BIOL 160 Test One Study Guide
BIOL 160 Test One Study Guide BIOL 160 - 021
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BIOL 160 - 021
Mary Alison Bennett
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Popular in Biology
This 22 page Study Guide was uploaded by Mary Alison Bennett on Friday September 25, 2015. The Study Guide belongs to BIOL 160 - 021 at University of Tennessee - Knoxville taught by Purnima D Pinnaduwage in Fall 2015. Since its upload, it has received 126 views. For similar materials see Cellular and Molecular Biology in Biology at University of Tennessee - Knoxville.
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Date Created: 09/25/15
Cellular amp Molecular Biology BIOL 160 Chapter 2 Review The Five Big Ideas FBls 0 Evolution populations of organisms and their cellular components have changed over time through both selective and nonselective evolutionary processes 0 Structure and Function all living systems are made of structural subunits which impact the functioning of those systems 0 Information Flow and Storage DNA is the information code for life how it is used and exchanged within and among organisms is the basis of life on the planet 0 Transformations of Energy and Matter all living things acquire use and release matter and energy for cellular functioning 0 Systems living systems are interconnected and interact and influence each other on multiple levels Five Scientific Practices FSPs 0 Link topics and synthesize information particularly in reference to the FBls 0 Ask scientific questions based on models and data 0 lnterpret scientific representations and come to an evidenced conclusion 0 Summarize information from scientific articles or other sources 0 Predict the consequences of changes to systems or pathways EvidenceBased Studv of Life 0 There are many sources from which scientific problems and questions come from 0 Biology is studied at many levels of organization Cellular and Molecular Biology 0 The cell is the fundamental structural unit of all organisms What Makes a Cell a Living Orqanism o Organisms range from millions of cells to just one o The range of functions for organisms is huge 0 But they are all alive Biomolecules o Biomolecules are unique to the living world 0 Includes proteins ch3 nucleic acids ch4 carbohydrates ch5 and lipids ch6 Cellular amp Molecular Biology BIOL 160 Chapter 2 Chemical Elements Bonds and Water Basic Atomic Structure 0 Atoms are composed of protons neutrons and electrons o Protons have a positive charge and reside in the atomic nucleus 0 Neutrons are electrically neutral and also reside in the atomic nucleus 0 Electrons have a negative charge and orbit the atomic nucleus in orbitals O 0 Each element has numbers to describe it 0 Mass Number equal to the number of protons plus neutrons 0 Atomic Number equal to the number of protons o The number of protons of any given element will always be the same regardless of charge Chemical Bondinq o Atoms use their outer electrons to bond to each other 0 The number of valence electrons usually equals the number of bonds the atom will form ex H91 C94 N93 092 0 However there are double and triple bonds that may change this 0 There are multiple types of bonds Covalent Bonds 0 Make atoms more stable by allowing them to share electrons and achieve full valence shells 0 Can be polar or nonpolar 0 Polar Covalent Bonds electrons are shared unevenly and result in partial charges in the atoms ex H2 CH4 0 NonPolar Covalent Bonds electrons are shared completely evenly ex NH3 H2O Cellular amp Molecular Biology BIOL 160 Chapter 2 o Electronegativity determines whether bonds will be polar or nonpolar o Electronegafivify depends on the number of protons in an atom and the distance between protons and the valence electrons o Electronegativity is the greatest in the upper right corner of the periodic table 0 IMPORTANT 9 OgtNgtCSH Ionic Bonds 0 Form between ions typically a metal from the left side of the PT cation and a nonmetal from the right sideanion ex NaCl 0 When one atom gives up its electron to another atom so both can form full valence shells cl 8 r 5 8 Hen HCH H zuz H 3 3 C392 0 06 8H H 5 H H 8 NonPolar Covalent Polar Covalent lonic W Water as a Solvent 0 Water is a very effective solvent the solvent of life 0 Polarity and hydrogen bonds 0 Polar molecules are hydrophilic because the charged atoms will attract the opposite partial charges in water molecules 0 NonPolar molecules are hydrophobic because they do not attract the partial charges 0 Water has a unique structure 0 Small 0 Bent Shape 0 Highly polar bonds 0 Polar overall Special Properties of Water primarily due to water s ability to form hydrogen bonds Cellular amp Molecular Biology BIOL 160 Chapter 2 0 Water is cohesive water molecules are attracted to each other 0 Water is adhesive water molecules water molecules hydrogen bonding to other substances 0 Water is denser as a liquid than a solid ice floats 0 Water is able to absorb large amounts of energy Acids Bases and pH o The concentration of H is the basis for pH measurement pH IogH1gt o H antilogpH 10quot H H concentration of H 0 have Ht higher than 10397M o Acidic molecules release H into the solution 0 pH 07 m 0 Have Ht lower than 10397M 0 Basic molecules accept or pick up H ions in the solution 0 pH 814 Cellular amp Molecular Biology BIOL 160 Chapter 2 Functional Groups Functional Family of Group Formula Molecules Properties Example H l39l Acts as a base HxN13d9 Amino R N Amines tends to attract a H OH H proton Glycine 39 OH Acts as an acid HCCquot Carboxyl Carboxylic Acids tends to lose a l C OH proton Hl Acetic Acid Can react with H H I certain HC39C C Aldehydes compounds to R H produce larger H gt Carbonyl molecules Acetaldehyde H H 0 Wag Hes JL Ketones I II I R R39 Acetone Highly polar makes I If compounds more HCCO Hydroxyl OH Alcohols water soluble Ill 39139 H can be adweak Ethanol acn Multiple M NH 0 hosphates can Hot390rl0rto lt5 l organIC p 0H Em c39iH The N N Phosphate R 0 Fl 0H Phosphates store large I OH amounts of energy ATP 0 Can form k H Sulfhydryl 5 Thiols disulfide bonds in HS 0 H proteins NH Cysteine Cellular amp Molecular Biology Chapter 3 Week 2 Proteins The Structure of Proteins o A hydrogen atom H 0 An amino functional group NH2 0 A carboxyl functional group COOH o A distinctive Rgroup or side chain Side Chains H H O 0 H H H 0 H3N c c H3N J C J 0 H3N c o H3N Co H3N C quot 0 V H H393CCH 0 CH3 39 quot use Eris tn Glycine G Alanine A Valine V Leucine L lsoleucine I Nonpolar Gly Ala Val Leu lle side chains H o H3N Clt H yo 0 H 0 Hi 0 H3Nic o Hthc c ltCH39 1 o l39 CH2 CH3 Methionine M Phenylalanine F Tryptophan W Proline P Met Phe Trp Pro H H I O H o I o H H H H N C C l H3N C C I O I 0 o 3 I o HgNLC Clt o H3N c c H3N c c H3N C H2 clI 0 H2 2 Polar side CH2 0 CI 0 CH2 0 IC ICH2 chains Ho CH3 5 C OH H2N 0 HZN o Serine S Threonine T Cysteine C Tyrosine Y Asparagine N Glutamine Q Ser Thr Cys Tyr Asn Gln Acidic Basic H H H 0 I o l 0 H3N c c H3N c c o H3N C Clt quot o T o CH2 o i 2 H3N c c Electrically I quot2 l 0 charged H2 Hz CH39 H side chains CH2 l gt N NH CH2 NH2 NH3 NH Aspartate D Glutamate E Lysine K Arginine R Histidine H Asp Glu Lys Arg His Figure 3 5 Biological Science 2e 2005 Pearson Prentice Hall Inc 0 Side chains can be acidic basic polar but uncharged or nonpolar 0 Determining they type of side chain 0 Negatively charged 9 acidic it has donated H ions to its surroundings o Positively charged 9 basic it has picked up surrounding H ions Cellular amp Molecular Biology Chapter 3 Week 2 o Is there an O atom 9 uncharged polar there is a polar covalent bond Side Chains Functional Groups and Reactivity Side chains will contain different functional groups which will affect their reactivity Polar side chains will be hydrophilic polar likes polar Nonpolar side chains will be hydrophobic Different functional groups in side chains will also affect formation of entire proteins Peptide Bonds Proteins form by connecting amino acids with peptide bonds Peptide bonds form through a condensation reaction between two monomers amino acids in this case HO Monomer H L H l 7 Vl Mgloinler H H 0H Peptide bonds can be broken through hydrolysis putting water in Electron sharing from the N makes the peptide bond very similar to a double bond more stable Important qualities of the Peptide Bond Side chain orientation side chains will interact with each other and with water Directionalify the protein backbone will always have an amino group NH3 on one end and a carboxyl group COO39 on the other 0 The amino end is the Nterminus and the carboxyl end is the Cterminus Flexibility the peptide bond itself cannot rotate but the single bonds on either side of it can meaning that protein structure is flexible What do Proteins Look Like Proteins are incredibly diverse in their structure and function despite there only being 20 different amino acids Cellular amp Molecular Biology Chapter 3 Week 2 0 Due in part to large number of amino acids that make up proteins and the huge number of interactions that can form between so many side chains 0 FUNCTION COMES FROM STRUCTURE Primary Structure 0 The unique sequence of amino acids in proteins 0 Absolutely fundamental to the other structure levels 0 Just one misplaced amino acid can cause a major malfunction sickle cell Secondary Structure 0 Arises from hydrogen bonding between different parts of the amino acids 0 Hbonding can occur between carbonyl and amino groups of two different amino acids 0 Gives rise to either ochelix or Bpleated sheet 0 a helix the backbone of the polypeptide coils o Bpleated sheet parts of the backbone bend to fold into the same plane 0 Depends on the primary structure especially the properties of the amino acids involved Tertiary Structure o Arises form side chain interactions including 0 Hydrogen bonds between polar side chains and opposite partial charges in other side chains or the backbone o Hydrophobic interactions in aqueous solution hydrophilic side chains interact with H20 molecules but hydrophobic side chains form globular masses 0 Van der Waals interactions electrical attractions that occur between all molecules Very weak but helps stabilize hydrophobic side chains that are very close 0 Covalent disulfide bonds strong links that connect different distinct regions of the polypeptide or even two separate polypeptides Cellular amp Molecular Biology Chapter 3 Week 2 o lonic bonds form between groups that have full and opposite charges 0 All of these different types of interactions can occur in one polypeptide leading to very diverse possibilities Quaternary Structure 0 Many proteins have multiple polypeptide subunits interacting to make one structure 0 The exact bonding that occurs is quaternary structure Folding and Function 0 Folding typically happens spontaneously the folded form is usually more stable 0 Proper folding is vital to proper function 0 Unfolded or denatured proteins are pretty much useless 0 Sometimes proteins spontaneously form incorrectly in which case molecular chaperones help them reach the proper formation 0 Folding is often regulated by the chaperones to ensure the best functioning of the organism they re in What do Proteins Do 0 Cafalysis further explained in the next section 0 Defense attack and destroy viruses and diseasecausing bacteria 0 Movement proteins move the cell itself and different cargo inside the cell 0 Signaling send and receive signals cell to cell trigger different enzymes 0 Structure compose fingernails and hair keep blood cells in shape 0 Transport allow certain molecules to enter and exit cells Enzymes and Catalysis o Cafalysis probably the most vital and fundamental function of proteins 0 Enzymes catalytic proteins located in specific sites within the cell 0 Enzymes bind substrates reactant molecules 0 Most enzymes are proteins but some are RNA DNA and RNA DNA Structure some RNA Cellular amp Molecular Biology Chapter 3 Week 2 0 Nucleic acids DNA and RNA are made of monomers called nucleotides The Monomers of Nucleic Acids o Phosphate Group always the same bonded to the 5 carbon in the sugar 0 Sugar middle part of the NA 0 Ribose in RNA 0 Deoxyribose in DNA missing an O on the 2 C o Nitrogenous Base one or two ring structures containing nitrogen will form the inside of the double helix 0 Purines have two rings Guanine G and Adenine A o Pyrimidines only have one ring Cytosine C Thymine T DNA and Uracil U RNA The Formation of NAs o Phosphodiester LinkageBonding joins two sugars through a phosphate o The backbone bonding is always directional 5 93 pigs o Condensation Reaction Primary Structure quot 39 9 o quot o The sequence of the individual nucleotides bonded in of the backbone on ou on on Secondary Structure 0 Formed by hydrogen bonds 0 DNA is a double helix Watson and Crick Franklin and Wilkins Chargaff etc 0 Within the double helix purines can only pair with pyrimidines o A T has two H bonds C G has three Function of DNA 0 DNA can store and transmit Biological information o Carries information to grow and reproduce o Sequencing of bases contains all the vital information Replication 0 DNA has to be able to replicate itself o It does so through the following process Cellular amp Molecular Biology Chapter 3 Week 2 0 Heating or catalysis cause the molecule to break in half lengthwise 0 Free nucleotides deoxyribose base pair with the newly exposed backbone 0 Two identical strands of DNA are produced Cell Storage of DNA Eukaryotes o The cell keeps DNA within the nuclear envelope 0 The nucleus contains chromosomes and is surrounded by a double membrane that has porelike openings all over it 0 Nuclear membrane and ER were probably formed by infolding of the outer membrane Prokaryotes 0 Do not have a nucleus 0 Keep DNA in the cytoplasm 0 DNA is circular M 0 RNA is more reactive and less stable than DNA Primary Secondary and Tertiary Structure 0 Primary Structure same as DNA the backbone 0 Secondary Structure results from base pairing but generally forms within the same strand hairpin structure still antiparallel o Tertiary Structure when secondary structures fold to form more complex patterns 0 Table 41 in the book can help with differentiating Function of RNA 0 Can function as a catalytic molecule 0 Has some degree of complexity and can catalyze multiple chemical reactions 0 DNA is not so versatile its too stable 0 It s likely that the first life form began with RNA Cellular amp Molecular Biology Chapter 3 Week 2 RNA and the Beginning of Life o The theory life began with a lone selfreplicator with no membrane in a solution 0 The initial molecule would have to be capable of providing a template that could be copied and of catalyzing reactions that would link monomers into a copy 0 RNA is capable of both Carbohvd rates Structure Monosaccharides the building blocks of carbohydrates Can vary in 0 Location of carbonyl aldose or ketose o Arrangement and number of hydroxyls 0 Number of Carbon atoms triose pentose hexose etc 0 Spatial arrangement of atoms 0 Shape and form linear and ring Rings form in aqueous solutions Monosaccharides are unique in structure and function Of the formula CH20n Exist in alpha and beta forms depends on the C1 hydroxyl alpha down beta up lecosidic Linkage 0 Links monosaccharides o Condensation reaction 0 Alpha and beta linkages depend on the plane certain atoms land on 0 Alpha points down in pictures beta points up Func on m o The sugarenergy storage in plants 0 Alpha 14 and alpha 16 glycosidic linkage 1 4 is usual so when 16 occurs it causes branching in the molecule 0 Unbranched helices are called amylose branched are amylopectin Cellular amp Molecular Biology Chapter 3 Week 2 Glycogen o The energy storage in animals ex In the liver and muscles 0 Alpha 14 and 16 glycosidic linkage 0 Much more branched than starch to hold more energy Cellulose 0 Structural support of cell walls in plants and algae 0 Beta 1 4glycosidic linkages form parallel strands of monomers that hydrogen bond with the strands around it Chitin 0 Structural support in cell walls of fungi and exoskeleton of insects and crustaceans 0 Beta 1 4 glycosidic linkage o Monosaccharide monomers have a NHCOCH3 group on one carbon 0 Parallel strands lined up with hydrogen bonds Peptidocllvcan 0 Structural support in bacterial cell walls 0 Beta 1 4 glycosidic linkage o Monosaccharide monomers have a NHCOCH3 group on one carbon 0 Monomers also have 4 amino acids on another carbon 0 The amino acid chains react with each other to provide parallel structure through peptide bonds 0 Lysozyme an enzyme that can break down peptidoglycan Overview 0 Energy storing carbohydrates ESC utilize alpha linkage while structural carbohydrates SC utilize beta linkage o ESCs are helical and often branched o SCs form straight chains that make parallel lines with other chains through hydrogen bonds 0 SCs are very difficult to hydrolyze break apart while ESCs are easier Cellular amp Molecular Biology Chapter 3 Week 2 Within the Cell 0 Carbohydrates have NO catalytic activity 0 But they do have many diverse functions Glycoproteins o Aid in cell identity 0 Cellcell recognition and cellcell signaling 0 Display information on the outer surface of the cell 0 Example helps sperm cells locate and bind to egg cells 0 Example Glycoproteins denote your blood type Energy Storage 0 The multitude of C H and C C bonds in carbohydrates are prime for energy storage 0 The bonds are shared very equally and therefore easy to break to obtain energy unlike C O bonds for example 0 To obtain energy 0 GlycogenStarch is hydrolyzed o The glucose from the polymers in broken down 0 The released energy is captured in the synthesis of ATP cellular energy source Lipids Membranes and Transnort lm 0 Lipids are nonpolar heterogeneous hydrocarbons 0 They do not have one monomer like the other biomolecules 0 They serve many purposes 0 Fats and Oils TAGs for energy storage glycerol 0 Phospholipids cell membranes phosphate group and 2 FAs o Sferoids diverse functions ex Cholesterol distinct 4 ring structure Structure 0 Fatty acids are the building blocks of lipids Cellular amp Molecular Biology Chapter 3 Week 2 0 Although there is much more variation in lipids since FAs bond to things that aren t each other Fatty Acids 0 Made of chains of carbon and hydrogen with COOH group on one end hence acid 0 Can be saturated or unsaturated 0 Saturated has no C C double bonds hydrogens with every carbon excepting the COOH o Unsaturated contains at least one CC double bond creates a kink in the chain since the carbons cannot rotate around a double bond 0 Saturation affects boiling point The FA with the LONGEST chain and FEWEST double bonds will have the HIGHEST boiling point 0 When unsaturated can be cis or trans o Cis when the hydrogens attached to the double bonded carbons are on the same side of the chain common in natural FAs 0 Trans when they hydrogens attached to the double bonded carbons are on opposite sides of the chain common in hydrogenated oils Qpids Found in Cells m Structure 0 Consist of a glycerol and three FAs 0 Joined by ester linkages 0 Form through dehydration reactions 0 Depending on length and saturation can be solid or liquid at room temp 0 Animal fats tend to be solid at room temp more saturated 0 Plant oils tend to be liquid at room temp more kinks Func on o Absorb some vitamins 0 Energy storage Cellular amp Molecular Biology Chapter 3 Week 2 0 Protect organs and bones 0 Provide insulation Steroids Structure 0 4 ring carbon structure 0 Can be attached to various polar or nonpolar side groups ex lsoprenoid and hydroxyl like in cholesterol Func on 0 Cholesterol Vitamin D2 Cortisol Testosterone o All are steroids with very different functions 0 Cholesterol plays an especially important role in animal cell membranes Phospholipids Structure 0 Composed of three parts 0 Polar Head Group a phosphate and a choline o Glycerol Backbone o 2 Fatty Acid chains 0 Such structure makes the heads hydrophilic and the tails hydrophobic Func on o Primarily function as lipid bilayers membranes or micelles Micelles 0 Example soap 0 Form a circular shape with hydrophilic heads on the outside and hydrophobic tails on the inside 0 Tend to form from FAs or other simple amphipathic hydrocarbon chains Membranes Phospholipid Bilaver 0 Example cellular membrane 0 Forms when two sheets of phosphor lipids join together with the heads on the outside and tails on the inside Cellular amp Molecular Biology Chapter 3 Week 2 o Separates life from nonlife Artificial Membrane Experiments 0 Done to learn about the permeability of lipid membranes 0 Permeabilify a structure s tendency to allow a given substance to pass through 0 Question how rapidly can different solutes cross the membrane considering witch phospholipids are used and whether or not proteins or other molecules have been added 0 Discovery phospholipid bilayers are selectively permeable o Selective Permeability some substances can cross the membrane easily while others cannot What Can Cross a Phospholipid Bilayer 0 Small nonpolar molecules can pass the easiest ex 02 CO2 N2 0 Small uncharged polar molecules are next ex H20 glycerol 0 Large uncharged polar molecules can pass sometimes glucose sucrose 0 lons cannot cross Cl39 K Nat Factors that Affect Membrane Permeability o Bilayers with short unsaturated hydrocarbon tails have higher permeability o Easier to pass through because there is more room among the tails o Bilayers with long saturated hydrocarbon tails have lower permeability 0 Long straight tails mean the molecules will be more densely packed and harder to pass through 0 Cholesterol molecules within the membrane tend to reduce permeability 0 Temperature also affects the membrane 0 Low temps can decrease fluidity and even cause solidification Transport Passive Transport 0 Does not require an input of energy Diffusion o Involves a concentration gradient Cellular amp Molecular Biology Chapter 3 Week 2 0 Concentration Gradient difference in levels of solute on two sides of a membrane 0 Within a concentration gradient molecules and ions move from higher concentrations to lower concentrations until an equilibrium is reached Osmosis a type of diffusion 0 Water can move across lipid bilayers o Osmosis is the special type of diffusion that involves only water 0 Primarily occurs when the solute cannot cross the membrane so water moves to make the concentrations equal 0 Only occurs across selectively permeable membranes 0 Water moves from low solute concentrations to high solute concentrations 0 Hypertonic hypotonic and isotonic 0 Words that refer to the amount of solute in one solution compared to another 0 Hypertonic refers to the solution with more solute particles 0 Hypotonic refers to the solution with fewer solute particles 0 lsotonic when both solutions have the same amount of solute particles Membrane Proteins o Amphipathic proteins on top of or imbedded in the cell membrane to help facilitate different functions 0 May be as many proteins as phospholipids in membranes 0 Peripheral Membrane Protein a protein that lies only on the exterior or interior of the cell membrane hydrophilic o Integral Membrane Protein a protein that entirely passes through the membrane amphipathic transmembrane proteins Membrane Proteins as Transporters 0 Ion Channels 0 Allow ions usually unable to pass through the membrane to pass and follow the electrochemical gradient 0 Form a pore in the membrane Cellular amp Molecular Biology Chapter 3 Week 2 0 Each kind has specific structure 0 There can be many different kinds within one membrane 0 Water channels are known as aquaporin 0 Some channels are gated and require a certain signal or charge to open 0 Ion and molecule flow is regulated 0 Carrier Proteins o Membrane proteins that change shape during transportation 0 Interact strongly with cargo 0 Pumps 0 Pumps move molecules AGAINST the concentration gradient 0 Requires ATP or an electrochemical gradient energy sources 0 Pumps set up electrochemical gradients o The gradients make it possible for secondary active transport to happen by providing potential energy Active Transport and Vesicles o Exocyfosis vesicles containing certain molecules fuse to the membrane from the inside to release said molecules into the extracellular fluid Endocyfosis a vesicle buds into the cell to bring in Inside the Cell Prokarvotic Cells 0 Prokaryotes do NOT have a membranebound nucleus 0 Their DNA is kept in a single chromosome nucleoid o Prokaryotes DO almost always have a plasma membrane stiff cell wall and ribosomes Eukarvotic Cells 0 Considerably larger than prokaryotic cells 0 Size can make it difficult for molecules to diffuse across the entire cell 0 A problem partly solved by membranebound organelles Origin of Eukarvotic Cells 0 Endosymbiosis Theory cells engulfed other cells that became mitochondria and chloroplasts explains the double membranes surrounding these organelles Cellular amp Molecular Biology Chapter 3 Week 2 o Eukaryotes likely evolved form prokaryotes same 20 amino acids and nucleic acids as hereditary material Parts of Eukarvotic Cells Ribosomes 0 not technically considered organelles 0 Structure large and small subunits containing LOTS of protein molecules may be attached to ER or free in the cytoplasm 0 Function Synthesize proteins Nucleus 0 Structure double membrane nuclear envelope contains many openings nucleolus manufacturing RNA and ribosome subunits 0 Function stores hereditary information synthesizes RNA and ribosome parts Endoplasmic Reticulum 0 Structure single membrane branching sacs rough ER has ribosomes attached smooth ER does not part of the endomembrane system 0 Endomembrane System composed of the ER Golgi and lysosomes primary system for protein and lipid synthesis 0 Function Rough ER creates and processes proteins smooth ER creates and processes lipids Golgi Apparatus 0 Structure single membrane stack of flattened membrane sacs 0 Function protein lipid and carbohydrate processing Lysosomes 0 Structure single membrane contains protein pumps contain around 40 different digestive enzymes low pH found only in animal cells 0 Function digestion and recycling Protein Transport in the Cell 0 Most proteins are found in the nucleus peroxisomes mitochondria and chloroplasts Cellular amp Molecular Biology Chapter 3 Week 2 0 Proteins will have a target sequence that sends them to the appropriate organelles 0 Moving proteins in and out of the nucleus requires energy 0 Proteins that need to enter the nucleus will have a nuclear localization signal NLS that allows them in Transport and the Endomembrane System 0 The endomembrane system ER golgi and lysosomes manufactures and ships proteins 0 PulseChase experiments have been used to track protein movement 0 Label proteins with radioactive amino acids 0 Wash away excess amino acid leaving labeled proteins 0 Follow the tagged proteins to find their path 0 Pulsechase found that proteins move from Rough ER to Golgi to vesicles The Signal Hypothesis 0 Proteins headed for the endomembrane system have a signal sequence that sends them in the right direction 20 amino acids long 0 Protein synthesis begins on a free ribosome 0 Signal sequence sends the building protein to the appropriate location on the rough ER thanks to a signal recognition particle SRP 0 Protein synthesis continues into the rough ER 0 When synthesis is complete the signal sequence is removed and the ribosome and protein detach from the lumen of the rough ER 0 After the ER proteins move to the golgi in vesicles 0 Vesicle buds off the ER and travels to the golgi where it binds on the cis side and dumps its contents o If the protein is to stay within the ER it will have a special retention tag 0 Once proteins reach the golgi they are tagged sorted and sent in vesicles and delivered to their specific sites Delivery to Lysosomes o Autophagy the lysosome binds to a damaged organelle to be recycled Cellular amp Molecular Biology Chapter 3 Week 2 o Phagocytosis the phagosome is engulfed by the cell and sent to the lysosome to extract necessary molecules 0 ReceptorMeditated Endocytosis macromolecules bind to receptors and are engulfed by the cell the vesicle formed fuses with an early endosome and the pH lowers after receiving digestive enzymes the endosome becomes a lysosome Cvtoskeleton o The cytoskeleton is composed of protein fibers and gives the cell shape and stability Also aids in movement of the cell and materials within the cell Very helpful with organization of the cell 0 Microfilaments made of actin resist tension move cells divide cells move organelles o Microtubules made of alpha and beta tubulin dimers resist compression move cells cilia and flagella move chromosomes assist cell division move organelles tracks for intracellular transport 0 Intermediate Filaments make of keratin among other things resist tension and anchor some organelles
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