TAILIEUCHUNG - Lecture Biology 25 (Human Biology): Chapter 3 - Prof. Gonsalves

In this chapter you will learn: State the basic principles of the cell theory, explain how the surface area-to-volume ratio limits cell size, summarize the role of microscopy in the study of cells, identify the components of a human cell and state its function, distinguish between the structure of a prokaryotic cell and that of a eukaryotic cell,. | Chapter 3 Biology 25: Human Biology Prof. Gonsalves Los Angeles City College Loosely Based on Mader’s Human Biology,7th edition Cell Theory: Developed in late 1800s. 1. All living organisms are made up of one or more cells. 2. The smallest living organisms are single cells, and cells are the functional units of multicellular organisms. 3. All cells arise from preexisting cells. Microscope Features Magnification: Increase in apparent size of an object. Ratio of image size to specimen size. Resolving power: Measures clarity of image. Ability to see fine detail. Ability to distinguish two objects as separate. Minimum distance between 2 points at which they can be distinguished as separate and distinct. Microscopes Light Microscopes: Earliest microscopes used. Lenses pass visible light through a specimen. Magnification: Highest possible from 1000 X to 2000 X. Resolving power: Up to mm (1 mm = 1/1000 mm). Types of Microscope Electron Microscopes: Developed in 1950s. Electron beam passes through specimen. Magnification: Up to 200,000 X. Resolving power: Up to nm (1nm = 1/1’000,000 mm). Two types of electron microscopes: 1. Scanning Electron Microscope: Used to study cell or virus surfaces. 2. Transmission Electron Microscope: Used to study internal cell structures. Components of All Cells: 1. Plasma membrane: Separates cell contents from outside environment. Made up of phospholipid bilayers and proteins. 2. Cytoplasm: Liquid, jelly-like material inside cell. 3. Ribosomes: Necessary for protein synthesis. Prokaryotic versus Eukaryotic Cells Feature Prokaryotic Eukaryotic Organisms Bacteria All others (animals, plants, fungi, and protozoa) Nucleus Absent Present DNA One chromosome Multiple chromosomes Size Small (1-10 um) Large (10 or more um) Membrane Absent Present (mitochondria, Bound golgi, chloroplasts, etc.) Organelles Division Rapid process Complex process (Binary fission) (Mitosis) Eukaryotic Cells Include protist, fungi, plant, and animal cells. Nucleus: .

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