Cells and Tissues

1. Cells and Tissues

2. Cells and Tissues • Cells are the building blocks of all living things. • Tissues are groups of cells that are similar in structure and function. • Together, they carry out all chemical activities needed to sustain life.

3. Anatomy of the Cell • Cells are not all the same • All cells share the same general structures • All cells have three main regions: • Region 1: Nucleus • Region 2: Plasma Membrane • Region 3: Cytoplasm Figure 3.1a

4. Region 1: The Nucleus • Control center of the cell • Contains genetic material (DNA) • Three main areas: • Nuclear envelope (membrane)—Contains the nuclear material and separates it from cytoplasm • Nucleolus—Involved in protein synthesis • Chromatin—Unorganized DNA

5. Areas of the Nucleus • Control center of the cell • Contains genetic material (DNA) • Nuclear envelope (membrane) • Barrier of the nucleus • Consists of a double layer membrane • Contains nuclear pores that allow for exchange of material with the rest of the cell

6. Areas of the Nucleus • Nucleolus • Nucleus contains one or more nucleoli • Sites of ribosome assembly • Ribosomes migrate into the cytoplasm through nuclear pores

7. Areas of the Nucleus • Chromatin • Composed of DNA and protein • Present when the cell is not dividing • Scattered throughout the nucleus • Condenses to form chromosomes when the cell divides

8. Region 2: Plasma Membrane • Barrier for cell contents • Consists of a double phospholipid layer • Hydrophilic heads (Hydro = water, philos = love), pointed outward • Hydrophobic tails (Hydro = water, phobe = fear). pointed inward • Also contains proteins, cholesterol, and glycoproteins

9. Region 2: Plasma Membrane Video Clip: The Plasma Membrane Figure 3.2

10. Plasma Membrane Specializations • Microvilli • Finger-like projections that increase surface area for absorption

11. Plasma Membrane Specializations • Types of Membrane Junctions • Tight Junctions • Impermeablejunctions • Bind cells together into leakproof sheets • Desmosomes • Anchoring junctions that prevent cells from being pulled apart • Gap Junctions • Allow communication between cells

12. Plasma Membrane Specializations Video Clip: AP Intracellular Junctions TPS: Checkpoint #1

13. Region 3: Cytoplasm • Cytoplasm is the material outside the nucleus and inside the plasma membrane • Contains three major elements: • Cytosol • Fluid that suspends other elements • Organelles • Metabolic machinery of the cell • “Little organs” that perform specific functions for the cell • Inclusions • Chemical substances such as stored nutrients or cell products

14. Region 3: Cytoplasmic Organelles Figure 3.4

15. Region 3: Cytoplasmic Organelles • Mitochondria • “Powerhouses” of the cell • Change shape continuously • Carry out reactions where oxygen is used to break down food • Provides ATP for cellular energy

16. Cytoplasmic Organelles • Ribosomes • Made of protein and RNA • Sites of protein synthesis • Found at two locations: • Free floating in the cytoplasm • As part of the rough endoplasmic reticulum

17. Cytoplasmic Organelles • Endoplasmic reticulum (ER) • Fluid-filled tubules for carrying substances • Two types of ER • Rough endoplasmic reticulum • Studded with ribosomes • Synthesizes proteins • Smooth endoplasmic reticulum • Functions in lipid metabolism and detoxification of drugs and pesticides

18. Video Clip: Endoplasmic Reticulum

19. As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern. Ribosome mRNA Rough ER Protein RER & Protein Synthesis Figure 3.5, step 1

20. As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern. Ribosome mRNA Rough ER In the cistern, the protein folds into its functional shape. Short sugarchains may be attachedto the protein (forming aglycoprotein). Protein RER & Protein Synthesis Figure 3.5, step 2

21. As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern. Ribosome mRNA Rough ER In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein). Protein The protein is packaged in a tiny membranous sac called atransport vesicle. Transportvesicle buds off RER & Protein Synthesis Figure 3.5, step 3

22. The transport vesicle buds fromthe rough ER and travels to theGolgi Apparatus for furtherprocessing OR goes directly tothe plasmamembrane where itscontents are secreted. Ribosome mRNA Rough ER Protein Transportvesicle buds off Protein insidetransport vesicle RER & Protein Synthesis Figure 3.5, step 4

23. Cytoplasmic Organelles • Golgi Apparatus • Modifies and packages proteins • Produces different types of packages: • Secretory vesicles-help organize various cellular substances • Cell membrane components • Lysosomes—digestive system of the cell

24. Secretion byexocytosis Pathway 1 Proteins in cisterna Rough ER Cisterna Membrane Transportvesicle Golgiapparatus Secretory vesicles Proteins Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle Plasma membrane Extracellular fluid Figure 3.6, step 5

25. Pathway 2 Proteins in cisterna Rough ER Cisterna Membrane Transportvesicle Golgi vesicle containingmembrane componentsfuses with the plasmamembrane Golgiapparatus Plasma membrane Extracellular fluid Figure 3.6, step 8

26. Pathway 3 Lysosome fuses withingested substances Proteins in cisterna Rough ER Cisterna Membrane Transportvesicle Golgi vesicle containingdigestive enzymesbecomes a lysosome Golgiapparatus Plasma membrane Extracellular fluid Figure 3.6, step 11

27. Cytoplasmic Organelles • Peroxisomes • Membranous sacs of oxidase enzymes • Detoxifyharmful substances such as alcohol and formaldehyde • Break down free radicals (highly reactivechemicals) • Replicate by pinching in half • Lysosomes • Contain enzymes that digest worn-out or nonusable materials within the cell Checkpoint #2: Label the organelles & pathways in the cell diagrams in notes.

28. Video Clip: The Structure & Function of Lysosomes

29. Cytoplasmic Organelles • Cytoskeleton • Network of protein structures that extend throughout the cytoplasm • Provides the cell with an internal framework Figure 3.7a

30. Cytoplasmic Organelles • Cytoskeleton • Three different types of filaments • Microfilaments (largest) • Intermediate filaments • Microtubules (smallest) Video Clip: The Cytoskeleton Figure 3.7b–d

31. Cytoplasmic Organelles • Centrioles • Rod-shaped bodies made of microtubules • Direct the formation of mitotic spindle during cell division

32. Cellular Projections • Not found in all cells • Used for movement • Cilia move materials across the cell surface • Located in the respiratory system to move mucus • Flagella propel the cell • The only flagellated cell in the human body is sperm

33. Cell Diversity—Fibroblasts & Erythrocytes Figure 3.8a

34. Cell Diversity—Epithelial Cells Figure 3.8b

35. Cell Diversity—Skeletal & Smooth Muscle Cells Figure 3.8c

36. Cell Diversity—Fat Cell Figure 3.8d

37. Cell Diversity--Macrophage Figure 3.8e

38. Cell Diversity—Nerve Cell Figure 3.8f

39. Cell Diversity Figure 3.8g