BIO 311C Textbook Notes based on Handout 5
BIO 311C Textbook Notes based on Handout 5 Bio 311C
Popular in Introductory Biology I
verified elite notetaker
Popular in Biology
This 11 page Class Notes was uploaded by Sena Sarikaya on Wednesday September 21, 2016. The Class Notes belongs to Bio 311C at University of Texas at Austin taught by Dr. Buskirk in Fall 2016. Since its upload, it has received 10 views. For similar materials see Introductory Biology I in Biology at University of Texas at Austin.
Reviews for BIO 311C Textbook Notes based on Handout 5
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/21/16
Textbook Notes Based on Handout 5 Ch. 6 6.1 Biologists Use Microscopes and the Tools of Biochemistry to Study Cells A. Microscopy light microscope (LM): visible light passes through specimen then through glass lenses first used by Renaissance scientists & used in labs lenses refract light so that image of specimen is magnified as it’s projected to eye 3 important parameters in microscopy magnification = ratio of object’s image size to real size LM mag. to 1,000x actual size resolution = measure of clarity of image LM cannot resolve more than 0.3 micrometers regardless of mag. contrast = difference in brightness between light and dark areas staining & labeling cell components enhance contrast organelles: membraneenclosed structures in eukaryotic cells until recently LM resolution barrier prevented studying electron microscope (EM): focuses beam of elections through specimen or onto its surface resolution inversely related to wavelength of light shorter wavelengths than vis. light theoretically can resolve about 0.002 nanometers in practice can only resolve about 2 nanometers scanning electron microscope (SEM): electron beam scans surface o sample usually coated w/ film of gold; beam excited surface e and secondary e are detected by device that translate pattern of e into electronic signal sent to video screen useful for detailed topography 3D look uses electromagnets as lenses not glass transmission electron microscope (TEM): aims electron beam through thin section of specimen; specimen stained w/ atoms of heavy metals which attaches to cell struct.; some parts of cell’s e density are enhanced image displays pattern of transmitted e study internal structure of cells uses electromagnets as lenses not glass advantage of EM… subcellular struc. revealed disadvantage of EM… methods for prep kill specimen cytology = study of cell struc. A. Cell Fractionation cell fractionation: takes cells apart & separates organelles & subcellular struc. from one another centrifuge used 6.2 Eukaryotic Cells Have Internal Membranes that Compartmentalizes Their Functions Bacteria & Archaea = prokaryotic protists (unicellular eukaryotes), fungi, animals, plants = eukaryotic A. Comparing Prokaryotic & Eukaryotic Cells cytosol: semifluid, jellylike substance where subcellular components suspend eukaryotic cell: most of DNA is in the nucleus bounded by a double membrane prokaryotic cell: DNA is concentrated in nucleoid; not membrane enclosed eukaryotic = true nucleus cytoplasm: interior of a cell in eukaryotes = btwn nucleus & plasma mem. in prokaryotes = prokaryotes don’t have membranebound struct. organized in diff. regions eukaryotic cells larger plasma membrane: selective barrier that allows passage of oxygen, nutrients, wastes ratio to volume is critical when cell grows, surface area grows less than volume utilize microvilli or folds larger organisms DO NOT have larger cells, they have more cells B. A Panoramic View of the Eukaryotic Cell 6.3 The Eukaryotic Cell’s Genetic Instructions Are Housed in The Nucleus And Carried Out By the Ribosomes A. The Nucleus: Information Central nucleus: contains genes in eukaryotic cell nuclear envelope: encloses the nucleus; separates from cytoplasm double membrane lipid bilayer pore complex = intricate protein structure regulating entry & exit of proteins & RNAs & macromol. nuclear lamina: netlike protein filament array giving nucleus the shape w/ mechanical support not @ pores nuclear matrix = framework of protein fibers through nuclear interior chromosomes: in nucleus how DNA is organized into discrete units each has one long DNA mol. w/ associated proteins chromatin: complex of DNA & protein making up chromosomes chromosomes can’t be distinguished nucleolus: dense granules & fibers joining chromatin where rRNA (ribosomal RNA) is synthesized proteins imported from cytoplasm are assembled w/ rRNA into large & small ribosome subunits nucleus directs protein synthesis synthesizes mRNA (messenger RNA) according to DNA mRNA transported to cytoplasm by nuclear pores ribosomes translate mRNA genetic message into primary structure B. Ribosomes: Protein Factories ribosomes: complexes made of rRNA & protein; carry out protein synthesis NOT an organelle b/c not membrane bound free ribosomes = suspended in cytosol proteins made by them funx in cytosol ex. enzymes bound ribosomes = attached to endoplasmic reticulum proteins made by them are inserted into membrane or packaged into lysosome or secreted can alternate btwn free & bound 6.4 The Endomembrane System Regulates Protein Traffic & Performs Metabolic Functions in the Cell endomembrane system: nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, plasma membrane tasks… protein synthesis, protein transport into membranes & organelles & out, metabolism, lipid movement, poison detox vesicles: sacs of membrane A. The Endoplasmic Reticulum: Biosynthetic Factor endoplasmic reticulum (ER): extensive network of membranes; more than half of total membrane in eukaryotic cells ER lumen = cavity/ cisternal space separate from cytosol by ER mem. smooth ER: no bound ribosomes rough ER: bound ribosomes a. Functions of Smooth ER lipid synthesis, carbohydrate metabolism, poison detox, calcium ion storage steroids, sex hormones secreted adding hydroxyl to drug mol. more soluble > easy to flush out b. Functions of Rough ER secreted protein production glycoproteins: proteins w/ carbohydrates covalently bonded built into ER membrane transport vesicles: vesicles in transit from one part of cell to others membrane factory for cell makes membrane phospholipids from cytosol precursors B. Golgi Apparatus: Shipping & Receiving Center Golgi apparatus: warehouse for receiving, sorting, shipping, & some manufact. products of ER are modified & stored & sent to other destination flattened membranous sacs = cisternae structural directionality cis face = where vesicles from ER can add membrane to Golgi trans face = where vesicles pinch off & travel to other sites manufactures some macromolecules pectin, non cellulose polysaccharides cisternal maturation model = cisternae of Golgi progress forward from cis to trans face carrying modified cargo during move molecular identification tags added like mailing labels ex. phosphate groups transport vesicles from Golgi have external mol. on membrane that recog. “docking sites” on specific organelle surfaces or plasma mem. correct targeting of vesicles C. Lysosomes: Digestive Compartments lysosome: membranous sac of hydrolytic enzymes for digesting macromol. too many lysosome leakages can destroy cell by selfdigestion hydrolytic enzymes & membrane made by rough ER then transferred to Golgi for processing 3D shapes of proteins protect vulnerable bonds from own enzymatic attack phagocytosis: eating by engulfing smaller organisms/ food ex. amoebas & unicellular eukaryotes, some human cells (macrophages) autophagy = recycle cell’s own organic material TaySachs disease caused by accumulation of lipids b/c lipiddigesting enzyme is missing/ inactive brain is impaired D. Vacuoles: Diverse Maintenance Compartments vacuoles: large vesicles from endoplasmic reticulum & Golgi apparatus food vacuoles: formed by phagocytosis contractile vacuoles: pumps excess water out of cell in unicellular eukaryotes in fresh water maintain suitable conc. of ions & molec. certain vac. in plants & fungi have enzymatic hydrolysis carried out plants have small vac. to reserve organ. compounds help protect plants against herbivores b/c have poisonous compounds stored some have pigments to attract pollination central vacuole: coalescence of smaller vacuoles in mature plant cells cell sap made inside E. The Endomembrane System: A Review Concept Check 6.4 1. Describe functional and structural distinctions between rough and smooth ER. The rough ER has ribosomes; both make phospholipids 2. Describe how transport vesicles integrate the endomembrane system. Substances are enclosed between endomembrane components. 3. Describe the proteins path through the cell staring with the mRNA molecule that specifies the protein if a protein function in the ER but requires modification in the Golgi apparatus before achieving that function. mRNA is synthesized in the nucleus and then to nuclear pore and then to bound ribosome on the rough ER where protein is synthesized and transport vesicle takes the protein to the Golgi apparatus and then back the ER. 6.5 Mitochondria & Chloroplasts Change Energy From One Form to Another mitochondria: site of cellular respiration; oxygen to ATP by extracting nrg from sugars chloroplasts: sites of photosynthesis A. The Evolutionary Origins of Mitochondria and Chloroplasts endosymbiont theory: early ancestry of eukaryotic cells engulfs oxygenusing nonphotosynthetic prokaryotic cell B. Mitochondria: Chemical Energy Conversion double phospholipid bilayer outer membrane is smooth cristae: membrane inner foldings creates larger surface area mitochondrial matrix: enclosed by inner membrane composed of enzymes C. Chloroplasts: Capture of Light Energy double membrane thylakoids: another membranous system of flattened interconnects sacs granum: thylakoid stacks stroma: fluid outside the thylakoids; contains chloroplast DNA plastids: chloroplasts a member of this specialized family ex. amyloplasts = colorless organelle that stores starch (amylose) ex. chromoplast = gives yellow/orange color to fruits & flowers D. Peroxisomes: Oxidation peroxisome: specialized metabolic compartment bound by single membrane enzymes remove hydrogen atoms from substrates & transfer to oxygen produces hydrogen peroxide ex. glyoxysomes = fat storing tissues of plants have these to converse fatty acid to sugar Concept Check 6.5 1. Describe two common characteristics of chloroplasts and mitochondria. Function = energy Membrane structure = folding or thylakoid membrane for larger surface area 2. Do plant cells have mitochondria? Explain. Yes; mitochondria make energy from sugars 3. Argue against why mitochondria and chloroplasts should be classified in the endomembrane system. Neither are synthesized by the ER and are not bound to a single membrane. 6.6 The Cytoskeleton is a Network of Fibers that Organizes Structures & Activities in the Cell cytoskeleton: network of fibers extending throughout cytoplasm A. Roles of the Cytoskeleton: Support & Motility obvious function = mechanical support & maintain shape especially important for animal cells b/c no cell walls some cell motility motor proteins: interacts w/ cytoskeleton to move ex. how vesicles w/ neurotransmitter mol. migrate to axon tips manipulates plasma membrane bending to form food vacuoles/ phagocytic vesicles B. Components of the Cytoskeleton a. Microtubules microtubules: hollow rods constructed from globular protein (tubulin) each protein is a dimer = mol. of 2 subunits alphatubulin & betatubulin grows by adding dimers one end can accumulate or release tubulin dimers @ higher rate plus end guides vesicles from ER to Golgi apparatus to plasma membrane i. Centrosomes & Centrioles centrosome: where microtubules grow out of near nucleus centrioles: within centrosome; composed of 9 sets of triplet microtubules in a ring shape ii. Cilia & Flagella flagella & cilia: microtubulecontaining extensions that project from some cells flagella undulate like a fish tail cilia work like oars w/ alt. power & recovery strokes cilia can be signalreceiving “antenna” motile will have nine doublets of microtubules in a ring shape w/ 2 single microtubules in center “9+2” nonmotile will have “9+0” basal body: what cilia/flagella are anchored by; struct. similar to centriole “9+0” like a centriole sperm flagellum becomes centriole when entering the egg dyeins: large motor proteins that bend the flagella & motile cilia attached along outer microtubule doublet 2 “feet” that “walk” along microtubule of adjacent doublet using ATP b. Microfilaments (Actin Filaments) microfilaments: thin solid rods built by actin actin: globular protein twisted double chai of actin subunits like microtubules, present in all eukaryotic cells NOT compressionresisting like microtubule but tension bearing cortical microfilaments = support cell shape cortex: outer cytoplasmic layer of cell shaped by cortical microfila. to be semisolid consistency of gel myosin: protein that makes up actin filaments & thicker filaments interaction causes contraction of muscle cells pseudopodia: extending cellular extensions that allow cell to crawl along a surface cytoplasmic streaming: circular flow of cytoplasm within cells actinmyosin interactions contribute c. Intermediate Filaments intermediate filaments: named for diameter; only found in cells of some animals (ex. vertebrates) specialized for bearing tension each constructed from family of proteins who include keratins more permanent than microfilaments & microtubules persist even after cell death especially sturdy for reinforcing shape of a cell & position of organelles ex. nucleus sits in cage of intermediate filaments End of Chapter 6 Qs 1. Which structure is not part of the endomembrane system? A. Nuclear envelope C. Golgi apparatus B. Chloroplast D. Plasma membrane 2. Which structure is common to plant and animal cells? A. Chloroplast C. Mitochondrion B. Central vacuole D. Centriole 3. Which of the following is present in a prokaryotic cell? A. Mitochondrion C. Nuclear envelope B. Ribosome Chloroplasts 6. What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell? A. Golgi→ ER → Lysosome B. Nucleus→ ER → Golgi C. ER → Golgi → vesicles that fuse with plasma membrane D. ER → Lysossome → vessicels that fuse with plasma membrane 7. Which cell would be best for studying lysosomes? A. Muscle Cell B. Nerve Cell C. Phagocytic White Blood Cell D. Bacterial Cell
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'