1. Chemical Evolution (prebiotic) Preceded Biological Evolution
Hypotheses for prebiotic chemistry on the early Earth: formation of early organic compounds.
Urey (1952)
The experiment confirmed Alexander Oparin's and J. B. S. Haldane's hypothesis that putative conditions on the primitive Earth favored chemical reactions that synthesized more complex organic compounds from simpler inorganic precursors.
Miller (1953)

2. Chemical Evolution (prebiotic) Preceded Biological Evolution
Hypotheses for prebiotic chemistry on the early Earth: The first Protocells (protobionts)
Model of an early Protocell (aka. Protobiont) on the brink of integrating metabolism and reproduction.

3. Chemical Evolution (prebiotic) Preceded Biological Evolution
Hypotheses for prebiotic chemistry on the early Earth: The first Protocells (protobionts)

4. Chemical Evolution (prebiotic) Preceded Biological Evolution

5. “Probably all of the organic beings which have ever lived on this Earth have descended from some one primordial form.”
- Charles Darwin, 1858

6. Comparing “Prokaryotic” and Eukaryotic Cells
All cells have several basic features in common
They are bounded by a plasma membrane.
They contain a semifluid substance called the cytosol.
They contain chromosomes.
They all have ribosomes.
Why?
Paramecium caudatum, a Protist
200 µm
E. coli, a bacterium

7. How many parts can you identify and label?
Cells in General
“Prokaryotic” cells (Archaea and Bacteria)
Organize their genetic material in a nucleoid. 1 7
How many parts can you identify and label? 2 3 4 5
Flagellum
Cell membrane
Nucleoid/Chromosome
Nucleic Acid
Cell wall
Capsule
Ribosimes 6

8. How many parts can you identify and label?
Cells in General
“Prokaryotic” cells (Archaea and Bacteria)
Organize their genetic material in a nucleoid. 1 7
How many parts can you identify and label? 2 3 4 5
6 Flagellum
4 Cell membrane
7 Nucleoid/Chromosome
2 Nucleic Acid
5 Cell wall
1 Capsule
3 Ribosimes 6

9. Cells in General Eukaryotic cells
Contain a true nucleus, bounded by a membranous nuclear envelope.
Are generally much bigger than prokaryotic cells.

10. You must be able to draw and label plant and animal cells
A animal cell: structure and function of components?
Rough ER
Smooth ER
Centrosome
CYTOSKELETON
Microfilaments
Microtubules
Microvilli
Peroxisome
Lysosome
Golgi apparatus
Ribosomes
In animal cells but not plant cells:
Lysosomes
Centrioles
Flagella (in some plant sperm)
Nucleolus
Chromatin
NUCLEUS
Flagelium
Intermediate filaments
ENDOPLASMIC RETICULUM (ER)
Mitochondrion
Nuclear envelope
Plasma membrane

11. You must be able to draw and label plant and animal cells
A plant cell: structure and function of components?
Ribosomes (small brwon dots)
Central vacuole
Microfilaments
Intermediate
filaments
Microtubules
Rough
endoplasmic
reticulum
Smooth
Chromatin
NUCLEUS
Nuclear envelope
Nucleolus
Chloroplast
Plasmodesmata
Wall of adjacent cell
Cell wall
Golgi apparatus
Peroxisome
Tonoplast
Centrosome
Plasma membrane
Mitochondrion
CYTOSKELETON
In plant cells but not animal cells:
Chloroplasts
Central vacuole and tonoplast
Cell wall
Plasmodesmata

12. Why are cells so small?
200 µm

13. Sketch what these relationships should look like

14. Sketch what these relationships should look like

15. Sketch what this relationship should look like

16. Sketch what this relationship should look like

17. Why are cells so small?
The plasma membrane functions as a selective barrier and allows sufficient passage of nutrients and waste.
The logistics of carrying out cellular metabolism and environmental exchange sets limits on the size of cells, so…
Cells with a higher surface to volume ratio can more efficiently facilitate the exchange of materials into and out of the cell.
Surface area increases while
total volume remains constant 5 1
Total surface area
(height  width 
number of sides 
number of boxes)
Total volume
(height  width  length
 number of boxes)
Surface-to-volume
ratio
(surface area  volume) 6
150
125 12
750

18. Determining Cell Size
Magnification and microscopic field are inversely proportional.
Methods for determining cell size?
Calculation: How big is an E. coli cell (in μm) if an electron micrograph of it is 12.45cm and has been magnified to 90,000X?
100 µm

19. The Nucleus: Genetic Library of the Cell
The nucleus is enclosed by the nuclear envelope and contains most of the genes in the eukaryotic cell.
Nucleus
Nucleolus
Chromatin
Nuclear envelope:
Inner membrane
Outer membrane
Nuclear pore
Rough ER
Pore
complex
Surface of nuclear envelope.
Pore complexes (TEM).
Nuclear lamina (TEM).
Close-up of nuclear
envelope
Ribosome
1 µm
0.25 µm
ER is continuous with nuclear envelope

20. Functions of Smooth ER The smooth ER
Synthesizes lipids, like testosterone and estrogen in testes and ovary cells
Metabolizes carbohydrates
Stores calcium in ER lumen in muscle cells and releases it into cytosol to trigger muscle contraction
Detoxifies drugs, alcohol, and poisons in liver cells by adding OH groups

21. Functions of Smooth ER
Lieber, C. S Hepatic and other medical disorders of alcoholism: from pathogenesis to treatment. Journal of Studies on Alcohol 59:9-25.

22. Functions of Rough ER The rough ER Has bound ribosomes
Produces glycoproteins and membranes, which are distributed by transport vesicles

23. Animation: The Cis-maturation Model
Allen and Balch (1999)
Animation: The Cis-maturation Model

24. The Golgi Apparatus: Shipping and Receiving Center
Example of how the Golgi apparatus participates with the rough ER in membrane synthesis (from CH 7, Fig 7.10).
Synthesis of membrane proteins and lipids in the ER. Carbohydrates (green) are added to the proteins (purple) making them glycoproteins.
Carbohydrate modification and glycolipid synthesis.
Vesicle transport (HOW?) to the plasma membrane.
Plasma membrane fusion. Notice inverted nature of membrane before fusion. 24

25. Lysosomes: Digestive Compartments
A lysosome is a membranous sac of hydrolytic enzymes that can digest all kinds of macromolecules.
Lysosomes carry out intracellular digestion by phagocytosis (phago = eating; cyto = cell) and forming food vacuoles.
Autophagy is the use of lysosomes to break down a cell’s own damaged or old components.

26. Vacuoles: Diverse Maintenance Compartments
A plant or fungal cell may have one or several vacuoles.
Food vacuoles are formed by phagocytosis.
Contractile vacuoles pump excess water out of protist cells.
Central vacuoles are found in plant cells and hold reserves of important organic compounds and water.
Spiderwort (Tradescantia sp.) central vacuole 26

27. Vacuoles: Diverse Maintenance Compartments
A plant or fungal cell may have one or several vacuoles.
Food vacuoles are formed by phagocytosis.
Contractile vacuoles pump excess water out of protist cells (osmoregulation).
Central vacuoles are found in plant cells and hold reserves of important organic compounds and water.
Example of an osmoregulation adaptation in Paramecium sp. (from CH 7, Fig 7.14)
Food vacuoles
When the contractile vacuole fails

28. The Cell: A Living Unit Greater Than the Sum of Its Parts
The Inner Life of a Cell (long version)
The Inner Life of a Cell (narrated version)

29. The Cytoskeleton
The cytoskeleton is a network of fibers extending throughout the cytoplasm that gives mechanical support for the cell.
Composed of large microtubules, smaller microfilaments, and intermediate filaments.

30. The cytoskeleton is involved in cell motility, which utilizes motor proteins.

31. There are three main types of fibers that make up the cytoskeleton.

32. A cell contains a pair of centrosomes that perform as organizing sites for microtubules and anchors for pulling apart chromosomes during mitosis.
Animal cells contain two centrioles with each centrosome.

33. Microfilaments (Actin Filaments)
Microfilaments are built from molecules of the protein actin.
Microfilaments that function in cellular motility also contain the protein myosin in addition to actin.

34. Amoeboid Movement in Amoeba proteus
Amoeboid movement involves the contraction of actin and myosin filaments.
Amoeboid Movement in Amoeba proteus

35. Cytoplasmic Streaming in Elodea canadensis
Cytoplasmic streaming is another form of locomotion created by microfilaments.
Cytoplasmic Streaming in Elodea canadensis

36. Membrane Structure and Function
The Fluid Mosaic Model of Membrane Structure

37. The Extracellular Matrix (ECM) of Animal Cells
Animal cells lack cell walls and are covered by an elaborate matrix, the ECM.
The ECM is made up of collagen fibers, glycoproteins (e.g. proteoglycan), and other macromolecules.
Support
Adhesion
Movement
Regulation

38. What is the role of cholesterol in cell membrane function?
Membrane Fluidity
What is the role of cholesterol in cell membrane function? 38

39. Membrane Proteins and their Functions39

40. The Permeability of the Lipid Bilayer
A cell must exchange materials with its surroundings, a process controlled by the plasma membrane. This is called selective permeability.
Osmosis is the movement of water across a semipermeable membrane and is affected by the concentration gradient of dissolved substances.
Water molecules
Higher Concentration
of Water
Outside Cell
Cell
membrane
Lower Concentration
of Water
Inside Cell
Sugar molecules

41. Diffusion and Osmosis
Substances diffuse down their concentration gradient, the difference in concentration of a substance from one area to another.
Osmosis is the diffusion of water across a selectively permeable membrane down its concentration gradient.

42. Diffusion and Osmosis Osmosis in Plant Tissues
Potato tissue soaked for 24 hours in five different molar solutions of sucrose; n = 16.

43. Controlling Movement Across Membranes
The sodium-potassium pump generates a membrane potential 43

44. Maintenance of Membrane Potential by Ion Pumps
Membrane potential is the voltage difference across a membrane. THAT CAN BE USED TO DO WORK.
Membrane potential is a product of an electrochemical gradient the forms when there are more positive ions on one side of the membrane than negative ions on the other side of the membrane.
An electrogenic pump is a transport protein that generates the voltage across a membrane by pumping protons against their concentration gradient.

45. Membrane Potential at Work: Explain
Crash Course on Action Potential
How does this work?
What maintains resting potential?

46. What is the difference between membrane potential and water potential?

47. The Cell: A Living Unit Greater Than the Sum of Its Parts
Cells rely on the integration of structures and organelles in order to function.
E.g. macrophage function is a product of the emergent properties of cellular functions all working together.

48. Mitochondria and Chloroplasts
Mitochondria and chloroplasts change energy from one form to another.
Mitochondria are the sites of cellular respiration.
Chloroplasts are found only in plants and are the sites of photosynthesis.

49. How do we explain the presence of Mitochondria and Chloroplasts in eukaryotic cells?

50. Endosymbiotic Theory: Lynn Sagan (Margulis)
1967 paper: The Origin of Mitosing Eukaryotic Cells
Published after 15 tries in The Journal of Theoretical Biology

51. Mitochondria and Chloroplasts
Mitochondria and chloroplasts may have an extracellular origin (the Endosymbiotic Theory):
Contain their own DNA.
Contain their own ribosomes.
Contain a double membrane system.
Divide by binary fission.
Similar in size to “prokaryotic” cells.