Cells

1. Cells Cytology

2. I. The Cell Theory 2.1.1 • Made up of three parts: • All living things are made up of cells • Cells come from other cells • Cells are the basic unit of structure of all living things

3. THE CELL THEORY 2.1.2 • Evidence to support the cell theory: • Robert Hooke first views “cells” in cork (1665) • Anton von Leeuwenhoek views living cells in algae (1674) • Schwann and Schleiden study plants and come up with the theory (1838) • Improved microscopes have allowed for a more exact study of living things, and no organism has been discovered that is not made of cells

4. Arguable “EXCEPTIONS” to the Cell Theory: • Some tissue has extracellular material (like tooth dentine), and the cells make up only a tiny percentage of the total tissue volume • Skeletal muscle “cells” contain hundreds of nuclei each (and can be 30 cm in length) • Hyphae cells in fungus are continuous due to septa, and have many nuclei • Viruses are non-cellular (and thus debatably “non-living” • Consist of only DNA or RNA surrounded by a protein coat

5. Unicellular organisms are unique (and argued by some to be “acellular”) because they carry out all the Functions of Life within a single cytoplasm… (2.1.3)

6. Functions Of Life • Metabolism – chemical reactions necessary for life • Response • Homeostasis – maintenance of internal stability (equilibrium) • Growth • Reproduction • Nutrition

7. Stem Cells (2.1.9 & 2.1.10) • Stem Cells are unique cells that are undifferentiated, meaning that they don’t yet have an identity, or function. • Depending on the type of stem cell, they may be induced to become any particular type of cell. • Due to the work of Christopher Reeve, stem cells are now being use to regrow neural tissue (in mice.) There are between 10 and 100 trillion cells in a human body. There are also approx half as many bacteria in there as well. Each cell has ~ 30,000 genes, and about 3 billion nucleotide pairs. There are ~100 billion neurons in the brain, and about 25 times as many support cells (glia.)

8. 1 mm = 1 x 10-3 meters =1 “millimeter” 1 µm = 1 x 10-6 meters = 1 “micrometer” 1 nm = 1 x 10-9 meters = 1 “nanometer” Every step to the left represents an increase of 10X 1 mm10 µm 100 nm 1 nm (1 angstrom) 10 mm 100 µm 1 µm 10 nm 0.1 nm Resolution of human eye The size of a molecule (DNA = 2nm) Size of a virus Eukaryotic cells Thickness of a cell membrane Average bacteria 2.1.5 Size of organelles (varies)

9. II. Importance of Surface Area to Volume ratio in determining cell size (2.1.6) • Cells can not keep growing – they reach a maximum size and then divide

10. As the cell gets larger, the surface area to volume ratio gets SMALLER For a cube… • SidesS.A.VolRatio • 1 cm • 2 cm • 3 cm • 4 cm • 5 cm

11. As the cell gets larger, the surface area to volume ratio gets SMALLER For a cube… • SidesS.A.VolRatio • 1 cm 6 cm2 • 2 cm 24 cm2 • 3 cm 54 cm2 • 4 cm 96 cm2 • 5 cm 150 cm2

12. As the cell gets larger, the surface area to volume ratio gets SMALLER For a cube… • SidesS.A.VolRatio • 1 cm 6 cm2 1 cm3 • 2 cm 24 cm2 8 cm3 • 3 cm 54 cm2 27 cm3 • 4 cm 96 cm2 64 cm3 • 5 cm 150 cm2 125 cm3

13. As the cell gets LARGER, the surface area to volume ratio gets SMALLER For a cube… • SidesS.A.VolRatio • 1 cm 6 cm2 1 cm3 6 • 2 cm 24 cm2 8 cm3 3 • 3 cm 54 cm2 27 cm3 2 • 4 cm 96 cm2 64 cm3 1.5 • 5 cm 150 cm2 125 cm3 1.2

14. …cell size, cont’d • The rate that things can enter and leave a cell depend on thesurface area • The metabolic rate depends on volume • Cells that get too large can’t take in essential materials (food!) or excrete wastes quickly enough • The same principle holds true for heat – cells must be able to release it

15. Small cells are the most efficient, because they can easily transport materials throughout the cell… Example: Potato cubes (starch) in Iodine 1) 4 cm 2) 2 cm 3) 1 cm All blue/black

16. III. Prokaryotic vs. Eukaryotic“Before”“Nucleus”“True”“Nucleus” p5 in IBRB – 2.2.1 A. Prokaryotic Cell = “bacteria” Mesosome Ribosome Plasmid (DNA) Plasma Mem- brane cytoplasm Cell Wall Slime Capsule Ring-shaped chromosome (DNA) “Naked DNA”… (only loosely associated with proteins)

17. 2. 1. 4. 3. Basal Body 10. 5. 6. 8. 7. 9.

18. ...diagram explanation 2.2.2 Make sure you can label these things in an E. coli micrograph – use the IBRB! 2.2.3 • Ribosome – protein synthesis; 70s • Mesosome (extra)– increases the surface area of the plasma membrane for more ATP production; might move naked DNA to different ends of the cell during bacterial cell division (called binary fission) • Slime Capsule – protection; adhesion (tooth plaque) • Flagellum – movement

19. Cell Wall – protects from bursting or shrinking • Plasma Membrane – controls passage of material in and out of cells • Naked DNA (nucleoid)–stores genetic information; located in an area of the cell called the nucleoid; DNA not associated with histone proteins like eukaryotic DNA (thus naked) • Cytoplasm – contains enzymes to catalyze reactions important for metabolism • Pili- used for adhering to surfaces as well as joining to other bacteria in order to conjugate- that means SEX!!

20. Multi-cellular organisms vs. Unicellular organisms • Multicellular organisms All cells have the same DNA but… differentiated cells carry out specialized functions by expressing some of their genes but not others 2.1.8 • “cell differentiation” – when cells become specialized in structure and function • Unicellular organisms carry out all of the functions of life within a single cell 2.1.3

21. The heart is a single organ that comes together to form the cardiovascular system (an ORGAN SYSTEM) • Multicellular organisms show “emergent properties” (2.1.7) • When a number of simple entities (in this case cells) come together to form a more complex collective Cardiac tissue comes together to form the heart (an ORGAN) Cardiac muscle cells form this cardiac TISSUE

23. *Make sure you can label and annotate a diagram! 2.3.1, 2.3.2,2.3.3 B. Eukaryotic Cells • Nucleus – stores genetic material in chromatin (DNA mixed with proteins); during cell division the chromatin clumps into chromosomes; membrane bound • Ribosomes (free and rough)– make proteins, ribosomes have no membranes; 80s • In the cytoplasm or on the ER depending on what sort of proteins they produce (for the cell or to be secreted) • Endoplasmic reticulum – network of interconnecting tubes; continuous with the nuclear membrane; detoxifies molecules, produces lipids, metabolizes carbs, makes membranes …

24. Golgi body (apparatus) – accepts vesicles from the ER that contain proteins needing to be processed and exported from the cell (as glycoproteins, lipoproteins… glycolipids) • cis – end nearest to the nucleus and the ER • trans – face nearest to the cell membrane • Vesicles – membrane-bound “packages” in the cell used to transport molecules around safely… • Mitochondria – enclosed in an envelope of two phospholipid bilayers; site of cellular respiration (making ATP through catabolism) • Lysosomes – contains hydrolytic digestive enzymes to break the 4 major biological molecules down (so their parts can be used elsewhere)

25. Using all of the eukaryotic organelles, explain their functions as they work together to produce some cellular product.

26. C. Prokaryotic vs. Eukaryotic • See p. 6 in IBRB • (differ in type of DNA, location of DNA, presence of mitochondria for ATP synthesis, size of ribosomes (.70S vs .80S), and membrane-bound organelles) 2.3.4 • See p. 6 in IBRB • (differ in presence of cell wall, chloroplasts, and vacuole, type of carbohydrate used for storage, and shape) 2.3.5 D. Plant vs. Animal Cell

28. E. Extracellular components – the plant cell wall 2.3.6(wall protects, maintains shape, and prevents excessive water uptake) Microfibrils (bundles) of Cellulose Pectin (DON’ T WRITE): Pectin is an adhesive which helps to hold plant cells together (it is added to jam as a thickener, and removed from fruit juice with pectinase to keep it from solidifying) Cell wall is 10X-100X thicker than plasma membrane

29. Animal cell extracellular component: glycoproteins • These carbohydrate-protein molecules aid in support, adhesion (for cell-to-cell connection), and movement

30. IV. Movement in and out of cells 2.4.4 A. Diffusion – random movement of molecules from a high concentration to a low concentration

31. B. Osmosis- movement of water across a semi-permeable membrane from a low solute to a high solute concentration 2.4.4 Osmotic pressure is the pressure that water puts on something when it wants to cross a membrane 10% sucrose 90% water… bag is hypertonic 1% sucrose 99% water… water is hypotonic Bag will GAIN water.

32. *DON’T WRITE: Molecules will always diffuse with respect to their own concentration gradient… Here, water wants to move left, down its concentration gradient. Red circles want to move right, down their concentration gradient. Here, water wants to move left, down its concentration gradient Green circles want to move left, down their concentration gradient. Purple circles want to move right, down their concentration gradient.

33. *DON’T WRITE: This membrane is permeable to H2O, but not to the sugar molecules floating in it… what will happen?

34. *DON’T WRITE: …water will diffuse until the two sides are isotonic (in equilibrium)

35. Isotonic – both solutions have the same concentration of solute Potato 0.5 M glucose 0.5 M Solution of glucose There is NO net movement of glucose or water (equilibrium)

36. Solutions can be compared to others using two RELATIVE terms: • Hypertonic – higher solute concentration • Hypotonic – lower solute concentration • Water will always try to move towards the HYPERTONIC solution

37. *DON’T WRITE: Practice: • Q: Cell will shrink or swell? • A: Shrink, because the solution is hypertonic! 1% salt 99% water 5% salt 95% water

38. examples… • In animal cells: blood cells • In plants: RBC In hypotonic solution… water goes in In hypertonic solution, In hypotonic solution… water goes in In hypertonic solution, water leaves -could have plasmolysis! CELL BURSTS …LYSIS! Cell wrinkles Turgid Wilted RBC

39. The phospholipid bilayer has fluidity, which allows it to change shape…

40. Hydrophilic portion of the phospholipid will remain exposed to the water • the hydrophobic and hyrophilic properties of each phospholipid help to maintain the bilayer’s structure… 2.4.1, 2.4.2 Hydrophobic portion will stay away from the water, towards the middle Cholesterol molecules are also embedded along with hydrophobic tails (for structure) INTEGRAL PROTEIN PERIPHERAL PROTEIN

41. Functions of membrane proteins2.4.3 • Hormone binding sites – transmit a signal when a hormone is present • Enzymes • Electron carriers – pass electrons along • Channels for passive transport – allow a single substance to pass • Passive tranport = no energy necessary • Pumps for active transport – use ATP (ATP  ADP + P) as energy to push things through (oftentimes against their gradient) • p7 in IBRB

42. 2.4.5 and 2.4.6 • FACILITATED DIFFUSION (IBRB p8) – passive diffusion through a channel protein • ACTIVE TRANSPORT (IBRB p8) – unlike facilitated diffusion, it can be used to move substances into or out of the cell AGAINST their concentration gradient (this takes ATP energy and can be done through by protein pumps)

43. Phospholipid-bound bubbles called “vesicles” are used to transport materials within the cell… (2.4.6) • ENDOCYTOSIS – bringing thingsinto the cell via vesicles • EXOCYTOSIS – secreting things out of the cell via vesicles

44. In exocytosis… (2.4.7, 2.4.8) • Vesicles transport materials • Rough ER  Golgi  membrane