Overview. Chapter 3: Cells and Their Functions. The Cell. Key Terms. Microscopes. Microscopes. Cytology The study of cells

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1 Overview Chapter 3: Cells and Their Functions Key Terms The Cell active transport filtration mitochondria cancer gene mitosis carcinogen hemolysis mutation chromosome hypertonic nucleus cytology hypotonic organelle cytoplasm interphase osmosis diffusion isotonic phagocytosis DNA membrane potential endocytosis micrometer ribosome exocytosis microscope RNA plasma membrane Cytology The study of cells The Cell The basic unit of life Shows life characteristics Organization Metabolism Responsiveness Homeostasis Growth Reproduction Microscopes 1. List three types of microscopes used to study cells. Microscopes Cytology The study of cells Microscope Types of microscopes: Compound light microscope Most common in labs Transmission electron microscope 1 million x Scanning electron microscope 3D, 100,001x Micrometer unit for microscopic measurements Staining cells enables them to be seen 1

2 Figure 3-1 Cilia photographed under three different microscopes. Microscopes Checkpoints 3-1 What characteristics of life does a cell show? 3-2 Name three types of microscopes. Which microscope shows the most internal structure of the cilia? Which shows the cilia in three dimensions? 2. Describe the composition and functions of the plasma membrane. 3. Describe the cytoplasm of the cell, including the name and function of the main organelles. General Cell Organization Plasma membrane Nucleus Cytoplasm Cytosol Organelles Figure 3-2 A generalized animal cell, sectional view. Encloses cell contents Regulates what enters and leaves cell Plasma membrane components Phospholipid bilayer double fat layer Cholesterol strengthens the membrane Proteins: What is attached to the ER to make it look rough? What is the liquid part of the cytoplasm called? 2

3 Figure 3-3 The plasma membrane. Table 3-1 Proteins in the plasma membrane and their functions. Type of Protein Channels Transporters Receptors Enzymes Linkers Cell identity markers Function Pores in membrane that allow passage of specific substances Shuttle substances across membrane Allow for attachment of substances to membrane; used for cell-to-cell signaling Participate in chemical reactions at membrane surface Give structure to membrane and attach cells to other cells Proteins unique to a person s cells; important for immunity Why is the plasma membrane described as a bilayer? (components animation) Membrane potential The difference in electric charge on either side of the plasma membrane Ion concentrations are determined by Channels Pumps Membrane potential allows the plasma membrane to act as a battery. It uses electrical energy to power membrane functions. Figure 3-4 The membrane potential. Movement of Substances Across the Plasma Membrane What large, negatively charged ions contribute to the negative charge along the intracellular membrane? 4. Describe methods by which substances enter and leave cells that do not require cellular energy. 5. Describe methods by which substances enter and leave cells that require cellular energy. 6. Explain what will happen if cells are placed in solutions with concentrations the same as or different from those of the cell fluids. 3

4 Semipermeable only some things get through Selective Permeability Travel across membrane is based on several factors Molecular size, Solubility, Electrical charge Types of travel Passive - Movement that does not require cellular energy Active - Movement that requires cellular energy Movement That Does Not Require Cellular Energy Process Definition Example Diffusion Facilitated diffusion Osmosis Filtration Solute travels across plasma membrane down its concentration gradient Solute diffuses with help of a transporter Solvent travels across plasma membrane down its concentration gradient Mechanical force pushes solute and solvent across plasma membrane Movement of lipidsoluble materials across plasma membrane Movement of glucose into cell Movement of water across plasma membrane Movement of solutes and water out of blood under force of blood pressure Figure 3-6 Diffusion of a solid in a liquid. Figure 3-7 Facilitated diffusion. How would a change in the number of transporters affect a solute s movement by facilitated diffusion? Figure 3-8 A simple demonstration of osmosis. Figure 3-9 Osmotic pressure. What would happen in this system if the solute could pass through the membrane? Osmosis, diffusion What would happen to osmotic pressure if the concentration of solute were increased on side B of this system? 4

5 How Osmosis Affects Cells Another way to think about osmosis is in terms of solute concentration. Low Solute High Solute Osmosis High Water Low Water Solutions and Their Effects on Cells Solution Description Examples Effect on Cells Isotonic Hypotonic Has same solute concentration as cell Has lower solute concentration than cell Hypertonic Has higher solute concentration than cell 0.9% salt; 5% glucose <0.9% salt; <5% glucose >0.9% salt; >5% glucose None Cell takes in water and may burst (lysis) Cell loses water and shrinks (crenation) Water Follows the Salt Figure 3-10 The effect of osmosis on cells. Figure 3-11 Filtration. What would happen to red blood cells in the body if blood lost through injury were replaced with pure water? Movement That Requires Cellular Energy Process Definition Example Active transport Endocytosis Exocytosis Solute moves through plasma membrane against its concentration gradient with help of transporters Large amounts of solute and solvent are transported into cell using vesicles Large amounts of solute and solvent are transported out of the using vesicles Ion movement in nervous system and muscular system Phagocytosis of waste materials by white blood cells Release of neurotransmitters from neurons 5

6 Figure 3-12 Phagocytosis. Figure 3-13 Exocytosis. What organelle would likely help to destroy a particle taken in by phagocytosis? pinocytosis animation Movement of Substances Across the Checkpoints 3-8 What types of movement through the plasma membrane do not require cellular energy? 3-9 What term describes a fluid that is the same concentration as the intracellular fluid? What type of fluid is less concentrated? More concentrated? Protein Synthesis Checkpoints 3-10 What are the building blocks of nucleic acids? 3-11 What category of compounds does DNA code for in the cell? 3-12 What three types of RNA are active in protein synthesis? Cell Division 10. Name and briefly describe the stages in mitosis. Cell Aging As cells multiply, changes occur that may lead to their damage or death. Free radical injury Enzyme injury Gene mutation Slowing cell activity Apoptosis 6

7 Cells and Cancer 11. Discuss the role of cell changes in cancer, and list several cancer risk factors. Cells and Cancer Development of Cancer Genetic mutations may cause uncontrolled cell division. Cells may spread (metastasize), producing cancer. Cancer cells form tumors, crowding out normal cells. Cells and Cancer Cancer Risk Factors Heredity Chemicals Radiation Physical irritation Diet Viruses Case Study 12. Use the case study to discuss the importance of cells to the functioning of the body as a whole. Case Study Jim s lifestyle put him at risk of having a heart attack. Stress Overweight Sedentary High blood pressure During his heart attack, oxygen deficiency damaged Jim s cardiac muscle cells, making them unable to contract, which caused Jim s heart to stop beating. Word Anatomy 13. Show how word parts are used to build words related to cells and their functions. 7

8 Word Anatomy Word Part Meaning Example cyt/o cell Cytology is the study of cells. endo- in, within The endoplasmic reticulum within the cytoplasm. hypo- hyper- exo- deficient, below, beneath above, over, excessive outside, out of, away A hypotonic solution s concentration is lower than cytoplasm s. A hypertonic solution s concentration is higher than cytoplasm s. In exocytosis, the cell moves material out from vesicles. pro- before, in front Prophase is the first stage of mitosis. meta- change During metaphase chromosomes change position and line up across the equator. ana- upward, back, again During anaphase, chromosomes move to opposite sides of the cell. tel/o end Telophase is the last stage of mitosis. 8