Cells, Membranes, and Homeostasis Reading Guide PDF

**Chapter 3 Reading Guide** **Cells, Membranes, and Homeostasis** This reading guide is intended to assist your study, directing your attention to the content that will help you meet the Learning Objectives (LOs). There are detailed Learning Objectives at the end if you need extra guidance. Answer...

**Chapter 3 Reading Guide** **Cells, Membranes, and Homeostasis** This reading guide is intended to assist your study, directing your attention to the content that will help you meet the Learning Objectives (LOs). There are detailed Learning Objectives at the end if you need extra guidance. Answers to the Self-Assessment Questions are also included. **3.1 Cell Theory** The cell is the fundamental unit of life. *[LO 3.1]* Explain why the cell is the fundamental unit of life, and the differences between prokaryotic and eukaryotic cells. *[Terminology:]* Cell theory Nucleus Prokaryote Eukaryote Nucleoid Organelle *Figures:* - 3.1 First observation of cells - 3.2 Diverse cell types - 3.3 Prokaryotic and eukaryotic cells [*Self-Assessment Questions:* ] 1\. What are three basic tenets of the cell theory? 2\. What are the major differences between prokaryotic and eukaryotic cells? Compare their organization, degree of compartmentalization, and relative size. **\ ** **3.2 Structure of Cell Membranes** Cell membranes are composed of lipids, proteins, and carbohydrates. *[LO 3.2 ]* Describe the composition of cell membranes. [*Terminology:* ] Amphipathic Micelle Bilayer Liposome Fluid Cholesterol Lipid raft Transporter Receptor Enzyme Anchor Integral membrane protein Peripheral membrane protein Transmembrane protein Fluid mosaic model *[Figures:]* - 3.4 Phospholipid structure - 3.5 Behavior of phospholipids in water - 3.6 Saturated and unsaturated fatty acids - 3.7 Cholesterol - 3.8 Membrane proteins - 3.9 Integral and peripheral membrane proteins - *Animation: Fluid Mosaic Model* - 3.10 **How Do We Know?** Do proteins move in the plane of the membrane? [*Self-Assessment Questions:* ] 3\. How do lipids with hydrophilic and hydrophobic regions behave in an aqueous environment? 4\. Like cell membranes, many fats and oils are made up in part of fatty acids. Most animal fats (like butter) are solid at room temperature, whereas plant fats (like canola oil) tend to be liquid. Can you predict which type of fat contains saturated fatty acids and which type contains unsaturated fatty acids? 5\. What are two ways in which proteins associate with membranes? 6\. What would happen in the FRAP experiment if proteins did not move in the plane of a membrane? **\ ** **3.3 Membrane Transport** The cell membrane is a selective barrier that maintains homeostasis by controlling the movement of substances into and out of the cell. *[LO 3.3 ]* Explain the basis for the selective permeability of membranes and the mechanisms by which some substances are allowed to pass while other substances are not. *[Terminology:]* Cell membrane Homeostasis Selectively permeable Diffusion Passive transport Facilitated diffusion Channel protein Carrier protein Aquaporin Osmosis Osmotic pressure Active transport Primary active transport Secondary active transport Electrochemical gradient Contractile vacuole Cell wall Turgor pressure Vacuole Cytoskeleton *[Figures: ]* - 3.11 Diffusion - *Animation: Diffusion* - 3.12 Simple diffusion and facilitated diffusion - 3.13 Osmosis - *Animation: Osmosis* - 3.14 Primary active transport - *Animation: Active Transport* - 3.15 Secondary active transport - 3.16 Changes in red blood cell shape due to osmosis - 3.17 Contractile vacuole - 3.18 Turgor pressure [*Self-Assessment Questions:* ] 7\. What are the roles of lipids and proteins in maintaining the selective permeability of membranes? 8\. A container is divided into two compartments by a membrane that is fully permeable to water and small ions. Water is added to one side of the membrane (side A), and a 5% solution of sodium chloride (NaCl) is added to the other side (side B). In which direction will water molecules move? In which direction will sodium and chloride ions move? When the concentration is equal on both sides, will movement stop? 9\. What is the difference between passive and active transport? 10\. In the absence of the sodium--potassium pump, the extracellular solution becomes hypotonic relative to the inside of the cell. Poisons such as ouabain can interfere with the action of the sodium--potassium pump. What are the consequences for the cell? 11\. What are three different ways in which cells maintain size and shape? **3.4 The Endomembrane System** The endomembrane system is an interconnected set of membranes in eukaryotes that defines spaces in the cell. *[LO 3.4 ]* Relate the structural organization of the eukaryotic endomembrane system to the specialized functions of each of its membrane-bound compartments. *[Terminology:]* Cytoplasm Cytosol Vesicle Endomembrane system Exocytosis Endocytosis Nuclear envelope Nuclear pore Ribosome Endoplasmic reticulum (ER) Lumen Rough endoplasmic reticulum Smooth endoplasmic reticulum Golgi apparatus Cisternae (singular, cisterna) Lysosome *[Figures: ]* - 3.19 An animal and a plant cell - 3.20 The endomembrane system - *Animation: Endomembrane System* - 3.21 The nuclear envelope - 3.22 The endoplasmic reticulum (ER) - 3.23 The Golgi apparatus - 3.24 Lysosomes [*Self-Assessment Questions:* ] 12\. What are the names and functions of the major organelles of the endomembrane system in eukaryotic cells? 13\. How do lysosomes illustrate the importance of compartmentalizing certain reactions in different spaces in the cell? **\ ** **3.5 Mitochondria and Chloroplasts** Mitochondria and chloroplasts are organelles that harness energy, and likely evolved from free-living prokaryotes. *[LO 3.5]* Describe the structure and function of mitochondria and chloroplasts. *[Terminology:]* Mitochondria (singular, mitochondrion) Chloroplast Photosynthesis Thylakoid membrane Chlorophyll *[Figures: ]* - 3.25 Mitochondria - 3.26 Chloroplasts [*Self-Assessment Questions:* ] 14\. Are mitochondria present in animal cells, plants cells, or both? 15\. What are three similarities between mitochondria and chloroplasts? **\ [Answers to Self-Assessment Questions]** [ ] 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. **[Detailed Learning Objectives]** **3.1 Explain why the cell is the fundamental unit of life, and the differences between prokaryotic and eukaryotic cells.** - 3.1a Explain the three tenets of the cell theory. - 3.1b Describe the close relationship between structure and function in biological systems. - 3.1c Compare and contrast prokaryotic cells and eukaryotic cells. **3.2 Describe the composition of cell membranes.** - 3.2a Explain why micelles, bilayers, and liposomes form spontaneously when phospholipids are placed in an aqueous environment. - 3.2b Relate the effects of phospholipid fatty acid tail length, the presence of saturated versus unsaturated fatty acid tails, and the presence of cholesterol to the fluidity of a membrane. - 3.2c Predict the manner in which a protein would be associated with the cell membrane, given the protein's function. **3.3 Explain the basis for the selective permeability of membranes and the mechanisms by which some substances are allowed to pass while other substances are not.** - 3.3a Predict the net direction of movement of molecules by diffusion in a concentration gradient. - 3.3b Predict whether a molecule can move by simple diffusion or facilitated diffusion through a membrane based on the molecule's size and electrical charge. - 3.3c Compare and contrast primary active transport and secondary active transport of molecules across a cell membrane with respect to the sources of energy utilized by each transport mechanism. - 3.3d Relate the function of active transport proteins, such as the sodium--potassium pump, to the maintenance of cytoplasmic isotonicity, cell size, and cell shape. - 3.3e Describe the role of the cell wall and cytoskeleton in maintaining the size and shape of plant, fungal, and bacterial cells. **3.4 Relate the structural organization of the eukaryotic endomembrane system to the specialized functions of each of its membrane-bound compartments.** - 3.4a Explain the roles of the nuclear envelope in regulating the movement of molecules into and out of the nucleus. - 3.4b Relate the different parts of the endoplasmic reticulum to their roles in the manufacture of proteins and lipids. - 3.4c Relate the role of the Golgi apparatus to the modification and distribution of proteins in the cell. - 3.4d Describe the role of lysosomes in recycling cellular components. **3.5 Describe the structure and function of mitochondria and chloroplasts.** - 3.5a Describe the structure and function of mitochondria in plant and animal cells. - 3.5b Describe the structure and function of chloroplasts in plant and algal cells.