Lesson 2: Parts of the Cells and Their Functions PDF

PARTS OF THE CELL AND THEIR FUNCTIONS MODULE 2 https://www.youtube.com/watch?v=WKbjiO3lRdM Cell Structure and Function Nucleus: Endoplasmic reticulum: 2 Prokaryotic Cells...

PARTS OF THE CELL AND THEIR FUNCTIONS MODULE 2 https://www.youtube.com/watch?v=WKbjiO3lRdM Cell Structure and Function Nucleus: Endoplasmic reticulum: 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 3 The Structure of Bacteria Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. spirillum spirochete bacillus coccus 4 5 The Structure of Bacteria 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). 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 Glycocalyx - layer of polysaccharides on the outside of the cell wall Well organized and resistant to removal (capsule) 6 The Structure of Bacteria Cytoplasm & 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 Appendages Flagella – Provide motility Fimbriae – small, bristle-like fibers that sprout from the cell surface Sex pili – rigid tubular structures used to pass DNA from cell to cell 7 The Structure of Bacteria Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. protein molecules phospholipid bilayer 8 Eukaryotic Cells Domain Eukarya includes: Protists Fungi Plants Animals Cells contain: Membrane-bound nucleus that houses DNA Specialized organelles Plasma membrane Much larger than prokaryotic cells Some cells (e.g., plant cells) have a cell wall 9 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 & chloroplasts Basically independent & self-sufficient 10 Cell Fractionation and Differential Centrifugation Cell fractionation is the breaking apart of cellular components Differential centrifugation: Allows separation of cell parts Separated out by size & density Works like spin cycle of washer The faster the machine spins, the smaller the parts that are settled out 11  Plasma membrane: outer surface that regulates entrance and exit of molecules Animal Cell Anatomy protein phospholipid Nucleus: command center of cell Nuclear envelope: double membrane with Cytoskeleton: maintains cell shape and assists nuclear pores that encloses nucleus Chromatin: diffuse threads containing DNA and movement of cell parts: protein Microtubules: proteincy linders that move Nucleolus: region that produces subunits of organelles ribosomes Endoplasmic reticulum: Intermediate filaments: protein fibers that provide protein and lipid metabolism stability of shape Rough ER: studded with ribosomes Actin filaments: protein fibers that play a role that synthesize proteins in change of shape Smooth ER: lacks ribosomes, synthesizes lipid molecules Centrioles*: short cylinders of microtubules of unknown function Peroxisome: vesicle that is involved in fatty acid metabolism Centrosome: microtubule organizing center that Ribosomes: particles that carry contains a pair of centrioles out protein synthesis Lysosome*: vesicle that digests macromolecules Polyribosome: string of ribosomes and even cell parts simultaneously synthesizing same protein Vesicle: small membrane- bounded sac that stores and transports substances Mitochondrion: organelle that carries out cellular respiration, Cytoplasm: semifluid producing ATP molecules matrix outside nucleus *not in plant cells that contains organelles Golgi apparatus: processes, packages, and secretes modified proteins 12  Nucleus: command center of cell Plant Cell Anatomy Nuclear envelope: double membrane with nuclear pores Central vacuole*: large, fluid-filled sac that stores that encloses nucleus metabolites and helps maintain turgor pressure Nucleolus: produces subunits of ribosomes Chromatin: diffuse threads containing DNA and protein Cell wall of adjacent cell Nuclear pore: permits passage of proteins into Middle lamella: cements nucleus and ribosomal subunits out of nucleus together the primary cell walls of Ribosomes: carry adjacent plant cells out protein synthesis Chloroplast*: carries out Centrosome:microtubule organizing photosynthesis, producing sugars center (lacks centrioles) Granum*: a stack of chlorophyll containing Endoplasmic reticulum: protein thylakoids in a chloroplast and lipid metabolism Mitochondrion: organelle Rough ER: studded with ribosomes that carries out cellular respiration, thatsynthesize proteins producing ATP molecules Smooth ER: lacks ribosomes, Microtubules: protein cylinders synthesizes lipid molecules that aid movement of organelles Peroxisome: vesicle that is involved in Actin filaments: protein fibers that fatty acid metabolism play a role in movement of cell and organelles Golgi apparatus: processes, packages, and secretes modified proteins Plasma membrane: surrounds cytoplasm, and regulates entrance and exit of molecules Cytoplasm: semifluid matrix outside Cell wall*: outer surface that shapes, nucleus that contains organelles supports, and protects cell *not in animal cells 13 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 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 rRNA Produces subunits of ribosomes 14  nuclear envelope nucleolus Nuclear envelope: nuclear inner membrane pore outer membrane chromatin nuclear pore nucleoplasm phospholipid 15 Ribosomes Are the site of protein synthesis in the cell Composed of rRNA 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 16  Cytoplasm Endoplasmic reticulum (ER) protein ER membrane 4. An enzyme removes Lumen of ER 5. Ribosomal subunits and mRNA break the away. The protein remains in the ER and folds signal peptide. enzyme into its final shape. mRNA receptor SRP signal recognition particle (SRP) 2. Signal recognition 3. SRP attaches to receptor (purple); p a channel opens; article (SRP) binds and the to Nucleus, polypeptide signal peptide signal peptide. ribosomal enters ER.. nuclear pore subunits ribosome mRNA Ribosomes, 1. mRNA is leaving the s and is attached nucleu mRNA DNA Nucleus & ER ribosome; protein sis is occurring. to the synthe 17 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 18 Endomembrane System: The 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 Smooth ER No ribosomes Synthesis of lipids Site of various synthetic processes, detoxification, and storage Forms transport vesicles 19 Endomembrane System: The Golgi Apparatus Golgi Apparatus Consists of 3-20 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” in v Packages them in vesicles from trans (or outer face) Within cell Export from cell (secretion, exocytosis) 20 Endoplasmic Reticulum ribosomes nuclear envelope rough endoplasmic reticulum smooth endoplasmic reticulum 0.08 m 21 Golgi Apparatus secretion transport saccules vesicle transport vesicle trans face cis face Golgi apparatus Nucleus 0.1 m 22 Endomembrane System: 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 Apoptosis (programmed cell death, like tadpole losing tail) Some genetic diseases Caused by defect in lysosomal enzyme Lysosomal storage diseases (Tay-Sachs) 23 Lysosomes lysosome mitochondrion peroxisome fragment a. Mitochondrion and a peroxisome in a lysosome b. Storage bodies in a cell with defective lysosomes 24 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. 25  secretion plasma membrane incoming vesicle brings substances into the secretory vesicle fuses with the plasma Endomembrane cell that are digested when the vesicle fuses with a lysosome membrane as secretion occurs System: enzyme Golgi apparatus modifies lipids and proteins A Visual lysosome contains digestive enzymes from the ER; sorts them and packages them in Summary that break down worn-out vesicles cell parts or substances protein entering the cell at the transport vesicle transport vesicle plasma membrane shuttles proteins to shuttles lipids to various various locations such as locations such as the the Golgi apparatus Golgi apparatus lipid rough endoplasmic smooth endoplasmic reticulum reticulum synthesizes proteins and synthesizes lipids and packages them in vesicles; also performs various ribosome Nucleus vesicles commonly go to other functions the Golgi apparatus 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 H2O2 Toxic Broken down to water & O2 by catalase Peroxisomes 100 nm 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 29 Vacuoles 100 nm 30 Energy-Related Organelles: Chloroplast Structure Bounded by double membrane Inner membrane infolded 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 31 Energy-Related Organelles: Chloroplasts Membranous organelles (a type of plastid) that serve as the site of photosynthesis Captures light energy to drive cellular machinery Photosynthesis Synthesizes carbohydrates from CO2 & H2O Makes own food using CO2 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 32 Energy-Related Organelles: Chloroplasts Bound by a double membrane organized into flattened disc-like sacs called thylakoids Chlorophyll and other pigments capture solar energy Enzymes synthesize carbohydrates 33 Chloroplast Structure a. 500 nm outer thylakoid grana stroma thylakoid membrane double membrane space inner membrane membrane b. 34 Energy-Related Organelles: 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 35 Mitochondrial Structure a. 200 nm outer membrane cristae matrix double inner membrane membrane b. 36 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 37 The Cytoskeleton: 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 Pinch mother cell in two after animal mitosis Important component in muscle contraction (other is myosin) 38 The Cytoskeleton: Actin Filament Operation Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. actin filament ATP ADP + P myosin molecules tail head membrane 39 The Cytoskeleton: Intermediate Filaments Intermediate in size between actin filaments and microtubules Rope-like assembly of fibrous polypeptides Vary in nature From tissue to tissue From time to time Functions: Support nuclear envelope Cell-cell junctions, like those holding skin cells tightly together 40 The Cytoskeleton: Microtubules Hollow cylinders made of two globular proteins called α and β tubulin Spontaneous pairing of α and β tubulin molecules form structures called dimers Dimers then arrange themselves into tubular spirals of 13 dimers around Assembly: Under control of Microtubule Organizing Center (MTOC) Most important MTOC is centrosome Interacts with proteins kinesin and dynein to cause movement of organelles 41 The Cytoskeleton: Microtubule Operation ATP vesicle kinesin kinesin receptor vesicle moves, not microtubule 42 The Cytoskeleton actin subunit Chara a. Actin filaments fibrous subunits peacock b. Intermediate filaments tubulin dimer chameleon c. Microtubules 43 Microtubular Arrays: Centrioles Short, hollow cylinders Composed of 27 microtubules Microtubules arranged into 9 overlapping triplets 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 44  empty center of centriole one microtubule triplet Cytoskeleton: Centrioles one centrosome: one pair of centrioles two centrosomes: two pairs of centrioles 200 nm 45 Microtubular Arrays: Cilia and Flagella Hair-like projections from cell surface that aid in cell movement Very different from prokaryote flagella Outer covering of plasma membrane Inside this is a cylinder of 18 microtubules arranged in 9 pairs In center are two single microtubules This 9 + 2 pattern used by all cilia & flagella In eukaryotes, cilia are much shorter than flagella Cilia move in coordinated waves like oars Flagella move like a propeller or cork screw 46  outer Flagellum microtubule doublet radial spoke central shaft The shaft of the microtubules Structure flagellum has a ring of nine microtubule dynein doublets anchored side arm to a central pair of microtubules. 25 nm Flagellum cross section Sperm The side arms of each doublet dynein of a Flagellu plasma side arms triplets membrane are composed of dynein, a motor molecule. Basal body m ATP In the presence of ATP, the dynein side arms reach out to The basal body of a flagellum has their neighbors, Basal body cross section 100 nm a ring of nine microtubule triplets and bending occurs. with no central microtubules. 47