Cell Metabolism and Mitosis

1. Cell Metabolism and Mitosis • Cellular Respiration • Total cell metabolism • Mitosis • Review of cells

2. Cell metabolism

3. Catabolic pathways:  break down larger molecules in to smaller ones (starch into sugar, proteins into amino acids, for example) releasing energy, most of which is lost as heat, but some can be stored as ATP Anabolic pathways:  Build up larger molecules from smaller component parts (for example, assembling proteins from amino acids, assembling lipid membranes from fatty acids).  These reactions use energy, usually provided by breaking high energy phosphate bonds of ATP

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

5. Oxygen and "cellular respiration” • Cells use carbohydrates to make ATP, which stores high energy bonds for anabolic pathways. • Oxygen allows for complete "burning" or catabolic breakdown of sugars in Krebs Cycle • But some ATP can be obtained in anaerobic, or pathways that are free of oxygen

6. Glycolysis

8. Kreb’s cycle

9. Electron transport chain

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

13. "Raw material" for anabolic or synthetic pathways • amino acids • fatty acids • nucleotides • sugars • Some cells can make most of these from crude and even inorganic material.  Some cells need to obtain these from environment

14. 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

15. Fermentation is oxygen-free respiration where organic molecules are ultimate electron acceptor.  Many groups of bacteria are fermenters.

16. 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!

17. Ecocyc—database of complete E. coli metabolism

18. 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.)

19. Blue Gene http://www.research.ibm.com/journal/sj/402/allen.html

20. GENETICS (the quick view—much more later) • Cells divide and pass on instructions coded in DNA of chromosomes • Each chromosome is a huge DNA molecule with coded information • DNA replicates to pass on information • DNA is transcribed to make proteins that run cell metabolism • Cancer—example of what happens when genetic control goes awry • Normal inheritance and meiosis

21. Mitosis—cell division • Why do cells divide? • Growth—so tissues/structures can become larger • Replacement—many tissues are constantly being replaced because they get worn out or used up. E.g. blood, skin, lining of gut, sperm • Repair—when tissues get damaged due to injury

22. Mitosis—what happens (overview) • DNA/chrosomes replicate (make exact copies • Copies line up at center of cell • Copies pulled to opposite ends of cells by centromeres/spindles • Cell membrane pinches off and splits cell into two

23. Mitosis—details/stages 1. Prophase 3. Anaphase 4. Telophase 2. Metaphase

24. Chromosomes condense and become visible Nuclear envelope fragments Nucleolus disappears Centrosomes move to opposite poles Spindle fibers appear and attach to the centromere 1. Mitosis: Prophase

25. Chromosomes line up at the middle of the cell (equator) Fully formed spindle 2. Mitosis: Metaphase

26. Sister chromatids separate at the centromeres and move towards the poles 3. Mitosis: Anaphase

27. Chromosomes arrive at the poles Chromosomes become indistinct chromatin again Nucleoli reappear Spindle disappears Nuclear envelope reassembles Two daughter cells are formed by a ring of actin filaments (cleavage furrow) 4. Mitosis:Telophase and cytokinesis

28. Mitosis—constant, fast, keeps body functioning • Remember, mitosis produces two identical daughter cells • Mitosis is constantly happening in your body to allow for growth, replacement and repair • While you read this slide, millions of new cells were produced by mitosis in the tissues of your body! • Don’t forget cellular scale and intelligence—it’s a whole planet happening at the sub-microscopic level

29. Review of class so far

30. The Carbon-chain Molecules of Life

31. 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

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

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

35. Cell metabolism

36. 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?

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

38. Ecocyc—database of complete E. coli metabolism E. Coli Metaobolism website

39. Mitosis—cell division • Why do cells divide? • Growth—so tissues/structures can become larger • Replacement—many tissues are constantly being replaced because they get worn out or used up. E.g. blood, skin, lining of gut, sperm • Repair—when tissues get damaged due to injury

40. Mitosis—what happens (overview) • DNA/chrosomes replicate (make exact copies • Copies line up at center of cell • Copies pulled to opposite ends of cells by centromeres/spindles • Cell membrane pinches off and splits cell into two

41. This initial review of life and cells is crucial! • Please read your book chapters, review the web links and get this part of the course. • We’ll come back to cells and how they work again and again. • I am aware this is a LOT of information! • But master this, and the rest of the course will seem easy.