Antisense Theory Essays - RNA, DNA, Molecular Biology, Nucleic Acids

Antisense Theory Essays - RNA, DNA, Molecular Biology, Nucleic Acids Antisense Theory It is estimated that cancer affects three out of four families in the United States alone the disease and its treatments cause substantial mortality and morbidity, prompting intense interest in cancer prevention. Most available treatments for cancers are non-specific; meaning that they target all rapidly growing cells, both normal and cancerous. Consequences of these treatments include side effects towards the normal cells. In addition, cancer is a genetically unstable disease. Cancer cells can develop drug resistance through repeated rounds of mutation and selection. This may render a particular non-specific chemotherapeutic treatment ineffective so that new drugs must be administered in its place. To remedy this occurrence, current research is focusing on the genetic level to terminate the disease and to avoid the damaging side effects and development of drug resistance. One avenue of research focuses on antisense oligonucleotide to target the oncogenes, or cancer causing genes, in a specific fashion to completely inhibit the expression of the oncogenes. Information necessary to produce proteins in cells is contained in genes. In humans it is contained in the human genome and its collection of more than 100,000 genes. Genes are made up of DNA. The DNA molecule is a double helix. They are made up of Adenine, Thymidine, Guanine and Cytosine and are bound by hydrogen to complementary nucleotides on the other strand. RNA is the DNA intermediary and carries the information necessary for the cell to produce its specific protein. During the transferring on information the DNA strand partly uncoils. The sense strand separates from the antisense strand. Because RNA is translated by the cell it is called the sense strand. The hybridization of an antisense strand to mRNA can interfere with its translation to protein . Antisense oligonucleotide are polymers of nucleic acids, which can vary from 12-25 base pairs in length, and which are sequence specific and bind to the target mRNA or DNA through complementary hydrogen bonding. Antisense theory proposes that oligonucleotide, or oligos, recognize specific sequences of mRNA or DNA and bind to them, thus preventing translation or transcription of a gene. Through the binding of an oligo to an mRNA that translates an essential protein for cancer growth, the action of the protein is terminated because the product, an oncoprotein, is never formed The main advantage of antisense is it offers specificity and point of attack. Traditional drugs are less effective because they are not as specific and only work when the disease causing protein has already been produced. Whereas, antisense drugs are complementary strands of Mrna and bind to specific nucleotides in its Mrna to inhibit production of a disease causing protein. They can bind to multiple areas whereas traditional drugs can only bind at two points of interaction. Another advantage of antisense is that it is less complex, than traditional drugs that target proteins. Proteins are complex molecules whose structure is hard to predict, antisense compound are designed to bind to Mrna whose structures are easy to understand. Experimental results seem to support the antisense theory model. If an antisense oligonucleotide does indeed act in a sequence specific, antisense manner to target a gene that is over expressed in cancer or leukemia cells, gene expression can be inhibited and cell growth can be terminated. The application of this theory offers the potential to halt the growth of cancer cells if the over expressed gene can be targeted. The hopes for the future include studying other cell types for similar effects by targeting different over expressed genes using different antisense oligonucleotide.

How to Use the French Conditional (le Conditionnel)

How to Use the French Conditional (le Conditionnel) The French conditional (le conditionnel) mood is very similar to the English conditional mood. It describes events that are not guaranteed to occur, those that are often dependent on certain conditions. While the French conditional mood has a full set of conjugations, the English equivalent is simply the modal verb would plus the main verb. Le Conditionnel: If...then The French conditional is mainly used in  if...then  constructs. It  expresses the idea that  if  this were to happen,  then  that would be the result.   While French uses the word  si  in the if or condition clause, it does not use a term for then in the result clause.  The conditional verb itself is used in the result (then) clause, while only four other tenses are permitted in the  si  clause:  prà ©sent, passà ©Ã‚  composà ©, imparfait,  and  plus-que-parfait. Il mangerait sil avait faim:  He would eat if he were hungrySi nous à ©tudiions, nous serions plus intelligents:  If we studied, (then) we would be smarterIl mangerait avec nous si nous linvitions:  He would eat with us if we invited him Special Cases: Vouloir and Aimer The verb vouloir (to want)  is used in the conditional to express a polite request: Je voudrais une pomme:  I would like an appleJe voudrais y aller avec vous:  I would like to go with you However, you cant say si vous voudriez to mean if you would like, because the French conditional can never be used after si. The verb aimer (to like, love)  is used to express a polite desire, sometimes one that cannot be fulfilled: Jaimerais bien le voir:  I would really like to see itJaimerais y aller, mais je dois travailler:  I would like to go, but I have to work Conjugating le Conditionnel Conjugating the conditional  may be one of the simplest French conjugations youll encounter. There is only one set of endings for all verbs. Most of them - even many that are irregular in the present tense - use their infinitives as the root. There are only about two dozen  stem-changing  or  irregular verbs  that have irregular conditional stems but take the same endings. To show you how easy conditional conjugations are, lets take a look at how it applies to different types of verbs. Well use  jouer  (to play) as our regular  -er  example,  finir  (to finish) as our irregular  -ir  example, and  dire  (to say) as one exception to the rules. Subject Ending Jouer Finir Dire je -ais jouerais finirais dirais tu -ais jouerais finirais dirais il -ait jouerait finirait dirait nous -irons jouerions finirions dirions vous -iez joueriez finiriez diriez ils -aient joueraient finiraient diraient Notice how we had to drop the e in  dire  before adding the conditional endings. This is the sort of change you will find in that handful of verbs that do not follow the standard conditional conjugation pattern. Other than that, you can see how easy it is to form the conditional from almost any verb, even the irregular ones. The Verbs That Don't Follow the Rules So which verbs are you going to have to pay attention to when it comes to the conditional verb mood?  Dire  and other verbs that end in  -ire  are easy compared to some of the others, a few barely resemble the infinitive form while others take on more subtle changes.   The following verbs are irregular in the conditional mood. Notice how the stems change and that they do not use the infinitive form like the other verbs do. There are two rules here: The conditional stem always ends in r.  The exact same verbs are irregular in the  future tense  and use the same stems. When conjugating these into the conditional, simply attach the endings noted above according to the subject pronoun in your sentence. Infinitive Verb Conditional Stem Similar Verbs acheter achà ¨ter- achever, amener, emmener, lever, promener acquà ©rir acquerr- conquà ©rir, s'enquà ©rir appeler appeller- à ©peler, rappeler, renouveler aller ir- avoir aur- courir courr- concourir, discourir, parcourir devoir devr- envoyer enverr- essayer essaier- balayer, effrayer, payer essuyer essuier- appuyer, ennuyer à ªtre ser- faire fer- falloir faudr- jeter jetter- feuilleter, hoqueter, projeter, rejeter nettoyer nettoier employer, noyer, tutoyer,-ayer stem-changing verbs pleuvoir pleuvr- pouvoir pourr- savoir saur- tenir tiendr- maintenir, obtenir, soutenir valoir vaudr- venir viendr- devenir, parvenir, revenir voir verr- revoir vouloir voudr-