Week 2, The Cellular Level of Organization and Cellular Membrane PDF

Because learning changes everything.® Chapter 03 Cell Biology Seeley’s ANATOMY & PHYSIOLOGY Thirteenth Edition Cinnamon VanPutte, Jennifer Regan, Andrew Russo © 2023 McGraw Hill, LLC. All rights res...

Because learning changes everything.® Chapter 03 Cell Biology Seeley’s ANATOMY & PHYSIOLOGY Thirteenth Edition Cinnamon VanPutte, Jennifer Regan, Andrew Russo © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.  Learning Outcomes The cellular level of organization and cellular membrane Cell components: a nucleus and cytoplasmic organelles. Plasma membrane, transport mechanisms. © McGraw Hill, LLC 2  Lecture Outline - Cell is the structural and functional unit of all living organisms. It is the basic unit of life and is composed of : -a plasma membrane - cytoplasm, which includes a nucleus and cytoplasmic organelles. Access the text alternative for slide images. © McGraw Hill, LLC 3  3.1 General parts of a cell: Plasma (cell) membrane – outer boundary that allows cell interaction with its external environment. Nucleus – directs cell activities (control center of the cell) Cytoplasm – located between plasma membrane and nucleus; contains organelles that perform specific functions. © McGraw Hill, LLC 4  3.3 Plasma Membrane Functions: A boundary separating the cytoplasmic (intracellular) substances from the extracellular environment of the cells. Encloses and supports the cell contents. Attaches to the extracellular environment or to other cells. The ability to recognize and communicate with other cells. Determines what moves into and out of cells. © McGraw Hill, LLC 5  Composition of the Plasma Membrane The plasma membrane is primarily made of lipids and proteins with a very small amount of carbohydrates. Glycocalyx: combinations of carbohydrates and lipids (glycolipids) and proteins (glycoproteins) on outer surface. Access the text alternative for slide images. © McGraw Hill, LLC 6  3.4 Membrane Lipids Phospholipids and cholesterol predominate. Phospholipids: bilayer. (a hydrophilic head and hydrophobic tails). - Polar heads facing water in the interior and exterior of the cell (hydrophilic); nonpolar tails facing each other on the interior of the membrane (hydrophobic). Cholesterol: interspersed among phospholipids. Amount determines fluid nature of the membrane, providing stability to the membrane. Access the text alternative for slide images. © McGraw Hill, LLC 7  3.5 Membrane Proteins Integral membrane proteins. Extend deeply into membrane, often extending from one surface to the other. Can form channels through the membrane. Peripheral membrane proteins. Attached to integral proteins at either the inner or outer surfaces of the lipid bilayer or to polar heads of phospholipids. © McGraw Hill, LLC 8  Transport Proteins Includes: -channel proteins, - carrier proteins -ATP-powered pumps. © McGraw Hill, LLC 9  Channel Proteins Channel proteins – integral membrane proteins that form tiny channels through membrane. Channel proteins- membrane proteins form a passageway through the plasma membrane. The channel determines the size, shape and charge of what can move through. © McGraw Hill, LLC 10  Leak and Gated Ion Channels Leak ion channels (nongated ion channels): always open. Responsible for the permeability of the plasma membrane to ions when the plasma membrane is at rest. Gated ion channels: opened or closed by certain stimuli. Ligand-gated ion channel: open in response to small molecules that bind to proteins or glycoproteins. Voltage-gated ion channel: open when there is a change in charge across the plasma membrane. © McGraw Hill, LLC 11  Leak and Gated Membrane Channels © McGraw Hill, LLC 12  Carrier Proteins 1 Also called transporters. Integral proteins move ions from one side of membrane to the other. © McGraw Hill, LLC 13  Carrier Proteins 2 Carrier proteins come in several forms. Uniporters – moves one ion/molecule. Symporters –two different ions/molecules move in the same direction at the same time (cotransport). Antiporters – move two ions/molecules in opposite directions at the same time (countertransport). © McGraw Hill, LLC 14  Membrane Transport Mechanisms 1. Passive membrane transport – the cell does not expend ATP; movement from higher concentration to lower concentration. Diffusion. Osmosis. Facilitated diffusion. 2. Active membrane transport – AT P is used to move from lower concentration to higher concentration. Active transport. Secondary active transport. 3. Vesicular transport – uses a membrane-bound sac. Endocytosis. Exocytosis. © McGraw Hill, LLC 17  Diffusion Net movement of solutes from an area of higher concentration to lower concentration in solution. Concentration gradient: concentration difference between two points. Solutes move down their concentration gradient until an equilibrium is established. © McGraw Hill, LLC 18  Osmosis Diffusion of water (solvent) across a selectively permeable membrane. - Water moves from an area of low concentration of solute (high amount of water) to an area of high concentration of solute (low amount of water). © McGraw Hill, LLC 19  Osmosis and Cells Important because large volume changes caused by water movement disrupt normal cell function. Isotonic: cell neither shrinks nor swells when placed in a solution. Hypertonic: cell shrinks (crenation) when placed in a solution; water moves out of the cell. Hypotonic: cell swells and may rupture (lysis) when place in a solution; water moves into the cell. © McGraw Hill, LLC 20  Effects of Hypotonic, Isotonic, and Hypertonic Solutions on Red Blood Cells gains Loses water. water neither gains nor loses water. © McGraw Hill, LLC 21  Facilitated diffusion Transport process requires a carrier molecule but does not use cellular energy Access the text alternative for slide images. © McGraw Hill, LLC 22  Active Membrane Transport: Active Transport Requires ATP. Substances can be moved against their concentration gradients (that is, from low to high), allowing the substance to accumulate on one side of the plasma membrane. Example: sodium-potassium (Na + K + ) pump that creates electrical potentials across membranes. © McGraw Hill, LLC 23  Vesicular Transport Movement of larger substances by formation or release of a vesicle. Requires ATP. Phagocytosis Types: Endocytosis: movement into cell. Phagocytosis: solid particle is ingested, and large vesicle is formed. E.g Cells ingest Bacteria. Pinocytosis: dissolved molecules ingested, and small vesicles are formed. Exocytosis: movement out of cell. Transcytosis: movement through a cell by a combination of endocytosis on one surface and exocytosis on the opposite surface. © McGraw Hill, LLC 24  3.7 Cytoplasm Cytoplasm: cellular material outside nucleus but inside plasma membrane. Composed of cytosol, organelles, cytoskeleton, cytoplasmic inclusions. Cytosol is the fluid portion. Dissolved molecules, ions, and suspended molecules of proteins, especially enzymes. © McGraw Hill, LLC 25  Cytoskeleton - Cytoskeleton Supports the cell but allows for movements like changes in cell shape and movements of cilia. - Cytoskeleton is consist of microtubules, actin filaments, and intermediate filaments. © McGraw Hill, LLC 26  3.8 The Nucleus and Cytoplasmic Organelles Organelles: small specialized structures with particular functions. Vary in number and type depending on cell function. Most have membranes that separate interior of organelles from cytoplasm. © McGraw Hill, LLC 27  The Nucleus Large membrane-bound structure containing DNA. Consists of nucleoplasm surrounded by nuclear envelope which is a double membrane with many fused areas called nuclear pores that regulate movement into/out of nucleus. DNA contained in nucleus specifies the structure of proteins. Nucleolus: dense region(s) within the nucleus where ribosomes are manufactured. © McGraw Hill, LLC 28  Nucleus (b) Don W. Fawcett/Science Source; (c) Bernard Gilula/Science Source Access the text alternative for slide images. © McGraw Hill, LLC 29  Chromosome Structure DNA is found in nucleus, associated with proteins called histones to form chromosomes. Nucleosomes are structural units of chromosomes. During much of cell cycle, chromosomes are dispersed as chromatin. During cell division, chromatin condenses into compact chromosomes. © McGraw Hill, LLC 30  Ribosomes responsible for protein synthesis. Composed of a large and a small subunit. Composed of ribosomal RNA (rRNA) + proteins. Types: Free – synthesize proteins used inside the cell. Attached (to endoplasmic reticulum) – produce integral proteins and proteins secreted from the cell. © McGraw Hill, LLC 31  Endoplasmic Reticulum (ER) Organelle consisting of a network of membranes that is continuous with outer membrane of nuclear envelope; internal spaces are cisternae. Rough ER: has attached ribosomes; where proteins are produced and modified. Smooth ER: no attached ribosomes; manufactures lipids, participates in detoxification, and calcium ion storage. (b) J. David Robertson, from Charles Flickinger, Medical Cell Biology, Philadelphia © McGraw Hill, LLC 32  Golgi Apparatus Flattened membrane sacs, containing cisternae, stacked on each other. Modifies, packages, and distributes proteins and lipids for secretion or internal use. Substances packaged into transport vesicles. (b) Biophoto Associates/Science Source © McGraw Hill, LLC 33  Lysosomes and Peroxisomes Lysosomes. Form at the Golgi Apparatus. Contain hydrolytic enzymes that function in digesting cellular material. Digest material ingested by cell – nutrients and phagocytized bacteria. Destruction nonfunctional organelles no longer functional (autophagy). Peroxisomes. Smaller than lysosomes. Contain enzymes to break down fatty acids and amino acids. Hydrogen peroxide H2O2 (toxic) is a by-product of breakdown. Also contain the enzyme catalase which breaks down hydrogen peroxide into water and oxygen © McGraw Hill, LLC 34  Mitochondria Major site of ATP synthesis. Membranes: Cristae: Infoldings of inner membrane; contain enzymes of the electron transport chain. Matrix: Substance located in space formed by inner membrane; contains the enzymes for the citric acid or Krebs cycle. (b) EM Research Services/ Newcastle University © McGraw Hill, LLC 35  Cilia and Flagella Appendages projecting from cell surfaces, capable of movement. Cilia move materials over the surface of cells. For example, mucus in respiratory tract. Flagella used for movement by sperm cells (flagellum) © McGraw Hill, LLC 36  Microvilli Extension of plasma membrane that increases surface area; some modified as sensory receptors. (b) Don W. Fawcett/Science Source © McGraw Hill, LLC 37 Because learning changes everything. ® www.mheducation.com © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.