Campbell Essential Biology, Seventh Edition, Global Edition and Campbell Essential Biology with Physiology, Sixth Edition, Global Edition Chapter 04 A Tour of the Cell PowerPoint® Lectures created by Edward J. Zalisko, Eric J. Simon, Jean L. Dickey, and Jane B. Reece Copyright © 2019 Pearson Education Ltd. All Rights Reserved Without the Cytoskeleton, Your Cells Would Collapse in on Themselves, Much Like a Building Collapses When the Infrastructure Fails Copyright © 2019 Pearson Education Ltd. All Rights Reserved Biology and Society Antibiotics: Drugs that Target Bacterial Cells Antibiotics are drugs that disable or kill infectious bacteria. The goal of antibiotic treatment is to kill invading bacteria while doing no damage to the human host. Most antibiotics are so precise Copyright © 2019 Pearson Education Ltd. All Rights Reserved Biology and Society Antibiotics: Drugs that Target Bacterial Cells Antibiotics are drugs that disable or kill infectious bacteria. The goal of antibiotic treatment is to kill invading bacteria while doing no damage to the human host. Most antibiotics are so precise because they bind to structures found only in bacterial cells. Researchers continue to exploit the unique structures of bacterial cells to design and discover new antibiotics. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Staphylococcus Aureus Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Microscopic World of Cells Organisms are either single-celled, such as most prokaryotes and protists, or multicellular, such as plants, animals, and most fungi. Cell theory states that all living things are composed of cells and that all cells come from earlier cells. So every cell in your body (and in every other living organism on Earth) was formed by division of a previously living cell. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Types of Micrographs Copyright © 2019 Pearson Education Ltd. All Rights Reserved Types of Micrographs Copyright © 2019 Pearson Education Ltd. All Rights Reserved Types of Micrographs Copyright © 2019 Pearson Education Ltd. All Rights Reserved Size Ranges Copyright © 2019 Pearson Education Ltd. All Rights Reserved Critical thinking question for Chapter 4 You are comparing two cells. One cell is very small, and the other cell is huge. Under which conditions would you expect the larger cell to be more successful, or the small cell to be more successful? What would your answer be? Give a specific explanation for your answer. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Two Major Categories of Cells Biologists classify all life into three major groups called domains. Organisms of the domains Bacteria and Archaea are composed of prokaryotic cells. Organisms of the domain Eukarya including protists, plants, fungi, and animals are composed of eukaryotic cells. Table 4.1 compares their characteristics. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Comparing Prokaryotic and Eukaryotic Cells Checkpoint: How is the nucleoid region of a prokaryotic cell different from the nucleus of a eukaryotic cell? Copyright © 2019 Pearson Education Ltd. All Rights Reserved A Prokaryotic Cell Copyright © 2019 Pearson Education Ltd. All Rights Reserved An Idealized Animal Cell and Plant Cell (1 of 2) Copyright © 2019 Pearson Education Ltd. All Rights Reserved An Idealized Animal Cell Copyright © 2019 Pearson Education Ltd. All Rights Reserved An Idealized Plant Cell Copyright © 2019 Pearson Education Ltd. All Rights Reserved Membrane Structure The plasma membrane separates the living cell from its nonliving surroundings. The plasma membrane and other membranes of the cell are composed mostly of phospholipids, arranged into a two-layer sheet called a phospholipid bilayer. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Membrane Structure The plasma membrane is a fluid mosaic: fluid because molecules can move freely past one another and a mosaic because of the diversity of proteins in the membrane. Copyright © 2019 Pearson Education Ltd. All Rights Reserved https://www.leica-microsystems.com/science-lab/brief-introduction-to-freezefracture-and-etching/ Cell Surfaces Plant cells have a cell wall made of cellulose fibers. Plant cell walls protect the cells, maintain cell shape, and keep cells from absorbing too much water. Animal cells lack cell walls and most secrete a sticky coat called the extracellular matrix. In addition, the surfaces of most animal cells contain cell junctions, structures that connect cells together into tissues, allowing the cells to function in a coordinated way. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Process of Science: How was the First 21st-Century Antibiotic Discovered? (1 of 2) Background: To address the growing problem of antibiotic resistance, medical researchers are trying to produce new antibiotics. Method: In one approach, individual soil bacteria were isolated in separate compartments. The devices were then buried in the original soil. Membranes allowed nutrients into each compartment but kept other bacteria species out. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Search for New Antibiotics Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Process of Science: How was the First 21st-Century Antibiotic Discovered? (2 of 2) The bacteria were next tested for their ability to kill the bacteria Staphylococcus aureus, which causes deadly MRSA (methicillin-resistant S. aureus) infections and tuberculosis. Results: They found that the bacterium most effective in killing S. aureus was a new species (Eleftheria terrae) that produced teixobactin, a new type of antibiotic. It will take several years until this new antibiotic can be tested against S. aureus in human clinical trials. Vancomycin Treatment of serious infections caused by susceptible organisms resistant to penicillins (methicillin-resistant S. aureus (MRSA) and multidrug-resistant S. epidermidis (MRSE)) or in individuals with serious allergy to penicillins. -Wikipedia Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Process of Drug development NME: new molecular entity Acta Pharm Sin B 2022 12:3049 Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Nucleus and Ribosomes: Genetic Control of the Cell The nucleus is the control center of the cell. Each gene is a stretch of DNA that stores the information necessary to produce a protein. Proteins do most of the actual work of the cell. The nucleus is separated from the cytoplasm by a double membrane called the nuclear envelope. Pores in the envelope allow certain materials to pass between the nucleus and the surrounding cytoplasm. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Nucleus (1 of 2) Within the nucleus, long DNA molecules and associated proteins form fibers called chromatin. Each long chromatin fiber constitutes one chromosome. The nucleolus is a prominent structure within the nucleus and the site where the components of ribosomes are made. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Nucleus (2 of 2) Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Relationship Between DNA, Chromatin, and a Chromosome Histones Copyright © 2019 Pearson Education Ltd. All Rights Reserved Histone modification - epigenetics Front. Behav. Neurosci., 2017 11:41 The Organization of Chromosomes 3D organization of our genome https://www.youtube.com/watch?v=Pl44JjA--2k Cell 2015 160:1049 How DNA Directs Protein Production DNA transfers its coded information to a molecule called messenger RNA (mRNA), which exits the nucleus through pores in the nuclear envelope and travels to the cytoplasm, where it binds to a ribosome. A ribosome moves along the mRNA, translating the genetic message into a protein with a specific amino acid sequence. Copyright © 2019 Pearson Education Ltd. All Rights Reserved DNA RNA Protein Copyright © 2019 Pearson Education Ltd. All Rights Reserved Identifying Major Themes (1 of 3) The genetic message contained in DNA is used to build proteins. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2019 Pearson Education Ltd. All Rights Reserved Ribosomes Ribosomes are responsible for protein synthesis. In eukaryotic cells, components of ribosomes are made in the nucleus and then transported through the pores of the nuclear envelope into the cytoplasm, where ribosomes begin their work. Some ribosomes make proteins that remain within the cytosol. Other ribosomes make proteins that are incorporated into membranes or secreted by the cell. Copyright © 2019 Pearson Education Ltd. All Rights Reserved A Computer Model of a Ribosome in the Process of Synthesizing a Protein Copyright © 2019 Pearson Education Ltd. All Rights Reserved Ribosomes Ribosomes are responsible for protein synthesis. In eukaryotic cells, components of ribosomes are made in the nucleus and then transported through the pores of the nuclear envelope into the cytoplasm, where ribosomes begin their work. Some ribosomes make proteins that remain within the cytosol. Other ribosomes make proteins that are incorporated into membranes or secreted by the cell. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Figure 11.24 Ribosome assembly Ribosomal proteins are imported to the nucleolus from the cytoplasm and begin to assemble on pre-rRNA prior to its cleavage. As the pre-rRNA is processed, additional ribosomal proteins and the 5S rRNA (which is synthesized elsewhere in the nucleus) assemble to form pre-ribosomal particles. The final steps of maturation follow the export of pre-ribosomal particles to the cytoplasm, yielding the 40S and 60S ribosomal subunits. ER-Bound Ribosomes Copyright © 2019 Pearson Education Ltd. All Rights Reserved Nuclear Bodies Curr Opin Cell Biol 2014 28:76 An idealized Animal Cell and Plant Cell (2 of 2) Copyright © 2019 Pearson Education Ltd. All Rights Reserved Review of the Endomembrane System Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Endoplasmic Reticulum The endoplasmic reticulum (ER) is one of the main manufacturing facilities in a cell. The ER produces an enormous variety of molecules, is connected to the nuclear envelope, and is composed of interconnected rough and smooth ER that have different structures and functions. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Endoplasmic Reticulum (ER) Copyright © 2019 Pearson Education Ltd. All Rights Reserved Figure 12.6 Cotranslational targeting of secretory proteins to the ER Figure 11.9 Posttranslational translocation of proteins into the ER Chaperone: (especially in the past) an older person, especially a woman, who stays with and takes care of a younger woman who is not married when she is in public. - Cambridge Dictionary (Molecular) chaperone: proteins that assist the conformational folding or unfolding of large proteins or macromolecular protein complexes - Wikipedia Rough ER (1 of 2) rough ER refers to ribosomes that stud the outside of its membrane. The ER makes more membrane. Ribosomes attached to the rough ER produce proteins that will be inserted into the growing ER membrane, transported to other organelles, and eventually exported. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Rough ER (2 of 2) Some products manufactured by rough ER are chemically modified and then packaged into transport vesicles, sacs made of membrane that bud off from the rough ER. Then these transport vesicles may be dispatched to other locations in the cell. Copyright © 2019 Pearson Education Ltd. All Rights Reserved How Rough ER Manufactures and Packages Secretory Proteins Copyright © 2019 Pearson Education Ltd. All Rights Reserved Smooth ER The smooth ER lacks surface ribosomes, produces lipids, including steroids, and helps liver cells detoxify circulating drugs. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Golgi Apparatus (1 of 2) The Golgi apparatus works in partnership with the ER and receives, refines, stores, and distributes chemical products of the cell. Checkpoint: Place the following cellular structures in the order they would be used in the production and secretion of a protein: Golgi apparatus, nucleus, plasma membrane, ribosome, transport vesicle. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Golgi Apparatus (2 of 2) Copyright © 2019 Pearson Education Ltd. All Rights Reserved Identifying Major Themes (2 of 3) Several different organelles work together to carry out instructions in DNA. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2019 Pearson Education Ltd. All Rights Reserved Lysosomes (1 of 2) A lysosome is a membrane-enclosed sac of digestive enzymes found in animal cells. Most plant cells do not contain lysosomes. Enzymes in a lysosome can break down large molecules such as proteins, polysaccharides, fats, and nucleic acids. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Lysosomes (2 of 2) Lysosomes can also destroy harmful bacteria, engulf and digest parts of another organelle, and sculpt tissues during embryonic development, helping to form structures such as fingers. The importance of lysosomes to cell function and human health is made clear by hereditary disorders called lysosomal storage diseases. Most of these diseases are fatal in early childhood. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Two Functions of Lysosomes Copyright © 2019 Pearson Education Ltd. All Rights Reserved Review of the Endomembrane System Copyright © 2019 Pearson Education Ltd. All Rights Reserved Chloroplasts and Mitochondria: Providing Cellular Energy One of the central themes of biology is the transformation of energy: how it enters living systems, is converted from one form to another, and is eventually given off as heat. Two organelles act as cellular power stations: 1. chloroplasts and 2. mitochondria. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Chloroplasts Most of the living world runs on the energy provided by photosynthesis. Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar and other organic molecules. Chloroplasts are unique to the photosynthetic cells of plants and algae and the organelles that perform photosynthesis. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Chloroplast: Site of Photosynthesis Copyright © 2019 Pearson Education Ltd. All Rights Reserved Mitochondria Mitochondria are found in almost all eukaryotic cells, are the organelles in which cellular respiration takes place, and produce ATP from the energy of food molecules. Cells use molecules of ATP as the direct energy source for most of their work. Checkpoint: Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Mitochondrion: Site of Cellular Respiration Copyright © 2019 Pearson Education Ltd. All Rights Reserved Chloroplasts and Mitochondria (1 of 2) Chloroplasts and mitochondria contain their own DNA that encodes some of their own proteins made by their own ribosomes. Each chloroplast and mitochondrion contains a single circular DNA chromosome that resembles a prokaryotic chromosome and can grow and pinch in two, reproducing themselves. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Chloroplasts and Mitochondria (2 of 2) This is evidence that mitochondria and chloroplasts evolved from ancient free-living prokaryotes that established residence within other, larger host prokaryotes. This phenomenon, where one species lives inside a host species, is a special type of symbiosis. Over time, mitochondria and chloroplasts likely became increasingly interdependent with the host prokaryote, eventually evolving into a single organism with inseparable parts. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Identifying Major Themes (3 of 3) Sunlight can be used to drive the photosynthesis of sugars. Which major theme is illustrated by this action? 1. The relationship of structure to function 2. Information flow 3. Pathways that transform energy and matter 4. Interactions within biological systems 5. Evolution Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Cytoskeleton: Cell Shape and Movement The cytoskeleton is a network of protein fibers extending throughout the cytoplasm and movement. The cytoskeleton provides mechanical support to the cell and helps a cell maintain its shape. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Maintaining Cell Shape The cytoskeleton contains several types of fibers made from different proteins. Microtubules are hollow tubes of protein. The other kinds of cytoskeletal fibers, called intermediate filaments and microfilaments, are thinner and solid. The cytoskeleton provides anchorage and reinforcement for many organelles in a cell. Other organelles use the cytoskeleton for movement. Copyright © 2019 Pearson Education Ltd. All Rights Reserved The Cytoskeleton Copyright © 2019 Pearson Education Ltd. All Rights Reserved Examples of Flagella and Cilia Copyright © 2019 Pearson Education Ltd. All Rights Reserved Cilia and Flagella (1 of 3) In some eukaryotic cells, microtubules are arranged into structures called flagella and cilia, extensions from a cell that aid in movement. Eukaryotic flagella propel cells through an undulating, whiplike motion. They often occur singly, such as in human sperm cells, but may also appear in groups on the outer surface of protists. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Cilia and Flagella (2 of 3) Cilia (singular, cilium) are generally shorter and more numerous than flagella and move in a coordinated back-and-forth motion, like the rhythmic oars of a rowing team. Cilia and flagella also propel protists through water. Cilia may extend from nonmoving cells. For example, on cells lining the human trachea, cilia sweep mucus with trapped debris out of the lungs. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Cilia and Flagella (3 of 3) Because human sperm rely on flagella for movement, it is easy to understand why problems with flagella can lead to male infertility. Some men with a type of hereditary sterility also suffer from respiratory problems because of a defect in the structure of their flagella and cilia. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Evolution Connection: The Evolution of Bacterial Resistance in Humans (1 of 2) Within a human population, the persistent presence of a disease can provide a new basis for measuring those individuals who are best suited for survival in the local environment. Because Bangladeshis have lived for so long in an environment that teems with cholera bacteria, one might expect that natural selection would favor individuals who have some resistance to the bacteria. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Vibrio Cholerae, the Cause of the Deadly Disease Cholera Copyright © 2019 Pearson Education Ltd. All Rights Reserved Evolution Connection: The Evolution of Bacterial Resistance in Humans (2 of 2) Recent studies of people from Bangladesh revealed mutations in several genes that appear to confer an increased resistance to cholera. In addition to providing insight into the recent evolutionary past, data from this study reveal potential ways that humans might thwart the cholera bacterium. Perhaps pharmaceutical companies can exploit the proteins produced by the identified mutations to create a new generation of antibiotics. Copyright © 2019 Pearson Education Ltd. All Rights Reserved Copyright Copyright © 2019 Pearson Education Ltd. 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