1. A tour of a cell

2. Key Concepts To study cells, biologists use microscopes and the tools of biochemistry Eukaryotic cells have internal membranes that compartmentalize their functions The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes The endomembrane system regulates protein traffic and performs metabolic functions in the cell Mitochondria and chloroplasts change energy from one form to another The cytoskeleton is a network of fibers that organizes structures and activities in the cell

3. Early encounters with cells

4. Cell theory emerges Every organism consists of one or more cells The cell is the structural and functional unit of life A cell is the smallest unit of life Cells contain hereditary information which they pass on to their offspring during division

5. Our ability to study cells has improved dramatically Light microscope uses visible light to illuminate a specimen.

6. Our ability to study cells has improved dramatically Fluorescence microscope allows users to view light emitted from the specimen when it is illuminated with a specific wavelength of light.

7. Our ability to study cells has improved dramatically Electron microscopes use electrons instead of light. -Transmission electron microscope- electrons form an image after passing through the specimen -Scanning electron microscope- image forms from electrons that bounce off the surface of the specimen

8. What have we learned about cells? There are two main types of cells, prokaryotic and eukaryotic ProkaryotesEukaryotes How are they similar? Which organisms fall into each category? How do they differ?

9. ProkaryotesEukaryotes How are they similar? Which organisms fall into each category? How do they differ?

10. ProkaryotesEukaryotes How are they similar? -All cells have a plasma membrane -All cells contain DNA -All cells contain ribosomes -All cells have cytosol (fluid mixture of water sugar, ions, proteins) -All cells are small (need a large surface are to volume ratio) Which organisms fall into each category? How do they differ?

11. ProkaryotesEukaryotes How are they similar? -All cells have a plasma membrane -All cells contain DNA -All cells contain ribosomes -All cells have cytosol (fluid mixture of water sugar, ions, proteins) -All cells are small (need a large surface are to volume ratio) Which organisms fall into each category? -Bacteria -Archea -Eukaryotes (plants, animals, protists, fungi) How do they differ?

12. ProkaryotesEukaryotes How are they similar? -All cells have a plasma membrane -All cells contain DNA -All cells contain ribosomes -All cells have cytosol (fluid mixture of water sugar, ions, proteins) -All cells are small (need a large surface are to volume ratio) Which organisms fall into each category? -Bacteria -Archea -Eukaryotes (plants, animals, protists, fungi) How do they differ? -Single celled -Not divided into functional compartments -small in size (1-5µm) -cell wall surrounding the plasma membrane -single chromosome in a nucleoid region (not membrane-enclosed) also in plasmids (small circular strands of DNA) -Can be multicellular -Divided into functional compartments (or organelles) -larger in size (10-100µm) -not all eukaryotes have a cell wall surrounding the plasma membrane -many chromosomes in a nucleus (membrane- enclosed)

13. An overview of the eukaryotic cell Watch the animal and plant cell videos

14. The cell as a city

15. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes

16. Nucleus Enclosed by the nuclear envelope Contains most of the genes in the eukaryotic cells DNA is organized into chromosomes inside the nucleus Contains a nucleolus-a place of RNA and ribosome synthesis

17. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes Nucleus Enclosed by the nuclear envelope Contains most of the genes in the eukaryotic cells DNA is organized into chromosomes inside the nucleus Contains a nucleolus-a place of RNA and ribosome synthesis What is a ribosome?

18. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes Ribosomes Complexes of rRNA and proteins They are located on the ER or free in cytoplasm Their function is protein synthesis

19. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes

20. Are there analogous entities in a city? DNA Nucleus Nuclear envelope Ribosomes

21. The endomembrane system regulates protein traffic and performs metabolic functions in the cell

22. Endomembrane system Includes: Nuclear envelope ER Golgi Lysosomes Vacuoles Plasma membrane

23. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Endoplasmic reticulum Smooth v. Rough Smooth ER lacks ribosomes Involved in synthesis of lipids, metabolism of carbohydrates, and detoxification of poisons Rough ER Has attached ribosomes Makes proteins and phospholipids Smooth ER Rough ER Nuclear envelope Rough ER Smooth ER ER lumen 200 nm

24. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Endoplasmic reticulum Smooth v. Rough Smooth ER lacks ribosomes Involved in synthesis of lipids, metabolism of carbohydrates, and detoxification of poisons Rough ER Has attached ribosomes Makes proteins and phospholipids Smooth ER Rough ER Nuclear envelope Rough ER Smooth ER ER lumen 200 nm Transport vesicles-transport materials from the ER to the Golgi

25. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Golgi Looks like a stack of pancakes

26. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Golgi Looks like a stack of pancakes Receives, modifies, manufactures, and stores products of the ER cis face (“receiving” side of Golgi apparatus) trans face (“shipping” side of Golgi apparatus)

27. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Golgi Looks like a stack of pancakes Receives, modifies, manufactures, and stores products of the ER Has a cis and trans side cis face (“receiving” side of Golgi apparatus) trans face (“shipping” side of Golgi apparatus)

28. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Lysosomes (digestive compartments in animal cells) Sac filled with hydrolytic enzymes (produced by the Golgi) Its function is to digest macromolecules Monomers are released to the cytosol for reuse Nucleus 1 µm Lysosome Digestive enzymes Lysosome Plasma membrane Food vacuole (a) Phagocytosis Digestion (b) Autophagy Peroxisome Vesicle Lysosome Mitochondrion Peroxisome fragment Mitochondrion fragment Vesicle containing two damaged organelles 1 µm Digestion

29. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Vacuoles Have diverse roles Important in storage Can conduct hydrolysis Central vacuole in plants Hold reserves of organic compounds Sequester toxins Helps maintain turgor Central vacuole Cytosol Central vacuole Nucleus Cell wall Chloroplast 5 µm

30. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Smooth ER Nucleus Rough ER Plasma membrane cis Golgi trans Golgi

31. The endomembrane system regulates protein traffic and performs metabolic functions in the cell Are there analogous entities in a city? Endoplasmic reticulum Golgi Lysosomes Vacuoles Plasma membrane

32. Mitochondria and chloroplasts change energy from one form to another

33. Mitochondria Found in all eukaryotic cells (about 1-10 µm long) Contains DNA Double membrane-bound organelle Can reproduce on their own Sites of cellular respiration Free ribosomes in the mitochondrial matrix Intermembrane space Outer membrane Inner membrane Cristae Matrix 0.1 µm

34. Mitochondria and chloroplasts change energy from one form to another Chloroplasts Found in plants Contains DNA More than one membrane Can reproduce on their own Enable plants to convert solar energy to chemical energy (via photosynthesis) Ribosomes Thylakoid Stroma Granum Inner and outer membranes 1 µm

35. Mitochondria and chloroplasts change energy from one form to another Specialized metabolic compartments Bounded by a single membrane Peroxisomes produce hydrogen peroxide and convert it to water Oxygen is used to break down different types of molecules (i.e. fatty acids) Peroxisomes Chloroplast Peroxisome Mitochondrion

36. Mitochondria and chloroplasts change energy from one form to another

37. Are there analogous entities in a city? Chloroplasts Mitochondria

38. The cytoskeleton is a network of fibers that organizes structures and activities in the cell

39. The functions of the cytoskeleton are diverse Gives mechanical support to maintain cell shape Providing anchoring for organelles Can change the shape of a cell Can move a cell from point A to point B Can move cell parts

40. The cytoskeleton is a network of fibers that organizes structures and activities in the cell The components of the cytoskeleton are diverse Microtubules Microfilaments Intermediate filaments

41. The cytoskeleton is a network of fibers that organizes structures and activities in the cell Microtubules What are they? Hollow rods 25 nm in diameter Made of tubulin Cable of growing and shrinking by adding or subtracting tubulin What do they do? Compression resistant Shape and support the cell Tracks along which cellular components move

42. The cytoskeleton is a network of fibers that organizes structures and activities in the cell Microtubules Cilia and flagella Microtubule-containing extensions of the cell Locomotion appendages Both are made of a core of microtubule sheathed in an extension of the plasma membrane Cilia and flagella are anchored by a basal body Eukaryotes have a 9 + 2 arrangement Each doublet has a dynein (motor protein) associated with it

43. The cytoskeleton is a network of fibers that organizes structures and activities in the cell Microfilaments What are they? Solid rods (7nm in diameter) Twisted double chain of actin subunits Can also form branched networks What do they do? Withstand tension (pulling forces) Network of microfilaments inside the plasma membrane keep cell shape (the cortex) Important in muscle contraction Muscle cell Actin filament Myosin filament Myosin arm (a) Myosin motors in muscle cell contraction Cortex (outer cytoplasm): gel with actin network Inner cytoplasm: sol with actin subunits Extending pseudopodium (b) Amoeboid movement Nonmoving cortical cytoplasm (gel) Chloroplast Streaming cytoplasm (sol) Vacuole Cell wall Parallel actin filaments (c) Cytoplasmic streaming in plant cells

44. The cytoskeleton is a network of fibers that organizes structures and activities in the cell Intermediate filaments What are they? Fibrous proteins supercoiled into thicker cables 8-12 nm Formed from diverse proteins including keratins What do they do? Maintain cell shape (tension- bearing elements) Anchor the nucleus and other organelles

45. The cytoskeleton is a network of fibers that organizes structures and activities in the cell

46. Key Concepts To study cells, biologists use microscopes and the tools of biochemistry Eukaryotic cells have internal membranes that compartmentalize their functions The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes The endomembrane system regulates protein traffic and performs metabolic functions in the cell Mitochondria and chloroplasts change energy from one form to another The cytoskeleton is a network of fibers that organizes structures and activities in the cell