1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Human Biology Sylvia S. Mader Michael Windelspecht Chapter 3 Cell Structure and Function Lecture Outline Part 4

2 What is the cytoskeleton? A series of proteins that maintain cell shape, as well as anchors and/or moves organelles in the cell Made of 3 types of fibers: large microtubules, thin _______________, and medium-sized intermediate filaments 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions

3 Flagellum microtubules plasma membrane cilia sperm flagellum secretory cell flagellum b. c. a. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (b): © Y. Nikas/Photo Researchers, Inc.; (c): © David M. Phillips/Photo Researchers, Inc. Both are made of microtubules. Both are used in ___________. Cilia are about 20  shorter than flagella. What are cilia and flagella? Figure 3.15 Structure and function of the cilia and flagella. 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions

4 What are cell junctions? Junctions between the cells of human tissue that allow them to function in a coordinated manner 3 main types –______________ mechanically attach adjacent cells (common in skin cells). 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions Figure 3.16a Junctions between cells. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. filaments of cytoskeleton plasma membranes a. Adhesion junction intercellular space intercellular filaments

5 What are cell junctions? –_____________ are connections between the plasma membrane proteins of neighboring cells that produce a ____________ barrier (common in digestive system and kidney where fluids must be contained to a specific area). 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions Figure 3.16b Junctions between cells. plasma membranes tight junction proteins intercellular space b. Tight junction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

6 What are cell junctions? –____________ are communication portals between cells; channel proteins of the plasma membrane fuse, allowing easy movement between adjacent cells. 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions Figure 3.16c Junctions between cells. plasma membranes membrane channels intercellular space c. Gap junction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

7 What do mitochondria do and what do they look like? Highly folded organelles in eukaryotic cells Produce _______ in the form of ____ Thought to be derived from an engulfed prokaryotic cell 3.6 Mitochondria and Cellular Metabolism Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 200 nm matrix intermembrane space outer membrane inner membrane cristae (top) : © Dr. Don W. Fawcett/Visuals Unlimited Figure 3.17 The structure of a mitochondrion.

8 Enzymes are important for cellular respiration and many activities in the cell Most enzymes are ________. Enzymes are often named for the molecules that they work on, called ___________. Enzymes are __________ to what substrate they work on. Enzymes have active sites where a substrate binds. Enzymes are not used up in a reaction but instead are ___________. Some enzymes are aided by nonprotein molecules called coenzymes. 3.6 Mitochondria and Cellular Metabolism

9 How do enzymes work? Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. active site enzyme substrate products enzyme enzyme–substrate complex Synthesis Substrates are combined to produce a larger product. Degradation A substrate is broken down to smaller products. product enzyme enzyme–substrate complex enzyme active site substrates Figure 3.18 Action of an enzyme. 3.6 Mitochondria and Cellular Metabolism

10 What is cellular respiration? Production of _____ in a cell Includes 1.Glycolysis 2.Citric acid cycle (Krebs cycle) 3. Electron transport chain 3.6 Mitochondria and Cellular Metabolism

11 Figure 3.19 Production of ATP. 3.6 Mitochondria and Cellular Metabolism Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Outside cell Inside cell electrons transferred by NADH ATP mitochondrion Electron transport chain Citric acid cycle oxygen glucose electrons transferred by NADH glucose Glycolysis pyruvate

12 Glycolysis –Occurs in the _________ –Breaks ________ into 2 pyruvate –NADH and 2 ATP molecules are made –Does not require __________ 3.6 Mitochondria and cellular metabolism

13 Citric acid cycle (Krebs cycle) –A cyclical pathway that occurs in the ____________ –Produces NADH and 2 ATP –Releases carbon dioxide 3.6 Mitochondria and Cellular Metabolism

14 Electron transport chain Series of molecules embedded in the mitochondrial membrane –NADH made in steps 1 and 2 carry electrons here –___________ are made depending on the cell –Requires __________ as the final electron acceptor in the chain 3.6 Mitochondria and Cellular Metabolism

15 What other molecules besides glucose can be used in cellular respiration? Other carbohydrates Proteins Lipids 3.6 Mitochondria and Cellular Metabolism

16 How can a cell make ATP without oxygen? Fermentation: –occurs in the ___________. –does not require ________. –involves ___________. –makes 2 ATP and lactate in human cells. –can give humans a burst of energy for a short time. 3.6 Mitochondria and Cellular Metabolism