Cell Cytoplasm: Chapter 2 PDF

Cell Cytoplasm: Chapter 2 Dr. Claude E. Gagna, Professor New York Institute of Technology Department of Biological and Chemical Sciences © 2012 Pearson Education, Inc. Introduction There are trillions of cells in the b...

Cell Cytoplasm: Chapter 2 Dr. Claude E. Gagna, Professor New York Institute of Technology Department of Biological and Chemical Sciences © 2012 Pearson Education, Inc. Introduction There are trillions of cells in the body Cells are the structural “building blocks” of all plants and animals Cells are produced by the division of preexisting cells Cells form all the structures in the body Cells perform all vital functions of the body © 2012 Pearson Education, Inc. Introduction There are two types of cells in the body: Sex cells Sperm in males and oocytes in females Somatic cells All the other cells in the body that are not sex cells © 2012 Pearson Education, Inc. The Study of Cells Cytology Study of cells Common techniques used: Light microscopy (LM) Transmission electron microscopy (TEM) Scanning electron microscopy (SEM) © 2012 Pearson Education, Inc. The Study of Cells Light Microscopy Magnification up to 1000 times Sometimes 2000 maximum © 2012 Pearson Education, Inc. Figure 2.1a Different Techniques, Different Perspectives LM × 400 Cells as seen in light microscopy (respiratory tract) © 2012 Pearson Education, Inc. The Study of Cells Transmission Electron Microscopy Magnifies more than light microscopy © 2012 Pearson Education, Inc. Figure 2.1b Different Techniques, Different Perspectives TEM × 2400 Cells as seen in transmission electron microscopy (intestinal tract) © 2012 Pearson Education, Inc. The Study of Cells Scanning Electron Microscopy Shows three-dimensional images © 2012 Pearson Education, Inc. Figure 2.1c Different Techniques, Different Perspectives SEM × 14,000 Cells as seen in scanning electron microscopy (respiratory tract) © 2012 Pearson Education, Inc. The Study of Cells The diversity of the cells of the body The following figure shows the proportion of cell size of the variety of cells in the body © 2012 Pearson Education, Inc. Figure 2.2 The Diversity of Cells in the Body Cells lining Blood intestinal tract cells Smooth muscle cell Bone cell Neuron in brain Fat cell Oocyte Sperm © 2012 Pearson Education, Inc. Cellular Anatomy The cell consists of: Cytoplasm Cytosol Organelles Plasmalemma Cell membrane © 2012 Pearson Education, Inc. Figure 2.4 A Flowchart for the Study of Cell Structure THE CELL CYTOPLASM PLASMALEMMA CYTOSOL ORGANELLES NONMEMBRANOUS MEMBRANOUS ORGANELLES ORGANELLES Cytoskeleton Mitochondria Microvilli Nucleus Centrioles Endoplasmic Cilia reticulum Flagella Golgi apparatus Ribosomes Lysosomes Peroxisomes © 2012 Pearson Education, Inc. Cellular Anatomy Anatomical structures of the cell Organelles Nonmembranous organelles Membranous organelles © 2012 Pearson Education, Inc. Cellular Anatomy Organelles of the cell Nonmembranous organelles Cytoskeleton Microvilli Centrioles Cilia Flagella Ribosomes © 2012 Pearson Education, Inc. Figure 2.3 Anatomy of a Typical Cell Microvilli Secretory vesicles Cytosol Golgi apparatus Lysosome Mitochondrion Centrosome Centriole Peroxisome Chromatin Nucleoplasm Nucleolus Nuclear pores Smooth Nuclear envelope endoplasmic surrounding nucleus reticulum Rough endoplasmic reticulum Fixed ribosomes Cytoskeleton Free ribosomes Plasmalemma © 2012 Pearson Education, Inc. Table 2.1 Anatomy of a Representative Cell (Part 1 of 2) © 2012 Pearson Education, Inc. Cellular Anatomy Organelles of the cell Membranous organelles Mitochondria Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Peroxisomes © 2012 Pearson Education, Inc. Table 2.1-2 Anatomy of a Representative Cell (Part 2 of 2) © 2012 Pearson Education, Inc. Cellular Anatomy Plasmalemma A cell membrane composed of: Phospholipids Glycolipids Protein Cholesterol © 2012 Pearson Education, Inc. Table 2.1 Anatomy of a Representative Cell (Part 1 of 2) © 2012 Pearson Education, Inc. Figure 2.5 The Plasmalemma Hydrophilic heads Hydrophobic tails Cholesterol EXTRACELLULAR FLUID Glycolipids Phospholipid Integral protein Integral of glycocalyx bilayer with channel glycoproteins Hydrophobic tails The phospholipid bilayer Cholesterol Peripheral Hydrophilic proteins heads Gated Cytoskeleton channel = 2 nm (Microfilaments) CYTOPLASM The plasmalemma © 2012 Pearson Education, Inc. Cellular Anatomy Functions of the Plasmalemma Cell membrane (also called phospholipid bilayer) Major functions: Physical isolation Regulation of exchange with the environment (permeability) Sensitivity Structural support © 2012 Pearson Education, Inc. Cellular Anatomy Membrane permeability of the plasmalemma Passive processes Diffusion Osmosis Facilitative diffusion © 2012 Pearson Education, Inc. Figure 2.6 Diffusion across Plasmalemmae Lipids, lipid-soluble Water, small water- molecules, and soluble soluble molecules, gases (O2 and CO2) can and ions diffuse diffuse across the lipid through membrane bilayer of the plasmalemma. channels. EXTRACELLULAR FLUID Channel Plasmalemma protein Large molecules that cannot fit through the membrane channels and cannot diffuse CYTOPLASM through the membrane lipids can only cross the plasmalemma when transported by a carrier mechanism. © 2012 Pearson Education, Inc. Cellular Anatomy Membrane permeability of the plasmalemma Active processes Endocytosis Phagocytosis Pinocytosis Receptor-mediated endocytosis © 2012 Pearson Education, Inc. Cellular Anatomy Plasmalemma: Active processes Uses enzymes and carrier proteins Ion pumps use energy to transport charged particles such as Na+, Ca2+, Mg2+, K+ An ion pump that moves two ions simultaneously in opposite directions is called an exchange pump. © 2012 Pearson Education, Inc. Cellular Anatomy Plasmalemma: Endocytosis Phagocytosis: “cell eating” Pinocytosis: “cell drinking” Receptor-mediated endocytosis: Ligands will bind specific molecules to the receptors thereby allowing only specific molecules to enter the cell © 2012 Pearson Education, Inc. Figure 2.7 Phagocytosis Bacterium Pseudopodium Phagocytosis Phagosome Lysosome Phagosome fuses with a lysosome Secondary lysosome Golgi apparatus Exocytosis © 2012 Pearson Education, Inc. Figure 2.8a Receptor–Mediated Endocytosis Ligands Receptor-Mediated Endocytosis EXTRACELLULAR FLUID Ligands binding Target molecules (ligands) bind to to receptors receptors in plasmalemma. Exocytosis Areas coated with ligands form deep Endocytosis pockets in plasmalemma surface. Ligand receptors Pockets pinch off, forming endosomes known as coated vesicles. Coated Coated vesicles fuse with primary vesicle lysosomes to form secondary lysosomes. CYTOPLASM Ligands are removed and absorbed into the cytoplasm. The lysosomal and endosomal membranes separate. Primary The endosome fuses with the lysosome plasmalemma, and the receptors are again available for ligand binding. Ligands Secondary removed lysosome Steps in receptor-mediated endocytosis © 2012 Pearson Education, Inc.  Figure 2.8 Receptor–Mediated Endocytosis Early vesicle formation Plasmalemma Cytoplasm Completed vesicle TEMs × 60,000 Electron micrographs showing vesicle formation in receptor-mediated endocytosis © 2012 Pearson Education, Inc. Table 2.2 Summary of Mechanisms Involved in Movement across Plasmalemmae © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) The cytoskeleton consists of: Microfilaments Intermediate filaments Thick filaments Microtubules © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) Microfilaments Anchor cytoskeleton to integral proteins Stabilize the position of membrane proteins Anchor plasmalemma to the cytoplasm Produce movement of the cell © 2012 Pearson Education, Inc. Figure 2.9 The Cytoskeleton Microvilli Microfilaments Plasmalemma SEM × 30,000 A SEM image of the microfilaments and microvilli of an intestinal cell Terminal web Mitochondrion Intermediate filaments Endoplasmic reticulum The cytoskeleton provides strength Microtubule and structural support for the cell and its organelles. Interactions between cytoskeletal elements are Secretory LM × 3200 also important in moving organelles vesicle and in changing the shape of the Microtubules in a living cell, as cell. seen after special fluorescent labeling © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) Intermediate filaments Provide strength Stabilize organelle position Transport material within the cytosol © 2012 Pearson Education, Inc. Figure 2.9 The Cytoskeleton Microvilli Microfilaments Plasmalemma SEM × 30,000 A SEM image of the microfilaments and microvilli of an intestinal cell Terminal web Mitochondrion Intermediate filaments Endoplasmic reticulum The cytoskeleton provides strength Microtubule and structural support for the cell and its organelles. Interactions between cytoskeletal elements are Secretory LM × 3200 also important in moving organelles vesicle and in changing the shape of the Microtubules in a living cell, as cell. seen after special fluorescent labeling © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) Thick filaments Found in muscle cells: involved in muscle contraction Microtubules Involved in the formation of centrioles, which are involved in cell reproduction © 2012 Pearson Education, Inc. Figure 2.9 The Cytoskeleton Microvilli Microfilaments Plasmalemma SEM × 30,000 A SEM image of the microfilaments and microvilli of an intestinal cell Terminal web Mitochondrion Intermediate filaments Endoplasmic reticulum The cytoskeleton provides strength Microtubule and structural support for the cell and its organelles. Interactions between cytoskeletal elements are Secretory LM × 3200 also important in moving organelles vesicle and in changing the shape of the Microtubules in a living cell, as cell. seen after special fluorescent labeling © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) Examples of microtubules Centrioles Cilia Flagella © 2012 Pearson Education, Inc. Figure 2.10 Centrioles and Cilia Microtubules Plasmalemma A centriole consists Microtubules of nine microtubule triplets (9 + 0 array). The centrosome contains a pair of centrioles oriented at right angles to one another. Basal body A cilium contains nine pairs of microtubules surrounding a central pair (9 + 2 array). Power stroke Return stroke A single cilium swings forward and then returns to its original position. During the power stroke, the cilium is relatively TEM × 240,000 stiff, but during the return stroke, it bends and moves parallel to the cell surface. © 2012 Pearson Education, Inc. Table 2.3 A Comparison of Centrioles, Cilia, and Flagella © 2012 Pearson Education, Inc. Cellular Anatomy Nonmembranous Organelles (details) Ribosomes Free ribosomes: float in the cytoplasm Fixed ribosomes: attached to the endoplasmic reticulum Both are involved in producing protein © 2012 Pearson Education, Inc. Figure 2.11 Ribosomes Nucleus Free ribosomes Small ribosomal subunit Large ribosomal subunit Endoplasmic reticulum with attached fixed ribosomes An individual ribosome, consisting of small and TEM × 73,600 large subunits Both free and fixed ribosomes can be seen in the cytoplasm of this cell. © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Double-membraned organelles Mitochondria: produce ATP Nucleus: contains chromosomes Endoplasmic reticulum: network of hollow tubes Golgi apparatus: modifies protein Lysosomes: contain cellular digestive enzymes Peroxisomes: contain catalase to break down hydrogen peroxide © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Mitochondria Consist of cristae Consist of mitochondrial matrix Produce ATP © 2012 Pearson Education, Inc. Figure 2.12 Mitochondria Inner membrane Cytoplasm of cell Cristae Matrix Organic molecules and O2 Outer CO2 membrane ATP Matrix Cristae Enzymes TEM × 61,776 © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Endoplasmic Reticulum (ER) There are two types Rough endoplasmic reticulum (RER) Smooth endoplasmic reticulum (SER) © 2012 Pearson Education, Inc. Figure 2.15 The Endoplasmic Reticulum Rough endoplasmic reticulum with Ribosomes fixed (attached) ribosomes Free ribosomes Smooth endoplasmic reticulum Endoplasmic TEM × 11,000 Reticulum Cisternae © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Rough endoplasmic reticulum Consists of fixed ribosomes Proteins enter the ER © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Smooth endoplasmic reticulum Synthesizes lipids, steroids, and carbohydrates Storage of calcium ions Detoxification of toxins © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Golgi apparatus Synthesis and packaging of secretions Packaging of enzymes (modifies protein) Renewal and modification of the plasmalemma © 2012 Pearson Education, Inc. Figure 2.16a The Golgi Apparatus Vesicles Maturing (trans) face Forming (cis) face TEM × 83,520 A sectional view of the Golgi apparatus of an active secretory cell © 2012 Pearson Education, Inc. Figure 2.16b The Golgi Apparatus EXTRACELLULAR FLUID CYTOSOL Membrane renewal vesicles Lysosome Secretory Cisternae vesicle Maturing (trans) face This diagram shows the functional link between the ER and the Golgi apparatus. Golgi structure has been simplified to clarify the relationships between the membranes. Transport vesicles carry the secretory product from the endoplasmic reticulum to the Golgi apparatus, and transfer vesicles move membrane and materials between the Golgi cisternae. At the Forming maturing face, three functional categories of vesicles (cis) face develop. Secretory vesicles carry the secretion from Transport the Golgi to the cell surface, where exocytosis vesicle releases the contents into the extracellular fluid. Other vesicles add surface area and integral proteins to the plasmalemma. Lysosomes, which remain in the cytoplasm, are vesicles filled with enzymes. © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Lysosomes Fuse with phagosomes to digest solid materials Recycle damaged organelles Sometimes rupture, thus killing the entire cell (called autolysis) © 2012 Pearson Education, Inc. Figure 2.17 Lysosomal Functions Waste products and debris are then ejected from the cell when the vesicle fuses with the plasma membrane. Function 1: A primary Endocytosis lysosome may fuse with the membrane of another organelle, such as a mitochondrion, forming a Extracellular secondary lysosome. solid or fluid Function 2: A secondary lysosome may also form As the materials when a primary lysosome or pathogens are fuses with a vesicle Primary broken down, containing fluid or solid lysosomes nutrients are materials from outside the contain absorbed. cell. inactive As digestion enzymes. occurs, nutrients are reabsorbed for recycling. Function 3: The lysosomal membrane breaks down following injury to, or death of, the cell. The digestive enzymes then attack the Golgi cytoplasm in a destructive apparatus process known as autolysis. For this reason lysosomes are sometimes called “suicide packets.” © 2012 Pearson Education, Inc. Cellular Anatomy Membranous Organelles (details) Peroxisomes Consist of catalase Abundant in liver cells Convert hydrogen peroxide to water and oxidants © 2012 Pearson Education, Inc. Cellular Anatomy Membrane flow This is the continuous movement and recycling of the cell membrane Transport vesicles connect the endoplasmic reticulum with the Golgi apparatus Secretory vesicles connect the Golgi apparatus with the plasmalemma © 2012 Pearson Education, Inc. Intercellular Attachment Examples of Intercellular Attachment: Communicating junctions Adhering junctions Tight junctions Anchoring junctions © 2012 Pearson Education, Inc.  Figure 2.18ab Cell Attachments (Part 1 of 4) Tight junction Zonula adherens Terminal web Embedded Button proteins desmosome (connexons) Communicating junction Communicating junctions permit Anchoring junction the free diffusion of ions and small molecules between two cells. Hemidesmosome A diagrammatic view of an epithelial cell shows the major types of intercellular connections. © 2012 Pearson Education, Inc.  Figure 2.18ac Cell Attachments (Part 2 of 4) Tight junction Interlocking junctional proteins Tight junction Zonula adherens Terminal web Button desmosome Communicating Zonula junction adherens Anchoring junction A tight junction is formed by the fusion of the outer layers of two Hemidesmosome plasmalemmae. Tight junctions prevent the diffusion of fluids and A diagrammatic view of an solutes between the cells. epithelial cell shows the major types of intercellular connections. © 2012 Pearson Education, Inc. Figure 2.18ad Cell Attachments (Part 3 of 4) Tight junction Zonula adherens Terminal web Button desmosome Communicating junction Anchoring junction Hemidesmosome A diagrammatic view of an epithelial cell shows the major types of intercellular connections. Intermediate filaments (cytokeratin) Anchoring junctions attach Cell adhesion one cell to another. A macula molecules adherens has a more (CAMs) organized network of Dense area intermediate filaments. An adhesion belt is a form of anchoring junction that encircles the cell. This complex Intercellular is tied to the microfilaments of cement the terminal web. © 2012 Pearson Education, Inc. The Cell Life Cycle Cell reproduction consists of special events Interphase Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Overlaps with anaphase and telophase © 2012 Pearson Education, Inc.