Cell Biology - Anatomy & Physiology 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 re...

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.  Lecture Outline The cell is the basic unit of life and is composed of a plasma membrane and the cytoplasm, which includes a nucleus and cytoplasmic organelles. Access the text alternative for slide images. © McGraw Hill, LLC 2  3.1 Functions of the Cell General parts of a cell: Plasma (cell) membrane – outer boundary that allows cell interaction with its external environment. Nucleus – directs cell activities. Cytoplasm – located between plasma membrane and nucleus; contains organelles that perform specific functions. © McGraw Hill, LLC 3  A Human Cell Access the text alternative for slide images. © 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  Production of a membrane potential An electrical charge difference across the plasma membrane that results from the cell’s regulation of ion movement into and out of the cell. There are more positively charged ions along the outside of the plasma membrane, giving it a positive charge. There are more negatively charged ions and proteins on the inside of the plasma membrane, giving it a negative charge. © McGraw Hill, LLC 6  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 7  3.4 Membrane Lipids Phospholipids and cholesterol predominate. Phospholipids: bilayer. 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 8  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 9  Transport Proteins Includes channel proteins, carrier proteins, and ATP- powered pumps. © McGraw Hill, LLC 10  Channel Proteins Channel proteins – integral membrane proteins that form tiny channels through membrane. The channel determines the size, shape and charge of what can move through. Hydrophobic regions face outward toward the hydrophobic part of the plasma membrane. Hydrophilic regions face inward and line the tunnel. The charge of the hydrophilic tunnel determines the types of ions that can move through. © McGraw Hill, LLC 11  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. Cystic Fibrosis is a genetic disorder that affects chloride ion channels and causes cells to produce thick, viscous secretions. © McGraw Hill, LLC 12  Leak and Gated Membrane Channels © McGraw Hill, LLC 13  Carrier Proteins 1 Also called transporters. Integral proteins move ions from one side of membrane to the other. 1. Specific molecule enters the carrier. 2. Molecule attaches to binding site in carrier. 3. Protein changes shape to transport to the other side. Resumes original shape after transport. © McGraw Hill, LLC 14  Carrier Proteins 2 Carrier proteins come in several forms. Uniporters – moves one ion/molecule. Symporters – move two ions/molecules 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 15  ATP-Powered Pumps Require the breakdown of ATP. 1. ATP-powered pumps have binding sites for specific ions or molecules and ATP. 2. Hydrolysis of ATP to A DP, releases energy to change the shape of the carrier to move the substance across the membrane. 3. The ion and phosphate are released and the pump resumes its original shape. © McGraw Hill, LLC 16  Opening and Closing of Ligand-Gated Channels 1. Acetylcholine binds to the receptor sites linked to a Na+ channel. When the receptor sites are not occupied by ACh, the channel remains closed. 2. The binding of ACh molecules to the receptor sites opens the channels in the plasma membrane allowing to move into the cell. © McGraw Hill, LLC 17  Membrane Transport Mechanisms Passive membrane transport – the cell does not expend A TP; movement from higher concentration to lower concentration. Diffusion. Osmosis. Facilitated diffusion. Active membrane transport – AT P is used to move from lower concentration to higher concentration. Active transport. Secondary active transport. Vesicular transport – uses a membrane-bound sac. Endocytosis. Exocytosis. © McGraw Hill, LLC 18  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. Solute and solvent particles will continue to move even once an equilibrium has been established. © McGraw Hill, LLC 19  Diffusion of Salt in a Beaker of Water 1. A salt crystal is placed in a beaker of water. A concentration difference exists between the salt crystal and the water surrounding it. 2. Salt ions, moving randomly, spread through the beaker of water. 3. Eventually, the salt ions will become evenly distributed throughout the water. Access the text alternative for slide images. © McGraw Hill, LLC 20  Diffusion Through the Plasma Membrane Access the text alternative for slide images. © McGraw Hill, LLC 21  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). Aquaporins – water channel proteins. Osmotic pressure: force required to prevent water from moving across a membrane by osmosis. © McGraw Hill, LLC 22  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 23  Effects of Hypotonic, Isotonic, and Hypertonic Solutions on Red Blood Cells David M. Phillips/Science Source Access the text alternative for slide images. © McGraw Hill, LLC 24  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. Rate of transport depends on concentration of substrate, the number of ATP pumps, and amount of ATP. Example: sodium-potassium pump that creates electrical potentials across membranes. © McGraw Hill, LLC 25  Active Transport: Sodium-Potassium Pump 1. Three sodium ions and adenosine triphosphate (ATP) bind to the sodium–potassium pump. 2. Three sodium ions and adenosine triphosphate (ATP) bind to the sodium–potassium pump. 3. The pump changes shape, and the are transported across the membrane and into the extra cellular fluid. 4. Two potassium ions (K+) bind to the pump. 5. Two potassium ions (K+) bind to the pump. 6. The pump changes shape, transporting across the membrane and into the cytoplasm. The pump can again bind to and ATP. Access the text alternative for slide images. © McGraw Hill, LLC 26  Secondary Active Transport Use of potential energy in concentration gradient of one substance (established by primary active transport) to help move another substance. 1. A Na+−K+ pump maintains a concentration of Na+ that is higher outside the cell than inside. 2. Na+ move back into the cell through a transport protein that also moves glucose. The concentration gradient for Na+ provides the energy required to move glucose against its concentration gradient. © McGraw Hill, LLC 27  Vesicular Transport Movement of larger substances by Phagocytosis formation or release of a vesicle. Requires ATP. Types: Endocytosis: movement into cell. Phagocytosis: solid particle is ingested and large vesicle is formed. Pinocytosis: dissolved molecules ingested and small vesicles are Transcytosis: movement formed. through a cell by a combination of endocytosis Exocytosis: movement out of on one surface and cell. exocytosis on the opposite surface. © McGraw Hill, LLC 28  Pinocytosis and Transcytosis Access the text alternative for slide images. © McGraw Hill, LLC 29  Exocytosis 1. Within the cell, secretions accumulate within vesicles that move to the plasma membrane. 2. The vesicle membrane fuses with the plasma membrane. 3. The vesicle contents are expelled from the cell into the extracellular fluid. (b) JOSE CALVO/Science Source © McGraw Hill, LLC 30  3.7 Cytoplasm Cytoplasm: cellular material outside nucleus but inside plasma membrane. Composed of cytosol, cytoskeleton, cytoplasmic inclusions, organelles. Cytosol is the fluid portion. Dissolved molecules, ions, and suspended molecules of proteins, especially enzymes. © McGraw Hill, LLC 31  Cytoskeleton Supports the cell but allows for movements like changes in cell shape and movements of cilia. © McGraw Hill, LLC 32  3.8 The Nucleus and Cytoplasmic Organelles Organelles: small specialized structures with particular functions. Most have membranes that separate interior of organelles from cytoplasm. Related to specific structure and function of the cell. © McGraw Hill, LLC 33  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. RNA serves as an intermediate during protein synthesis and consists of three types: mRNA, rRNA, and tRNA. Nucleolus: dense region(s) within the nucleus where ribosomes are manufactured. © McGraw Hill, LLC 34  Nucleus (b) Don W. Fawcett/Science Source; (c) Bernard Gilula/Science Source Access the text alternative for slide images. © McGraw Hill, LLC 35  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 36  Ribosomes Sites of 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 37  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 38  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 39  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. Digest organelles no longer functional (autophagy). Peroxisomes. Smaller than lysosomes. Contain enzymes to break down fatty acids and amino acids. Hydrogen peroxide (toxic) is a by-product of breakdown. Also contain the enzyme catalase which breaks down hydrogen peroxide into water and oxygen © McGraw Hill, LLC 40  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. Mitochondria increase in number when cell energy requirements increase. (b) EM Research Services/ Newcastle University © McGraw Hill, LLC 41  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. © McGraw Hill, LLC 42  Microvilli Extension of plasma membrane that increases surface area; some modified as sensory receptors. Normally many on each cell. One-tenth to one-twentieth the size of cilia. Do not move; supported with actin filaments. (b) Don W. Fawcett/Science Source © McGraw Hill, LLC 43 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.