Biology Sylvia S Mader Michael Windelspecht Chapter 4

Biology Sylvia S. Mader Michael Windelspecht Chapter 4 Cell Structure and Function Lecture Outline See separate Flex. Art Power. Point slides for all figures and tables pre-inserted into Power. Point without notes. 1 Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display.

4. 1 Cellular Level of Organization • Cell Theory: § All organisms are composed of cells • German botanist Matthais Schleiden (1804 -1881) • German zoologist Theodor Schwann (1810 -1882) § All cells come only from preexisting cells • German physician Rudolph Virchow (1821 -1902) § Cells are the smallest structural and functional unit of organisms 2

Cell Size • The surface‑area‑to‑volume ratio requires that cells be small § Large cells - surface area relative to volume decreases § Small cells – larger surface area to volume ratio is advantageous for exchanging molecules 3

EK 2. A. 3 b: Surface area-to-volume ratios affect a biological system’s ability to obtain necessary resources or eliminate waste products. Learning Objectives: (AP EXAM) LO 2. 6 The student is able to use calculated surface area-to-volume ratios to predict which cell(s) might eliminate wastes or procure nutrients faster by diffusion. LO 2. 7 Students will be able to explain how cell size and shape affect the overall rate of nutrient intake and the rate of waste elimination. 4

Surface to Volume Ratio Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. One 4 -cm cube Total surface area 96 cm 2 Eight 2 -cm cubes 192 cm 2 Sixty-four 1 -cm cubes 384 cm 2 (height × width × number of sides × number of cubes) Total volume 64 cm 3 (height × width × length × number of cubes) Surface area: 1. 5: 1 3: 1 6: 1 Volume per cube (surface area ÷ volume) 5

Practice • Surface Area to Volume Ratios Worksheet 6

Evidence of student learning is a demonstrated understanding of each of the following: 1. As cells increase in volume, the relative surface area decreases and demand for material resources increases; more cellular structures are necessary to adequately exchange materials and energy with the environment. These limitations restrict cell size. 1. The surface area of the plasma membrane must be large enough to adequately exchange materials; smaller cells have a more favorable surface area-to-volume ratio for exchange of materials with the environment. 7

4. 2 Prokaryotic Cells • Lack a membrane-bound nucleus • Structurally smaller and simpler than eukaryotic cells (which have a nucleus). • Prokaryotic cells are placed in two taxonomic domains: § Bacteria § Archaea • Live in extreme habitats § Domains are structurally similar but biochemically different 8

The Structure of Prokaryotes • Extremely small: 1– 1. 5 μm wide and 2– 6 μm long • Occur in three basic shapes: § Spherical coccus, § Rod-shaped bacillus, § Spiral spirillum (if rigid) or spirochete (if flexible). 9

The Structure of Prokaryotes Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for

Prokaryotic Cell Shape • http: //highered. mheducation. com/sites/007 337525 x/student_view 0/exercise 9/procary otic_cell_shapes. html 11

The Structure of Prokaryotes • Cell Envelope includes: § Plasma membrane - lipid bilayer with imbedded and peripheral protein § Form internal pouches (mesosomes) § Cell wall - maintains the shape of the cell and is strengthened by peptidoglycan (EK 2. B. 1. c Cell walls provide structural boundary as well as a permeability barrier for some substances to the internal environment. ) § Glycocalyx - layer of polysaccharides on the outside of the cell wall • Well organized and resistant to removal (capsule) 12

The Structure of Prokaryotes Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Ribosome: site of protein synthesis Inclusion body: stored nutrients for later use Mesosome: plasma membrane that folds into the cytoplasm and increases surface area Fimbriae: hairlike bristles that allow adhesion to the surfaces Conjugation pilus: elongated, hollow appendage used for DNA transfer to other bacterial cells Nucleoid: location of the bacterial chromosome Plasma membrane: sheath around cytoplasm that regulates entrance and exit of molecules Cell wall: covering that supports, shapes, and protects cell Glycocalyx: gel-like coating outside cell wall; if compact, called a capsule; if diffuse, called a slime layer Flagellum: rotating filament present in some bacteria that pushes the cell forward Escherichia coli © Howard Sochurek/The Medical File/Peter Arnold, Inc. 13

Prokaryotic Cytoplasm and Appendages • Cytoplasm § Semifluid solution • Bounded by plasma membrane • Contains water, inorganic and organic molecules, and enzymes § Nucleoid is a region that contains the single, circular DNA molecule § Plasmids are small accessory (extrachromosomal) rings of DNA 14

Prokaryotic Cytoplasm and Appendages • Appendages § Flagella – provide motility § Fimbriae – small, bristle-like fibers that sprout from the cell surface § Conjugation pili – rigid tubular structures used to pass DNA from cell to cell 15

Bacteria Locomotion • http: //highered. mheducation. com/sites/007 337525 x/student_view 0/exercises_3590/bacterial_locomotion. html 16

4. 3 Introducing Eukaryotic Cells • Cells contain: § Membrane-bound nucleus that houses DNA § Specialized organelles § Plasma membrane • Much larger than prokaryotic cells 17

Origin of Eukaryotic Cells • http: //highered. mheducation. com/sites/983 4092339/student_view 0/chapter 4/animatio n_-_endosymbiosis. html • Essential knowledge 1. B. 1: Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today. b. Structural evidence supports the relatedness of all eukaryotes. 18

Origin of Organelles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Original prokaryotic cell DNA 1. Cell gains a nucleus by the plasma membrane invaginating and surrounding the DNA with a double membrane. Nucleus allows specific functions to be assigned, freeing up cellular resources for other work. 2. Cell gains an endomembrane system by proliferation of membrane. Increased surface area allows higher rate of transport of materials within a cell. 3. Cell gains mitochondria. aerobic bacterium Ability to metabolize sugars in the presence of oxygen enables greater function and success. mitochondrion 4. Cell gains chloroplasts. Ability to produce sugars from sunlight enables greater function and success. Animal cell has mitochondria, but not chloroplasts. photosynthetic bacterium chloroplast Plant cell has both mitochondria and chloroplasts. 19

Exam Essential knowledge 2. B. 3: Eukaryotic cells maintain internal membranes that partition the cell into specialized regions. • Internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur. • Membranes and membrane-bound organelles in eukaryotic cells localize (compartmentalize) intracellular metabolic processes and specific enzymatic reactions. 20

Eukaryotic Cells: Organelles • Eukaryotic cells are compartmentalized § They contain small structures called organelles • Perform specific functions • Isolates reactions from others • Two classes of organelles: § Endomembrane system • Organelles that communicate with one another – Via membrane channels – Via small vesicles § Energy related organelles • Mitochondria and chloroplasts • Independent and self-sufficient 21

Animal Cell Anatomy Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. mitochondrion chromatin nucleolus nuclear envelope Plasma membrane: outer surface that regulates entrance and exit of molecules endoplasmic reticulum protein 2. 5 µm phospholipid Nucleus: command center of cell • Nuclear envelope: double membrane with nuclear pores that encloses nucleus Cytoskeleton: maintains cell shape and assists movement of cell parts: • Chromatin: diffuse threads containing DNA and protein • Nucleolus: region that produces subunits of ribosomes Endoplasmic reticulum: protein and lipid metabolism • Microtubules: protein cylinders that move organelles • Intermediate filaments: protein fibers that provide stability of shape • Rough ER: studded with ribosomes that synthesize proteins • Actin filaments: protein fibers that play a role in cell division and shape • Smooth ER: lacks ribosomes, synthesizes lipid molecules Centrioles*: short cylinders of microtubules Peroxisome: vesicle that is involved in fattyacid metabolism Centrosome: microtubule organizing center that contains a pair of centrioles Ribosomes: particles that carry out protein synthesis Lysosome*: vesicle that digests macromolecules and even cell parts Vesicle: small membranebounded sac that stores and transports substances Polyribosome: string of ribosomes simultaneously synthesizing same protein Mitochondrion: organelle that carries out cellular respiration, producing ATP molecules Cytoplasm: semifluid matrix outside nucleus that contains organelles Golgi apparatus: processes, packages, and secretes modified proteins *not in plant cells © Dr. Dennis Kunkel/Visuals Unlimited 22

Plant Cell Anatomy Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. peroxisome mitochondrion nucleus ribosomes central vacuole plasma membrane cell wall chloroplast 1 µm Nucleus: command center of cell Central vacuole*: large, fluid-filled sac that stores metabolites and helps maintain turgor pressure • Nuclear envelope: double membrane with nuclear pores that encloses nucleus • Nucleolus: produces subunits of ribosomes Cell wall of adjacent cell • Chromatin: diffuse threads containing DNA and protein • Nuclear pore: permits passage of proteins into nucleus and ribosomal subunits out of nucleus Middle lamella: cements together the primary cell walls of adjacent plant cells Ribosomes: carry out protein synthesis Chloroplast*: carries out photosynthesis, producing sugars Centrosome: microtubule organizing center (lacks centrioles) Granum*: a stack of chlorophyllcontaining thylakoids in a chloroplast Endoplasmic reticulum : protein and lipid metabolism • Rough ER: studded with ribosomes that synthesize proteins Mitochondrion: organelle that carries out cellular respiration, producing ATP molecules • Smooth ER: lacks ribosomes, synthesizes lipid molecules Microtubules: protein cylinders that aid movement of organelles Peroxisome: vesicle that is involved in fatty acid metabolism Actin filaments: proteinfibers that play a role in cell division and shape Golgi apparatus: processes, packages, and secretes modified proteins Cytoplasm: semifluid matrix outside nucleus that contains organelles Plasma membrane: surrounds cytoplasm, and regulates entrance and exit of molecules Cell wall*: outer surface that shapes, supports, and protects cell *not in animal cells © Newcomb/Wergin/Biological Photo Service (FIRST USE) 23

4. 4 The Nucleus and Ribosomes • The Nucleus § Command center of cell, usually near center § Separated from cytoplasm by nuclear envelope • Consists of double layer of membrane • Nuclear pores permit exchange between nucleoplasm & cytoplasm 24

4. 4 The Nucleus and Ribosomes • The Nucleus § Contains chromatin in semifluid nucleoplasm • Chromatin contains DNA of genes, and proteins • Condenses to form chromosomes – Chromosomes are formed during cell division § Dark nucleolus composed of r. RNA • Produces subunits of ribosomes 25

Anatomy of the Nucleus Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. nuclear envelope nucleolus Nuclear envelope: inner membrane outer membrane nuclear pore chromatin nucleoplasm phospholipid (Bottom): Courtesy Ron Milligan/Scripps Research Institute; (Top right): Courtesy E. G. Pollock 26

Ribosomes • Are the site of protein synthesis in the cell • Composed of r. RNA § Consists of a large subunit and a small subunit § Subunits made in nucleolus • May be located: § On the endoplasmic reticulum (thereby making it “rough”), or § Free in the cytoplasm, either singly or in groups, called polyribosomes 27

4. 5 The Endomembrane System • Series of intracellular membranes that compartmentalize the cell • Restrict enzymatic reactions to specific compartments within cell • Consists of: § § Nuclear envelope Membranes of endoplasmic reticulum Golgi apparatus Vesicles • Several types • Transport materials between organelles of system 28

Endoplasmic Reticulum and Golgi Apparatus • http: //bcs. whfreeman. com/thelifewire/conte nt/chp 04/0402002. html 29

Endoplasmic Reticulum • A system of membrane channels and saccules (flattened vesicles) continuous with the outer membrane of the nuclear envelope • Rough ER § Studded with ribosomes on cytoplasmic side § Protein anabolism (Synthesizes proteins) • Modifies and processes proteins – Adds sugar to protein – Results in glycoproteins 30

Endoplasmic Reticulum • Smooth ER § No ribosomes § Synthesis of lipids § Site of various synthetic processes, detoxification, and storage § Forms transport vesicles 31

Endoplasmic Reticulum Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. ribosomes Nuclear envelope rough endoplasmic reticulum smooth endoplasmic reticulum 0. 08 µm © R. Bolender & D. Fawcett/Visuals Unlimited 32

The Golgi Apparatus § Consists of flattened, curved saccules § Resembles stack of hollow pancakes § Modifies proteins and lipids • Receives vesicles from ER on cis (or inner face) • Packages them in vesicles • Prepares for “shipment” and packages them in vesicles from trans (or outer face) – Within cell – Export from cell (secretion, exocytosis) 33

Golgi Apparatus Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. secretion transport saccules vesicle transport vesicles trans face cis face Golgi apparatus Nucleus 0. 1µm Courtesy Charles Flickinger, from Journal of Cell Biology 49: 221 -226, 1971, Fig. 1 page 224 34

Lysosomes • Membrane-bound vesicles (not in plants) § Produced by the Golgi apparatus § Contain powerful digestive enzymes and are highly acidic • Digestion of large molecules • Recycling of cellular resources • Some genetic diseases § Caused by defect in lysosomal enzyme § Lysosomal storage diseases (Tay-Sachs) 35

Lysososmes • http: //highered. mheducation. com/sites/007 2495855/student_view 0/chapter 2/animatio n__lysosomes. html 36

Endomembrane System Summary • Proteins produced in rough ER and lipids from smooth ER are carried in vesicles to the Golgi apparatus. • The Golgi apparatus modifies these products and then sorts and packages them into vesicles that go to various cell destinations. • Secretory vesicles carry products to the membrane where exocytosis produces secretions. • Lysosomes fuse with incoming vesicles and digest macromolecules. 37

Endomembrane System Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Consumption Secretion 5. Secretion plasma membrane 4. Secretory vesicle fuses with the plasma membrane as secretion occurs. Incoming vesicle brings substances into the cell that are digested when the vesicle fuses with a lysosome. enzyme 3. Golgiapparatus modifies lipids and proteins from the ER; sorts them and packages them in vesicles. Lysosome Contains digestive enzymes that breakdown worn-out cell parts or substances entering the cell at the plasma membrane. protein 2. Transport vesicle shuttles proteins to various locations such as the Golgi apparatus. Transport vesicle shuttles lipids to various locations such as the Golgi apparatus. lipid 1. Rough endoplasmic reticulum synthesizes proteins and packages them in vesicles; vesicles commonly go to the Golgi apparatus Smooth endoplasmic reticulum synthesizes lipids and also performs various other functions. ribosome Nucleus 38

4. 6 Other Vesicles and Vacuoles • Peroxisomes § Similar to lysosomes • Membrane-bounded vesicles • Enclose enzymes § However • Enzymes synthesized by free ribosomes in cytoplasm (instead of ER) • Active in lipid metabolism • Catalyze reactions that produce hydrogen peroxide H 2 O 2 – Toxic – Broken down to water & O 2 by catalase 39

Peroxisomes 40

Vacuoles • Membranous sacs that are larger than vesicles § Store materials that occur in excess § Others very specialized (contractile vacuole) • Plants cells typically have a central vacuole § Up to 90% volume of some cells § Functions in: • Storage of water, nutrients, pigments, and waste products • Development of turgor pressure • Some functions performed by lysosomes in other eukaryotes 41

Plant Cell Central Vacuole Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for

4. 7 Energy-Related Organelles • Chloroplasts § Bounded by double membrane § Inner membrane infolded (why? ) • Forms disc-like thylakoids, which are stacked to form grana • Suspended in semi-fluid stroma § Green due to chlorophyll • Green photosynthetic pigment • Found ONLY in inner membranes of chloroplast 43

Chloroplasts • Serve as the site of photosynthesis • Captures light energy to drive cellular machinery • Photosynthesis § Synthesizes carbohydrates from CO 2 & H 2 O § Makes own food using CO 2 as only carbon source § Energy-poor compounds converted to energy-rich compounds solar energy + carbon dioxide + water → carbohydrate + oxygen § Only plants, algae, and certain bacteria are capable of conducting photosynthesis 44

Chloroplast Structure Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. a. 500 nm outer membrane double membrane inner membrane grana thylakoid stroma space thylakoid membrane b. Courtesy Herbert W. Israel, Cornell University 45

Mitochondria • Smaller than chloroplast • Contain ribosomes and their own DNA • Surrounded by a double membrane § Inner membrane surrounds the matrix and is convoluted (folds) to form cristae. § Matrix – Inner semifluid containing respiratory enzymes • Break down carbohydrates • Involved in cellular respiration • Produce most of ATP utilized by the cell 46

Mitochondrion Structure Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. a. double membrane outer membrane inner membrane 200 nm cristae matrix b. Courtesy Dr. Keith Porter 47

Origin of Mitochondria and Chloroplasts • http: //www. sumanasinc. com/webcontent/a nimations/content/organelles. html • http: //highered. mheducation. com/sites/983 4092339/student_view 0/chapter 4/animatio n_-_endosymbiosis. html 48

4. 8 The Cytoskeleton • Maintains cell shape • Assists in movement of cell and organelles • Three types of macromolecular fibers § Actin filaments § Intermediate filaments § Microtubules • Assemble and disassemble as needed 49

Actin Filaments • Extremely thin filaments like twisted pearl necklace • Dense web just under plasma membrane maintains cell shape • Support for microvilli in intestinal cells • Intracellular traffic control § For moving stuff around within cell § Cytoplasmic streaming • Function in pseudopods of amoeboid cells • Important component in muscle contraction (other is myosin) 50

Actin Filament Operation Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction

Intermediate Filaments • Intermediate in size between actin filaments and microtubules • Rope-like assembly of fibrous polypeptides • Vary in nature § From tissue to tissue • Function: § Support nuclear envelope § Cell-cell junctions, like those holding skin cells tightly together 52

Microtubules • Hollow cylinders made of two globular proteins called a and b tubulin • Interacts with proteins kinesin and dynein to cause movement of organelles 53

Microtubule Operation Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or

Centrioles • Short, hollow cylinders • One pair per animal cell § Located in centrosome of animal cells § Oriented at right angles to each other § Separate during mitosis to determine plane of division • May give rise to basal bodies of cilia and flagella 55

Centrioles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. empty center of centriole one microtubule triplet one centrosome: one pair of centrioles two centrosomes: two pairs of centrioles 200 nm (Middle): Courtesy Kent Mc. Donald, University of Colorado Boulder; (Bottom): Journal of Structural Biology, Online by Manley Mc. Gill et al. Copyright 1976 by Elsevier Science & Technology Journals. Reproduced with permission of Elsevier Science & Technology Journals in the format Textbook via Copyright Clearance Center 56

Cilia and Flagella • Hair-like projections from cell surface that aid in cell movement • Very different from prokaryote flagella § Outer covering of plasma membrane • In eukaryotes, cilia are much shorter than flagella § Cilia move in coordinated waves like oars § Flagella move like a propeller or cork screw 57

Structure of a Flagellum Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. outer microtubule doublet Flagellum radial spoke central microtubules The shaft of the flagellum has a ring of nine microtubule doublets anchored to a central pair of microtubules. shaft dynein side arm Flagellum cross section Sperm plasma membrane triplets Basal body cross section 100 nm The basal body of a flagellum has a ring of nine microtubule triplets with no central microtubules. 25 nm The side arms of each doublet are composed of dynein, a motor molecule. dynein side arms ATP In the presence of ATP, the dynein side arms reach out to their neighbors, and bending occurs. (Flagellum, Basal body): © William L. Dentler/Biological Photo Service 58

Review – Bozeman Biology • http: //www. bozemanscience. com/043 cellular-organelles 59

Mini-Lab Cell Size 1. Calculate the surface area and volume of the 2 cubes and the SA/V ratio. Record in notes. 2. Place each of the 2 cubes into a beaker and cover them with 0. 1 M Na. OH for 10 minutes. 3. Remove the cubes and blot them dry. 4. Cut each cube in half and measure the pale yellow area in the center. 5. Calculate the volume of this region. Record in your notes. 6. Subtract the volume of the yellow region from the volume of the cube to get the volume of the pink region. 7. Calculate (Vol. Pink/Vol. Cube) X 100%