Cells and Tissues

1. Carry out all chemical activities needed to sustain life Cells are the building blocks of all living things Tissues are groups of cells that are similar in structure and function Cells and Tissues

2. Cells are not all the same • All cells share general structures • Cells are organized into three main regions • Nucleus • Cytoplasm • Plasma membrane Anatomy of the Cell Figure 3.1a

3. Control center of the cell • Contains genetic material (DNA) • Three regions • Nuclear membrane • Nucleolus • Chromatin The Nucleus Figure 3.1b

4. Nuclear Membrane • Barrier of nucleus • Consists of a double phospholipid membrane • Contain nuclear pores that allow for exchange of material with the rest of the cell • Nucleoli • Nucleus contains one or more nucleoli • Sites of ribosome production • Ribosomes then migrate to the cytoplasm through nuclear pores Nuclear Membrane

5. Composed of DNA and protein Scattered throughout the nucleus Chromatin condenses to form chromosomes when the cell divides Chromatin

6. Barrier for cell contents • Double phospholipid layer • Hydrophilic heads • Hydrophobic tails • Also contains protein, cholesterol, and glycoproteins • Microvilli • Finger-like projections that increase surface area for absorption Plasma Membrane

7. Plasma Membrane Extracellular fluid (watery environment) Glycoprotein Glycolipid Cholesterol Sugar group Polar heads of phospholipid molecules Bimolecular lipid layer containingproteins Channel Nonpolar tailsof phospholipid molecules Proteins Filaments of cytoskeleton Cytoplasm (watery environment) Figure 3.2

8. Microvilli Tight (impermeable) junction Desmosome (anchoring junction) Plasma membranes of adjacent cells Connexon Gap (communicating) junction Underlying basement membrane Extracellular space between cells Figure 3.3

9. Material outside the nucleus and inside the plasma membrane • Cytosol • Fluid that suspends other elements • Organelles • Metabolic machinery of the cell • “Little organs” • Inclusions • Non-functioning units (stored nutrients, cell products, etc.) Cytoplasm

10. Chromatin Nuclear envelope Nucleolus Nucleus Plasma membrane Smooth endoplasmic reticulum Cytosol Lysosome Mitochondrion Rough endoplasmic reticulum Centrioles Ribosomes Golgi apparatus Secretion being released from cell by exocytosis Microtubule Peroxisome Intermediate filaments Figure 3.4

11. Ribosomes • Made of protein and RNA • Sites of protein synthesis • Found at two locations • Free in the cytoplasm • Attached to rough endoplasmic reticulum Cytoplasmic Organelles

12. Endoplasmic reticulum (ER) • Fluid-filled tubules for carrying substances • Two types of ER • Rough Endoplasmic Reticulum • Studded with ribosomes • Site where building materials of cellular membrane are formed • Smooth Endoplasmic Reticulum • Functions in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs Cytoplasmic Organelles

13. Golgi apparatus • Modifies and packages proteins • Produces different types of packages • Secretory vesicles • Cell membrane components • Lysosomes Cytoplasmic Organelles

14. 1 Protein- containing vesicles pinch off rough ER and migrate to fuse with membranes of Golgi apparatus. Rough ER Phagosome ER membrane Plasma mem- brane Proteins in cisterna Pathway C: Lysosome containing acid hydrolase enzymes 2 Proteins are modified within the Golgi compartments. Vesicle becomes lysosome 3 Proteins are then packaged within different vesicle types, depending on their ultimate destination. Secretory vesicle Pathway B: Vesicle membrane to be incorporated into plasma membrane Golgi apparatus Pathway A: Vesicle contents destined for exocytosis Secretion by exocytosis Extracellular fluid Figure 3.20

15. Lysosomes • Contain enzymes that digest nonusable materials within the cell • Packaged by Golgi apparatus • Peroxisomes • Membranous sacs of oxidase enzymes • Detoxify harmful substances • Break down free radicals (highly reactive chemicals) • Replicate by pinching in half Cytoplasmic Organelles

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

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

18. (b) Intermediate filaments (c) Microtubules (a) Microfilaments Tubulin subunits Fibrous subunits Actin subunit 25 nm 10 nm 7 nm Intermediate filaments form the purple batlike network. Microtubules appear as gold networks surrounding the cells’ pink nuclei. Microfilaments form the blue network surrounding the pink nucleus. Figure 3.7a-c

19. Centrioles • Rod-shaped bodies • Direct formation of mitotic spindle during cell division Cytoplasmic Organelles

20. Not found in all cells • Used for movement • Cilia moves materials across the cell surface • Flagellum propels the cell Cellular Projections

21. Cell Diversity Figure 3.8a–b

22. Cell Diversity Figure 3.8c

23. Cell Diversity Figure 3.8d–e

24. Cell Diversity Figure 3.8f–g