AP Biology Discussion Notes

1. AP Biology Discussion Notes Tuesday 10/7/2014

2. Goals for the Day • Become familiar with the cell organelles and their functions. • Be able to describe the function of specific organelles, and which types of organisms have them • Describe how things are transported in/out of the cell

3. Question of the Day What is osmosis & what kind of transport would it be considered?

4. Question of the Day What is osmosis & what kind of transport would it be considered?

5. The “tonics”

6. Hypotonic

7. Isotonic

8. Hypertonic

9. Species of the day 10/6 Curculio spp. • Acorn Weevil

10. Species of the day 10/6 Curculio spp. • Acorn Weevil Do the acorn and the weevil share the same cell parts? EXPLAIN your answer!

11. Structures of Plant Cells Plants have three(for now) unique structures that are not found in animal cells: • Cell Wall • Chloroplasts • Central Vacuole

12. Cell Wall • Provides Structure and Support • Contains cellulose ( in plants) • Contains _______ in Fungi • Contains ______________ in bacteria • Allows the cell to build pressure

13. Cell Walls of Plants • The cell wall is an extracellular structure that distinguishes plant cells from animal cells • Prokaryotes, fungi, and some protists also have cell walls • The cell wall protects the plant cell, maintains its shape, and prevents excessive uptake of water • Plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein

14. Plant cell walls may have multiple layers • Primary cell wall: relatively thin and flexible • Middle lamella: thin layer between primary walls of adjacent cells • Secondary cell wall (in some cells): added between the plasma membrane and the primary cell wall • Plasmodesmata are channels between adjacent plant cells

15. Figure 6.28 Secondarycell wall Primarycell wall Middlelamella 1 m Central vacuole Cytosol Plasma membrane Plant cell walls Plasmodesmata

16. Plasmodesmata in Plant Cells • Plasmodesmataare channels that perforate plant cell walls • Through plasmodesmata, water and small solutes (and sometimes proteins and RNA) can pass from cell to cell

17. Figure 6.31 Cell walls Interiorof cell Interiorof cell Plasma membranes Plasmodesmata 0.5 m

18. Central Vacuole Central Vacuole: Most of a plant cell’s volume is taken up by a large, membrane-bound space called the central vacuole. The central vacuole stores water and may contain ions, nutrients, and wastes.

19. Peroxisomes: Oxidation • Peroxisomes are specialized metabolic compartments bounded by a single membrane • Peroxisomes produce hydrogen peroxide and convert it to water • Peroxisomes perform reactions with many different functions • What does that remind you of???

20. Figure 6.19 1 m Chloroplast Peroxisome Mitochondrion

21. Chloroplast • Site of photosynthesis • Light Energy -> Chemical Energy • Double-membraned • Stacks of thylakoids

22. Mitochondria • Generate ATP from glucose • Generate ____________energy • Site of cellular respiration • Double membraned—cristae

23. Mitochondria & Chloroplasts • Unique features: • Both are energy-related organelles • Have two membranes • Have their own DNA • Reproduce independently of the cell • Have Ribosomes

24. Endosymbiotic(Endosymbiont)Theory • What does endomean? • What is symbiosis?

25. Endosymbiotic Theory If mitochondria and chloroplasts originally came from independent prokaryotes, what would be true of their DNA? (What do you know about the DNA of prokaryotes compared to Eukaryotes?)

26. Endosymbiotic Theory

27. Endoplasmicreticulum Nucleus Figure 6.16 Engulfing of oxygen-using nonphotosyntheticprokaryote, whichbecomes a mitochondrion Nuclear envelope Ancestor ofeukaryotic cells(host cell) Mitochondrion Engulfing ofphotosyntheticprokaryote At leastone cell Chloroplast Nonphotosyntheticeukaryote Mitochondrion Photosynthetic eukaryote

28. The cytoskeleton is a network of fibers that organizes structures and activities in the cell • The cytoskeleton is a network of fibers extending throughout the cytoplasm • It organizes the cell’s structures and activities, anchoring many organelles • It is composed of three types of molecular structures • Microtubules • Microfilaments • Intermediate filaments

29. Figure 6.20 10 m

30. Roles of the Cytoskeleton: Support and Motility • The cytoskeleton helps to support the cell and maintain its shape • It interacts with motor proteins to produce motility • Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton • Recent evidence suggests that the cytoskeleton may help regulate biochemical activities

31. Figure 6.21 Vesicle ATP Receptor formotor protein Microtubuleof cytoskeleton Motor protein(ATP powered) (a) Microtubule Vesicles 0.25 m (b)

32. Components of the Cytoskeleton • Three main types of fibers make up the cytoskeleton • Microtubulesare the thickest of the three components of the cytoskeleton • Microfilaments, also called actin filaments, are the thinnest components • Intermediate filamentsare fibers with diameters in a middle range

33. Table 6.1 5 m 10 m 10 m Column of tubulin dimers Keratin proteins Actin subunit Fibrous subunit (keratinscoiled together) 25 nm 812 nm 7 nm Tubulin dimer  

34. Table 6.1a 10 m Column of tubulin dimers 25 nm Tubulin dimer  

35. Table 6.1b 10 m Actin subunit 7 nm

36. Table 6.1c 5 m Keratin proteins Fibrous subunit (keratinscoiled together) 812 nm

37. Microtubules • Microtubules are hollow rods about 25 nm in diameter and about 200 nm to 25 microns long • Functions of microtubules • Shaping the cell • Guiding movement of organelles • Separating chromosomes during cell division

38. Centrosomes and Centrioles • In many cells, microtubules grow out from a centrosome near the nucleus • The centrosome is a “microtubule-organizing center” • In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring

39. Figure 6.22 Centrosome Microtubule Centrioles 0.25 m Longitudinalsection ofone centriole Microtubules Cross sectionof the other centriole

40. Cilia & Flagella • What would be the function in 1 word?

41. Organelles Organized

42. Species of the Day • Resurrection Plant - Selaginellalepidophylla • This plant belongs to the Lycophyta and has the oldest known lineage of any VASCULAR plant. Being as this plant represents one of the most primitive vascular plants.

43. Species of the Day • Resurrection Plant - Selaginellalepidophylla • Predict how long it would take for this plant to begin to be active again.