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Cell Physiology

by: Clarissa Hermiston DVM

Cell Physiology BIO 121

Clarissa Hermiston DVM

GPA 3.58

Thom Landerholm

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Thom Landerholm
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This 36 page Class Notes was uploaded by Clarissa Hermiston DVM on Monday October 5, 2015. The Class Notes belongs to BIO 121 at California State University - Sacramento taught by Thom Landerholm in Fall. Since its upload, it has received 8 views. For similar materials see /class/218816/bio-121-california-state-university-sacramento in Biological Sciences at California State University - Sacramento.

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Date Created: 10/05/15
Outline 2 Organization of the Cell Biological Sciences 121 Spring 2010 You have all encountered portions of this material in other classes but now we will try to put it all together Section A The Endomembrane System You all know that cells have membranes between themselves and the outside world that they are lipid bilayers and that the primary difference between eukaryotes like ourselves and prokaryotes is that we have membranebound organelles including the nucleus endoplasmic reticulum Golgi apparatus endosome system lysosomes and mitochondria We will also learn how information stored in the nucleus as DNA can be used to build and change the structures inside and outside of the cell Section B The Cytoskeleton Some of you have also heard of the intracellular internal cytoskeleton and its ability to move materials around inside of the cell We have also talked about the material outside of the cell in multicellular organisms the eXtracellular matriX In Section C Adhesion we will learn how a cell uses its plasma membrane to link its cytoskeleton to structures outside of the cell A The Big Picture The Eukaryotic Membrane System and Vesicular Transport All membranebound organelles are part of one big cellular manufacturing and transportation system called the Vesicular Transport System or Endomembrane System used to move stuff into and out of the cell as well as to move stuff around inside the cell The important thing to remember here is that these systems are heavily hydrophobic in an aqueous environment This system is the central link to all eukaryotic cell functions As with all things biological organelle Function and Structure are inseparable Their physical organization is designed for their activity All eukaryotic cells have each of the organelles but the number and organization depends on the cells function 1 Introduction Structure and Function of Eukaryotic Membranes Function and Structure are inseparable sides of the same coin The physical organization of membranes is designed for their activities This is a recuning theme in biology from the organization of the whole animal to the modular design of protein structure You must learn structure to understand function and vice versa a What are the Principle Functions of Cell Membranes 1 Compartmentilization of Cell Functions 2 Defense and Integrity of Cellular or Compartmental Contents 3 Selective Permeability in Two Directions 4 Regulation of Internal Cellular or Compartmental Activities 5 Attachment and Movement of the cell or Compartment 6 Response to Signals from Outside of the Cell or Compartment b The Three Principle Components of Cell Membranes 1 The lipid bilayer makesup the primary structural element of the membrane Two layers of amphipathic lipid molecules 7 heads out tails in a Amphipathic hydrophilic heads and hydrophobic tails b The average lipid bilayer is about 40100 A thick c Amphipathic properties of membrane lipids give them structural integrity 1 They seal and heal spontaneously in aqueous solutions a Goal is to hide hydrophobic regions internally 2 This also provides the primary biochemical barrier 2 Membrane proteins provide additional structure and many of the unique functions a Proteinlipid ratio varies hugely in different membranes protein M l myelin sheath 20 80 2 outer mitochondrial 50 50 3 inner mitochondrial 80 20 b Often classi ed by location and chemical bond interaction 1 Integral proteins are bound by hydrophobic forces 2 Peripheral proteins are bound by electrostatic forces a Endoproteins are found on the cytoplasmic face b Ectoproteins are found on the eXtracellular face 5 Transmembrane proteins are bound by both forces a Single pass vs multipass c Better information when classi ed by function 1 Transporters a Channels b Carriers 2 Receptors for signaling molecules a We ll look at these in detail in the third section of Cell Phys 3 Adhesion proteins a Used by the cell to anchor itself or its organelles in place 4 Proteins involved in metabolic pathways and other cell functions 3 The SubMembrane Protein Meshwork provides structural integrity and links to the cytosolic components SubMembrane Meshwork is special class of cytosolic membrane associated proteins a EXist in all cells and to some eXtent in all membranes b Directly link the membrane to the interior functions of the cell c Membrane protein patching is driven by transitory links to the meshwork 2 The Nucleus a What are the Principle Functions of the Nucleus 1 Store and protect the DNA 2 Provide an environment for transcription of DNA 3 Deliver RNAs for translation c What are the Key StructureFunction Relationships in the Nucleus 1 Store and protect the DNA a Nuclear envelope 2 parallel bilayered membranes b Envelope and contents controlled by a nucleoskeleton the brous lamina c Condensed heterochromatin binds to inner membrane 1 Can be pulled out and used when needed 2 Provide an environment for transcription of DNA a Structure is found in the organization of molecules b Huge protein concentration highly organized 1 Proteins of the brous lamina system 2 Proteins to interpret signals from outside 3 Proteins to regulate chromatin structure 4 Transcriptional proteins 5 DNA repair proteins c Huge RNA concentration highly organized 1 Transfer RNAs for making DNA and RNA 2 Messenger RNAs being made and on the way out 3 Ribosomal RNAs made in the nucleoli a Contain nucleolar organizer DNA 1 Codes for ribosomal RNA 3 Deliver RNAs for translation a Nuclear pores need be very large 8 protein subunits b The outer membrane is often continuous with the rough endoplasmic reticulum and may even have ribosomes on it c Free ribosomes direct cytosolic translation 1 Free and bound ribosomes are structurally identical 2 mRNA sequence directs them on or off the RER surface 3 Free is a relative term 7 they appear anchored to the cytoskeleton 3 The Endoplasmic Reticulum 11 What are the Principle Functions of the ER 1 Lipid biosynthesis 2 Membranebound ribosomal translation of mRNA into protein 3 Initial integration of lipid and protein constituents 4 Detoxi cation of lipidsoluble and insoluble materials 5 Calcium sequestration b What are the Key StructureFunction Relationships in the ER 1 Lipid biosynthesis a The ER eXtends to nearly every part of the cell most is smooth ER 1 Can make up more than half of all cell membrane b Synthesis apparatus for membrane lipids steroids lipoproteins HDL LDL 2 Translation of mRNA into protein a Membrane is continuous with outer nuclear membrane 1 This means that the inside of the RER is equal to outside cell b Ribosomes stud the outer membrane cytosolic sheaf 3 Initial integration of lipid and protein constituents a Aminoterminus leader sequences on proteins direct expressionlinked placement into proper oritentation l Membrane proteins go into the membrane of the RER 2 Those needed inside of stuff are placed into the lumen of the RER b Lipids associate based on amino acid structures as well c The key to it all is DNA sequence 4 Detoxi cation of lipidsoluble and insoluble materials cytochrome P450 5 Calcium sequestration c The Vesicular Transport System really starts here 1 Vesicular Budding Remember 7 this is all occuring in hydrophobic materials within an aqueous environment This process is very similar to the mechanisms used to separate two cells from one during cytokinesis Picture putting a rubber band onto a water balloon as the band tightens the balloon splits into two separate internal components without breaking the outer covering Now remember what we said about membrane fusion and you ve got the picture The two components continue to separate until the membranes of both spontaneously seal to form two distinct cells or vesicles 2 Movement is cytoskeletonmediated 7 coming in the neXt section 4 The Golgi Apparatus a What are the Principle Functions of the Golgi Apparatus l Post translational modi cation of membrane and protein constituents a Cistemae l cis 2 medial 3 trans b Sulfation glycosylation adenylation phosphorylation etc 2 Membrane Targeting Control of the cellular destinations of prepared membrane and protein vesicles a Regulated secretion by means of the KD25 signaling pathway b Lysosome building by means of the mannose6phosphate signaling pathway c Constituitive secretion by means of an undiscovered mechanism 5 The Endosomal System a What are the Principle Functions of the Endasamal System 1 Inward ow of materials back into the Vesicular Transport System a Phagocytosis and Pinocytosis of extracellular components b Membrane recycling of all of the components of membranes b What are the Key StructureFunction Relationships in the Endasamal System 1 Phagocytosis Pinocytosis and Recycling and Reusing membrane components all are accomplished by the same mechanisms The Vesicle formed has a portion of the plasma membrane around a portion of the extracellular space a Transmembrane proteins combine with meshwork and cytoskeleton b Primary Endosomes c Secondary Endosomes l Reusable surface membrane material d Lysosomes 1 Many types of digestive enzymes a Act at low pH 6 Mitochondria and Chloroplasts a What are the Principle Functions ofAitachandria and Chlaraplasts l Captive energy plants for the cell 2 Store protect express their own DNA b What are the Key StructureFunction quot 39 39 39 39 in 39 39 39 39 andfquot 39 f39 quot l Captive energy plants for the cell a The captive prokaryote hypothesis Endosymbiotic Theory 1 a quick bite becomes synergistic coexistence 2 both mitochondria and chloroplasts b Energy production focused on inner membrane 1 Kreb s cycle 2 Boxidation 3 Electron transport 4 ADP phosphorylation 5 Photosynthesis u c quot 39 39 39 39 where is most intense I Found apically in ciliated cells 2 Concentrated basally in ion pumping cells 3 Found centrally along the agella in sperm 2 Store protect express their own DNA a Many fewer genes much smaller operation b Have many of the same attributes as the nucleus 3 Many genes have been moved to the nucleus a Sequences used to be part of the mitochondrial or chloroplast genome b Gene delivery to the Mitochondria is a sophisticated 3part transport system 7 Peroxisomes a Peroxisomes are specialized metabolic compartments bounded by a single membrane b Peroxisomes produce hydrogen peroxide and convert it to water c Oxygen is used to break down different types of molecules d What do you know about singlet oxygen 8 The Plasma Membrane a What are the Principle Functions of the Plasma Membrane 1 Defense and Integrity of the Cell 2 Selective Permeability in Two Directions 3 Attachment and Movement 4 Response to External Signals b What are the Key StructureFunction Relationships in the Plasma Membrane 1 Defense and Integrity of the Cell 2 Selective Permeability in Two Directions a Selective Permeability l Hydrophobic nonpolar molecules such as hydrocarbons can dissolve in the lipid bilayer and pass through the membrane rapidly 2 Charged or strongly polar molecules such as ions sugars and proteins do not cross the membrane easily 3 Some small molecules even if polar can pass through the lipid bilayer very slowly oxygen carbon dioxide urea water b Diffusion l Diffusion requires that the membrane be permeable to the substance that is diffusing 2 Diffusion is spontaneous and passive 7 requiring no Energy 3 A substance moves with its concentration gradient during diffusion 4 Diffusion results from thermal motion heat 5 Osmosis is the diffusion of a solute across a selectivelypermeable membrane 6 At dynamic equilibrium as many molecules cross in one direction across the membrane as in the other direction 7 Tonicity is the ability of a solution to cause a cell to gain or lose water a Considers both solute concentration and Membrane permeability b Depends on concentration of nonpenetrating solutes c Isotonic solution Solute concentration is the same as that inside the cell no net water movement across the plasma membrane d Hypertonic solution Solute concentration is greater than that inside the cell cell loses water e Hypotonic solution Solute concentration is less than that inside the cell cell gains water c Transmembrane Transport Proteins can help hydrophilic substances cross the membrane 1 All Transport Proteins are very speci c for their molecules 2 Facilitated Diffusion a Aqueous channels for charged or polar molecules to diffuse through 1 Aquaporins for facilitated diffusion of water 2 Ion channels that open or close in response to a stimulus gated channels b Passive carrier mechanisms that move molecules from higher to lower concentration 7 usually in either direction 1 We have glucose transporters and amino acid transporters 3 Active Transport a ATPdependent carrier that can move charged or polar molecules against their concentration gradient b Active transport allows cells to maintain concentrations of things different from what would occur naturally c We have calcium pumps hydrogen ion pumps and sodium potassium pumps among others d We also have glucose transporters and amino acid transporters 7 even large protein transporters d Bulk transport across the plasma membrane occurs by exocytosis and endocytosis f Neurons and muscle cells in animals and phloem cells in plants rely on electrical signaling 1 Electricity is the energy created by the movement of charged particles 7 it s named for the example of electrons 2 When a cell uses electricity it does it by allowing ions that it has concentrated by active transport to rush from one side of the membrane to the other through channel proteins 3 The opening and closing of the channels determines when the electrical current is owing 4 Voltage is a measure of how many ions are on the move 5 Membrane potential is a measure of how many ions have been actively concentrated across a membrane 6 Concentrated ions diffuse faster than uncharged molecules a Two combined forces collectively called the electrochemical gradient drive the diffusion of ions across a membrane g Cotransport occurs when active transport of a solute indirectly drives transport of another solute 1 Plants commonly use the gradient of hydrogen ions generated by proton pumps to drive active transport of nutrients into the cell 3 Attachment and Movement 4 Response to EXtemal Signals 9 How Do the Structures of Cell Membranes Affect Vesicular Transport a Lipid Signatures are a Major Player in Membrane Functions 1 Membranes have distinctive cytosolic and noncytosolic faces or sheaths a Glycolipids occur only on the noncytosolic face b In double membranes the noncytosolic faces face each other 1 Nucleus and mitochondria 2 De ned as the differences in the types of lipids and the ratios of lipid types a Lipid Types include Phospholipids like phosphotidylcholine olestero Sphyngolipids Cerebrosides b Relative asymmetry occurs in any given membrane c Signatures are unique for each membrane and each face 3 Allows for identi cation and fusion of membranes a During fabrication repair and other activities b How Do Membrane Proteins A ect Membrane Function Again if proteins are a principle structural element of membranes then they have important functions Keep looking back to the functions of membranes and making the connections between structure and function 1 Protein signatures are critical for membrane activities movement and identi cation a Protein signatures and protein functions are all about amino acid sequence b Absolute assymetry in amino acid sequences between sheaths c Transmembrane proteins usually have aminoterminal on EC face t quot face like glycolipids dC39 I 39 39 39 onthe u 2 Proteins are less exible than lipids give the membrane tensile strength a Proteins are also uid in the membrane to some extent 1 Proteins move more slowly than lipids due to size and charge 2 Integral proteins usually both hydrophobic and electrostatic b Complexes exist between membrane proteins and inside and outside of cell 1 Transmembrane proteins can be patched into unique structures a 6 connexins 1 connexon many connexons gap junction b Rows and columns of many proteins make tight junctions 2 Dispersed proteins can be drawn together when needed a Coupling of mitochondrial respiratory chain c Whatis the SubMembrane Structural Meshwork This is an absolutely critical component of the plasma membrane Similar structures have been found on nuclear membranes in some organisms and may be present in other organelles 1 Key Properties are both Flexibility and Strength a Provide structural support that is highly mobile 1 This is absolutely indispensable to motility contraction cell division b Directly link the cell interior to the exterior l The only way a cell can pull against anything c Membrane protein patching is driven by transitory links to the meshwork B The Cytoskeleton Modular adaptable multifunctional amazing 1 Provide Structural Support Large Scale Cell Movements Vesicle Movement Most Biologists underestimate the importance of the cytoskeletal apparatus in the cell All of the structural morphology of the cell as a whole and much of its integrity the morphology and integrity of its internal components the movement of materials inward and outward the ability of a cell to respond to its physical environment the positional coordination of enzymatic pathways and the large scale movements of the entire cell all depend completely on the cytoskeleton and its associated molecular motors we ll get into these in more detail later The cytoskeleton is made up of three very different kinds of protein bers and as a result is both dynamic and stable It is the variety of structural and functional elements that can be formed within the cytoskeleton that make it so important a The Cytoskeleton 1 Found in all eukaryotes may comprise onethird of all cellular proteins 2 Recently microtubulelike polymers found in prokaryotes 3 Organize and compartmentalize the cell 4 Provide signal transmission by sensing space and movement b Three Main Types of Cytoskeletal Fibers 1 Intermediate Filaments Composed of a Large Variety of Proteins 2 Micro laments Composed of Polymers of Actin monomers 3 Microtubules Composed of Polymers of Tubulin dimers e A Large Variety of Accessory Proteins Associate with Fibers 1 Assembly and disassembly apparatus 2 Molecular motors kinesins dyneins and myosins 3 Linker proteins that integrate the cytoskeleton with all cell structures 2 Intermediate Filaments a The Key Structural Elements 1 Apolar 7 not structurally nor functionally oriented towards one end Very Important 2 Cytosolic varieties surround nucleus and eXtend outward like spokes while the lamins compose the brous lamina of the nucleus 3100 A lOnm diameter laments in a bundle of eight proto laments a parallel brous monomers make up dimers b two antiparallel dimers makle up tetramers c proto laments are made up of polymers of tetramers 4 The primary amino acid sequences are tissue speci c and useful cell markers a nuclear lamins brous lamina in all cells b cytokeratins epithelia c glial brillary acidic protein desmin vimentin l glia muscle a variety ofcells d neuro laments b The Key Functional Elements 1 Form the stable skeletal network due to their apolarity 2 Form the functional compartments of the cytosolic space proteins DNA RNA 3 Interact with microtubules and micro laments 7 guidelines 4 Form the prominent intracellular connections to intercellular junctions 5 Form the primary connections between muscle lament bundles 3 Micro laments b The Key Structural Elements 1 structural polarity 7 unequally sequences and structures directed towards each end 2 70 A laments factin polymers of globular monomers gactin a gactin is added and removed most readily at barbed end 3 Trimer is enough to nucleate a less labile than microtubules 4 Micro lament Associated Proteins MFAPs a micro laments are the same MFAPs determine activity b The Key F unetiamll Elements 1 dynamic instability 7 rapidly made and unmade a MFAP s are right there ready for either job b unstable does not mean uncontrolled 2 variable structural skeleton 7 can form actual gels a can form crosslink breakdown and reform rapidly l actin polymerase and gelsolintype proteins 2 superb compaItmentalization activity b Lots of interesting jobs with fancy names 1 Actin trucks use myosin motors to move materials short distances inside the cell 2 Stress bers bear tension resist pulling forces 3 The cortex just inside the plasma membrane supports the cell s shape 4 Actin bundles make up the core of microvilli 5 Actin treadmills form the basis for cell migration 6 Thin filaments work with myosin to contract muscle cells 7 Purse strings of actin separate the daughter cells during cell division 4 Microtubules 11 The Key Structural Elements 1 polar 7 unequally directed towards each end a most 7 end toward nucleus and end to cell membrane 2 250 A laments formed as a hollow bundle of 13 proto laments a proto laments are long polymers of tubulin dimers b dimers are one alpha and one beta globular monomers c long rigid polymers similar in all eukaryotes 1 0c and 3 sequences are 90 the same in all organisms 2 0c vs 3 sequences are lt50 in any one organism 3 The axenome is a special structure in cilia and agella a 9 microtubule doublets in a ring around 2 central singlets 4 Microtubule Organizing Centers MTOC a sites of nucleation centrisome 2 centrioles near nucleus basal bodies away from nucleus 5 Microtubule Associated Proteins MAPS a all tubules are the same it s MAPS that determine activity b The Key Functional Elements 1 dynamic instability 2 Movement of vesicles and organelles a throughout cell body or as far as a meter in some neurons b anteriograde away from nucleation site uses kinesin c retrograde toward nucleation site uses dynein 3 The axenome of the cilia and agella uses dynein 4 chromosome movement in mitosis mitotic spindle can last only 30 seconds 5 Molecular Motors are ATPases that Couple Hydrolysis with Movement 11 The three basic types 1 Dyneins move along microtubules towards the negative end 2 Kinesins move along microtubules towards the positive end 3 Myosins move along micro laments towards the positive end mostly a Some myosin gene products move toward negative end b All have the Same Basic Structural Design 1 Globular heads on brous tails a Heads have ATPase activity and dictate lament track direction and speed b Tails have cargo binding and myosin thick lament organizing activity e Kinesins and Myasins are Evalutianurily Related 1 Both have single head type I and double head type 11 designs 2 Little sequence similarity but remarkable similarities in tertiary structures cl Dyneins are Something Else 1 They are an ancient family of proteins found in all eukaryotes a Cytosolic dyneins move most structures ciliar dyneins move cilia and agella 2 Generally similar structure to the others 7 can have trimer heads e Power Stroke mechanism to couple movement to A TP metabolism 1 ATP binding Filament Release 2 ATP Hydrolysis Conformational Relaxation to 90 3 Release of P Filament Binding 4 Release of ADP Conformational Stroke to 45 C Adhesion The cellular interface with the external environment a Cellmatrix adhesion integrin snperfamily of transmembrane proteins 1 Intermediate laments Hemidesmosomes a Half rivetlike spots of cellmatrix contact b Anchor protein network beneath membrane contains plectin 2 Micro laments Focal adhesions a Used to grab ECM 7 either for immobilization or migration b Anchor protein network contains talin lamin Vinculin ocactinin b Cellcell adhesion cadherin snperfamily of transmembrane proteins 1 Intermediate laments Desmosomes tight junctions zonula adherens a Full rivetlike spots of cellcell contact b Anchor protein network contains plakoglobin desmoplakin 2 Micro laments Adherens junctions a Punctate spots in most cells zonula adherens in some epithelium b Anchor protein network contains catenins Vinculin ocactinin Slide 1 Slide 2 Slide 3 Prokaryoljc vs Eukaryo c cells The basic unit of every organism is either prokaryotic or eukaryotic cells F39rukaryutes include Bacterla and Arcnaea Eukaryutes include F39rutlsts Fungi Arllmals and Plants Basic features of all cells Plasma membrane Semirluid substance called cytosol Duubleestranded DNA RNA and prutelns Pmkaiyms Cyluplasm buund by plasma memblaneinu ulganelles Nu nucleus DNAln an unbuund YEngn called We nucleuid Elaml emumu Tne plasma membrane is a selemlve balllellhal alluws sullicieni passage ul d Was12 in sen qugEVlinuUlEMSi an ice ine vulume ul Evely cell Slide 4 Slide 5 Slide 6 Eukaryo cells are generally much larger than prokaryotic cells Eukaryotic cells are also characterized by having stuff prokaryotes don39t have 7 Membranerbound organelles 7 Cytoskelelon r compartmentalized function Wimp m in NuLilrmmqyk WWW imam um mum P Flantani a mm ai cells have m ust uf calm vpm mm 39 quot mmmm m mum Slide 7 Slide 8 Slide 9 The Extracellular Matrix ECM Animal cells are covered by an elaborate ECM Plants cells secrete a cell wall Functions ofthe ECM 7 Regulation 3 Glycusaminuglycans pruteuglycans fibruus pruteins and 4 elastin pruteins Inlerccllular Junctions Neighboring cells in tissues organs or organ systems often adhere intera communicate through direct physical contact Intercellular junctions facilitate this contact There are several types of intercellular junctions r Plasmodesmata and gaplunctions r Tightlunctions and desmosomes cadhenns r Hemidesmosomes integrlns r Deltarnotch and ephrephnns Slide 10 Slide 11 Slide 12 W 79mm lame m a mamas wnhehai Mls W cm mistler m 5mm ms W vrvwdec lnvlisuc mmm m am My smizm WW viammsm a legam daublerhelical madel Mme shutting m eaxwmnmmam mDNA Slide 13 mg Poseiin Frankiin s eray Width ofthe heiix arid the Spacing ofthe mm Slide 14 lw 05mm J The KHZ mm Centrai ipv4 a Dogma mm P WWW a mm Slide 15 f W04 osmem J The KHZ mRNA Centrai rd W Dogma I mm i WWW m m Mm m J mm m mpim ma We Slide 16 Slide 17 Slide 18 1 Wm m m m m Chmmzlinis a cumplexulDNAand pmlem mm eukavyulicnucleus sinnvsave pmlemslhal ave vespunsible luvlhelimlevel ulDNA packing m cmumaim lnusely packed hvumalm iscalled euchrnmmin D2nse packing mum helernuhmmzlin makesil mmcummme cellm Expvessgenelic Wuvmaliuncuded in these vegiuns 3 rnm ha limped dnmzins Metaphase j rnm her chmmnsnme Slide 19 Slide 20 Slide 21 Most Macromolecules are polymers built from monomers A polymer is a long molecule consisting of many similar building blocks These small buildingblockmolecules are called monomers Three ofthe four classes of life s organic molecules are polymers 7 Carbohydrates 7 Proteins 7 Nucleic acids The Synthesis and Breakdown of Polymers A condensation reaction or more specmcallya dehydration reaction occurs Wnen two monomers bond togetherthrough tne loss of a Water molecule The Synthesis and Breakdown of Polymers Polymers are dlsassembled to monomers by hydrolysis a reactlol39lthat ls essentlallythe reverse ofthe denydratlon actlol39l Slide 22 Slide 23 Slide 24 The Structure of Nucleic Acids What are the nucleic acids monomers called What are the nucleic acid polymers called hm nuclemme canal mlmgul u n ska2 amine quotJquot mlquotm1m e a purlmomma nr nucluc em me nuclemdew hnmlhe Dhnavmtelsclled meow l l Colllent 7 me emenee nthu 1mm as me 0 mm mm Ilnng nun nr mum e m Dnlymu e unmuemr any n meumlhe gene unusulme nn me 5v man an me nexl One DNA molecule includes many genes Slide 25 Slide 26 Slide 27 Fig 138 1 New 0 cu t N u M m 2 5w Admmemt Mmem o N n m urn 1 Swan ammo mnln ct 5v em Nydmgm hand 19 a Weme at DNA We in ma Emmi grumure The Basic Principle Base Pairing to a Template Strand Since the two strands of DNA are complementary each strand acts as a template for building a new strand in replication n DNA replication the parent molecule unwinds and two new daughter strands are built based on basepairing rules 1 Slide 28 Slide 29 Slide 30 Fig 16794 IlPIemmrlecule Fig 167972 mpmmmm MSwnnnnm 51mm Fig 167973 mpmmmm MSwnnnnm wammwnunmmus 51mm sch Ennls ng 11 one Druml nm Ind an new Inna Slide 31 Slide 32 Slide 33 quot 5quot 5 end 3 end Twn pnynueiemiues Mvmph e spiraling amine an memes imaginary zx39 mm a Dnuhle Helix est Dzir ruined Dy nyemren mane What is meant byAntiparallel f Lquot I y 5 end v a the What DNA bases can palrup7 purine pyrimidine Getting Started Replication begins at special sites called origins of replication where the two DNA strands are separated opening up a replication bubble A eukaryotic chromosome may have hundreds or even thousands of origins of replication Replication proceeds in both directions from each origin until he entire moleculeis copied uv mm rimming Slide 34 Slide 35 Slide 36 DNA Replication A Clnser ak The copying of DNA is remarkable in its speed and accuracy More than a dozen enzymes and other proteins participate in DNA replication 7 432 i Iquot in l JWV wwuczssm f quot39 quot I No 1 hlEuhrywmc cal Molecular Comp onems or Transcription RNA synthesis is catalyzed by RNA polymerase which pries he DNA strands apart and hooks together he RNA nucleotides RNA synthesis follows the same basepairing rules as NA except uracil substitutes for thymine The DNA sequence where RNA polymerase attaches is called the promoter Slide 37 Slide 38 Slide 39 RNA Pulymeme Binding minimum uf Trmm39m39nn Promoters signal the initiation of RNA synthesis Transcription factors mediate the binding of R A polymerase and he initiation of transcript39on The completed assembly oftranscription factors and RNA polymerase II b promoter is called a transcription mplex a ation A promoter called a TATA box is crucial in forming the initiation complex in eukaryotes quot39 mquot vmmaw mum Ianum Gm lr J Yrnscnvllnn 39 Furlan mm W m Wmquot mm wiw quotHangman xmpmm W p a mum Slide 40 wiw mungmm 9mm a ma an mm mm m mp H mm mm 5mmquot 39 J Slide 41 Slide 42 wiw mungmm xmm a mum m mum mm mm mm 3mm 7 A a mm a mum am Nnnlemplme strand nmNA RNA n clemidvs Elnngminn RNA pnlymuase 5 mm m Imnscr an ann mum YamIda srmumnun uew mm RNA Slide 43 Slide 44 Slide 45 5n aug x Pau WM Stl pnlm Yunrlle nun nnn 9mm fclms 39 ans L T 3D an 5u RNADnIynznsell 39 Cell Svecmctnmcrlvlmnhclnrs m iii Ru Alnnscrlvl Ynnsc lnnlnllnmn cf wlw What DNA and RNA bases can pair up7 M M 77 arid 777 777C777 and 77777 777T77 an d 77777 77 77 75 777 and 77777 77 Elnnga nn uflhe RNA Strand As RNA polymerase moves along the DNA it untwists the double helix 10 to 20 bases at a time Transcription progresses at a rate of40 nucleotides per second in eukaryotes A gene can be transcribed simultaneously by several RNA polymerases Slide 46 Slide 47 Slide 48 Alteration of mRNA Ends Each end ofa pre mRNA molecule is modi ed in a particu arway r The 5 ehd receives a modified nucleotide 539 cap 7 The 339 end gets a polyA tail These modi cations share several functions 7 They seem to facilitate the export of mRNA 7 They protect rnRNA irorn hydrolytic enzymes 7 They help ribosomes attach to the 5 ehd aquot RNA splicing remuves intruns andiuins Exuns creating an mRNA mciecuie With a cuntinuuus Ending sequence lmmnsct um um umquot avl ed Ingmar mnun 1 as 5D um an um m RNAIrnscllv vre mum quotz m 1 immg n z xnn 2 ome Splicensnmes PM cunsis1 uta aneiyci piuleins and seveial small iibunucleupiule inssnR NPs that vecugnize the mime sites Slide 49 Slide 50 Slide 51 mm re 5 nun mum z xnn 1 lmmn z nnZ sin Zn immunst rare mum z xnn 1 Immu z x nnZ cunnnmms mnun 5n nm mm Th Funt nnal and Evaum39nnmy Importance uf Inb unx Some genes can encode more than one kind of polypeptide depending on which segments are reated as exons during RNA splicing Such Variations are called alternative RNA splicing Because of alternative splicing the number of different proteins an organism can produce is much greater than its number of genes Slide 52 Slide 53 Slide 54 P otei s o en have a modular architecture r n consisting of discrete regions called domains In many cases different exons code for the different domains in a protein Exon shu ling may result in the evolution of new proteins m G E nun I M to m m Yrnscllvllnn v nun Drncsln v unium v Kw It V Pnlynwlme Mulagens Spontaneous muta ions can occur during DNA replication recombination or repa39r Nhtagens are physical or chemical agents that can cause muta ions Slide 55 Slide 56 Slide 57 Sublian A basepair substitution replaces one nucleotide and its partnerwith another pair of nucleoti es Silent mutations have no effect on the amino acid pro uce by a co on becauseo redundancy in the genetic code Nissense mutations sti code for an amino acid but not necessarIIythe rIght amIno acId Nonsense mutations change an amino acid codon into a stop codon nearly always leading to a nonfunctional protein Inui 39nm and Dele nnx Insertions and deletions are additions or losses ofnucleotide pairs in a gene These muta ions have a disastrous effect on the resulting protein more olten than substitutions do Insertion or deletion of nucleotides may alter the reading 39ame producing a frameshift mutation Proofreading and Rep airing DNA DNA polymerases proo 39ead newly made DNA replacingany incorrectnucleoti es In mismatch repair of DNA repair enzymes correct errors in base pairing DNA can be damaged by chemicals radioactive emissions Xrays UV light and certain molecules in cigarette smoke for example In nucleotide excision repair a nuclease cuts out and replaces damaged stretches of DN Slide 58 Hg 1648 m I m


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StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.