Week 4 + 5 - The Cell PDF

Chapter 3 The Cell Lecture Presentation by Tonya Bates, UNC Charlotte © 2017 Pearson Education, Inc.  The Cell Outline:  Eukaryotic Cells Compared with Prokaryotic Cells  Cell Size and...

Chapter 3 The Cell Lecture Presentation by Tonya Bates, UNC Charlotte © 2017 Pearson Education, Inc.  The Cell Outline:  Eukaryotic Cells Compared with Prokaryotic Cells  Cell Size and Microscopy  Cell Structure and Function  Plasma Membrane  Organelles  Cytoskeleton  Cellular Respiration and Fermentation in the Generation of ATP © 2017 Pearson Education, Inc.  3.1 Eukaryotic Cells Compared with Prokaryotic Cells  The cell theory is a fundamental organizing principle of biology that states the following: The cell is the smallest unit of life Cells make up all living things, including unicellular and multicellular organisms New cells can arise only from preexisting cells  There are two basic types of cells: Prokaryotic Eukaryotic © 2017 Pearson Education, Inc. What is a Cell?  Cell – Basic unit of living things. Organisms are either:  Unicellular – made of one cell such as bacteria and amoebas. OR  Multicellular – made of many cells such as plants and animals. Cells are the Fundamental Units of Life Confirmed discoveries that all scientists believe to be true about cells: 1.All living things are made up of cells. 2.Cells are the smallest working units of all living things. 3.All cells come from preexisting cells through cell division. All Cells are Either Prokaryotic or Eukaryotic Prokaryotic before nucleus Eukaryotic true nucleus  3.1 Eukaryotic Cells Compared with Prokaryotic Cells Prokaryotic Cells Eukaryotic Cells  Structurally simple  Structurally complex  Typically smaller  Typically larger  Lack membrane-bound  Have membrane-bound organelles organelles  Include bacteria and  Found in plants, animals, Archaea fungi, protist © 2017 Pearson Education, Inc. What is a Cell?  Cell – Basic unit of living things. Organisms are either:  Unicellular – made of one cell such as bacteria and amoebas. OR  Multicellular – made of many cells such as plants and animals. Cells are the Fundamental Units of Life Confirmed discoveries that all scientists believe to be true about cells: 1.All living things are made up of cells. 2.Cells are the smallest working units of all living things. 3.All cells come from preexisting cells through cell division. Prokaryotes 1. NO nucleus 2. NO membrane bound organelles (just ribosomes) 3. ALL are unicellular 4. Smaller than eukaryotic cells 5. Forerunner to eukaryotic cells (smaller and more simple) 6. DNA – single strand and circular 7. Ex: ALL Bacteria Similarities 1. Contain all four biomolecules (lipids, carbs, proteins, and nucleic acids) 1. Have ribosomes 2. Have DNA 3. Similar Metabolism 4. Can be unicellular All Cells are Either Prokaryotic or Eukaryotic Prokaryotic cells Eukaryotic cells DNA within membrane-bound in “nucleoid” region nucleus Size much smaller much larger Organization always single-celled often multicellular Organelles only one type of organelle many types of organelles Figure 4.2 Figure 3.1 Plasma membrane DNA region (no nucleus) Cytoplasm Ribosome Cell wall 1–10 m © 2017 Pearson Education, Inc. The Eukaryotic Cell nuclear pores nucleus DNA nuclear envelope smooth endoplasmic nucleolus reticulum free ribosomes cytoskeleton cytosol lysosomes rough endoplasmic reticulum Golgi complex plasma membrane transport vesicle mitochondria Figure 4.4 Table 3.1 © 2017 Pearson Education, Inc.  3.2 Cell Size and Microscopy  Cells vary in size, but they can never exceed the volume that can be nourished by materials passing through the surface membrane  The small size of cells is dictated by a physical relationship known as the surface-to-volume ratio As a cell gets larger, its surface area increases far more slowly than its volume © 2017 Pearson Education, Inc. Figure 3.3 1 6 Measurement Surface area 6 216 (height × width × number of sides) Volume 1 216 (height × width × length) Surface-to-volume ratio 6:1 1:1 (surface area:volume) © 2017 Pearson Education, Inc.  3.2 Cell Size and Microscopy  Most eukaryotic and prokaryotic cells are typically measured in micrometers (μm), which equal 10–6 meters  They can be seen through either light or electron microscopes  Micrographs are the photographs taken with the microscope © 2017 Pearson Education, Inc. Figure 3.4 (a) Striated muscle cells viewed with a (b) Striated muscle cells viewed with a (c) Striated muscle cells viewed with a light microscope transmission electron microscope scanning electron microscope © 2017 Pearson Education, Inc.  3.3 Cell Structure and Function  Although we begin life as only one cell, that cell differentiates into many specialized cells These specialized cells have structures that reflect their particular functions © 2017 Pearson Education, Inc. Figure 3.5 (a) A sperm is specialized to be highly mobile. (b) A mature red blood cell, devoid of most (c) A cardiac muscle cell is specialized for In contrast, an egg is specialized to be large, organelles, is specialized for carrying contraction and for propagating the signal immobile, and packed with material needed to oxygen. for contraction. initiate development. © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  The outer boundary of the cell  Controls the movement of substances in and out of the cell  The phospholipid bilayer separates the extracellular fluid from the material contained in the cytoplasm inside the cell  Proteins, cholesterol, and carbohydrates are also part of the membrane and give it the qualities of a fluid mosaic © 2017 Pearson Education, Inc.  3.4 Plasma Membrane © 2017 Pearson Education, Inc. Figure 3.6 Carbohydrate Glycoprotein Plasma membrane Embedded Cholesterol Glycolipid Outer surface of protein plasma membrane Extracellular fluid Plasma membrane Inner surface of plasma membrane Phospholipid bilayer Surface Filaments of Cytoplasm protein cytoskeleton © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Functions of the structure of the plasma membrane: Maintains structural integrity of the cell Selectively permeable as it regulates movement of substances into and out of the cell Glycoproteins provide recognition between cells Receptors provide communication between cells Cell adhesion molecules stick cells together to form tissues and organs © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  There are two types of movement across the plasma membrane: Passive transport  Movement across the membrane that doesn’t require energy Simple diffusion, facilitated diffusion, osmosis Active transport  Movement across the membrane that requires energy © 2017 Pearson Education, Inc.  3.4 Plasma Membrane © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Simple diffusion Movement of a substance following a concentration gradient, from high concentration to low concentration End result is an equal distribution of the substance in the two areas Eliminates the concentration gradient © 2017 Pearson Education, Inc. Figure 3.7 A lipid-soluble substance moves through the lipid bilayer from high to low concentration. Extracellular fluid High concentration Plasma membrane Low concentration Cytoplasm © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Facilitated diffusion Movement of a substance from a region of higher concentration to a region of lower concentration with the aid of a membrane protein To cross a cell membrane, water-soluble substances need to be assisted or “facilitated” by carrier proteins © 2017 Pearson Education, Inc. Figure 3.8 Glucose moves through the lipid bilayer from high to low concentration with aid from a carrier protein. Extracellular fluid High Glucose concentration Carrier protein Plasma membrane Low concentration Cytoplasm © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Osmosis Movement of water across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration  The water molecules move to dilute the solution © 2017 Pearson Education, Inc.  3.4 Plasma Membrane © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc. Figure 3.9 The bag gains and loses the same amount of water and maintains its shape. The bag gains 98% water, more water than The bag loses more water than 2% sugar it loses and swells. it gains and shrivels. (a) Hypertonic (b) Isotonic (c) Hypotonic solution solution solution (90% water, (98% water, (100% water, 10% sugar) 2% sugar) distilled) © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Active transport Movement from a region of lower to higher concentration with the aid of a carrier protein and energy, typically ATP E © 2017 Pearson Education, Inc. Figure 3.10 Extracellular fluid Extracellular fluid Low Plasma concentration membrane A substance moves through the lipid bilayer from low to high concentration with the aid of a carrier protein and energy. Carrier protein ATP ADP High concentration Cytoplasm Cytoplasm © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Endocytosis A region of the plasma membrane engulfs the substance to be ingested and then pinches off from the rest of the membrane, enclosing the substance in a vesicle, which travels through the cytoplasm  Applies to large molecules, single-celled organisms, and droplets of fluid containing dissolved substances  Two types of endocytosis: Phagocytosis (cell eating): large particles or bacteria Pinocytosis (cell drinking): droplets of fluid © 2017 Pearson Education, Inc. Figure 3.11 Extracellular fluid Plasma membrane Bacterium Cytoplasm Vesicle (a) Phagocytosis (“cell eating”) occurs when cells engulf bacteria or other large particles. Extracellular fluid Plasma membrane Vesicle Dissolved substances Cytoplasm (b) Pinocytosis (“cell drinking”) occurs when cells engulf droplets of extracellular fluid and the dissolved substances therein. © 2017 Pearson Education, Inc.  3.4 Plasma Membrane  Exocytosis Large molecules are enclosed in membrane-bound vesicles, which travel to plasma membranes, where they are released to the outside © 2017 Pearson Education, Inc.  3.4 Plasma Membrane © 2017 Pearson Education, Inc. Figure 3.12 Cytoplasm Vesicle 1 The vesicle moves through the Plasma cytoplasm toward the membrane plasma membrane. 2 The membrane of the vesicle fuses with the plasma membrane. 3 The vesicle spills its contents outside the cell. Extracellular fluid © 2017 Pearson Education, Inc. Table 3.2 © 2017 Pearson Education, Inc. Inside the Cell  3.5 Organelles  Inside eukaryotic cells are membrane-bound organelles, which have different functions  Organelles include: Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Mitochondrion  Non-membranous organelles also perform specific cellular functions © 2017 Pearson Education, Inc.  3.5 Organelles  Nucleus Contains almost all of the genetic information of the cell, DNA Surrounded by nuclear envelope, a double membrane that allows communication through nuclear pores The genetic information is organized into chromosomes  Chromosomes are threadlike structures made of DNA, and associated proteins called histones  Humans have 46 chromosomes (23 pairs) in the loose form (chromatin) or condensed, which are then visible in the light microscope during cell division © 2017 Pearson Education, Inc. Figure 3.13 In some areas, the nuclear membrane is continuous with Nucleus the endoplasmic reticulum. Rough endoplasmic reticulum Nucleus Nucleolus Nucleoplasm Nuclear envelope Chromatin (DNA and its associated proteins) Nuclear pore (a) Diagram of the nucleus (b) Electron micrograph of the nucleus and surrounding cytoplasm © 2017 Pearson Education, Inc. Figure 3.14 Nucleus Chromatin (a) Individual chromosomes are visible during cell (b) At all other times, the genetic material is dispersed division, when they shorten and condense. and called chromatin. © 2017 Pearson Education, Inc.  3.5 Organelles  Nucleus Nucleoplasm  Made of chromatin and the other contents of the nucleus Nucleolus  A specialized region within the nucleus  Involved in the production of ribosomal RNA © 2017 Pearson Education, Inc. Endoplasmic Reticulum  Moves materials around in cell  Smooth type: lacks ribosomes  Rough type (pictured): ribosomes embedded in surface The endoplasmic reticulum serves many general functions: -Including the folding of protein molecules and the transport of synthesized proteins in vesicles to the Golgi apparatus.  3.5 Organelles  Endoplasmic reticulum An extensive network of channels connected to the plasma membrane, the nuclear envelope, and certain organelles Two types of endoplasmic reticulum:  Rough endoplasmic reticulum (RER) Contains ribosomes that guide the production of cell products  Smooth endoplasmic reticulum (SER) Lacks ribosomes Involved in the production of phospholipids and detoxification © 2017 Pearson Education, Inc. Figure 3.15 Rough endoplasmic reticulum (RER) has ribosomes attached to its surface and modifies proteins made by the ribosomes. Endoplasmic reticulum Smooth endoplasmic reticulum (SER) lacks Nucleus ribosomes and detoxifies certain drugs and produces phospholipids for incorporation into membranes. © 2017 Pearson Education, Inc.  3.5 Organelles  Golgi complex A series of interconnected, flattened membranous sacs Proteins are packaged in vesicles and transferred to the Golgi complex for processing and packaging  Lysosomes Contain about 40 digestive enzymes that break down macromolecules, old organelles, and invaders © 2017 Pearson Education, Inc. Figure 3.16 Golgi complex New vesicle forming Golgi complex (a) Diagram of the Golgi complex. This organelle serves as the (b) Electron micrograph showing the Golgi complex and its site for protein processing and packaging within the cell. associated vesicles © 2017 Pearson Education, Inc. Figure 3.17 Rough endoplasmic reticulum Proteins Ribosome Transport Vesicles carrying proteins from the RER vesicle arrive at the “receiving” side of the Golgi complex and empty their contents to the inside, where the proteins are modified. Golgi complex Lysosome with Secretory proteins vesicle Vesicles containing the Plasma membrane Protein modified proteins leave the expelled “shipping” side of the Golgi complex and travel to their specific destinations. © 2017 Pearson Education, Inc. Figure 3.18 Nucleus 1 Cell engulfs bacterium through phagocytosis. Bacterium Rough ER 2 Lysosome fuses Transport with vesicle containing vesicle bacterium. Vesicle containing Golgi bacterium complex Damaged organelle 3 Lysosomal enzymes Lysosome break the bacterium down into smaller molecules that Digestion diffuse into cytoplasm. 1 Lysosome engulfs a damaged organelle. 4 Some indigestible substances leave the cell by exocytosis. 2 Lysosomal enzymes break down 5 Other indigestible the organelle into smaller molecules that substances remain in the will return to the cytoplasm for reuse. cell. © 2017 Pearson Education, Inc. A Tour of the Animal Cell: Along the Protein Production Path Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Endoplasmic Reticulum The endoplasmic reticulum is a network of folded membranes that form channels. The Endoplasmic Reticulum makes protein and lipid components. Consists of a smooth ER and a rough ER. This organelle is responsible of moving proteins and other carbohydrates to the Golgi Apparatus, lysosomes, and other places which need carbohydrates. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Rough Endoplasmic Reticulum (RER) The RER is dotted with ribosomes. (Which is why it is called “rough.”) The RER is involved with protein production, protein folding, quality control and dispatch. The RER is involved with the synthesis of proteins. They produce and process specific proteins at ribosomal sites. Consists of network-like tunnels with tubules, vesicles and cisternae which is held together by the cytoskeleton of the cell. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Smooth Endoplasmic Reticulum (SME) SME is more tubular then RER and forms a separate interconnecting network. (Is found evenly distributed among the Cytoplasm.) SME has no ribosomes on it. Smooth ER manufactures lipids and in some cases the metabolism of them and associated products. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Tour of the Animal Cell: Along the Protein Production Path Information for the construction of proteins is contained in the DNA located in the cell nucleus. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Protein Production Path This information is copied onto a length of messenger RNA (mRNA). Messenger RNA (mRNA) departs the cell nucleus through its nuclear pores (mRNA) goes to the sites of protein synthesis, structures called ribosomes, which lie in the cytoplasm. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Protein Production Path Many ribosomes that receive mRNA chains process only a short stretch of them before migrating to, and then embedding in, one of a series of sacs in a membrane network called the rough endoplasmic reticulum (RER). Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Protein Production Path The polypeptide chains produced by the ribosomal “reading” of the mRNA sequences are dropped from ribosomes into the internal spaces of the RER. There, the polypeptide chains fold up, thus becoming proteins, and undergo editing. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Protein Production Path Some ribosomes are not embedded in the RER but instead remain free-standing in the cytosol. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Protein Production Path Materials move from one structure to another in the cell via the endomembrane system. Here a piece of membrane, with proteins or other materials inside, can bud off from one organelle, move through the cell, and then fuse with another membrane-lined structure. Membrane-lined structures that carry cellular materials are called transport vesicles. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Protein Production Endomembrane system Path Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Protein Production Path Once protein processing is finished in the rough ER proteins undergoing processing move, via transport vesicles, to the Golgi complex. They are processed further and marked for shipment to appropriate cellular locations. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Golgi Complex Golgi complex 1. Transport vesicle from RER fuses with Golgi 2. Protein undergoes more processing in Golgi cisternae cisternal space vesicle Side chains are edited (sugars may be to cytosol 3. Proteins are trimmed, phosphate sorted and for export to plasma groups added). shipped… out of cell membrane Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.8  3.5 Organelles  Mitochondria Sites of cellular respiration, providing cell with energy through the breakdown of glucose to produce ATP  Double-membrane organelle  Contain inner foldings, called cristae, that provide increased membrane surface for cellular respiration  Singular: mitochondrion © 2017 Pearson Education, Inc. Figure 3.19 Outer membrane Inner membrane Mitochondrion Cristae (a) Diagram of a mitochondrion showing the double (b) Electron micrograph of a mitochondrion membrane that creates two compartments © 2017 Pearson Education, Inc.  3.6 Cytoskeleton  Network that provides shape and support for the cell  Composed of thick microtubules, intermediate filaments, and thin microfilaments Centriole: a microtubule-organizing center located near the nucleus Microtubules and microfilaments disassemble and reassemble, while intermediate filaments tend to be more permanent © 2017 Pearson Education, Inc.  3.6 Cytoskeleton  Centrioles Organized in a pair of centrioles Each composed of nine sets of three microtubules arranged in a ring May function in cell division and in the formation of cilia and flagella © 2017 Pearson Education, Inc. Figure 3.20 Centriole (a) Diagram of a centriole. Each centriole is (b) Electron micrograph showing the microtubules composed of nine sets of triplet microtubules of a centriole arranged in a ring. © 2017 Pearson Education, Inc.  3.6 Cytoskeleton  Microtubules Made of the protein tubulin Responsible for the structure and movement of cilia and flagella  Cilia are numerous short extensions in a cell that move back and forth Example: cells lining the respiratory tract  Flagella are larger than cilia and move in an undulating manner Example: in humans, found only on sperm cells © 2017 Pearson Education, Inc.  Cilia Cilia extend from cells in great numbers, serving to move the cell or to move material around the cell. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Flagella By contrast, one—or at most a few— flagella extend from cells that have them. The function of flagella is cell E movement. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 3.21 Cilium Flagellum Cilium (a) Cilia on cells lining the respiratory tract (b) Sperm cells in a fallopian tube. Each sperm cell (c) Several cilia in cross section showing the 9  2 has a single flagellum. pattern of microtubules. Flagella (not shown) have a similar arrangement of microtubules. © 2017 Pearson Education, Inc.  3.6 Cytoskeleton  Microfilaments: Made of the protein actin Function in muscle contraction Form a band that pinches cell in two during cell division  Intermediate filaments: Protein composition varies from one type of cell to another Diverse group of ropelike fibers that maintain cell shape and anchor organelles © 2017 Pearson Education, Inc.  Cytoskeleton © 2017 Pearson Education, Inc.  3.7 Cellular Respiration and Fermentation in the Generation of ATP  Cell metabolism includes all of the chemical reactions that take place in a cell Organized into metabolic pathways  Each pathway contains a series of steps  Specific enzymes speed up each step of the pathway  May be catabolic or anabolic © 2017 Pearson Education, Inc. © 2017 Pearson Education, Inc.  3.7 Cellular Respiration and Fermentation in the Generation of ATP  Both are catabolic pathways that generate cellular energy Complex molecules are broken down into simpler compounds Energy is released  Cellular respiration requires oxygen to break down glucose into final products: Carbon dioxide Water Energy as ATP © 2017 Pearson Education, Inc.  3.7 Cellular Respiration and Fermentation in the Generation of ATP  Four phases of cellular respiration: Glycolysis Transition reaction Citric acid cycle Electron transport chain  Phases occur continuously in the cell © 2017 Pearson Education, Inc.  3.7 Cellular Respiration  Phase 1: Glycolysis Occurs in the cytoplasm Splits glucose into two pyruvate molecules Generates a net gain of two ATP and two NADH molecules Does not require oxygen © 2017 Pearson Education, Inc. Figure 3.22 Glycolysis (in cytoplasm) Cytoplasm During the first steps, two molecules of ATP are consumed in preparing glucose for splitting. Glucose C C C C C C 2 ATP During the remaining Energy- steps, four molecules of investment ATP are produced. 2 ADP phase 4 ADP 4 ATP Energy- The two molecules of yielding pyruvate then diffuse 2 NAD phase from the cytoplasm into the inner compartment of the mitochondrion, where they pass through a few preparatory steps 2 NADH (the transition reaction) before entering the citric acid cycle. C C C Two molecules of nicotine adenine dinucleotide 2 Pyruvate (NADH), a carrier of high-energy electrons, C C C also are produced. © 2017 Pearson Education, Inc.  3.7 Cellular Respiration  Phase 2: Transition reaction Occurs within the mitochondria Removes carbon as CO2 from each pyruvate Generates an acetyl CoA molecule and NADH molecule from each pyruvate broken down © 2017 Pearson Education, Inc.  3.7 Cellular Respiration  Phase 3: Citric acid cycle or Krebs cycle Occurs within the mitochondria Acetyl CoA enters the citric acid cycle Produces two ATP, two FADH2, and six NADH molecules and releases CO2 as a waste product © 2017 Pearson Education, Inc. Figure 3.24 Citric Acid Cycle (in mitochondrion) Acetyl CoA, the two-carbon compound formed during the transition reaction, enters the citric acid cycle. The citric acid cycle also yields several molecules of FADH2 and NADH, carriers of high-energy electrons that Acetyl CoA enter the electron transport chain. C C — CoA CoA Oxaloacetate C C C C Citrate NADH C C C C C C CO2 C leaves NAD cycle C C C C NAD Malate Citric Acid Cycle FADH2 NADH ATP ADP  P FAD C C C C C C C C C α-Ketoglutarate Succinate C CO2 leaves cycle NAD NADH The citric acid cycle yields one ATP from each acetyl CoA that enters the cycle, for a net gain of two ATP. © 2017 Pearson Education, Inc. Figure 3.23 Transition Reaction (in mitochondrion) Pyruvate (from glycolysis) C C C One carbon (in the form of CO2) is removed from pyruvate. A molecule of NADH is formed when NAD gains two electrons and one proton. CO2 NAD NADH Coenzyme A (electron passes to electron The two-carbon transport chain) molecule, called an acetyl group, binds to coenzyme A (CoA), forming acetyl CoA, C C CoA which enters the Acetyl CoA citric acid cycle. Citric Acid Cycle © 2017 Pearson Education, Inc.  3.7 Cellular Respiration  Phase 4: Electron transport chain Occurs across the inner membrane of the mitochondria Requires oxygen Electrons from FADH2 and NADH are transferred from one protein to another, until they reach oxygen Releases energy that results in 32 ATP molecules © 2017 Pearson Education, Inc. Figure 3.25 Electron Transport Chain (inner membrane of mitochondrion) The molecules of NADH and FADH2 produced by earlier phases of cellular respiration pass their electrons to a series of protein molecules embedded in the inner membrane of the mitochondrion. High NADH NAD As the electrons are transferred from one protein to the next, energy is released and used to 2e make ATP. Potential energy FADH2 2e Membrane proteins FAD Eventually, the electrons are passed to oxygen, which combines with two 2e hydrogens to form 2e water. 2e H2O Low 1 2 H  2 O2 Energy released is used for synthesis of ATP. © 2017 Pearson Education, Inc. Table 3.4 © 2017 Pearson Education, Inc. Figure 3.26 Electrons transferred by NADH Cytoplasm Blood Electrons vessel transferred by NADH Glucose Plasma Electrons membrane transferred by NADH and FADH2 Carrier protein Citric Electron Glycolysis Transition Transport Acid glucose pyruvate Reaction Chain Cycle Oxygen Mitochondrion Extracellular fluid 2 ATP 2 ATP 32 ATP  36 ATP © 2017 Pearson Education, Inc.  3.7 Fermentation  Breakdown of glucose without oxygen Takes place entirely in the cytoplasm Is very inefficient, compared with cellular respiration, resulting in only two ATP Lactic acid fermentation takes place in the human body in muscles during strenuous exercise when the oxygen supply runs low  Muscle pain is caused partly by the accumulation of the waste product, lactic acid  Soreness disappears as lactic acid is converted back to pyruvate in the liver © 2017 Pearson Education, Inc.  3.7 Cellular Respiration and Fermentation in the Generation of ATP © 2017 Pearson Education, Inc. The Plant Cell nuclear envelope Plant cells have a cell nuclear pores wall, chloroplasts, and a nucleus DNA central vacuole, while nucleolus animal cells do not. cytoskeleton rough endoplasmic reticulum smooth endoplasmic reticulum cell wall free ribosomes chloroplast Golgi complex cytosol central plasma vacuole membrane mitochondrion Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.16  Chloroplasts Chloroplasts are the sites of photosynthesis. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Chloroplast Found only in plant cells and algae Contains green pigment, chlorophyll Changes sunlight (solar energy) into food like glucose (chemical energy) Sunlight + Carbon Dioxide + Water Sugar + Oxygen Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Cell Wall The cell wall gives the plant structural strength and helps regulate the intake and retention of water. Rigid, protective barrier (maintains cell shape). Located outside of the cell membrane. Made of cellulose (Carbohydrate fiber) Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Cell Wall Found in: Plant cells Some Prokaryote cells (bacterial cells). Work like a gates for the cells. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  The Central Vacuole Large central vacuole usually in plant cells. Many smaller vacuoles in animal cells. Storage container for water, food, enzymes, wastes, etc Supports cell shape in plants Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Vacuole and Turgor Pressure Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 4.8 Cell-to-Cell Communication Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Cell-to-Cell Communication Cells are able to communicate with each other through special structures. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Communication Among Plant Cells Plant cells have channels, called plasmodesmata.  Plasmodesmata are always open and hence have the effect of making the cytoplasm of one plant cell continuous with that of another. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings.  Communication Among Animal Cells Adjacent animal cells have channels, called gap junctions, that are composed of protein assemblages(groups) that open only as necessary. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Communication Among Animal Cells These gap junctions allow the movement of small molecules and electrical signals between cells. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Cell Communication Plant tissues plasma (a) Plasmodesmata membrane In plants, a series of tiny pores cell walls between plant cells, the plasmodesmata, allow for the cytoplasm movement of materials among cells. Thanks to the plasmodesmata plasmodesmata channels, the cytoplasm of one cell is continuous with the cytoplasm of the next; the plant as a whole can Animal tissues be thought of as having a single gap junction complement of continuous cytoplasm. plasma (b) Gap junctions membranes In animals, protein assemblies cytoplasm come into alignment with one another, forming communication channels between cells. A cluster of many such assemblies—perhaps several hundred—is called a gap junction. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 4.19 Structures in Plant and Animal Cells Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Table 4.1  You Should Now Be Able To:  Explain how the structure of the plasma membrane regulates the movement of materials in and out of the cell.  Describe the function and structural features of each of the following organelles: nucleus, endoplasmic reticulum, Golgi complex, lysosomes, and mitochondria.  Compare the structure and function of the three fibers that make up the cytoskeleton.  Summarize the efficiency of cellular respiration and fermentation as methods to harvest cellular energy from the food we eat. © 2017 Pearson Education, Inc.