Biol 130 First Midterm Notes

Unit 1 – Introduction to the Cell Robert Hooke – built the first microscope (30x magnification); viewed slices of cork called cellula (little rooms). Antoni Van Leeuwenhoek – worked with glass huge improvement in quality of lenses nearly 300x magnification became possible first to observe: * single-celled organisms â€Å"animalcules† * protists from pond water * bacteria from his mouth – â€Å"father of microbiology† * blood cells * banded pattern in muscle cells * sperm from †¦ 1830s – Compound microscope – improved magnification and resolution and allowed visualization of objects less than 1 ? . 1000-1500x magnification Beginning of Cell Theory Robert Brown (botanist) – noticed that every plant cell contained a round structure called it ‘kernel’-nucleus Matthias Schleiden (another botanist) – all plant tissues are composed of cells; embryonic plant always arose from a single cell Theodor Schwann (zoologist) – similar observations in animal cells; recognition of structural similarities btw plants and animals! * Cell Theory formulated by Schwann Cell Theory 1. all organisms consist of one or more cells 2. he cell is the basic unit of structure for all organisms 3. added 20 years later: all cells arise only from pre-existing cells fact (scientific) – an attempt to state our best current understanding, based on observations and experiments(valid only until revised or replaced) Steps in Scientific Method 1. make observations 2. use inductive reasoning to develop tentative explanation (hypothesis) 3. make predictions based on your hypothesis 4. make further observations or design and carry out controlled experiments to test your hypothesis 5. nterpret your results to see if they support your hypothesis Theory – a hypothesis that has been tested critically under many different conditions andby many different investigators . using a variety of different approa ches. By the time an explanation is regarded as a theory it is widely accepted by most scientists in the cell * the â€Å"solid ground† of science: evolution, germ theory, cell theory *If a theory is thoroughly tested and confirmed over many years by such large numbers of investigators that there is no doubt of its validity †¦ it may eventually be regarded as a law.Gravity, laws of thermodynamics, laws that govern behaviour of gases ‘Strands’ of Cell Biology 13 cytology 1600s Hooke looks at cork Leeuwenhoek looks at lots of things 1800s Brown notes nuclei bio-chemistry synthesis of urea in lab fermentation done by cells! glycolysis Krebs cycle every cell comes from a cell Schleiden & Schwann formulate cell theory electron microscopy stains & dyes genetics Mendel, pea plants DNA chromosomes chromosome theory 1930s DNA double helix DNA sequencing Dolly the sheep! nano-technology! genetic code Light Microscopy:Bright field – light passes through specimen , contrast is slow and specimen is hard to see Phase contrast – contrast is changed by changing light in microscope DIC – uses optical modifications to change contrast between cell and background – due to density differential Staining – stain used to visualize cell and components, only some stains can be used on living cells 14 bright field phase contrast DIC unstained (sperm cells) stained blood cells tissue – small intestine Fluorescent Microscopy – fluorescent dyes bind to protein or DNA to see where they are in cells – tracks movement Electron Microscopy(Scanning & Transmission):SEM – scan surface of specimen to form image by detecting electrons from outer surface. Good surface images TEM – forms image from electrons passing through specimen therefore fine details of internal organelles 16 SEM TEM Basic Properties of Cells: * are highly complex and organized * atoms molecules macromolecules (organelles ) enclosed in plasma membrane * use the same ‘genetic program’ Central Dogma * DNA RNA protein * are capable of reproducing themselves * must first replicate genetic material acquire and use energy (â€Å"bioenergetics†) and carry out a variety of chemical reactions (â€Å"cellular metabolism†) * have many processes that are highly conserved at the molecular level * membrane structure, genetic code, ATP synthesizing enzymes, actin filaments, eukaryotic flagella, †¦ * engage in many mechanical activities * transport of materials in/out, within * assembly and disassembly of structures * motility / movement * respond to environmental signals * move away or toward stimuli * respond to hormones, growth factors, etc * are capable of self-regulationâ€Å"homeostasis† most evident when control systems break down; defects in DNA replication, DNA repair, cell cycle control Two Classes of Cells – karyon = nucleus Prokaryotic Cells: lack of nucleus, NO CYTOSKELET ON(very small), membrane bound organelles. Mostly unicellular. Bacteria and Archaea. Single, circular strand of DNA(fewer proteins). Cell wall in addition to PM 1-10 uM in diameter. 2 types: 1. Eubacteria – all have cells walls except for mycoplasma(resistant to antibiotics that target cell wall synthesis). Mycoplasma(smallest) Cyanobacteria (largest and most complex). 2.Archaeabacteria – all have cell walls and are known as extermophiles, occupy broad range of habitats, halophiles=salty, acidophiles=acid, thermophiles= hot. Eukaryotic Cells: 10x larger than prokaryotic cells, membrane bound nucleus/organelles. More complex DNA due to histones/proteins. 4 groups: 1. Protists- very diverse group – mostly single cells; algae, water molds, slime molds, protozoa 2. Fungi – single cell(yeast) or multi-cellular(mushrooms) and have cell walls. Heterotrophs; depend on external source of organic compounds 3. Plant cells- multi-cellular and have cell walls. . Anima ls- multi-cellular, no cell walls and are heterotrophs Cytoplasm – everything between plasma membrane and nuclear membrane, includes all membrane-bound organelles (except nucleus) Cytosol – only fluid component Endomembrane system – internal membranes that are either in direct contact or connected via transfer of vesicles (sacs of membrane). including: nuclear envelope / membrane, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles Nucleus – stores genetic information Endomembrane System – creates intracellular compartments with different functions.Endoplasmic reticulum (ER; rough, smooth), Golgi apparatus, lysosomes. Mitochondria – generate energy to power the cell Chloroplasts – capture energy from sunlight, convert to carbohydrate Cytoskeleton – regulates cell shape, movements of materials within the cell, movement of the cell itself Flow of Traffic in EMS – Rough ER: synthesis of proteins for – ex port (secretion) – insertion into membranes – lysosomes Golgi apparatus: collection, packaging & distribution Lysosomes * cell ‘stomachs’ have enzymes that can digest †¦ * all 4 classes of biological macromolecules worn-out organelles (mitochondria replaced every 10 days) * material brought into cell by phagocytosis Phagocytosis – plasma membrane engulfs smaller molecule and then called phagosome. Lysosome takes it in and digests, small particles are releases into the cytoplasm. Autophagy – lysosome digests a damaged organelle, small particles are released into cytosol. mitochondria (all eukaryotic cells) and chloroplasts (plant cells): * contain DNA that encodes some (but not all) of their own proteins * have unusual double layers of membranesOrigin of Eukaryotic Cells: Endosymbiont Theory * once believed that eukaryotes evolved gradually, organelles becoming more and more complex * now accepted that early eukaryotes originated as preda tors * certain organelles (mitochondria, chloroplasts) evolved from smaller prokaryotes engulfed by larger cell * later chloroplasts and the ability to perform photosynthesis Symbiosis – Mutual Advantage advantage to host cell: * aerobic respiration (aerobic bacteria mitochondria) * photosynthesis (cyanobacteria chloroplasts) advantage to bacteria: * protected environment supply of carbon compounds from host cell’s other prey Evidence Supporting Endosymbiont Theory mitochondria and chloroplasts †¦ * are similar size to bacteria, reproduced by fission like bacteria * have double membranes, consistent with engulfing mechanism * have their own ribosomes, which resemble those of prokaryotes rather than eukaryotes in terms of size, composition and sensitivity to antibiotics * have their own genomes, which are organized like those of bacteria last but not least: * are genetically similar to proposed ‘parent’ bacteria rather than ukaryotic cells Cytoskeleton important in: * cell shape * cell motility * movement / position of organelles * movement of materials within cell * movement of chromosomes during mitosis Cytoplasm in a living cell is never static * cytoskeleton is constantly being taken apart and rebuilt * organelles and vesicles are racing back and forth * can cross the cell in ~ 1 second * unattached proteins moving randomly, but rapidly * can visit every corner of the cell within a few seconds * contents of cytosol are in constant thermal motionCommon to all cells: * selectively permeable plasma membrane * genetic code; mechanism of transcription and translation * ATP for the transfer of energy and metabolic pathways Model Organisms 45 Unit 2a – Intro to Cellular Chemistry Most Common Elements in Living Organisms: * C H O N – make up 96% – also P and S are common too * Exist as complex macromolecules and simpler forms like water and carbon dioxide nucleus – dense core in centre, consists of protons and neutrons electrons – continually orbit the nucleus # of protons – defining feature of an element = atomic number – # protons + # neutrons = mass of an atom = mass number – by default, an atom is ‘neutral’, with # protons = # electrons – electrons influence reactivity of an atom †¦ Atomic mass = atomic number + # of neutrons (electrons are neglected because mass is so small) Isotopes – same number of protons but different number of neutrons in the same element Anion – gain electron and are negatively charged Cation – lose electron and are positively chargedOutermost ‘valence’ shell influences an atom’s reactivity * electrons in outermost shell valence electrons * unpaired valance electrons determine the number of bonds an atom can make * atoms with filled valance shell = most stable, atoms that are closest to filling are most reactive * elements abundant in organisms have at least one u npaired valence electron Some Definitions: covalent bonds – two or more atoms share pairs of valence electrons * strong bonds of biological systems non-covalent bonds, including * ionic bonds * hydrogen bonds (H-bonds) * hydrophobic interactions olecule – group of atoms held together by energy in a stable association compound – molecule composed of two or more different types of atoms Types of Covalent Bonds * electrons shared ‘equally’ * non-polar covalent bond * can be single (like H2), double (O2) or even triple, depending on number of electrons shared * electrons not shared equally * polar covalent bond * one of the atoms has a stronger pull on the electrons than the other * pull on electrons = electronegativity * water is the most abundant molecule in biological organisms * human body is ~70% water water as a solvent can dissolve more types of molecules than other molecule known * the polarity of water is key to its role in biology hydrogen bon ding – electrical attraction between electronegative atom and partial positive of hydrogen hydrophobic – no affinity for water – â€Å"water fearing† hydrophilic – affinity for water – â€Å"water loving† Acid-base Reaction substance that gives up (donates) protons acid (increases [H+] in solution) substance that accepts protons base (decreases [H+] in solution) chemical reaction that involves transfer of protons acid-base reaction * most olecules act as either an acid or a base * water can be both (both gives up and accepts protons) weak acid: very few molecules dissociated (acetic acid, water) strong acid: readily gives up protons (hydrochloric acid) when pH = pKa species is 50% ionized Carbon is the most important element in biology carbon atoms give biomolecules their shape but other atoms attached to carbons determine their reactivity * critical H, N, O containing attachments called functional groups *learn orgo functional groups for this courseMacromolecules * large, organized molecules that are typically created by polymerization * biological macromolecules (biomolecules) provide the structure and carry out the activities of a cell 4 groups: * carbohydrates(polysaccharides) * lipids(fats) * proteins * nucleic acids * monomers of groups are different – chemical reactions used to make the chains are similar Overview of Macromolecules 3 Proteins – more functions than any other group of macromolecule * enzymes – catalysis; accelerate chemical reactions transport – through cell membranes, in circulation * support – cytoskeleton, fibres of cartilage, hair, nails * signalling / regulatory – hormones, membrane proteins, intracellular messengers * movement- of the cell itself – contractile proteins, flagella – within the cell – motor proteins * defense – antibodies, complement proteins Proteins are Polymers * amino acids are connected in linear polymers of a specific sequence * 20 genetically encoded amino acid monomers to pick from * string of amino acids (AAs) = peptide or polypeptide polypeptide folded and coiled into a specific conformation = protein * sometimes 2 or more peptide chains (subunits) combine to form mature, functional protein Amino Acid Structure AAs are ionized under physiological conditions ionization increases solubililty, facilitates interactions with each other and other solutes, increases reactivity (zwitterions) 7 non-ionized ionized R group unique to each AA oxygens tend to pull electrons away, making it easy to lose proton gains a proton Amino Acid Side Chains – R Groups: * nonpolar – hydrophobic R groups no charged or electronegative atoms to form H bonds * insoluble in water * R groups bury themselves with the peptide chain to ‘hide’ from water * polar side chains – soluble in water * uncharged – but partial charges can form H-bonds * charged – gr oups containing acids or bases – highly soluble in water AA are linked together by covalent peptide bonds: carbon from carboxyl group is linked to N terminus of amino group. R groups and central C’s do not participate in the bond. Condensation Reaction – making the chain Hydrolysis – breaking the chain Polypeptide chain: side chains extend from peptide-bonded backbone * chain is flexible – can rotate at single bonds on either side of peptide bonds * so side chains are not all projecting to one side! * chains can be from 2-3 to thousands of AAs in length * backbone is directional, convention is to number AA ‘residues’ starting at N terminus this is the primary sequence Sickle Cell Anemia – disease in which red blood cells are abnormally shaped. Caused by single point mutation which results in substitution of single amino acid in one chain of hemoglobin protein Protein Structure:Primary Structure – unique sequence of amino acids Secondary Structure – Folding into elements of structure, hydrogen bonding between amino acids(R groups not involved). 2 shapes: alpha helix and beta pleated sheet(parallel and antiparallel). * learn more Tertiary Structure- interactions of elements of secondary structure forming a global fold, folded into these unique shapes by ionic bonds (electrostatic),hydrogen bonds, disulphide bridges, hydrophobic interaction, van der waals – dipole-dipole(all non-covalent except for S-S). Order of amino acids determines final shape.Maintain globular shape even if very weak. Quaternary Structure – more than one polypeptide chain put together to form the final functional protein, linked by covalent and non-covalent interactions. Protein Domain – segment of polypeptide that forms a compact, stable and independently folding structure. Often the building blocks for larger, more complex proteins. Disulfide bonds * covalent stabilization of protein structure found i n secreted proteins (destined for a more hostile extracellular environment) * formed in ER (oxidizing environment)Once folded, do proteins ever unfold? changes in physical or chemical conditions (pH, salt concentration, temperature) disruption of H-bonds, ionic bonds, disulfide bridges, etc that maintain the protein’s shape protein ‘denatures’ or unfolds Possible to renature Do proteins ever fold incorrectly? any mutation that leads to a missing or incorrect amino acid can lead to incorrectly folded protein WHY 32 Possible outcomes: mutation – leads to incorrectly folded protein * protein never functions properly loss of function protein folds properly at first but unfolds under certain conditions eventually loss of function * protein misfolds AND is deposited in insoluble aggregates within cell * loss of function and disruption of other aspects of cell activity * many human diseases now known to be associated with misfolded proteins . Alzheimers, cystic f ibrosis, type II diabetes, retinitis pigmentosa, Parkinsons, Creutzfeldt-Jakob, some cancers *read about catalysts and enzymes in Janelle’s notes, page 8-9 Nucleic Acids: Information Polymers * deoxy ribo nucleic acid (DNA) sequence of subunits in DNA polymer directs RNA synthesis * ribo nucleic acid (RNA) * RNA directs ordering of AAs in a peptide chain * information stored as DNA sequences enables living organisms to pass on hereditary information * also allows each cell to pass on hereditary information to the next generation of cells Monomers of Nucleic Acids: Deoxyribo nucleotides – phosphate + deoxyribose + nitrogenous base(A,C, G, or T) Ribo nucleotides – phosphate + ribose + base (A,C,G, or U) Nucleic acids are linear (unbranched) polymers of nucleotides * each nucleotide consists of three parts: * a nitrogenous base a (5-carbon) pentose sugar * a phosphate group Purines = A&GPyramidines= C,T and U * Ribose + base = nucleoside * Ribose + base + phosphate = nucleotide Functions of Nucleotides * monomeric units of RNA and DNA * important signal molecules within cells * cyclic adenosine monophosphate (cAMP) * important agents in energy transfer reactions * cleave off phosphate group to release stored energy * act as coenzymes – organic non-protein molecules required for enzyme function * usually adenine-containing nucleotides combined with B vitamins 8 condensation reaction 5’ end – beginning of chain. Chains always built 5’ 3’.Look at above example phosphate group is 5’ 3’ end – where new bases can be added Polymerization rxn’s are endergonic: * making phosphodiester bonds requires energy * energy comes from addition of 2 phosphate groups. * Activated nucleotides = nucleotide triphophates The most famous phosphorylated nucleotide †¦ adenosine triphosphate = ATP 11 adenine 4’ 5’ 5 6 1 2 3 9 4 8 7 1’ 3’ 2’ O P CH2 O O O– P O O O– P O –O O– OH OH O NH2 N N N N ribose adenine + ribose (= adenosine) Secondary Structure of DNA: two strands of DNA align in ‘antiparallel’ arrangement with bases facing inwards. H-bonds form between bases. P P P P P P P P C C G G AA T T P O O O O O O O O O O O C G OH P Note: 3 H-bonds between C and G, 2 between A and T. Only space in the sugar phosphate backbone is for Pyramidine and Purine to bond together. Features of DNA Double Helix * stabilized by H-bonds between complementary bases and hydrophobic interactions between bases * entire molecule water-soluble because charged phosphates backbone face outward * major and minor grooves are significant in regulation of gene transcription Higher Order DNA Structure: DNA molecules can adopt higher order structure – Allows for compact packaging and strict regulation of gene expression RNA vs DNA like DNA: sugar-phosphate backbone covalently linked by phosphodiester bonds * 4 different bases unl ike DNA: * uracil (U) instead of thymine (T) * pairing is A-U, C-G * sugar is ribose instead of deoxyribose * hydroxyl group makes ribose much more reactive * RNA is much less stable than DNA Secondary Structure of RNA: like DNA: * H-bonds form between complementary base pairs unlike DNA: * most of the time, this base-pairing is between bases on the same strand * leads to formation of ‘stem and loop’ structures with single-stranded regions and double-stranded antiparallel regions * H-bonding is spontaneous, stabilizes the molecule final molecule is single-stranded * Complex folds can result in some RNA having catalytic activity Carbohydrates * Group of molecules that contain carbon, hydrogen and oxygen in a 1:2:1 ratio: (CH2O)n Only monomers are in this ratio, oligomers you lose water * Monomer=monosaccharide * Dimer=disaccharide * Trimer=trisaccharide/oligosaccharide Types: 1. Monosaccharides – simple sugars 2. Oligosaccharides – small chains (oligo=few) * Attached to proteins – glycoproteins * Attached to lipids – glycolipids 3. Polysaccharides – very long sugar chains Typical Structural Features of Sugar Monomers: carbonyl group (either ketone or aldehyde) * lots of -OH groups * vary in length of carbon skeleton (C3, C5, C6, †¦) – triose, pentose, hexose * isomeric forms (glucose, fructose, galactose) * identical chemical groups arranged differently * monosaccharides often form rings in solution Isomers – same atoms, different arrangements structural isomer – identical groups but bonded to different carbons stereo (optical) isomer – identical groups bonded to same carbons but in different orientations sixteen different hexose structures possible, all with formula C6H12O6 C OH C OH OH H C OH H HO C H C O H C OH H H C OH H C OH H C OH H HO C H H C OH H structural isomer stereo- isomer H C C O HO C H H C OH H C OH H HO C H H C OH H fructose glucose galactose *arrangement of hydrox yl groups make a big difference in biological function Disaccharide – 2 sugar monomer: * glucose + fructose = sucrose(table sugar) * glucose + lactose = lactose * glucose + glucose = maltose Formation of disaccharides by condensation reactions. monomers are linked when C1 of one monosaccharide binds to a C on another – often C4 geometry of bond different depending on hether OH group of C1 is in ? or ? position which C of other sugar is involved in linkage 7 C1, ? C4 ?-glucose ?-glucose maltose, ? -1,4 glycosidic bond ?-galactose ?-glucose lactose, ? -1,4 glycosidic bond (glucose has flipped over) C1, ? C4 Polymerization to build Polysaccharides starch both are storage forms for energy starch – plants; glycogen – animals both consist of ? -glucose monomers linked by ? -1,4 bonds both coil into a helix (due to geometry of linkages) starch is mixture of unbranched amylose and branched amylopectin glycogen is highly branched lycogen Structural Polysaccharide in Plants: Cellulose 9 polymer of ? -glucose, joined by ? -1,4 linkages each glucose is flipped relative to adjacent ones allows for H-bonding between adjacent strands extremely stable most abundant organic molecule on earth parallel strands joined by H-bonds Structural Polysaccharide in Animals: Chitin a component of cell walls of fungi, exoskeletons of arthropods (insects, crustaceans), radulas of molluscs, beaks of cephalopods second most abundant organic molecule on earth like cellulose, joined by ? 1,4 linkages but rather than glucose, monomer is N-acetylglucosamine like cellulose, also strengthened by H-bonding btw strands 10 Structural Polysaccharide in Bacteria: Peptidoglycan component of bacterial cell walls the most complex CHO so far! two different alternating monomers linked by ? -1,4 bonds chain of amino acids attached to one of the sugars – peptide bonds instead of H-bonds (stronger) Significance of how monosaccharides are linked: * ? -1-4 linkages of starch and glycogen readily hydrolyzed * ? 1-4 linkages in structural polysaccharides very resistant to enzymatic degradation For example: enzymes that digest cellulose (cellulase) produced only by certain classes of bacteria, fungi and protozoa Difference between glycosidic bonds from peptide and phosphodiester bonds: in common: * condensation reactions different: * peptide and phosphodiester bonds always occur at the same position within their monomers * each sugar monomer has several hydroxyl groups, and geometry of glycosidic bonds is highly variable Functions of Carbohydrates: Structural: * cellulose, chitin and peptidoglycanCell-cell recognition: * membrane proteins covalently bonded to oligosaccharides Energy Storage * ? -1,4 –linkages of starch and glycogen are readily hydrolyzed to release stored energy Lipids * group of carbon-containing compounds that are largely non-polar / hydrophobic * significant proportion of a given lipid molecule is hydrocarbon * the only macromolecul e that is not a polymer major groups of lipids in cells: * fats / oils – energy storage * sterols * cholesterol – membrane component * steroids – hormones * * Phospholipids * major component of biological membranesFats (Triacylglycerols, Triglycerides) * form that fat is stores in apidose tissie * glycerol with 3 fatty acids attached * the link between glycerol and fatty acid = ester bond: condenstation rxn (liberates water) * hydrophobic * fatty acid(carboxylic acid with long hydrocarbon tail) Saturated Fatty Acid – have maximum number of hydrogen atoms on each atom; straight and flexible because of only single bonds Unsaturated Fatty Acid – contain at least 1 double bond. The double bond is rigid and creates a kink in the chain. The rest of the chain however is free to rotate about C-C bonds.Cis – H on the same side of double bond; don’t solidify easily Trans – H on the opposite side of the double bond. Hydrogenation – making a fat saturated/more solid at room temperature to improve shelf life therefore less healthy. Sterols – group of steroids based on cholesterol(important component of cell membrane) Phospholipids : * 1 glycerol, 2 fatty acids, 1 phosphate group(polar head group) * Amphipathic = hydrophilic and hydrophilic regions – their most important feature with respect to biology Micelles – sphere with hydrophobic tails ‘hiding’ in centre . Can only occur with relatively short tails Lipid Bilayer:Universal Structure for all Biological Membranes composition varies with: type of organism (prokaryote vs animal vs plant vs †¦) type of cell within organism (muscle, liver, sperm, egg, †¦) type of membrane within cell (plasma membrane, Golgi, ER) inner versus outer layer different patches or ‘domains’ within a particular membrane Fig 11-4 two closely apposed sheets of lipids, studded with proteins lipids serve as permeability barrier protei ns perform most of the functions carbohydrates (sugars) attached to protein and lipids in a non-random manner *all membrane lipids are amphipathic Lipid bilayers form spontaneously: hydrophobic molecules would exclude water, clustering together to minimize energy cost of organizing water molecules * form large droplets or surface film * amphipathic molecules are subject to conflicting forces * solved by formation of bilayer * energetically most favourable stable, spontaneous * lipid bilayers are †¦ * closed – no free edges * self-sealing * important feature for cell fusion, budding, locomotion Fluid Mosaic Model * The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane.That means the membrane is not solid, but more like a ‘fluid'. * phospholipids are constantly moving spinning in place; travelling laterally within ‘leaflet’ * phospholipids are occasionally ‘flipped’ to the opposite leaflet during membrane synthesis but they rarely ‘flop’ back * even proteins cruise slowly through the membrane! Membrane fluidity – how easily lipid molecules move within a membrane leaflet Alignment of phospholipid tails * tightly packed tails membrane more viscous, less fluid * freely moving tails higher fluidity What aspects of phospholipid composition influence this? length of fatty acids * from 14-24 carbons, 18-20 carbons most common * degree of saturation of fatty acids # double bonds * typically one saturated fatty acid and one with one or more double bonds Cholesterol: * under physiological conditions, cholesterol makes membrane stiffer – less fluid * cholesterol can make up to 50% of plasma membrane lipid in some animal cells Regulation of Membrane Fluidity: – fluid state must be maintained for normal cell function strategies for maintaining membrane fluidity: * chang e composition of membranes * alter phospholipids desaturate fatty acids (to deal with cold) eg cold water vs warm water fish * change length of FA chains (yeast, bacteria) * adjust amounts of cholesterol (animals) these mechanisms have been demonstrated in: * pond fish dealing with dramatic day / night temp differences * cold-resistant plants * extremophile bacteria living in hot springs * winter wheat preparing for autumn ^ polyunsaturated FAs * sperm reduce their cholesterol just before fertilization †¦ Functions of Lipids: * storage of chemical energy * signal molecules * vitamins * wax coating on leaves * biological membranes

Oscar Wilde was the fashion critic and editor of the magazine the Essay

Oscar Wilde was the fashion critic and editor of the magazine the woman's world(1887-1889). Analize this contribution to fashi - Essay Example e, which is not the case because Oscar Wilde did not completely erase the fashion issue but rather refined it by adding more content, because evidently, he only reduced the fashion section from four to two. Prior to Wilde reducing past issues in the magazine and adding up empowering content, Wilde also incorporated women authors who greatly contributed in writing the magazine (Tusan 2005, P.68). Generally, the aim of Oscar Wilde’s transformation was to create a new generation of modern woman who did not have to sit back and watch the men rule over, but instead women who embraced empowerment to battle up with the man in running the businesses of the world through education and other channels of knowledge exposure (Fortunato 2012, p. 34). Nevertheless, Wilde’s effort of empowering the 18th century woman through the â€Å"woman’s world† magazine did not send a positive note to everyone. Though majority never came up to criticize the content in the magazine, t he artists in various fields emerged to criticize the article. Surprisingly, women artists were among the critics who criticized Wilde’s view on fashion. Most of the critics had no issue with women empowerment content because what disturbed them the most was the editor’s negative stand on fashion. The fashion issue arose during transformation of the magazine where the editor reduced fashion content because he believed that it had no much relevance in the woman’s world as men usually perceive. Oscar Wilde’s stand on fashion irrelevance caught the attention of artists like Mary Eliza Haweis, an editor who authorized in connection with fashion, cosmetics, and decoration (Fortunato 2012, p. 37). She argued that fashion should not be side kicked because fashion was an essential form of art that she claims... Historically, the 18th century was an era of male dominance because men viewed women as inferior beings. The reason why women were inferior is that they could not participate in the development of the world’s progress. This was evident through vast arts that portrayed at the time that included Sydney Grundy’s play â€Å"the glass of fashion† that was produced in 1883. Another evidence of women's inferiority in the 18th century portrayed through the manner in which the â€Å"lady’s world† magazine was edited before Oscar Wilde came took over the editorship. Things changed when Oscar Wilde joined the publishing company as the editor of the magazine. The content and the appearance of the magazine never made much sense to him and that is why he transformed every bit of the magazine including its name Oscar Wilde claims that the magazine had no motivational content that concerned women because content mostly contained gossips, music, art, fashion, and ot her common issues. Oscar Wilde could be named as a renowned female reformist who undertook all the challenges in the 18th century literature field to empower the woman into modernity through intense education shunning the old fashion perception pinned on women. This did not mean that Wilde did not have any ideas in fashion and art, nor did he ignore them, because history claims that he was a frequent attended to art galleries and theater.

Summary for chapters 3,4,5 from (The Economics of women,men,and work) Assignment

Summary for chapters 3,4,5 from (The Economics of women,men,and work) - Assignment Example In this book, Chapter Three is all about family as an economic unit where the lesson tries to throw light on the changes that occurs after the marriage in the couple’s life and the changing family structure. The chapter tries to focus on the implications that these changes have on the market outcomes and new data on the allocation on the housework between the men and the women. The family is such a unit where the adult members are held responsible to make informed as well as rational decisions which will help to maximize the well being of the family. It has been frequently the case that women are more productive than men in home and men are more productive in the market. The main reason behind this is that both men and women are traditionally raised with different expectations. Moreover both the sex receives different education and training. It has also been found that women are basically discriminated in the labor market and it is because of this discrimination that the marke t earnings of the women are lowered as compared to men. The chapter tries to explain the importance of both spouses being employed in the family. If one of the spouses becomes unemployed then the earning of the other would be beneficial in these regards to cover at least the household expenses. After the marriage the complete picture changes and the change is found in the lives of the coupled family. The most affected factor is the income of the family. There is increase in the expenses of the family and men are held responsible for it. Employed women show less interest in the household work and are also characterized to be more educated then men. Allocation of time among the households and the labor market hold optimum importance in Chapter Four. In this chapter, the author tries to thoroughly review the trends in the labor supply of women and men to the market. The lesson wants to focus on the participation of

Power, Desire, Difference Essay Example | Topics and Well Written Essays - 2500 words

Power, Desire, Difference - Essay Example The specific psychical concerns of the symbolic may have been played down in some feminist writing, political issues have been played down (and deeply confused with psychical ones) in recent critiques of essentialism. The thing is, the challenge to Lacan is often read as, or reduced to, the challenge to patriarchal structures of language and phallogocentrism, which of course in part it is. Lacan's theory also covers the psychical organization, the argument that the symbolic is the condition of sanity; it is not purely about the patriarchal order of language (Chodorow: 1998:167). It should become evident that this facet of Lacan's theory has also received attention in French difference feminisms, especially from Irigaray. Moreover, it is only when this aspect of Lacan's theory is taken into account that the British feminist defence of him makes any sense. The symbolic's patriarchal nature relies on the interlocking functions of the symbolic father, and the notorious phallus. Lacan says the symbolic father intervenes in the imaginary ties between mother and child (Withford: 1986). For Lacan the actual father matters infinitely less than his structural, symbolic position as an intervening third party. In the imagination, the father's place is similar to the occupied by language, in that language intervenes in the imaginary dyad as the symbolic words that rupture the threads of phantasy that hold lack at bay and the illusion of union in place. To borrow the vocabulary of mainstream psychoanalysis for a moment, this intervention is critical to the process of psychical differentiation, to the subject's differentiating itself from others; and this is one reason why sanity relies on the symbolic (Withford:1988). How changing the sex of either the intervening third party or the primary care-giver, or the actual father's social spot, would af fect the process of differentiation is another matter; but real changes in either parenting models or the social position of women and men must have consequences for the symbolic. The phallus is the mark of need, and diversity in general and sexual difference in particular. As the mark of need, it pertains to the fact that the subject is not complete unto itself. It is here that the symbolic father and phallus connect; the former breaks up the illusion of unity, the latter represent that break (Withford: 1986:7). As the mark of difference in general, the phallus is allied with the logos, with the principle that the identification of difference is the condition of logic and language alike. That is to say, thinking as such requires difference. This brings to a critical Lacanian claim that sexual difference is the crucial one in being able to speak, thus think; and, mutatis mutandis, that speaking is critical to sexual difference. The visual recognition of sexual difference is a channel connecting the heterogeneous experience of the feeling, sensing body to something that is strange to it: the differential structure of language; in turn, that language allows it n ame the difference. In short, Irigaray, like Mitchell, may have a clinical issue in mind: the idea that the phallus is represented by the penis implies, according

Coca Cola and IT Logistics Assignment Example | Topics and Well Written Essays - 750 words

Coca Cola and IT Logistics - Assignment Example Supply Chain forms the backbone of logistics. Automation makes the supply chain extremely efficient. All kinds of transportation delays are removed. Transportation delays occur due to the presence of manual system in the different stages of supply chain. They cause delay due to the inherent limitations of physical labor. The positive consequence of automation in supply chain is that the concerned parties can get their supply on time. Moreover, companies can also reduce their cost of holding and carriage cost. Up to date inventory data can help prevent conditions of stock completion. The stocks can always be available on time. It will reduce customer waiting time. A customer can easily find out the product of his necessity. It also facilitates reduction of overhead costs like cost of labor, and inventory (McFarlene, n.d.). In this context a very appropriate automation technology used is the RFID Technology. The RFID (Radio Frequency Identification) technology plays a very important role in the supply chain distribution of Coca Cola. The primary application of this technology is in bar code reading. Bar codes have to be read to ascertain accurate information regarding the product such as price, manufacturing date, and date of expiry. This information’s are very important for the customers. Another sphere of application of this technology is in the form of what is called smart shelves in the retail stores.

Fulfillment of the prophecies and Promises of a new Temple in Ezekiel Research Paper

Fulfillment of the prophecies and Promises of a new Temple in Ezekiel 40-48 - Research Paper Example To understand whether the prophecies are fulfilled, one has to relate these prophecies to the language in which the text is rendered, the relationship between the New Temple and the Restoration of Israel, the literal animal sacrifices in the Kingdom Age, the promise of a New Temple and the Coming of Christ, and the development and portrayal of the idea of the New Temple in the New Testament. Scholars view the fulfillment of the prophecies and promises from different angles. While many are of the opinion that these prophecies are merely symbolic, others believe that these prophecies have a literal context, and these will be fulfilled in the future. While the former group considers the prophecies as a symbolic representation of idealistic views, the latter argues that Ezekiel meant the temple to be literally constructed and consecrated for worship. The debates notwithstanding, the fact remains that Ezekiel’s proposition of the temple is founded on literal premises, rather than f igurative allusions, by way of its reliance on earthly language, understanding of historical events, rituals to be performed in the temple, the expected Second Coming of Christ and the development and portrayal of the ideas of the New Temple in the New Testament. ... Besides, he refers to priests donning linen robes and performing rituals in the New Temple. Scholars such as Feinberg, Gray, Kelly, Pentacost and Scofield maintain that all these allusions tend to validate that Ezekiel meant the temple to be literal rather than symbolic or figurative. Ezekiel 40-48 is based on the hermeneutical assumptions and manifests the same exegetical techniques. Most of the terms used are Christian and the â€Å"allusions to Ezekiel in the book of revelation are based on the Hebrew text†1 On another level, the contents of the book promote ritual codes of behavior that protect the community from the threat of impurity and set the whole ritual system inside the impregnable fortress of the new community. It is not only in the content that the prophet’s background becomes evident but also in his constant and striking use of cultic language. Many scholars believe that Ezekiel’s text â€Å"uses for preference the priestly/cultic language of defi lement†2 Even when the sins illustrated in the work are not in themselves ritual, Ezekiel frequently applies cultic language to explain them. Ezekiel’s inventive reaction to the crisis was to refresh the old institution of the temple by expanding its symbolic language further than the strictly priestly sphere and taking it into a level where the literal meaning would become evident through his allusions about the ordinary materials such as common wood or stones (Ezekiel 40:16, 22, 26, 34, 37, 42, 41:16-22, 25-26). This is in utter contrast with John’s version, which speaks of a heavenly city made of â€Å"gold, pearls and rare gemstones† (Revelation 21: 16- 21). Thus, by the deployment

Evaluating Eligibility Rules Essay Example for Free

Evaluating Eligibility Rules Essay In determining which eligibility rules can be associated with the Lakeland Police Department, it the objectives of such institution must be looked into before going through the details in which such rules apply. The institution provides public and security measures to the community it holds. They promote the welfare of the people around them under the parameters mandated by the law in the creation of such institution. With this, the eligibility rules that the agency uses revolves around the (1) eligibility by administrative rule and regulation, (2) eligibility by administrative discretion and (3) eligibility by judicial decision. To understand whether the eligibility rules advocated by the agency promotes a stigmatization, trade-offs or off-target benefits, each rule must be looked into in accordance to the application of such within the Lakeland Police Department. The eligibility by administrative rule and regulations creates â€Å"an advantage to client beneficiaries because it gives social workers and other human service staff members a means by which to administer the benefit or service program evenhandedly and reliably, so that people similarly situated are given similar benefits. (Chambers and Wedal, 2005, p. 112) This rule can be seen to create trade-offs within the system of Lakeland Police Department. Trade-offs is evident because of the situational circumstances in which this rule can be applied to citizens within the district. There are implications of such applications in the way the police department addresses the people. â€Å"On the other hand, administrative rules restrict the freedom of staff members to use their discretion that is to judge need for the benefit or service in individual circumstances. (Chambers and Wedal, 2005, p. 112) The next thing is the eligibility by administrative discretion. This discretion sees to it that all particular concerns within a system need to be addressed by the agency. â€Å"All general organizational policies and administrative rules must be interpreted and applied to individual situations, so it is important to understand that such interpretation and applications necessarily involve significant personal judgment on the part of the staff member. † (Chambers and Wedal, 2005, p. 14) With this, it can be seen that there is a stigmatization of benefits among members of the community handled by the Lakeland Police Department. Their capability to address situations of its citizens particularly concerning their welfare in accordance to the law and mandates of the city can clearly be seen. This creates benefits among locals on the assurance that their welfare is protected by the agency. Lastly, is the eligibility of judicial decision. This rule can also be seen as applicable to the Lakeland Police Department. After a program has been in operation for a period of time, it is very likely that a contention will arise about whether the enabling legislation or whether an administrative rule or discretionary judgment was faithful to the spirit and intention of the law under which the program or policy was established. † (Chambers and Wedal, 2005, p. 115) It can be seen that this categorization creates an important part of the Lakeland Police Academy. This creates a stigmatization of benefits among local citizenry. It may be true that the agency can exercise administrative discretion, however issues may arise between the proper execution and application of such initiative among members of the community. This rule seeks to create a check-and-balance among the members of the police force. It is true that the objectives are in-line with the rules and mandates of the law, however, the actual practice remains to be on the part of local enforcers and policeman. This creates a subjective interpretation of actions by enforcers that more often than not leads to judicial contention. Appeals to the judiciary for clarification of the law are routine and in the end they can become as important as the legislation or administrative rules themselves. † (Chambers and Wedal, 2005, p. 115) To determine whether there are weak rules in the system of Lakeland Police Department, the three eligibility rules again must be looked into. On the eligibility by administrative rule and regulation, there exists a problematic issue on how to effectively distinguish what are the different parameters for such actions. The agency may have difficulty in promoting the necessary measures present if such issue persists. â€Å"Therefore, it is important to know whether a certain entitlement rule originates with judicial decisions, administrative rule, or individual staff discretion, for on that fact depends the probability of change – staff decisions certainly are changed more easily than are formal rules and statutes. † (Chambers and Wedal, 2005, p. 112) On the other hand, the two other eligibility rules are described to be minimal in problems. This is due to their ability to sink within the system and serve as both a check-and-balance among local authorities under the Lakewood Police Department and an initiative to further create changes that the department needs to address the changing needs of the future. Eligibility rules are characterized to create a foundation for actions by people. In the case of Lakewood Police Department, it seeks to cater the needs of the locals in promoting security and their welfare. In the issue of such eligibility rules being fair, it can be argued that they are indeed fair overall since it is based from the mandate of laws and legislation. The only issue here is the actual application of such rules by people who supposed to be fit for the description. Sometimes, there is a subjective interpretation of how such rules can be applied. This creates the sense of disparity of opinions and practices to both local and enforcers of such rules. On the other hand, tackling the issue of sufficiency, yes, it can be argued that the rules applied during that time are sufficient to address the current need of the locals. However, it may not be the case in the future as new issues and challenges arise within the new system. That is why, changes in the system and rules are needed to further pursue the interests of people. For one, rules are and regulations are meant for the people to ensure their security and welfare within the community.