter and Grendel propose that the membrane is two molecules thick (a phospholipid bilayer)
Needed a MODEL for how the molecules work together!

53. Model #1: The Davson-Danielli Model (1935)
Two Problems:
Not all membranes look alike!
Membrane proteins usually have hydrophobic and hydrophillic regions

54. Model #2: The Fluid Mosaic Model (1972)

55. The Fluid Mosaic Model

56. The Fluid Mosaic Model

57. (Confirmed by Freeze-Fracture)
The Fluid Mosaic Model
(Confirmed by Freeze-Fracture)

58. The Fluid Mosaic Model

59. Origins of Membrane Proteins
Result:
Membranes have an “inside” and an “outside”