Cells—the fundamental unit of life

1. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

2. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

3. What is Life? • Life needs energy • Life reproduces • Life grows and develops • Life maintains a stable condition—homeostasis • Life responds to stimulus • Life is organized because it has evolved

4. Humans Evolve • Life is organized hierarchically • Evolution explains organization at every level of hierarchy • Humans can be understood at every level of hierarchy • Humans have evolved and are evolving

5. Cells are fundamental unit of life • Cells are the basic and fundamental unit of life • The first life was cellular life • The Molecules of Life are what cells and all their internal parts are made up of

6. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

7. The Carbon-chain Molecules of Life

8. Carbohydrates • Components are simple sugars • Used for energy storage in complex form • Broken down to simple sugars to fuel cellular metabolism in mitochondria • So, why are simple sugars bad for us? And why do we love them so much? (p. 29 in text)

9. Proteins • Components are amino acids • Very complicated • Amino acid chain folds up to give complex form • Complex form allows for catalyzing very specific chemical reactino • GenBlue

10. Fats/Lipids • Fundamental to life and origins—separate cell interior from environment as cell membrane • Mammals and other vertebrates—long-term energy storage • Role in diet=big controversy!

11. DNA/RNA (Nucleic Acids) • DNA and RNA store and use information • Components are nucleotides or “bases” (A,C,T/U,G) • One DNA molecule can be very long and complex—millions of bases long • DNA duplicates to pass on information • Transcription to mRNA to be translated into protein’s amino acid chain • What do proteins do?

12. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

13. Cells are fundamental unit of life • Cells are the basic and fundamental unit of life • The first life was cellular life • The Molecules of Life are what cells and all their internal parts are made up of

14. Two types of cells • Prokaryotic cells • Relatively Simple • Relatively Small • No organelles with Molecules of Life distributed throughout cytoplasm • Bacteria are all prokaryotic cells • Eukaryotic cells • More complex • Much bigger (100 x size of prokaryotic cells) • Internally organized with membrane-bound organelles • Multi-cellular organisms, like plants and animals, are all made up of eukaryotic cells

15. Eukaryotic cell

16. Endosymbiotic origin of mitochondria and chloroplasts • Eukaryotic cells evolved from fusion or integration of prokaryotic cells • Best evidence is in bacterial or prokaryotic appearance of mitochondria and chloroplasts • These organelles are like little bacterial cells within our cells, now fully functionally integrated • They perform fundamental cell functions. Mitochondria process sugars to produce energy; chloroplasts make sugars by photosynthesis • But they maintain their own DNA and genetic control

17. Prokaryotic cells have: • Cell membrane • DNA molecule loose in cytoplasm • Small Ribosomes where proteins are assembled from DNA information • Microtubule structures like flagella and cilia • Mitochondria and chloroplasts share most of these features, including their own independent DNA

18. Eukaryotic cells (like our human cells) have: WHAT EUKARYOTIC CELLS HAVE: • Cell membrane • Nucleus • Mitochondria (and sometimes chloroplasts for photosynthesis) • Larger ribosomes for protein assembly from DNA information • Internal membranes that organize cellular spaces and distribution of Molecules of Life within cell (“cytoskeleton”)

20. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

21. A cell membrane or plasma membrane separates cell from outside world—creates ability to regulate internal environment (homeostasis)

22. cell membrane

23. cell membrane What are some characteristics of the plasma membrane? • It is a phospholipid bilayer • It is embedded with proteins that move in space • It contains cholesterol for support • It contains carbohydrates on proteins and lipids • Selectively permeable

24. cell membrane What does selectively permeable mean? • The membrane allows some things in while keeping other substances out

25. cell membrane How do things move across the plasma membrane? 1. Diffusion 2. Osmosis 3. Facilitated transport 4. Active transport 5. Endocytosis and exocytosis

26. cell membrane What are diffusion and osmosis? • 1. Diffusion is the random movement of molecules from a higher concentration to a lower concentration • 2. Osmosis is the diffusion of water molecules

27. cell membrane How does tonicity change a cell? • Hypertonic solutions have more solute than the insideof the cell and lead to lysis (bursting) • Hypotonic solutions have less solute than the inside of the cell and lead to crenation (shriveling) • Isotonic solutions have equal amounts of solute inside and outside the cell and thus does not affect the cell

28. cell membrane What are facilitated diffusion and active transport? • 3. Facilitated transport is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier • 4. Active transport is the movement of molecules from a lower to higher concentration using ATP as energy; requires a protein carrier

29. What are endocytosis and exocytosis? cell membrane • 5. Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle • 6. Exocytosis transports molecules outside the cell via fusion of a vesicle with the plasma membrane

30. Protein synthesis • Remember that proteins control cell metabolism—how and where are they made, or synthesized in the cell?

31. Protein synthesis What structures are involved in protein synthesis? • Nucleus • Ribosomes • Endomembrane system

32. Bound by a porous nuclear envelope Houses DNA and associated proteins called chromatin Contains nucleoplasm Nucleolus region(s) that contain ribosomal RNA (rRNA) What is the structure and function of the nucleus? Protein synthesis

33. Protein synthesis What is the structure and function of ribosomes? • Organelles made of RNA and protein • Found bound to the endoplasmic reticulum and free floating in the cell • Site of protein synthesis

34. Protein synthesis What is the endomembrane system? • A series of membranes in which molecules are transported in the cell • It consists of the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes and vesicles

35. How does the endomembrane system function and appear? Protein synthesis

36. Protein synthesis Summary of the parts of the endomembrane system? • Rough endoplasmic reticulum – studded with ribosomes used to make proteins • Smooth endoplasmic reticulum – lacks ribosomes but aids in making carbohydrates and lipids • Golgi apparatus – flattened stacks that process, package and deliver proteins and lipids from the ER • Lysosomes – membranous vesicles made by the Golgi that contain digestive enzymes • Vesicles – small membranous sacs used for transport

37. Both are made of microtubules Both are used in movement Cilia are about 20x shorter than flagella What are cilia and flagella?

38. A highly folded organelle in eukaryotic cells Produces energy in the form of ATP They are thought to be derived from an engulfed prokaryotic cell What do mitochondria do and what do they look like?

39. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

40. Occurs in the mitochondria Production of ATPin a cell Usually glucose is main “energy” molecule enters cellular respiration Includes: Glycolysis Citric acid cycle 3. Electron transport chain What is cellular respiration?

41. What other molecules besides glucose can be used in cellular respiration? • Other carbohydrates • Proteins • Lipids

42. How can a cell make ATP without oxygen? • Fermentation • Occurs in the cytoplasm • Does not require oxygen • Involves glycolysis • Makes 2 ATP and lactate in human cells • Is important in humans for a burst of energy for a short time

43. All of cell metabolism • Cell metabolism is much more than simply making ATP, or cellular respiration, which is just how the cell has an energy supply. • What does the cell do with that energy? • Get ready for what you are about to see… • The cell runs all the reactions that make it alive—see the first part of this presentation: grow, reproduce, develop, move, maintain internal homeostasis, respond to stimuli. • This involves a LOT of chemical reactions. • Here it is: most of the reactions involved in keeping the simplest of cells—an E. coli bacteria—alive!

44. Ecocyc—database of complete E. coli metabolism

45. What’s it all mean? • Every little box represents a stage in a particular chemical reaction. The sum of those reactions is the total cell metabolism—what makes the cell alive! • You’ll actually visit the ecocyc database under the web links for this section as the last thing you do • Remember three things: • every one of these reactions is catalyzed by a protein • The amino acid sequence for those proteins are coded for in the DNA • The world’s biggest super-computers are trying to figure out how, based on their unique amino acid sequence, all the different cellular proteins take on the particular shape they have, and control the particular reaction they catalyze. (You’ll also visit the Blue Gene IBM super-computer website in the web links for this section.)

46. Blue Gene

47. Cells—the fundamental unit of life • What is life? • Molecules of life • Cell as fundamental unit • Cell membranes and organelles • Cell metabolism • Cells organized into tissues • Types of tissues

48. What is a tissue? • Multi-cellular organisms are composed of millions and millions of cells whose metabolism is organized to work together. • A tissue is a collection of cells of the same type that perform a common function • There are 4 major tissue types in the body: • Connective • Muscular • Nervous • Epithelial

49. How many cell types?How many cells? • Each class of tissue might include a number of different cell types. In total, our bodies have a few hundred different types of cells • How many total cells are in our body?

50. How many cells are in an adult human? Lots. More than anyone could count, and the bigger you are the more cells there would be. Growth is a process of cellular reproduction, so as you grow bigger you are made up of more cells. Following a similar logic, a larger person is larger because they have more cells, not because their cells are larger. In fact, cell types have a fairly uniform size across the entire human species. The largest and smallest cells in the human body are the gametes, or the sex cells. The female sex cell, the oocyte, is about 35 microns in diameter, which puts it just on the edge of being visible if you have real good eyes. The male sex cell, spermatozoan, cell is only about 3 microns in diameter, and therefore is the smallest cell of the human body. Various other cell types have various other sizes within this range. Although no exact number can be given, the order of magnitude of the number of cells in a human body can be approximated to 10 14 or one hundred trillion cells. Source: MadSci Network http://www.madsci.org/posts/archives/mar98/889221957.An.r.html