Essay on Achilles as the Hero of Homer’s Iliad -- Iliad essays

Achilles as the Hero of Homer’s Iliad      Ã‚  Ã‚   When Homer lived, the stature of a hero was measured by the yardstick of fighting ability. In Homer's Iliad, the character of Achilles represents the epitome of the Greek 'heroic code'. Only Achilles fights for pure heroics, while the characters of Diomedes and Hector provide good contrasts. "Prowess on the battlefield was ranked supreme, high above any considerations of morality"(Martin 26). Nestor, for example, tells Agamemnon and Achilles that he has known much "better men than them" meaning men who are better at fighting. Achilles refuses Lycaon clemency because Patroclus. who is dead. was a much better man than he is by far i.e. a much better fighter. Achilles urges Hector to show his "worth" and fight like a man: "worth" means simply ability to fight. By this criterion Achilles ranks second to none. He is an immensely talented fighter and he considers himself a "prince among men". It is a reflection of his ability that the action speeds up rapidly on his return to the battle after Book 16 and Patroclus' death. Two thirds of the epic arc slow and tedious: on Achilles' return the last third is fast and moves most speedily. Achilles' unstoppable battle madness surpasses without doubt that of the other heroes in the lliad. He is brave, vicious and powerful. He splits the Trojans and drives them back without difficulty at all. Moreover, his bravery is not restricted to humans. He is angry with Apollo for deceiving him and his battle with the river god Xanthus ends in more success than Diomedes' attempts against the gods in Book 5 (although he admittedly has much divine support). The heroic code was recognised as a desire to excel. For the heroes 'excellent' was ... ... Finkelberg, Margalit. "Odysseus and the genus 'hero' ." Greece and Rome v. 42 (Apr. '95) p. 1-14. Goodrich, Norma. Myths of the hero. New York: Orion Press, 1962. Homer: Iliad. Trans. Robert Fagles. New York: Penguin Books, 1990. Martin, Richard. The Language of Heroes: Speech and Performance in the Iliad. Ithaca: Cornell University Press, 1989. Parry, Adam M. The Language of Achilles and Other Papers. Oxford: Clarendon Press, 1989. Schein, Seth L. The Mortal Hero: An Introduction to Homer's Iliad. Berkeley: University of California Press, 1984. Shive, David M. Naming Achilles. New York: Oxford University Press, 1987. Van Nortwick, Thomas. Somewhere I have travelled: the hero's journey. New York: Oxford University Press, 1996. Whitman, Cedric H. Homer and the Heroic Tradition. Cambridge, Mass.: Harvard University Press, 1958.

Of Mice and Men Film/Book Comparison

The lack of interaction between the Weak' ones of the ranch in the film version of Of Mice and Men results in the obscuring of the theme of handicaps that is present throughout the novel. In the film, the scene begins with Leonie approaching Crooks as the rest of the men are in the nearby town. They discuss Lien's desire to tend rabbits and later on, Leonie makes it clear his intention for George and he to be together till the end. George comes in, escorts Leonie out of the room where they encounter Curlers wife as she complains of her unhappy marriage and runs away.The book varies in the way that Curlers wife and Candy are both in the room as they all talk. As Candy, Leonie, and Crooks discuss the promise of a brighter future, Curlers wife is quick to crush their dreams with the reality of each of their situations. After she humiliates them, they are defeated and their harsh circumstances sink in. It is important to notice in the novel that each character has their own handicap, whe ther it is age, gender, race, mental capability, or physical capability; although they show strength even with their weak descriptions, the purpose of the theme is to convey the low tolerance their society has of handicaps.For example, Crooks, even being a bitter man, latches onto their dream of the little house for the promise of companionship, but because of his race and the prejudice during the time period, Curlers wife makes sure he knows that he will never be accepted. Although the handicaps are physically portrayed In the film, they are not reinforced well enough because there isn't as big of a power difference between Leonie and Crooks as there is between them and Curlers wife. Curlers wife may be handicapped as her loneliness makes her desperate, but she has the ability to take away any hope they eave.Also, in the novel, Curlers wife mentions that the men left the three Weak' ones at home. This comment serves to further describe the time period as there Is never enough prote ction for the weak from the strong. The theme of handicaps Is essential to the comprehension of the novel as It grasps the concept of Inequality; without the theme's distinction, there Is no closure, positive or negative, that Is needed for the reader to comprehend the negative Impact the fictional world has on a group of people that are not as strong as society requires them to be.

Humanity’s Evil Inspired William Golding’s Lord of the...

â€Å"Drug dealers go big, use Boeing for coke run†, â€Å"11 killed in Pakistan by suicide bomber†, â€Å"Parents largely unaware teen binge drinking is growing deadlier† (Edmonton Journal, November 18, 2009). It is truly staggering to see the number of articles concerning crime, felony and death in a newspaper, everyday. It is not hard to find articles about laws being broken, about lawbreakers going free and about people being killed. The concept of newspapers full of stories showing humanity’s evil suggests that there is something wrong with today’s world, but newspapers have always been full of such articles and events. It is clear that humanity’s evil inspired William Golding’s Lord of the Flies: a commentary on the innate evil in all man. In†¦show more content†¦However, these inventions were not flukes, as the Islamic inventors created the experimentation process, which constitutes testing a theory over and over until it is consistent; this method is still used today. In fact, all of the Islamic inventions of that era are still useful, and cherished today. Therefore, the world today has benefited from the Islamic quest for knowledge. Though Muslim’s had a quest for knowledge, a more recent group had a quest for peace: Live Aid was a series of concerts in 1985 dedicated to relieving hunger in Ethiopia. All the artists at Live Aid, such as David Bowie, Queen and Paul McCartney, performed for free, and all the profit from the concerts was donated to solving hunger in Ethiopia. These artists are used to making millions of dollars for touring the world, and selling their records, however, they all volunteered for a dire situation and made a much greater difference than if they had simply continued touring. Furthermore, in 2005, another series of concerts, entitled Live 8 were dedicated to attempting to solve certain issues in Africa, such as relinquishing their debt. Africa’s debt and Et hiopia’s needs were aided greatly by these performers. The performers from these concerts and anyone with computer access certainly use a utility that has facilitated the use of the internet: Google is a search-engine created by Lawrence PageShow MoreRelatedWilliam Golding s Lord Of The Flies1389 Words   |  6 PagesA response to Lord Of The Flies Imagine an airplane crash. The heat of flames scorch passengers’ backs in addition to the wind burning their faces. Lucky, this crash was over water and near an island so most passengers survive, with an exception of the airplane staff and the pilot. Even though alive, many are in fits of fear and panic, and others are in shock. After hurried deliberation, a lone member of the group is elected leader in hopes that they will calm the panic, and make the hard, but necessaryRead MoreWilliam Golding s Lord Of The Flies1044 Words   |  5 PagesSimilar to most literary classics, William Golding’s novel Lord of the Flies contains allusions to the Christian Bible and character archetypes that convey universal ideas. Golding’s story focuses on a group of British schoolboys who are stranded on an island and ultimately succumb to their innate savage tendencies. Literary analysts often compare components of Lord of the Flies to various aspects in the Christian Bible. For instance, the setting in Lord of the Flies is often linked to the Garden ofRead MoreHuman Nature In Lord Of The Flies Essay1136 Words   |  5 Pagesthinking, feeling, and acting, which humans tend to have naturally. William Golding’s book. â€Å"Lord of the flies† is an excellent novel that describes how humans, when put in a rough environment, react to power they are given. The title of the book â€Å"Lord of the Flies† refers to the Boars head idol that was surrounded by flies was later created by the boy. The title also represents the fall of the boy’s civilization. The reason William Golding used this title was because of his experiences from the navyRead MoreSAT Top 30 Essay Evidence18536 Words   |  75 Pages......................................................................... 27 Fiction and Literature: Hamlet by William Shakespeare (â€Å"To be? Or not to be?†) ...................................................................... 29 Harry Potter by J.K. Rowling (Witches, Wizards, and Muggles!) .......................................................... 31 Lord of the Flies, by William Golding (Murderous schoolboys stranded on an island!) ......................... 33 The Great Gatsby, by F. Scott

The Power of Pythons String Templates

Python is an interpreted, object-oriented, high-level programming language. It is easy to learn because its syntax emphasizes readability, which reduces the expense of program maintenance. Many programmers love working with Python because—without the compilation step—testing and debugging go quickly.​ Python Web Templating Templating, especially web templating, represents data in forms usually intended to be readable by  a viewer. The simplest form of a templating engine substitutes values into the template to produce the output.   Aside from the string constants and the deprecated string functions, which moved to string methods, Pythons string module also includes string templates. The template itself is a class that receives a string as its argument. The object instantiated from that class is called a template string object. Template strings were first introduced in Python 2.4. Where string formatting operators used the percentage sign for substitutions, the template object uses dollar signs. $$ is an escape sequence; it is replaced with a single $.$identifier names a substitution placeholder matching a mapping key of identifier. By default, identifier must spell a Python identifier. The first non-identifier character after the $ character terminates this placeholder specification.${identifier} is equivalent to $identifier. It is required when valid identifier characters follow the placeholder but are not part of the placeholder, such as ${noun}ification. Outside of these uses of the dollar sign, any appearance of $ causes a ValueError to be raised. The methods available through template strings are as follows: Class string. Template(template): The constructor takes a single argument, which is the template string.Substitute(mapping, **keywords): Method that substitutes the string values (mapping) for the template string values. Mapping is a dictionary-like object, and its values may be accessed as a dictionary. If the keywords argument is used, it represents placeholders. Where both mapping and keywords are used, the latter takes precedence. If a placeholder is missing from mapping or keywords, a KeyError is thrown.Safe_substitute(mapping, **keywords): Functions similarly to substitute(). However, if a placeholder is missing from mapping or keywords, the original placeholder is used by default, thus avoiding the KeyError. Also, any occurrence of $ returns a dollar sign. Template objects also have one publicly available attribute: Template is the object passed to the constructors template argument. While read-only access is not enforced, it is best not to change this attribute in your program. The sample shell session below serves to illustrate template string objects. from string import Template s Template($when, $who $action $what.) s.substitute(whenIn the summer, whoJohn, actiondrinks, whaticed tea) In the summer, John drinks iced tea. s.substitute(whenAt night, whoJean, actioneats, whatpopcorn) At night, Jean eats popcorn. s.template $when, $who $action $what. d dict(whenin the summer) Template($who $action $what $when).safe_substitute(d) $who $action $what in the summer

Essay about Symbolism in “The Story of an Hour” - 671 Words

The symbols and imagery used by Kate Chopins in â€Å"The Story of an Hour† give the reader a sense of Mrs. Mallard’s new life appearing before her through her view of an â€Å"open window† (para. 4). Louise Mallard experiences what most individuals long for throughout their lives; freedom and happiness. By spending an hour in a â€Å"comfortable, roomy armchair† (para.4) in front of an open window, she undergoes a transformation that makes her understand the importance of her freedom. The authors use of Spring time imagery also creates a sense of renewal that captures the authors idea that Mrs. Mallard was set free after the news of her husbands death. Right from the moment Louise Mallard hears of her husbands death, Kate Chopin dives into a her†¦show more content†¦Immediately after the news of her husbands death, Mrs. Mallard races upstairs into her room where she settles into â€Å"a comfortable, roomy armchair† (para.4). The armchair symbolizes the rest from the oppressive life she had and freedom from societys expectations. Since it was tradition for women to be married by a certain age, Louise Mallard must have obligated to marry Brently. Sitting in the armchair, she gazes out of the window and starts indulges in deep thought, which establishes her as an intelligent individual. The open window from which Louise gazes is symbolic for her freedom and the good fortune that she is now presented with. Her attention to the blue sky, fluffy clouds, tree tops and the delicious breath of rain denote her newly found inner well-being. The writers use of language is well-chosen as it explicitly portrays Mrs. Mallards true feelings. By capturing all the senses, the imagery created represents Louises new life and establishes her as a round character. The open window provides a clear and bright view into the distance of Louise’s own bright future, which was obstructed by the demands of her husband. As Mrs. Mallard left the room, there was a feverish triumph in her eyes, and she carried herself unwittingly like a goddess of Victory (para.19). â€Å"The goddess of victory† (para.19) embodies Louises triumph over repression, over the â€Å"powerful will bending hers in that blind persistence...right to impose a privateShow MoreRelatedSymbolism in The Story of an Hour758 Words   |  4 PagesSymbolism in the â€Å"Story of an Hour† by Kate Chopin For this lesson I read The Story of an Hour by Kate Chopin. Although there are many literary devices used in The Story of an Hour, I have decided to write my essay on the use of symbolism. The literary device symbolism is a technique used to represent ideas and events by using significant or important things that stand out in the story. A few things that stood out most in the story would be the comfortable chair, and Mrs. Mallards heartRead MoreThe Story Of An Hour Symbolism Essay1089 Words   |  5 Pages The Story of an Hour, by Kate Chopin, is a wonderful short story filled with many different peculiar twists and turns. Written in 1894, the author tells a tale of a woman who learns of her husband’s death, but comes to find joy in it. Many of the things Kate Chopin writes about in this story symbolize something more than just the surface meaning. Through this short story, told in less than one thousand one hundred words, Kate Chopin illustrates deeper meanings through many different forms of symbolismRead MoreSymbolism In Kate Chopins The Story Of An Hour1013 Words   |  5 PagesWhile most of Kate Chopin’s short stories were well received, â€Å"The Story of an Hour† was originally rejected by publishers until 1894 when Vogue decided to publish the short story. However after her death most of Chopin’s work was forgotten, that was until the 1950s when her work again was recognized as insightful and moving, setting into motion a Kate Chopin revival which was both successful and remarkable (Biography). â€Å"The Story of an Hour† focuses on the liberation and new found freedom of a newlyRead MoreSymbolism Of The Story Of An Hour By Kate Chopin945 Words   |  4 PagesSymbolism in â€Å"The Story of an Hour† In her piece â€Å"The Story of an Hour,† Kate Chopin uses several symbols to bring Louise Mallard’s dramatic hour to life, as well as the themes of freedom and disillusionment that come with marriage and life. Chopin used Mrs. Mallard’s heart trouble, the open window and spring life, and her final descent down the stairs that led to her death to show that Louise’s marriage to Brently was suffocating her free spirit and decreasing her quality of life. These main symbolsRead MoreSymbolism as Found in Kate Chopins Story of an Hour Essay1532 Words   |  7 PagesSymbolism as found in Kate Chopin’s â€Å"Story of an Hour† In Kate Chopin’s â€Å"Story of an Hour† the protagonist, Louise Mallard, is going through a life-changing event that is brought on by the news of the death of her husband, Brently Mallard. During this hour, she is told of her husband’s death, grieves for a short time, discovers that she will now be able to â€Å"live for herself† (16) and is finally able to free herself of the restrictive marriage she has been living in. The end of her last hour comesRead MoreThe Use of Symbolism to Foreshadow the Future in Kate Chopins The Story of an Hour and Toni Cade Bambaras The Lesson1673 Words   |  7 PagesThe Use of Symbolism to Foreshadow the Future in Kate Chopins The Story of an Hour and Toni Cade Bambaras The Lesson Often authors use signs to foreshadow events that will happen in the future in their stories. For example an author might write As he was walking down the dark eerie path dark skies began to form . Here the writer uses a usually negative sign to foreshadow a negative future. This is the most common way for authors to foreshadow in a story, but it isnt the only way. In someRead MoreEssay about Comp and Lit Comparison of Blue+Yellow/Story of an Hour1296 Words   |  6 Pagesthe short story â€Å"the Story of an Hour† by Kate Chopin and the short story â€Å"blue + yellow† by Chris Killen compare in many ways. These two stories use the same literary device strongly such as imagery. Imagery is a literary device in which the author uses words and phrases to paint a picture in the readers head throughout the story. These two short stories are written with very descriptive language to help paint a picture of the occurrences in the story and describe a scene. These two st ories also contrastRead MoreThe Story Of An Hour By Kate Chopin855 Words   |  4 PagesThe Story of an Hour In the â€Å"Story of an Hour† by Kate Chopin, is about pleasure of freedom and the oppression of marriage. Just like in Kate Chopin’s story, inside most marriages, even the ones that seem to be the happiest, one can be oppressed. Even though, one might seem to be happy deep inside they miss the pleasure of freedom and living life to the fullest. Just like, in this story Mrs. Mallard feels trapped and when she hears about her husband’s death she first feels distraught, but ultimatelyRead More The Story of an Hour and The Hand Essay1161 Words   |  5 PagesThe â€Å"Story of an Hour† by Kate Chopin and ‘†The Hand† by Sidonie-Gabrielle Colette are similar in theme and setting. Sidonie-Gabrielle Colette and Kate Chopin create the theme of obligatory love and the unhappiness it entails. Both stories illustrate the concealed emotions many women feel in their marriage yet fail to express them. The two stories take place in a sacred room o f the house and both transpire in a brief amount of time. The differences between the two stories are seen through theRead MoreThe Theme Of Loneliness1549 Words   |  7 PagesBrill by Katherine Mansfield what they both have in common is the literary device theme loneliness. Theme is the general idea or insight revealed in a narrative. These two stories are also different from the style of writing these two authors wrote how to tell their stories. Loneliness is introduced in the beginning of the short story â€Å"A Clean, Well-Lighted Place† by Hemingway. The deaf old man, with no wife and only a niece to care for him, is noticeably lonely. The younger waiter, upset that the old

Ap Biology - Modern Genetics free essay sample

DNA is the template (3’ to 5’) ! 3. RNA Polymerase Binds to promoters, separates strands of DNA and ! hook together RNA nucleotides (only add to 3’ end) ! a. TATA Box Where RNA polymerase H binds (eukaryotes) ! ! b. Transcription Factors Aid polymerase in locating promoters ! ! such as the TATA Box ! ! c. Reads in sets of 3 called codons. ! 4. Termination site on DNA indicates end in prokaryotes ! 5. Eukaryotes Pre-mRNA separates from DNA at the polyadenylation ! signal, but RNA polymerase continues to transcribe until it falls off the ! DNA. C. Pre-mRNA processing in eukaryotes ! 1. Heterogenous nuclear RNA (hnRNA) contains introns and exons. ! ! a. Introns not used (stay IN nucleus) ! ! b. Exons used (EXIT nucleus) ! 2. Small nuclear ribonucleic proteins (snRNP’s/snurps) help excise introns ! and fuse exons. ! 3. Splicosomes Snurps and proteins working together ! 4. Poly A tail is added to 3’ end which a 5’ cap is added to the 5’ end. ! ! a. Prevent damage to mRNA as it leaves nucleus ! ! b. Helps mRNA leave nucleus ! ! c. Helps mRNA attach to ribosome. D. rRNA Formed in nucleoli, makes up part of ribosome. ! 1. Ribosomes Binding site for rRNA. E. Translation ! 1. Initiation Brings mRNA and tRNA together by means of factors (start ! codon is AUG) ! 2. Elongation Amino acids are added with aide of elongation factors. ! ! a. Codon Recognition mRNA codon on A site forms H bonds with ! ! anticodon of incoming tRNA. ! ! b. Aminoacyl tRNA synthetase matches amino acid with correct ! ! tRNA ! ! c. Peptidyl transferase catalyzes the formation of a peptide bond ! ! between polypeptide at P site and amino acids at A site. ! ! d. Wobble Effect Exact base pairing is not always necessary. ! 3. Translocation ! ! a. A site on ribosome holds tRNA carrying the next amino acid to be ! ! added. ! ! b. P site on ribosome holds tRNA carrying the growing polypeptide ! ! chain. ! ! c. E site is where it exits. F. Termination Indicated by termination codons (UAA, UAG, UGA) ! . Release Factor Protein which binds to termination codon on A site ! causing hydrolysis reaction and freeing the polypeptide. ! 2. Posttranslational modi? cations now take place Protein goes into ! secondary, and tertiary structure. AP Bio Modern Genetics IV. Mutations ! A. Point Mutations Chemical changes in one or a few nucleotides. ! ! 1. Base Pair Substitutions Replacement of one nucleotide and its partner ! ! from a complementary DNA strand with another pair of nucleotides. ! ! ! a. Missense Mutations Altered codons still code from amino acids ! ! ! but don’t always make sense. ! ! b. Nonsense Mutations Change amino acids codon to a stop ! ! ! signal (most result in nonfunctional codons) ! ! 2. Insertions and Deletions Additions or losses of one or more nucleotide ! ! pairs in a gene. ! ! ! a. Frameshift Mutation Alters reading from (usually nonfunctional) ! B. Mutagenesis Creation of mutations ! ! 1. Hermann Muller discovered that genetic changes occurred when fruit ! ! ? ies were exposed to X-Rays. ! ! 2. Spontaneous mutations result from errors in DNA replication, repair, or ! ! recombination. ! ! 3. Mutagens Physical and chemical agent which cause mutations. Chapter 18 The Genetics of Viruses and Bacteria I. Viruses ! A. Wendell Stanley (American-1935) crystallized particle, now called tobacco ! mosaic virus (TMV) ! B. Genomes May be double or single stranded DNA or RNA. ! C. Capsid Protein shell enclosing genome, built from capsomere ! D. Phages Virus which infects bacteria. ! E. Lack enzymes for metabolism and have no ribosomes, nonliving ! F. Vaccine Harmless variation which stimulates immune response (? rst made ! from cowpox) ! G. Viroids Tiny molecules of naked RNA, upset metabolism of plants ! H. Prions Infectious proteins ! ! 1. Often cause brain diseases like mad cow and scrapie in sheep ! ! 2. Not killed by heat, long incubation period II. Sources of New Viruses ! A. Mutations of current viruses ! B. Spread between species typically due to new exposure. ! C. Spread within species between a small population and the rest of the world. III. Replication and Infection ! A. Obligate intracellular parasites ! B. Basic Infection ! ! 1. Some recognize host by a â€Å"lock and key† ? t, and only infect certain cells ! ! of the body. ! ! 2. Genome Enters Cell Method varies (leaving ghost behind-empty ! ! capsid) AP Bio Modern Genetics ! ! ! ! ! ! ! ! ! ! ! ! ! 3. Genome reprograms cell to copy viral genes and manufacture capsid ! proteins. ! ! a. DNA viruses use DNA polymerases of host cell ! ! b. RNA viruses contain their own enzymes to initiate replication. ! 4. Self Assembly Assembly of capsids and nucleic acid molecules into ! viruses. ! 5. Viruses leave host cell C. Bacteriophages Virus which infect b acteria ! 1. Lytic Cycle Reproductive cycle which ends with death of host cell ! 2. Lysogenic Cycle Reproduces viral genome without destroying host ! ! a. Viral DNA is incorporated into bacterial DNA (prophage) ! b. Prophage is replicated every time bacteria devices ! ! c. Eventually goes into lytic cycle. IV. Animal Viruses ! A. Viruses with Envelopes ! ! 1. Envelopes fuse with host membrane, inserting information ! ! 2. Enzymes remove capsid, genome replicates ! ! 3. Viral offspring are wrapped in a membrane and released ! ! 4. Provirus Some viruses become integrated into cell’s genome (infection ! ! tends to reoccur throughout life, HIV, herpes) ! B. RNA Viruses ! ! 1. Retroviruses Most complicated life cycle (HIV) ! ! ! a. Reverse Transcriptase Transcribes DNA from RNA template ! ! ! b. Newly formed DNA integrates as a provirus into a chromosome ! ! ! within the nucleus of the host cell. ! C. Viral Diseases ! ! 1. Vaccine Harmless variants or derivatives of pathogenic microbes ! ! which stimulate an immune response. V. Plant Viruses ! A. Horizontal Transmission Plant infected from external source ! B. Vertical Transmission Plant inherits infection from parent VI. Bacteria ! A. Single stranded, circular DNA, found in nucleoid region ! B. Plasmids Smaller circles of DNA, used in genetic engineering ! C. Replication of chromosome is followed by binary ? ssion (copying of DNA ! occurs in both directions) VII. Genetic Recombination of Bacteria ! A. Transformation Alteration of a bacterial cell’s genotype by the uptake of ! naked, foreign DNA from environment. ! B. Transduction Transfer of bacteria by means of a virus ! C. Conjugation Direct transfer of genetic material between two bacterial cells ! ! 1. Donor is â€Å"male† (requires F plasmid, F+), receiver is â€Å"female† (F-) AP Bio Modern Genetics ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 2. Plasmid Not required for survival or reproduction, but can be ! advantageous in stressful environments. ! ! a. Episomes Can replicate as a free molecule in cytoplasm or as ! part of the main bacterial chromosome. ! 3. R Plasmids cause bacteria to be resistant to antibiotics D. Transposons Pieces of DNA which can move from one location to another in a cell’s genome (jumping genes) discovered by Barbara McClintock. ! 1. Conservative Transposition Genes are not replicated, number of ! copies is conserved (cut and paste) ! 2. Replicative Transposition Transposon replicates at original site and a ! copy inserts at another location (copy and paste) E. Insertion Sequences Simplest transposons, consist of only the DNA necessary for act of transposition itself. F. Barbara McClintock (1940’s-50’s) worked with Indian corn, based on observations, she believed there were mobile elements. VII. Operons Unit of genetic function common in bacteria and phages and consisting of regulated clusters of genes with related function. ! A. Jacob and Monod Discovered operon model in 1961 ! B. Operon is made of an operator, promoter and the genes they control ! C. Operator Switch which gets turned on ! D. Oppressor Segment of DNA, functions as an on/off switch for an operon ! E. Repressor Protein which turns off the operon (operator speci? c) ! F. Corepressor Metabolite that cooperates with a repressor protein to switch an ! operon off ! G. E coli Operons ! ! 1. Lac Operon ! ! ! a. Regulatory Gene gt; Repressor gt; Binds to Operator ! ! ! b. RNA Polymerase cannot transcribe structural genes needed to ! ! ! make enzymes break down lactose ! ! ! c. When lactose is present, some of the lactose attaches to the ! ! ! repressor and shuts it down allowing RNA polymerase to transcribe ! ! ! (example of an inducible operon Usually off but can be induced. ) ! ! 2. Trp Operon (Tryptophan is an amino acid) ! ! ! a. Regulatory Gene gt; Inactive repressor that doesn’t attach to the ! ! ! operator so RNA polymerase can transcribe. ! ! ! b. Increased levels of trp combine with repressor to make it active ! ! ! and the RNA polymerase can’t transcribe (example of corepressor) ! ! ! c. Repressible Operon Transcription usually on but can be ! ! ! repressed Chapter 19 Eukaryotic Genomes: Organization, Regulation, and Evolution I. Key Terms ! A. Cellular Differentiation Process of cells becoming specialized and therefore ! only parts of genes expressed. AP Bio Modern Genetics ! ! ! ! ! ! ! ! ! B. Histones Positively charged proteins which bind to negative DNA and â€Å"package it together† C. Nucleosome Basic unit of DNA packaging in eukaryotes, consisting of DNA around a protein core (2 copies of each of the 4 types of histones) D. Multigene Families Collections of identical or similar genes (hemoglobin alpha and beta are expressed at different times) E. Pseudogenes Similar to functioning genes but are lacking some essential part. F. Heterochromatin, euchromatin, telomere. II. Gene Control Eukaryotes ! A. Transcriptional Control Factor which tell where to start and stop ! B. Posttranscriptional Splicing, cap and tail ! C. mRNA Degradation ! ! 1. Prokaryotic mRNA are usually broken down within minutes of use ! ! 2. Eukaryotic mRNA can live hours to weeks before being broken down by ! ! enzymes. ! D. Chromosomes Puffs In insects, regions of intense transcription, chemicals ! signal when they should form. ! E. Steroids in Humans ! ! 1. Steroid diffuses through cell (lipid soluble) into cytoplasm and binds to ! ! receptor. ! ! 2. Binding to an enhancer then occurs and activates transcription. ! ! 3. Steroid acts as a signal to turn on speci? c gene. ! F. Hormones bind to outside of cell (not lipid soluble) and operate with the help of ! receptor protein on the outside of the cell. ! G. Gene Ampli? cation Selective replication of certain genes. ! H. Immunoglobulin Proteins which speci? cally recognize and help ? ght viruses, ! bacteria and invaders. ! ! 1. Made by B lymphocytes ! ! 2. Antibody variation results from different combinations of variable and ! ! constant regions of immunoglobulin polypep tides. ! I. DNA Methylation III. Abnormal Expression of Genes ! A. Oncogenes Cancer causing genes found in RNA viruses ! B. Proto-Oncogenes Found in human cells, normal genes which may become ! oncogenes. ! ! 1. Increased activity may cause change ! 2. Gene Ampli? cation ! ! 3-5. Translocation, Gene Transposition, and Point Mutation ! C. Tumor Suppressor Genes Normally prevent cell division and may produce ! proteins which repair damaged DNA. ! D. The more mutations throughout life, the greater the chance of cancer. AP Bio Modern Genetics Chapter 20 DNA Technology I. Gene Manipulation ! A. Restriction Enzymes Bacterial enzymes which cut up foreign DNA forming ! sticky ends. ! ! 1. Sticky ends can be used to join DNA pieces originating from different ! ! sources. ! ! 2. Restriction fragments can be separated by gel electrophoresis ! ! ! a. Brief electric pulse is applied to a solution of DNA to separate ! ! ! DNA. ! ! ! b. DNA is negative and moves towards positive end ! ! ! c. Can be used to compare DNA of different species. ! B. Gene Cloning in a Plasmid ! ! 1. Isolate bacterial plasmid and eukaryotic DNA with gene desired ! ! 2. Both are treated with same restriction enzyme ! ! ! a. Plasmid DNA Cut at restriction site ! ! ! b. Eukaryotic DNA Generates thousands of fragments ! ! 3. Two types of DNA are mixed Sticky ends of each pair up ! ! 4. DNA ligase joins molecules (called recombinant DNA) ! ! 5. Recombinant DNA is introduced into a bacterial cell ! 6. Gene Cloning Production of multiple copies of desired gene ! C. Inserting DNA into Cells ! ! 1. Cloning Vectors Carriers for moving recombinant DNA (plasmids, ! ! phages-transformation) ! D. Sources of Genes for Cloning ! ! 1. DNA isolated directly from organism ! ! 2. Complementary DNA (cDNA) made in a lab from mRNA templates. ! E. Probes Nucleic molecules w hich will hydrogen bond speci? cally to a desired ! gene, location traced by labeling ! F. Sanger Method of Sequencing ! ! 1. Synthesizing in vitro DNA strands complementary to one of the strands ! ! being sequenced. ! G. Amplifying DNA ! ! 1. Polymerase chain reaction (PCR) technique by which any piece of DNA ! ! can be quickly ampli? ed in vitro ! ! ! a. DNA is incubated with DNA polymerase and primers. II. Applications ! A. Human Genome Project Mapping of entire human genome ! B. Analyzing genomes of other species ! C. Human Gene Therapy Correct Disorders ! D. Vaccines ! E. Mammalian Hormones and Proteins Growth hormones, clotting factor, insulin ! F. Treating Farm Animal with vaccines, antibodies and growth hormones ! G. Transgenic Organisms Contain genes from another species ! H. Manipulating Plant Genes Herbicide resistance, better foods

Sexually Transmitted Diseases Essays (2574 words) -

Sexually Transmitted Diseases Sexually transmitted diseases are infectious diseases that can be spread by sexual contact. Some can also be transmitted by non-sexual ways, but these make up a minority of the total number of cases. An estimated ten to twelve million Americans have sexually transmitted diseases. Sexually transmitted diseases in the United States affect both sexes, all races, and every economic stature. STD's come from different sources. Some are epidemic like gonorrhea, infections of the urethra, genital herpes, and genital warts. Some diseases are caused by a bacterium such as Chlamydia, and others are from protozoan or yeast. Many of these infections are transmitted largely by sexual contact with an infected person. The practice of anal and oral sex also lead to cases of anal and oral infections. Gonorrhea, syphilis, and chlamydial infections can also be transmitted from a pregnant woman to her infant, either in the uterus or during birth. Sexually transmitted diseases are very hard to control. Some public officials attribute the increase in many of these diseases to increasing sexual activity. Others say the replacement of the condom with birth control pills and diaphragms might also increase the risk of STD's. "Many STD's are transmitted more efficiently from men to women than the reverse, perhaps because the vagina serves as a reservoir that prolongs exposure to infectious secretion (Handsfield 2)" The physical examination of patients with STD or at risk is a simple procedure. All patients require inspection of the entire skin surface. At a minimum they carefully inspect all skin surfaces that are uncovered or exposed during genital examination. This includes the face, head, hands, lower arms, lower trunk, pubic area, thighs, mouth and throat. Also checked in men are the genitals and the pubic and inguinal regions, the penis, urethra, urethral bulb, and the scrotum are checked for tenderness and other abnormalities. "For homosexually active men, the anus and perineum are carefully inspected. The examination of women includes inspection of the pubis area, the external genitals, perineum and anus, speculum examination of the vaginal mucosa and cervix, and a bimanual pelvic examination (Handsfield 4)." A way to avoid STD's and unwanted pregnancies is to use a condom. "A condom is a sheath worn over the penis during oral, anal, and vaginal sexual contact (Virginia Tech Health Services)." Condoms can be made of latex rubber or animal membrane. Animal membrane condoms prevent pregnancy but have large enough pores for tiny HIV viruses to pass through. Latex condoms are much better in forming a barrier against HIV. Polyurethane condoms haven't been fully tested, so people should avoid using them. Do not use novelty condoms like the ones that glow in the dark, these are not FDA approved. Always check the expiration date. Never use a condom after the date stamped on the wrapper or on the seal. Do not use a condom that has been in a wallet for more than a month. Heat and pressure can damage it. Also, stay away from oil-based lubricants, like Vaseline, which can eat through the latex. And finally, do not open the packet with scissors or your teeth, the condom could rip. Nudge the condom away from the edge and gently tear the packet open. Next to abstinence, which is having no sexual relations at all, condoms are the best protection against STD's. When a condom is used correctly, they are about 90 percent effective in preventing pregnancy, and 95 percent effective when used with spermicide. Spermicide, also called Nonoxynol 9, has been found to be effective in killing the HIV virus in laboratory experiments when used at 5 percent strength. Spermicide immobilizes and kills sperm. It comes in jellies, creams, foams, suppositories, film, and as a coating on condoms. STD's can also be avoided by remaining monogamous. This means only having sex with one person whom only has sex with you. If you know that you are clean of all STD's and that your partner is also clean, then you both can avoid STD's by only being with each other. Chlamydia is a STD caused by the bacterium Chlamydia trachomatis. The bacterium is found in infected body fluids from the penis or vagina and it spreads through direct sexual contact and from mother to baby. Chlamydia is the most prevalent bacterial STD, about four million people will become infected with Chlamydia this year. Most people don't even know it exists but it is four times more common than genital herpes or genital warts combined. Up to 70 percent of women and 30 percent of men who are infected