Chapter 03 Lecture Outline PDF

Chapter 03 Lecture Outline See separate PowerPoint slides for all figures and tables pre- inserted into PowerPoint without notes. Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display. 1 Cell Structure and Function...

Chapter 03 Lecture Outline See separate PowerPoint slides for all figures and tables pre- inserted into PowerPoint without notes. Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display. 1 Cell Structure and Function 2  Points to ponder What is a cell? What are the common microscopes used? What do prokaryotic and eukaryotic cells have in common? How are cells organized? How do things move across the plasma membrane? What is the role of an enzyme in a metabolic reaction? What is cellular respiration? 3 3.1 What is a Cell? The Cell Theory 1. A cell is the basic unit of life (nothing smaller than a cell is considered to be alive) 2. All living things are made up of cells. 3. New cells arise from pre-existing cells. 4 3.1 What is a Cell? Microscopy provide a deeper look into how cells function 5 3.1 What is a Cell? What are some common microscopes used to view cells? ▪ 1. Light microscope ▪ 2. Transmission electron microscope (TEM) ▪ 3. Scanning electron microscope (SEM) 6 3.1 What is a Cell? Light Microscope vs Electron Microscope 7 3.1 What is a Cell? What are some common microscopes used to view cells? Light microscope – Lower magnification (magnification= ratio between the observed size of an image and its actual size) – Uses light beams to view images – Can view live specimens 8 3.1 What is a Cell? What are some common microscopes used to view cells? Transmission electron microscope – 2-D image – Uses electrons to view internal structure – High magnification, no live specimens Scanning electron microscope – 3-D image – Uses electrons to view surface structures – High magnification, no live specimens 9 Light Microscope vs Electron Microscopes 10 3.1 What is a Cell? Blood cells viewed with different microscopes Figure 3.3 Micrographs of human red blood cells. 11  Cells viewed with SEM Human Breast Neutrophil Pollen Grains engulfing fungus Cancer Cells 12 3.2 How Cells are Organized What are the 2 major types of cells in all living organisms? Prokaryotic cells (Represented mainly by bacteria) – Lack a nucleus – Have plasma membrane – Have cytoplasm – Have DNA – Have very few organelles (e.g. ribosomes) – Have capsule – Have hair-like extensions (Pilli) found on the surface Eukaryotic cells (human, animal, plant, protozoa, fungus) – Have a nucleus that houses DNA – Have many membrane-bound organelles ‫العضيات‬ – Have more complex structures than Prokaryotic cells 13 3.2 How Cells are Organized Prokaryotic vs Eukaryotic cells DNA Bacteria Human Cell 14 3.2 How Cells are Organized What do prokaryotic and eukaryotic cells have in common? 1) Plasma membrane that surrounds and delineates the cell 2) Cytoplasm: the semi-fluid substance inside the cell 3) DNA & RNA 4) Ribosomes 15  Prokaryotic vs Eukaryotic Cells https://www.youtube.com/watch?v=RQ-SMCmWB1s 16 3.3 The Plasma Membrane and How Substances Cross It The plasma membrane All human cells are surrounded by a plasma membrane The plasma membrane marks the boundary between the outside and the inside of the cell The integrity and function of the plasma membrane are necessary to the cell’s life 17 3.3 The Plasma Membrane and How Substances Cross It What are some characteristics of the plasma membrane? It is a phospholipid bilayer (made of 2 layers). It is embedded with proteins. It contains cholesterol for support. It contains carbohydrates on proteins and lipids. It is selectively permeable )‫(انتقائي‬. 18 Organization of the Plasma Membrane 19 3.3 The Plasma Membrane and How Substances Cross It What does selectively permeable mean? – + charged molecules The plasma membrane and ions allows some substances to H2O enter the cell while keeping other substances out aquaporin noncharged molecules In general, plasma macromolecule membrane is permeable to + – non-polar and non-charged molecules and impermeable to large, polar and charged molecules phospholipid molecule protein Figure 3.7 Selective permeability of the plasma membrane. 20 3.3 The Plasma Membrane and How Substances Cross It Test Your Knowledge Give examples of: 1- Small, uncharged, and non-polar molecules?...... 2- Small, uncharged, and polar molecules?.... 3- Large, uncharged, and polar molecules?.... 4- What about ions?.................. 21 3.3 The Plasma Membrane and How Substances Cross It 22 3.3 The Plasma Membrane and How Substances Cross It How do things move across the plasma membrane? 1. Passive Transport Diffusion Osmosis Facilitated Transport 2. Active Transport 3. Endocytosis and Exocytosis (Bulk Transportation) 23 3.3 The Plasma Membrane and How Substances Cross It 1- Diffusion and Osmosis 1. Diffusion is the random movement of molecules from a higher concentration (of solute molecules) to a lower concentration (of solute molecules) until they are equally distributed -No cellular energy is required 2. Osmosis is the movement of water molecules (from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules) -No cellular energy is required 24 3.3 The Plasma Membrane and How Substances Cross It Net movement of solutes Net movement of water 25 3.3 The Plasma Membrane and How Substances Cross It 2-What is facilitated transport? Facilitated transport is the transport of molecules across the plasma membrane from higher concentration to lower concentration via a protein carrier called transporter. No cellular energy is required Some form of Diabetes may occur when a number of glucose transporters are altered Figure 3.10 Facilitated transport across a cell membrane. 26 3.3 The Plasma Membrane and How Substances Cross It What is active transport? Active transport is the movement of molecules from a lower to higher concentration using ATP as energy; it requires a protein carrier called pump Na+/K+ pump transports 3 Na+ out of the cell and 2 K+ into the cell from low to high concentrations respectively, using ATP Active transport and the sodium–potassium pump. 27  3- What is endocytosis? plasma membrane Endocytosis transports molecules or cells into the cell via invagination of the plasma membrane to form a vesicle. vesicle a) phagocytosis: “Cell Eating” ‫البلعمة‬. Cell a. Phagocytosis engulfs solid matter either to destroy it or to feed on it. b) pinocytosis: “Cell Drinking” ‫اإلحتساء‬. Cell solute engulfs fluid matter either to destroy it or to vesicle feed on it. b. Pinocytosis c) receptor-mediated endocytosis: Cell receptor protein ingests matter by binding to a specific membrane receptor solute coated vesicle coated pit Figure 3.12 Movement of large molecules across the membrane. c. Receptor-mediated endocytosis 28 3.3 The Plasma Membrane and How Substances Cross It 3- What is exocytosis? Exocytosis transports molecules outside the cell via the fusion of a vesicle with the plasma membrane. Figure 3.12 Movement of large molecules across the membrane. 29 Isotonic, hypotonic, and hypertonic solutions Solute Extracellular Intracellular Isotonic Solution – Extracellular and intracellular ionic concentration equal Hypotonic Solution – Extracellular ionic concentration less than intracellular Hypertonic Solution – Extracellular ionic concentration higher than intracellular 30 3.3 The Plasma Membrane and How Substances Cross It How does tonicity affect a cell? Isotonic solution has equal amounts of solutes inside and outside the cell and thus do not affect the cell. Isotonic solution: 9 gram salt/1 liter solvent = (9 gram NaCl in 1 liter Water) a. Isotonic solution (same solute concen- tration as in cell) © Dennis Kunkel/Phototake Figure 3.9a Effects of changes in tonicity on red blood cells. 31 3.3 The Plasma Membrane and How Substances Cross It How does tonicity affect a cell? Hypotonic solution has less H2O amounts of solutes inside than outside the cell and lead to cell bursting and lysis. Hypotonic solution can be obtained by dissolving less than 9 gram salt/1 liter solvent b. Hypotonic solution (lower solute concen- tration than in cell) Figure 3.9b Effects of changes in tonicity on red blood cells. © Dennis Kunkel/Phototake 32 3.3 The Plasma Membrane and How Substances Cross It How does tonicity affect a cell? Hypertonic solution has more amounts of solutes inside than outside the cell and lead to cell shrinking. Hypertonic solution can be obtained by dissolving more than 9 gram salt/1 liter solvent c. Hypertonic solution (higher solute concen- tration than in cell) © Dennis Kunkel/Phototake Figure 3.9c Effects of changes in tonicity on red blood cells. 33 34 3.4 The Nucleus and Endomembrane System Gene expression: from DNA to protein Messenger RNA m ( by the ribosomes) 35 Internal Structures of an Animal Cytosol Cell Semifluid gel material inside the cell Peroxisome Destroys cellular toxic waste Nucleus Centrioles Information Microtubular structures center for the involved in cell division cell. Contains DNA Cytoskeleton Structural framework of the cell Smooth endoplas- mic reticulum Primary site of macromolecule synthesis other than proteins Rough endoplas- mic reticulum Primary site of protein synthesis by ribosomes Golgi apparatus Refines, packages, and ships macromolecular products Secretory vesicle Membrane-bound shipping container Ribosomes Site of protein synthesis Plasma membrane Mitochondrion Controls movement of Produces energy materials into and out of cell for the cell Lysosome Digests damaged organelles and cellular debris 36 Figure 3.14 3.4 The Nucleus and Endomembrane System What is the structure and function of the nucleus? Bound by a porous nuclear envelope Houses DNA: The genetic material Controls nearly all the activities of the cell 37 3.4 The Nucleus and Endomembrane System Figure 3.13 The nucleus and endoplasmic reticulum. 38  What is the structure and function of ribosomes? Ribosome Organelles made of RNA and Protein Found bound to the endoplasmic reticulum and free floating in the cytoplasm Sites of protein synthesis 39 3.4 The Nucleus and Endomembrane System What is the endomembrane system? It is a series of membranes and vesicles that work together to produce, package, secrete, and digest protein, lipids, and carbohydrates. It consists of: 1) Nuclear envelope 2) Endoplasmic reticulum (rough and smooth) 3) Golgi apparatus 4) Lysosomes 5) Vesicles 40 3.4 The Nucleus and Endomembrane System How does the endomembrane system function? secretion plasma membrane incoming vesicle secretory vesicle enzyme Golgi apparatus modifies lipids and proteins lysosome from the ER; sorts and packages contains digestive enzymes them in vesicles that break down cell parts or substances entering by vesicles protein transport vesicle transport vesicle takes proteins to takes lipids to Golgi apparatus Golgi apparatus lipid rough endoplasmic smooth endoplasmic reticulum reticulum synthesizes proteins and synthesizes lipids and has packages them in vesicles various other functions Nucleus ribosome Figure 3.14 The endomembrane system. 41 3.4 The Nucleus and Endomembrane System How can we summarize the parts of the endomembrane system? Rough endoplasmic reticulum – studded with ribosomes used to make proteins Smooth endoplasmic reticulum – lacks ribosomes but aids in making lipids and carbohydrates Golgi apparatus – flattened stacks that process, package, and deliver proteins and lipids from the ER 42 43 3.4 The Nucleus and Endomembrane System How can we summarize the parts of the endomembrane system? Lysosomes – membranous vesicles produced by the Golgi that contain digestive enzymes that breakdown cell debris or foreign particles. Vesicles – small membranous sacs used for transport of molecules from one part of the system to another. 44 3.5 The Cytoskeleton, Cell Movement, and Cell Junctions What is the cytoskeleton? A series of proteins that maintain cell shape, as well as anchors and/or moves organelles in the cell Made of 3 types of fibers: large microtubules, medium-sized intermediate filaments, and thin actin filaments 45 What is the cytoskeleton? 46  Cilia and Flagella Cilia: Short and many Flagella: Long and single Cilia are about 20 shorter than flagella. Both are made of microtubules. Both are used in cell movement. Cilia are found in the lining of the trachea (windpipe), where they sweep mucus and dirt out of the lungs and in the lining of the fallopian tube (oviduct), where they convey released ova to they uterine cavity Figure 3.15 Structure and function of the c) Human sperm cells fertilizing an egg. flagellum and cilia. 47  A Tour of the Cell https://www.youtube.com/watch?v=RKmaq7jPnYM 48 3.6 Metabolism and the Energy Reactions Metabolism Metabolism consists of all chemical reactions that occur in a cell Metabolism comprises of two major parts: anabolism and catabolism Catabolism is the set of metabolic processes that break down large molecules. It yields energy Anabolism is the set of metabolic pathways that construct molecules from smaller units. It requires energy input Metabolism requires metabolic pathways and is carried out by enzymes sequentially arranged in cells Metabolism = Catabolism + Anabolism 49 3.6 Metabolism and the Energy Reactions Enzymes are important for cellular respiration and many activities in the cell. Most enzymes are proteins. Enzymes are specific to what substrate they work on (Lock and Key). Enzymes have active sites where a substrate binds. Enzymes are not used up in a reaction but instead are recycled. Some enzymes are aided by non-protein molecules called coenzymes. 50 How do enzymes work? 51 3.6 Metabolism and the Energy Reactions What do mitochondria do and what do they look like? Highly folded organelles found in eukaryotic cells Produce energy in the form of ATP: powerhouse of the cell Thought to be derived from an engulfed prokaryotic cell Figure 3.17 The structure of a mitochondrion. 52 3.6 Metabolism and the Energy Reactions What is cellular respiration? Production of ATP in a cell Includes 3 steps: 1. Glycolysis: In the Cytoplasm 2. Citric Acid Cycle (Krebs cycle): In the Mitochondria 3. Electron Transport Chain: In the Mitochondria 53 3.6 Metabolism and the Energy Reactions Inside cell electrons transferred by NADH glucose electrons transferred by NADH Glycolysis Citric Electron acid transport glucose pyruvate cycle chain oxygen mitochondrion 2 ATP 2 ATP 32 ATP Outside cell Figure 3.19 Production of ATP. 54 3.6 Metabolism and the Energy Reactions Glycolysis – Occurs in the cytoplasm – Breaks glucose into 2 pyruvates – Produces 2 molecules of ATP – Does not require oxygen 55 3.6 Metabolism and the Energy Reactions Citric acid cycle (Krebs cycle) A cyclical pathway that – Occurs in the mitochondria – Produces 2 molecules of ATP – Requires Oxygen 56 3.6 Metabolism and the Energy Reactions Electron transport chain Series of enzymes embedded in the mitochondrial membrane -Requires Oxygen -Produces 32 molecules of ATP 57 58 3.6 Metabolism and the Energy Reactions What other molecules besides glucose can be used in cellular respiration? Carbohydrates (other than glucose) Lipids Proteins Fats have twice the energy of carbohydrates Proteins have same energy as carbohydrates 59 3.6 Metabolism and the Energy Reactions How can a cell make ATP without oxygen? Fermentation (anaerobic respiration; absence of oxygen) – Occurs in the cytoplasm – Does not require oxygen – Involves glycolysis step only – Makes 2 ATP and: 1) Lactic acid (Lactate) in human cells: painful sensation 2) Ethanol in yeast and bacteria - Can give humans a burst of energy for a short time. - Produces much less ATP than aerobic respiration 60 3.6 Metabolism and the Energy Reactions How can a cell make ATP without oxygen? Glucose (Glycolysis) (2) ATP Pyruvate Lactic acid/ ethanol buildup Mitochondrial metabolism blocked without oxygen Mitochondrion 61