Human Genetics Chapter 2 - Cells, Mitosis PDF

Because learning changes everything.® Chapter 02 Cells HUMAN GENETICS Concepts and Applications Fourteenth Edition Ricki Lewis © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Learning Outcomes 1...

Because learning changes everything.® Chapter 02 Cells HUMAN GENETICS Concepts and Applications Fourteenth Edition Ricki Lewis © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  Learning Outcomes 1 1. Explain why it is important to know the cellular basis of a disease. 2. Distinguish somatic cells from germ cells, and diploid and haploid. 3. Explain how cells differentiate. 4. List the four major chemicals in cells. 5. Describe how organelles interact to secrete, use energy, and clean up debris. 6. Describe the structure and function of a biological membrane. 7. List the components of the cytoskeleton. 8. Describe the main events of the cell cycle. © McGraw Hill 2  Learning Outcomes 2 1. Indicate how chromosomes change and interact during mitosis. 2. Discuss control of the cell cycle. 3. List the events of apoptosis. 4. Loading… List the characteristics of a stem cell and a progenitor cell. 5. Describe the three main sources of human stem cells. 6. Describe the components of the human microbiome. 7. List factors that can alter the human microbiome. © McGraw Hill 3  Introducing Cells 1 Inherited traits, quirks and illnesses arise from the activities of cells. Cells are the basic units of life and comprise the human body. Our bodies include more than 290 specialized, or differentiated, cell types These aggregate and interact to form the four basic tissue types: epithelial, connective, muscle, and nervous tissue All cells share certain features, but they are also specialized because they express different subsets of genes. © McGraw Hill 4  Introducing Cells 2 Table 2.1 Tissue Types Tissue Function/Location/Description Connective tissues A variety of cell types and surrounding materials that protect, support, bind to cells, and fill spaces throughout the body including cartilage, bone, blood, and fat Epithelium Loading… Tight cell layers that form linings that protect, secrete, absorb, and excrete Muscle Cells that contract, providing movement against rigid bones Nervous Neurons transmit information as electrochemical impulses that coordinate movement and sense and respond to environmental stimuli; neuroglia support and nourish neurons © McGraw Hill 5  Introducing Cells 3 Somatic cells are also called body cells. Have two copies of the genome and are said to be diploid Germ cells are the sperm and egg cells Have one copy of the genome and are haploid. The meeting of sperm and egg restores the diploid state Stem cells are diploid cells that divide to give rise to differentiated cells, and to other stem cells in a process called self-renewal © McGraw Hill 6  Domains of Life 1 Biologists recognize three basic types of cells that define three major “domains” of life: Archaea and Bacteria Unicellular prokaryotes No nucleus to contain DNA Eukarya Includes both unicellular and multicellular eukaryotes Has nucleus Other organelles © McGraw Hill 7  Domains of Life 2 Cells of all three domains contain ribosomes. Globular assemblies of RNA and protein Essential for protein synthesis The eukaryotes may have arisen from an ancient fusion of a bacterium with an archaean. © McGraw Hill 8  Eukaryotic and Prokaryotic Cells Kateryna Kon/Shutterstock © McGraw Hill 9  Cell Chemical Constituents The major macromolecules that make up cells are carbohydrates (sugars and starches), lipids (fats and oils), proteins, and nucleic acids (DNA and RNA). Carbohydrates provide energy and contribute to cell structure. Lipids form the basis of some hormones, form membranes, provide insulation, and store energy. Proteins have many diverse functions such as forming the contractile fibers of muscle cells, enabling blood to clot, and forming the bulk of connective tissues. Enzymes are especially important proteins because they facilitate, or catalyze, biochemical reactions. Nucleic acids (DNA and RNA) are most the most important macromolecules to the study of genetics. © McGraw Hill 10  Macromolecules of Life Table 2.2 Macromolecules of Life Molecule Type Structure Functions Examples Carbohydrates Sugars and Energy storage, cell Glucose, sucrose, polymers of identity cellulose, starch sugars Lipids sterols, Loading… Fatty acids, Form membranes, store energy, Fats, oils, waxes, cholesterol triglycerides waterproofing, form hormones Proteins Polymers of Enzymes, transport, Enzymes, antibodies, amino acids structures, cell identity, hemoglobin, collagen communication Nucleic acids Polymers of Genetic information DNA, RNA nucleotides © McGraw Hill 11  A Generalized Animal Cell 1 Surrounded by the plasma membrane (also called the cell membrane) Contains intracellular organelles Contains: Cytoplasm Stored proteins, carbohydrates, and lipids Pigment molecules Other small chemicals © McGraw Hill 12  A Generalized Animal Cell 2 (top): Jose Luis Calvo/Shutterstock; (left): Keith R. Porter/Science Source; (right): EM Research Services/Newcastle University Access the text alternative for slide images. © McGraw Hill 13  Organelles Divide labor by partitioning certain areas or serving specific functions Keep related biochemicals and structures close to one another to interact efficiently Functions: Enable a cell to retain and use its genetic instructions Acquire energy, secrete substances, and dismantle debris © McGraw Hill 14  The Nucleus 1 The most prominent organelle Surrounded by a layer called the nuclear envelope Contains: Nuclear pores that allow movement of biochemicals Nuclear lamina provides mechanical support and holds nuclear pores in place Nucleolus produces ribosomes Other contents —Chromosomes, RNA and nucleoplasm © McGraw Hill 15  The Nucleus 2 Access the text alternative for slide images. © McGraw Hill 16  Secretion: Making Milk 1 Secretion illustrates how organelles function together to coordinate the basic life functions. Access the text alternative for slide images. © McGraw Hill 17  Secretion: Making Milk 2 1. Genes that encode milk proteins and certain enzymes are transcribed into mRNA. 2. mRNA exits through nuclear pores. 3. mRNA moves to surface of rough E R, where proteins are synthesized on ribosomes using amino acids in the cytoplasm. 4. Lipids are synthesized in the smooth E R. 5. Sugars are synthesized and proteins folded in the Golgi apparatus, then both are released in vesicles that bud off the Golgi apparatus. 6. Protein- and sugar-laden vesicles move to the plasma membrane for release. Fat droplets pick up a layer of lipid from the plasma membrane as they exit the cell. © McGraw Hill 18  Endoplasmic Reticulum (E R) Interconnected membranous tubules and sacs The E R winds from the nuclear envelope to the plasma membrane Rough E R contains ribosomes and is involved in protein synthesis Smooth E R does not contain ribosomes and is important in lipid synthesis Proteins exit the E R in membrane-bounded, saclike organelles called vesicles © McGraw Hill 19  Golgi Apparatus Stack of interconnected flat, membrane-enclosed sacs Processing center that adds sugars forming glycoproteins and glycolipids Products are released into vesicles that bud off to the plasma membrane Some cell types have just a few Golgi apparatuses, but those that secrete may have hundreds © McGraw Hill 20  Exosomes Membrane-bound tiny bubbles released by all cells Transport thousands of types of protein, lipids, DNA, RNA, and smaller molecules Functions ─ remove debris, degrade wastes, transport immune system molecules, provide cellular communication network Faulty exomes cause disease and disorders © McGraw Hill 21  Exosomes are Vesicles that Transport Molecules from One Cell to another Access the text alternative for slide images. © McGraw Hill 22  Lysosomes 1 Membrane-bound sacs containing 43 types of digestive enzymes Dismantle bacterial remnants, worn-out organelles, and excess cholesterol Engage in autophagy Endosomes are vesicles derived from the plasma membrane that ferry materials to lysosomes. Example: low-density lipoprotein (L D L) cholesterol © McGraw Hill 23  Lysosomes 2 Professors Pietro M. Motta & Tomonori Naguro/Science Source Access the text alternative for slide images. © McGraw Hill 24  Lysosomes 3 Cells differ in the number of lysosomes they contain. Macrophages require many to digest bacteria Liver cells require may to break down cholesterol, toxins, and drugs Absence or malfunction of an enzyme causes a lysosomal storage disease. Tay-Sachs is an inherited disorder Nervous system becomes buried in lipid, causing death within 3 years of age © McGraw Hill 25  Peroxisomes Sacs with outer membranes studded with several types of enzymes Break down lipids, rare biochemicals Synthesize bile acids Detoxify compounds from exposure to oxygen free radicals Abundant in liver and kidney cells Adrenoleukodystrophy is an example of a genetic disease caused by an absent peroxisomal enzyme. © McGraw Hill 26  Mitochondria 1 Provide energy by breaking chemical bonds that hold together nutrient molecules in food Freed energy is stored in adenosine triphosphate (A T P) A mitochondrion is surrounded by 2 membranes Inner membrane forms folds called cristae Hold enzymes that catalyze biochemical reactions © McGraw Hill 27  Mitochondria 2 Bill Longcore/Science Source Access the text alternative for slide images. © McGraw Hill 28  Organelles of An Animal Cell Table 2.3 Structures and Functions of Organelles Organelle Structure Function Endoplasmic reticulum Membrane network; rough ER has Site of protein synthesis and folding; ribosomes, smooth ER does not lipid synthesis Golgi apparatus Stacks of membrane-enclosed sacs Site where sugars are made and linked into starches or joined to lipids or Loading… proteins; proteins finish folding; secretions stored Lysosome Sac containing digestive enzymes Degrades debris; recycles cell contents Mitochondrion Two membranes; inner membrane Releases energy from nutrients enzyme-studded Nucleus Porous, double-membraned sac Separates DNA within cell containing DNA Peroxisome Sac containing enzymes Breaks down and detoxifies various molecules Ribosome Two associated globular subunits of Scaffold and catalyst for protein RNA and protein synthesis Vesicle Membrane-bounded sac Temporarily stores or transports substances © McGraw Hill 29  Biological Membranes 1 A biological membrane has a distinctive structure. Composed of a double layer (bilayer) of molecules called phospholipids. Phosphate: hydrophilic (“water loving”) 2 fatty acid chains: hydrophobic (“water hating”) Proteins are embedded in the phospholipid bilayer. It contains carbohydrate molecules on the external surface. © McGraw Hill 30  Biological Membranes 2 Some membrane proteins form channels for ions “Channelopathies” are diseases that stem from faulty ion channels. Example: Cystic fibrosis © McGraw Hill 31  Biological Membranes 3 Access the text alternative for slide images. © McGraw Hill 32  Plasma Membrane — Cell-to-Cell Communication Many molecules that extend from the plasma membrane are receptors Bind ligands that may set into motion a cascade of chemical reactions inside the cell Signal transduction Molecules form pathways that detect signals from outside the cell and transmit them inward Cellular adhesion Plasma membrane helps cells attach to certain other cells © McGraw Hill 33  The Cytoskeleton 1 A meshwork of protein rods and tubules that serves as the cell’s architecture, positioning organelles and providing overall 3D shapes. Includes three major types of elements Hollow microtubules, made of tubulin Solid microfilaments, which consist of actin Intermediate filaments are made of more than one protein type. © McGraw Hill 34  The Cytoskeleton 2 Dr. Gopal Murti/Science Photo Library/Alamy Access the text alternative for slide images. © McGraw Hill 35  Cilia Are Built of Microtubules © McGraw Hill 36  Cell Division and Death An adult human body consists of about 30 trillion cells New cells form as old ones die, at different rates in different tissues. Growth, development, maintaining health, and healing from disease or injury require an intricate interplay between the rates of: Mitosis and cytokinesis—Division of DNA and rest of the cell Apoptosis—Cell death Precise, genetically programmed sequence of events © McGraw Hill 37  Mitosis and Apoptosis Mold a Body (b): Mediscan/Medical-on-Line/Alamy Stock Photo Access the text alternative for slide images. © McGraw Hill 38  The Cell Cycle The sequence of events associated with cell division Access the text alternative for slide images. © McGraw Hill 39  Stages of the Cell Cycle—Interphase 1 Continues the basic biochemical functions of life Prepares for cell division Replicates DNA and subcellular structures Composed of G1, s, and G2 phases Cells may exit the cell cycle at G1 or enter G0 , a quiet phase © McGraw Hill 40  Stages of the Cell Cycle—Interphase 2 Chromosomes are replicated during S phase prior to mitosis Result in each chromosome consisting of two copies joined at the centromere Proteins forming the mitotic spindle are synthesized Microtubules form centrioles near the nucleus © McGraw Hill 41  Interphase Interphase Chromosomes are uncondensed. © McGraw Hill 42  Replicated and Unreplicated Chromosomes (b): SPL/Science Source Access the text alternative for slide images. © McGraw Hill 43  Mitosis—Prophase 1 DNA coils tightly. Chromosomes are thus shortened and thickened Microtubules organize into a spindle. Nuclear membrane breaks down. Nucleolus is no longer visible. © McGraw Hill 44  Mitosis—Prophase 2 Photos: Ed Reschke Prophase Condensed chromosomes take up stain. The spindle assembles, centrioles appear, and the nuclear envelope breaks down. Access the text alternative for slide images. © McGraw Hill 45  Mitosis—Metaphase 1 Chromosomes attach to the spindle at their centromeres. Align along the cell’s equator Metaphase chromosomes are under great tension But they appear motionless because they are pulled with equal force on both sides. © McGraw Hill 46  Mitosis—Metaphase 2 Photos: Ed Reschke Metaphase Chromosome align. Access the text alternative for slide images. © McGraw Hill 47  Mitosis—Anaphase 1 Plasma membrane indents at the center Centromeres divide, which releases the tension Chromatids separate and become independent chromosomes. Move to opposite ends of the cell During this very brief phase, a cell fleetingly contains twice the normal number of chromosomes Plasma membrane indents at center © McGraw Hill 48  Mitosis—Anaphase 2 Photos: Ed Reschke Anaphase Centromeres part and chromatids separate. Access the text alternative for slide images. © McGraw Hill 49  Mitosis—Telophase 1 The cell looks like a dumbbell with a set of chromosomes at each end. Spindle falls apart. Nucleoli and membranes around the nuclei re-form at each end of the elongated cell. Division of the genetic material is now complete. © McGraw Hill 50  Mitosis—Telophase 2 Photos: Ed Reschke Telophase The spindle disassembles and the nuclear envelope re-forms. Access the text alternative for slide images. © McGraw Hill 51  Mitosis—Cytokinesis Organelles and macromolecules are distributed between the two daughter cells. Microfilament band contracts, separating the two cells. © McGraw Hill 52  Control of the Cell Cycle Control of mitosis is a daunting task. Too little, and an injury goes unrepaired Too much, and an abnormal growth forms Groups of interacting proteins function at specific times in the cell cycle, called checkpoints Ensure that chromosomes are correctly replicated and apportioned into daughter cells Internal and external factors can affect a cell’s mitotic clock. © McGraw Hill 53  Cell Cycle Checkpoints Access the text alternative for slide images. © McGraw Hill 54  Telomeres 1 Located at the ends of the chromosomes Contain hundreds to thousands of repeats of a 6-base DNA sequence (T T A G G G) Lose 50 to 200 endmost bases after each cell division After 50 divisions, shortened telomeres signal the cell to stop dividing Sperm, eggs, bone marrow, and cancer cells produce telomerase that prevent shortening of telomeres © McGraw Hill 55  Telomeres 2 Health Protection Agency/Science Source © McGraw Hill 56  Hormones and Growth Factors Chemical signals that control the cell cycle from outside the cell Hormone is made in a gland and transported in the bloodstream to another part of the body. Exerts a specific effect A growth factor acts locally. Epidermal growth factor (E G F) stimulates cell division in the skin beneath a scab. Two types of proteins, the cyclins and kinases, interact inside cells, activating the genes whose products carry out mitosis. © McGraw Hill 57  Apoptosis Begins when a “death receptor” on the plasma membrane receives a signal to die Killer enzymes called caspases are activated Destroy enzymes that replicate and repair DNA Tear apart the cytoskeleton Abolish cell’s ability to adhere to other cells Attract phagocytes that digest the cell remnants Dying cell forms bulges called blebs Membrane surrounds the pieces, preventing inflammation. © McGraw Hill 58  Death of a Cell 1 Mitosis and apoptosis work together to form functional body. Cancer can result from too much mitosis or too little apoptosis. © McGraw Hill 59  Death of a Cell 2 (top): David McCarthy/Photo Researchers/Science Source; (bottom): larisa Stefanjuk/Shutterstock Access the text alternative for slide images. © McGraw Hill 60  Stem Cells 1 A stem cell divides by mitosis. Produces two daughter cells or a stem cell and a progenitor cell, which may be partially specialized Progenitor cells do not have the capacity of self-renewal. Access the text alternative for slide images. © McGraw Hill 61  Stem Cells 2 Cells differentiate down cell lineages of stem, progenitor, and increasingly differentiated cells Stem cells and progenitor cells are described in terms of their developmental potential Totipotent—Can give rise to every cell type Pluripotent—Have fewer possible fates Multipotent—Have only a few developmental choices Many, if not all, of the organs in an adult human body have stem or progenitor cells. © McGraw Hill 62  Pathways to Cell Specialization Access the text alternative for slide images. © McGraw Hill 63  Stem Cell Sources 1 There are three general sources of human stem cells: Embryonic stem cells—Created in a lab dish using the inner cell mass (IC M) of an embryo Induced pluripotent stem (iP S) cells—Somatic cells reprogrammed to differentiate into any of several cell types Adult stem cells—Tissue-specific or somatic stem cells Researchers study stem cells to learn more about biology and to develop treatments for a variety of diseases and injuries © McGraw Hill 64  Stem Cell Sources 2 Table 2.4 Stem Cell Sources Stem Cell Type Source Embryonic stem cell Inner cell mass of very early embryo; somatic cell nuclear transfer into egg cell Induced pluripotent stem cell Genes or other chemicals reprogram somatic cell nucleus; no embryos required “Adult” stem cell Somatic cells that normally function as stem cells, from any stage of development from fertilized ovum through older age © McGraw Hill 65  Using stem cells to heal Access the text alternative for slide images. © McGraw Hill 66  Stem Cell Applications Stem cells are being used in four basic ways: Discovery and development of drugs Observing the earliest sign of disease Create tissues and organs, for use in implants and transplants, or to study Stimulating stem cells in the body via the introduction of reprogramming proteins © McGraw Hill 67  The Human Microbiome 1 Our bodies are vast ecosystems for microscopic life. The average person consists of approximately 30 trillion cells and approximately 39 trillion cells that are bacteria, fungi, protozoan, as well as viruses The cells within and on us that are not actually of us constitute the human microbiome. Different body parts house different communities of microbes. The microbiome changes with experience and environmental exposures. © McGraw Hill 68  The Human Microbiome 2 Source: From “The function of our microbiota: Who is out there and what do they do?” by N. Ottman, H. Smidt, W. M. de Vos, and C. Belzer. Front. Cell. Inf. Microbio. 2:104. DOI: 10.3389/fcimb.2012.00104. Courtesy, U.S. National Library of Medicine. Access the text alternative for slide images. © McGraw Hill 69  The Human Microbiome 3 Human microbiome studies have revealed that: Certain skin bacteria cause acne, but others keep skin clear. Circumcision protects against viral infections such as HIV. Lowered blood sugar following weight-loss surgery is partly due to a changed gut microbiome. An altered microbiome hastens starvation in malnourished children. Antibiotics temporarily alter the gut microbiome. Microbiome imbalances may contribute to or cause asthma, cancers, obesity, psoriasis, Crohn’s disease, ad gum disease. Babies born by Cesarean section (surgically) have different microbiomes than babies born vaginally. People living in isolated areas have different microbiomes than city residents. © McGraw Hill 70  End of Main Content Because learning changes everything.® www.mheducation.com © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.