Recap

1. Recap • Biochemistry • If you had to boil the previous unit down into four main ideas, what would they be?

2. Pre-Assessment • 1. What are the differences between a bacterial cell and one of your cells? • 2. Rank these in order from smallest to largest: Organism, organelle, atom, cell • 3. Name as many cell organelles as you know. • 4. How do things get in and out of a cell? • 5. The earliest cells that evolved were most similar to which: animal, plant, or bacteria cells?

3. Chapter 7: Cell Structure and Function

4. Section 7-1:Life is Cellular

5. Two Categories of Cells: Prokaryotes: • Small and simple cells • Do NOT contain a nucleus • Do NOT contain membrane-bound organelles • NEVER multicellular • Examples: bacteria Eukaryotes: • Large and complex cells • Contain a nucleus • Contain membrane-bound organelles • Some multi-, some uni- • Examples: animals, plants, fungi, protists

6. Prokaryote or Eukaryote? • Eukaryote (Paramecium, a protist) 200 µm long

7. Prokaryote or Eukaryote? • Prokaryotes (Streptococcus bacteria) Each = .7 µm (micrometers) diameter

8. Prokaryote or Eukaryote? • Eukaryote (Homo sapiens dermis) Each = 250 µm long

9. Prokaryote or Eukaryote? • Prokaryotes (Spirillum bacteria) Each = 30 µm long

10. Prokaryote or Eukaryote? • Eukaryote (Onion Allium cepa root) Each = 350 µm long

11. Prokaryote or Eukaryote? • Eukaryote (Rat adrenal gland tissue) Each = 350 µm long

12. Categories of Cells • The first cells to evolve on earth most closely resembled modern-day prokaryotes. • Eukaryotes first evolved more than 1 billion years later. • Pro = Latin prefix meaning “forward”

13. Section 7-2Cell Structures

14. Cell Structures • FYI • Cell organelle = Specialized cell part with a specific function. “Little organ.” • What you must know about each cell organelle: • Its function • Its appearance and location in the cell • What kinds of cell have it (prokaryotes (bacteria) vs animals vs plants vs fungi vs protists)

15. Cell Membrane • Thin, flexible barrier around the cell • Regulates what enters and exits the cell • Food & water pass into cell, wastes pass out • ALL cells have one

16. Cell Wall • Found in plants, fungi, and bacteria but NOT animal cells • Lies outside the cell membrane • Made from fibers of carbohydrate (cellulose) and protein • Provides support and protection for cell, no regulation function like cell membrane

17. Cytoplasm • The “goo” that the inside of the cell is filled with, and all the interior organelles

18. Cytoskeleton • Network of protein filaments called microtubules and microfilaments • Microtubules: • move organelles within the cell • help with cell movement (cilia/flagella) • Microfilaments: • help maintain cell shape

19. Movement Organelles • Three modes of cell movement: • Cilia • Short hairlike microtubules • Flagella • Long whiplike microtubules • Pseudopods • Projections of cell cytoplasm

20. Nucleus • stores genetic information (DNA) which controls most cell processes Parts of the nucleus: • Nucleolus – small dense region in the nucleus where ribosomes are assembled • Nuclear Membrane – forms the outside of the nucleus, has thousands of nuclear pores that allow materials to move in and out of nucleus

21. Ribosome • small particle made of RNA and protein • location of protein synthesis (where proteins are polymerized by bonding amino acids together in a chain)

22. Network of folded membranes Smooth ER: No ribosomes Assembles cell membrane lipids Rough ER: Covered w/ ribosomes Chemically modifies proteins Receives protein from ribosomes, sends it to golgi when done Endoplasmic Reticulum (ER)

23. Golgi Apparatus • Stack of membranes • Packages and marks proteins and other molecules for their final destination elsewhere in the cell

24. Lysosome • small sac filled with enzymes • breaks down unwanted materials into smaller molecules that the cell can reuse • Breaks down: waste, debris, damaged organelles, invading or consumed bacteria

25. Vacuole • small or large sac • stores materials like water, salts, proteins, carbohydrates • also can transport substances within cells • very large in plant cells

26. Chloroplast • in plants, some protists, some bacteria • conducts photosynthesis: uses energy from sunlight to make the energy-rich food molecule glucose • has a green pigment called chlorophyll

27. Mitochondrion • Plural: mitochondria • extracts energy from food molecules to “charge up” ATP • Energy used to power cell growth, movement, reproduction, survival

28. Coordinated Action • Cell organelles work together to achieve the cell’s survival functions, such as: • Getting energy to live and do nearly everything else on this list • Maintaining the cell’s structure • Protect the cell • Making proteins • Building and repairing other organelles • Disposing of waste • Movement • Storing macromolecules produced • How many connections can YOU map out in a basic plant cell?

29. Cell Membrane – Cell Wall – Nucleus – Ribosome – ER – Golgi Apparatus – Lysosome – Vacuole – Chloroplast – Mitochondrion – border patrol fence surrounding the city city hall factory trucking company post office recycling center storage company restaurant power plant A Cell Is Like A City

30. Plant Cell

31. Animal Cell

32. Comparing Cells

33. Organelle DNA • Chloroplasts and mitochondria have prokaryote DNA that’s essential for their function. • Lynn Margulis – discovered endosymbiotic theory, found that mitochondria and chloroplasts are actually descendants of ancient prokaryotes • Endosymbiosis – eukaryotic cells were first formed from a symbiosis among several different prokaryotic organisms

34. Section 7-3Movement Through the Membrane

35. Cell Membrane • Made of phospholipids and proteins. • Its structure determines its functions • Phospholipid:

36. Cell Membrane • Hydrophilic = Attracted to water (“Loves” water) • Hydrophobic = Repelled from water (“Fears” water) • Phospholipid’s phosphorus “head” = hydrophilic. • Fatty acid tails = hydrophobic.

37. Cell Membrane • What do phospholipids do in water? • Form a lipid bilayer (also called phospholipid bilayer)

38. Cell Membrane • Lipid bi-layer is flexible, but hydrophobic/hydrophilic action makes it tough because it never parts or splits on its own. • “Semi-permeable” or “selectively permeable” = allows some substances to pass through but not others

39. Fluid mosaic modelhttp://telstar.ote.cmu.edu/biology/downloads/membranes/index.html • Membrane proteins run through the lipid bi-layer: • Channel Proteins – help transport materials in & out of cell • Receptor Proteins – receive chemical signals from outside cell • Marker Proteins – stick off cell surface to act as identification tags so cells can recognize one another

40. Cell Membrane • Because the cell membrane is a hydrophilic/hydrophobic phospholipid bilayer, with transport protein channels inserted periodically, it has four ways for substances to pass through. • Know how each way works, and be able to tell the difference between them • Three of these ways happen through diffusion…

41. Diffusion Across the Membrane • Diffusion = molecules move from an area of high concentration to an area of low concentration • Happens automatically because molecules are constantly moving. Molecules or cell don’t choose or make it happen.

42. Diffusion Across the Membrane • Simple diffusion = The diffusion of small, non-polar, hydrophobic molecules through the membrane bilayer • Requires no energy • Only small molecules do it because only they can fit in between the phospholipids. Only non-polar, hydrophobic molecules can do it because the hydrophobic fatty acid tails will reject and repel hydrophilic molecules • Examples: oxygen and carbon dioxide

43. Facilitated Diffusion • Facilitated diffusion – molecules diffuse across the cell membrane through channel proteins • Requires no energy • Used to allow molecules to diffuse that can’t go through simple diffusion (too big or hydrophilic) • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffusion_works.html

44. Osmosis • Osmosis – simple diffusion of water across a membrane • Requires no energy • Will change the water levels in a container, or the shape of a cell • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

45. Osmotic Pressure • Isotonic solutions = The solutions on either side of the membrane have the same concentration • Osmosis in isotonic solution… Water moves in and out equally

46. Osmotic Pressure • When the solutions do not have the same concentration… more concentrated solutes = hypertonic, less concentrated solutes = hypotonic • Hyper = High, like “hyperactive” • Hypo = Low, like “hypothermia”

47. Osmotic Pressure • In hypertonic solution (outside of cell has more solutes), water flows out, cell shrivels.

48. Osmotic Pressure • In hypotonic solution (inside of cell has more solutes), water moves in, cell swells.

49. Osmotic Pressure • Which of these blood samples was placed in which kind of solution? Hypertonic, hypotonic, isotonic?

50. Active Transport • Active transport – molecules move against a concentration gradient, from an area of low concentration to high concentration • Cell spends ENERGY and uses a transport protein to force molecules to move against the direction of diffusion.