Chapter 4 notes.pptx - 4 Cells The Working Units of Life Chapter 4 Cells The Working Units of Life Key Concepts 4.1 Cells Provide Compartments for

Chapter 4 notes.pptx - 4 Cells The Working Units of Life...

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Cells: The Working Units of Life 4
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Chapter 4 Cells: The Working Units of Life Key Concepts 4.1 Cells Provide Compartments for Biochemical Reactions 4.2 Prokaryotic Cells Do Not Have a Nucleus 4.3 Eukaryotic Cells Have a Nucleus and Other Membrane-Bound Compartments 4.4 The Cytoskeleton Provides Strength and Movement 4.5 Extracellular Structures Provide Support and Protection For Cells and Tissues
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Concept 4.1 Cells Provide Compartments for Biochemical Reactions Cell theory was the first unifying theory of biology: Cells are the fundamental units of life. All organisms are composed of cells. All cells come from preexisting cells. Important implications of cell theory: Studying cell biology is the same as studying life. Life is continuous—all the way back to the evolution of the first living cells.
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Concept 4.1 Cells Provide Compartments for Biochemical Reactions Most cells are tiny, in order to maintain a good surface area-to-volume ratio . The volume of a cell determines its metabolic activity per unit of time. The surface area of a cell determines the amount of substances that can enter or leave the cell.
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Figure 4.2 Why Cells Are Small Surface area to volume ratio: why are cells small?
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Concept 4.1 Cells Provide Compartments for Biochemical Reactions As cells grow larger, metabolic activity and need for resources and rate of waste production increases faster than surface area. Some large cells increase surface area by folds in the cell membrane. To see small cells, there are two types of microscopes: Light microscopes use glass lenses and light Resolution = 0.2 μm Electron microscopes electromagnets focus an electron beam Resolution = 2 nm
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Photo 4.28 Chloroplasts in leaf cells. LM.
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Photo 4.39 Amoeba proteus engulfing cells of Paramecium sp. by phagocytosis. LM.
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Photo 4.45 Amoeba proteus ; numerous pseudopods. LM, phase contrast.
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Photo 4.20 Transmission electron microscope with scanning and scanning transmission systems.
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Photo 4.40 Small soil amoeba ( Vahlkampfia sp.) engulfing a cyst by phagocytosis. TEM.
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Photo 4.29 Chloroplast from a leaf mesophyll cell: grana, stroma, double membrane. TEM.
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Photo 4.21 Single-celled green alga. TEM.
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Photo 4.22 Plant parenchyma cell. TEM.
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Photo 4.23 Rat liver cell. TEM.
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Photo 4.34 Golgi apparatus (dictyosomes) in radish root hair cell: portion of RER at top. TEM.
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Figure 4.3 Microscopy
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Concept 4.1 Cells Provide Compartments for Biochemical Reactions Chemical analysis of cells involves breaking them open to make a cell-free extract. The composition and chemical reactions of the extract can be examined. Properties of the cell-free extract are the same as those inside the cell. Cell structures and macromolecules can be separated according to size in a centrifuge.
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Concept 4.1 Cells Provide Compartments for Biochemical Reactions The cell membrane : A selectively permeable barrier that allows cells to maintain a stable internal environment (homeostasis) Important in communication and receiving signals Often has proteins for binding and adhering to adjacent cells
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