Locating the Specimen under the Microscope

1. Locating the Specimen under the Microscope 1. Place the slide on the stage with the specimen over the beam of light. 2. Always begin at the lowest power (scanning- 4x) with the stage at its highest point. 3. While looking through the microscope, slowly lower the stage using the course adjustment knob until the sample comes into focus. 4. Use the fine adjustment knob to sharpen the image. 5. Turn to the low power (10x) objective and fine focus the image. 6. Turn to the high power (40x) objective and fine focus until the image is clear.

2. Unit 3C Cell Structure and Function

3. Euk examples: -Protists (paramecium/ amoeba) -Fungi (mushrooms/ yeast) -Plants -Animals Prok examples: -Bacteria (Eubacteria, archaebacteria) 2 Main Categories of Cells • Prokaryotic Cells- DO NOT have “membrane bound” organelles and DO NOT have a nucleus to hold the DNA • Eukaryotic Cells- contain membrane bound organelles including a nucleus to hold the DNA

4. Differences and Similarities Between the Two Cell Types: (+ present, - absent) + + + + + smaller + larger + - + + - + Bacteria Protists, plants, fungi, animals

5. Eukaryotes • Are organisms that have eukaryotic cells (prokaryotes do not) • Examples: animals, plants, fungi, protists • We will mainly be discussing the parts of eukaryotic cells and comparing prokaryotic and eukaryotic cells to each other.

6. Cell Organization • The Nucleus (Euk only) • Controls all of the cell’s activities because it… • Contains and protects the DNA • Surrounded by the nuclear envelope double lipid bilayer with pores that regulates what enters/exits the nucleus • Contains the nucleolus area of the nucleus that makes ribosomes

7. Cell Organization (continued) • Cytoplasm- the portion of the cell outside of the nucleus • Found in both prok and euk • Contains an aqueous solution called cytosol containing solutes needed for metabolic reactions • Contains the organelles (in euk) Shade in the region showing the cytoplasm Shade in the region showing the cytosol

8. Cell Organization (continued) • Organelles- specialized structures inside the cell (“Little Organs”) • Mostly found in the cytoplasm • If membrane bound (surrounded by a membrane)- only found in euk

9. Summarize cell organization at the bottom of pg. 2

10. Organelles and Cell Structures • The following slides discuss the organelles of a cell, they fall into the following categories: 1. Cellular boundaries 2. Organelles that capture and release energy 3. Organelles that store, clean up, and support 4. Organelles that build proteins

11. Cellular Boundaries Boundaries keep certain things inside and certain things outside of the cell. • Cell Walls • Cell Membranes

12. A. Cell Walls • Support, shape, and protect the cell • Lie outside the cell membrane • Have openings allowing small molecules in and out (semipermeable, not selectively permeable). • Found in most prokaryotes, many eukaryotes (protists, fungi, and plant cells), but NOT in animal cells • Why not? • We need to move/be flexible

13. Cell Wall Composition • In bacteria- contains various carbohydrates • In protists- carbs and silica (SiO2) • In fungi- chitin (a type of carb) • In Plants- mostly cellulose (polysaccharide made of glucose monomers)

14. B. Cell (or Plasma) Membranes • Found surrounding all cells (prok or euk) • Made of a lipid bilayer • Protects and supports the cell • Regulates what comes in and out of the cell- selectively permeable

15. Proteins in Membrane The Fluid Mosaic Model • Flexible and contains many transport proteins that help move materials in and out and help cells communicate. • Carbs on the outer surface help with communication and identification of the cell. Carbohydrates attached to proteins

16. Summarize cellular boundaries at the bottom of pg. 4.

17. Organelles that Capture and Release Energy Are membrane bound and thus found in eukaryotic cells only • Chloroplasts- found in plant cells; are the location of photosynthesis • Mitochondria- found in both plant and animal cells; location of energy production (ATP)

18. A. Chloroplasts and Photosynthesis • Contain a green colored pigment called chlorophyll which captures light energy to power photosynthesis • Have two membranes (inner and outer). • Contain a fluid called stroma, stacks called grana of folded structures called thylakoids surrounded by thylakoid membranes. Photosynthesis: 6CO2 + 6H2O→ C6H12O6 + 6O2

19. Label the chloroplast

20. If the pigment chlorophyll causes the green color in plants, do all plant parts contain chlorophyll? Support your answer. • Some prokaryotic bacteria are photosynthetic. Do They contain chloroplasts?

21. B. Mitochondria and Cellular Respiration • Contain its own unique DNA, proteins, and ribosomes; can self replicate • Contains an outer membrane, and a fluid called matrix inside a highly folded inner membrane. • This creates folds called cristae for the reactions of cellular respiration. Cellular Respiration: 6O2 + C6H12O6 → 6CO2 + 6H2O + ATP

22. Label the Mitochondria

23. Mitochondria and Cellular Respiration • Which do you think would contain more mitochondria, a heart muscle cell or a skin cell? • Why?

24. Summarize energy organelles at the bottom of pg. 5

25. Organelles that Store, Clean up, and Support • Storage: vacuoles (store material) and vesicles (move materials around the cell) • Vacuoles form by the combining of many vesicles • Clean up: lysosomes- contain enzymes to digest materials • Support: the cytoskeleton- meshwork that allows for movement of the cell and materials throughout the cell • Contains the centrioles (help the cell divide)

26. A. Vacuoles“Storage” • Membrane bound organelles found in eukaryotic cells • In Plant cells- typically have one large central vacuole to store water, nutrients, wastes, and enzymes. • Helps maintain turgor pressure- the pressure from inside the full vacuole that pushes the cell membrane against the cell wall and helps the plant cell stay rigid

27. Vacuoles“Storage” (cont.) • In Animal cells- have varying numbers of small vacuoles that function to store large molecules like: • food brought in by a vesicle during endocytosis • Molecules waiting to be released by exocytosis

28. Vacuoles“Storage” (cont.) • In Unicellular aquatic organisms- there are specialized vacuoles called contractile vacuoles which function to pump excess water from the cell’s cytoplasm • Think back to the unit on cell transport • Why are contractile vacuoles necessary in unicellular aquatic organisms? • Without them, cells would swell and explode due to water rushing in from the hypotonic environment of the pond

29. B. Lysosomes“Clean up” • Found in eukaryotes, though mainly in animal cells (rare in plant cells) • Membrane bound sacks that are the site of hydrolysis (digestion) • Have an acidic pH and are filled with digestive enzymes • Produced by the golgi apparatus

30. Lysosomes“Clean up” • Why is it important for the digestive enzymes to be bound by the lysosome, rather than being in the cytoplasm? • If the enzymes were free in the cytoplasm then they could break down other molecules and even organelles that need to stay intact.

31. Summarize storage and clean up at the bottom of pg. 6

32. -Thicker strands- microtubules -Thinner strands- microfilaments C. Cytoskeleton“Support” • Just like your body depends on your skeleton (bones) to keep your shape, so do cells. • Not membrane bound so also in prokaryotes • Consist of long networks of protein strands called microfilaments and microtubules.

33. The amazing marching proteins! The Cytoskeleton“Support”(continued) microfilaments – provide a framework and help move the cell - made of the protein actin Intermediate filaments – help anchor cells in place using a variety of proteins microtubules – Act as tracks for organelles to travel on as they move throughout the cell - help in cell reproduction and division by forming centrioles (not found in prok or plant cells) - made of proteins called tubulins

34. Ex: sperm cell- one flagella Other microorganisms- one or more flagella Cilia Ex: Paramecium Flagella More on Microtubules • May extend outside of the cell to form cilia (tiny hairs) or flagella (long tail-like hairs)- help the cell move

35. Summarize the cytoskeleton at the bottom of pg. 7

36. Rough ER tags and modifies the proteins and sends them to the Golgi in vesicles Ribosomes make proteins and insert them into the Rough ER The Golgi packages the proteins and sends them off in vesicles to where they are needed Organelles that build Proteins • Ribosomes • Rough Endoplasmic Reticulum (ER) • Golgi Apparatus

37. Ribosomes NOT membrane bound- so also found in prokaryotes Produced by the nucleolus (which is where?) There are two types of Ribosomes Free Ribosomes – move around in the cytoplasm ER Ribosomes – are attached to the rough endoplasmic reticulum Chloroplasts and mitochondria have their own ribosomes! (remember endosymbiosis?)

38. Ribosome Structure • Two parts (subunits) • One large subunit and one small subunit that fit together • Both made of RNA bound with proteins

39. Endoplasmic Reticulum (ER) • Network of membrane bound tubes and sacks. Constantly forming and breaking down.

40. Endoplasmic Reticulum (ER) There are two types of ER • Rough ER- has ribosomes on its surface • Proteins are made at the ribosomes and inserted into the rough ER. • The rough ER tags/modifies the proteins; telling the cell where to send them

41. ER (continued) 2. Smooth ER- no ribosomes on its surface - NOT involved in the synthesis of proteins - Helps make lipids - Site of detoxification of drugs like alcohol and sedatives - cells in people who use these drugs from large amounts of smooth ER.

42. Golgi Apparatus • Series of sack-like membranes, drawn like a stack of pita bread • Found between the rough ER and cell membrane • Modifies, sorts, and packages proteins coming from the rough ER • Sends the finished proteins to their destination by vesicles which bubble off of the main stacks. (Proteins may be sent either elsewhere in the cell or to its surface to leave the cell) • Lysosomes are formed from golgi vesicles • The “FedEx” of the cell

43. Summarize protein synthesis at the bottom of pg. 9

44. Differences between Plant and Animal Cells Plant cells share all the common features of animal cells, but also contain some additional organelles. • chloroplasts to convert sunlight into food chloroplast vacuole • Every plant cell is surrounded by a cell wall, and typically contains large central vacuole. cell wall • Plant cells do NOT have centrioles

45. Plant cells vs. Animal cells

46. Label the following Eukaryotic Cells A B C_______________________ D E AB AC AD AE BC BD BE CE Which cell – the one on the right or the left – is the Animal cell?_________ Plant cell?___________

47. Cells can function individually and work together in order for the organism to function as a whole

48. Homeostasis in Unicellular Organisms • Unicellular organism- an organism made of just 1 cell. • Can perform all necessary functions for life • Must maintain homeostasis • By growing, responding to their environment, transforming energy, and reproducing.

49. Homeostasis in Multicellular Life • Multicellular organisms are made of many cells that work together • Also must maintain homeostasis • To do this, cells become specialized for certain tasks and communicate with each other.

50. Cell Specialization • Different cells take on different roles • The process by which cells specialize is called cell differentiation