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Hgb Synthesis Essay

INTRODUCTION TO SYNTHESES

(mostly from Cassie Carter - with her kind permission)


CONTENTS
What is a synthesis?
Two types of syntheses
Standards for synthesis essays
How to write synthesis essays
Techniques for developing synthesis essays
Thesis statements, introductions, conclusions, and quotations

WHAT IS A SYNTHESIS?
A synthesis is a written discussion that draws on one or more sources. It follows that your ability to write syntheses depends on your ability to infer relationships among sources - essays, articles, fiction, and also nonwritten sources, such as lectures, interviews, observations. This process is nothing new for you, since you infer relationships all the time - say, between something you've read in the newspaper and something you've seen for yourself, or between the teaching styles of your favorite and least favorite instructors. In fact, if you've written research papers, you've already written syntheses. In an academic synthesis, you make explicit the relationships that you have inferred among separate sources.

The skills you've already been practicing in this course will be vital in writing syntheses. Clearly, before you're in a position to draw relationships between two or more sources, you must understand what those sources say; in other words, you must be able to summarize these sources. It will frequently be helpful for your readers if you provide at least partial summaries of sources in your synthesis essays. At the same time, you must go beyond summary to make judgments - judgments based, of course, on your critical reading of your sources - as you have practiced in your reading responses and in class discussions. You should already have drawn some conclusions about the quality and validity of these sources; and you should know how much you agree or disagree with the points made in your sources and the reasons for your agreement or disagreement.

Further, you must go beyond the critique of individual sources to determine the relationship among them. Is the information in source B, for example, an extended illustration of the generalizations in source A? Would it be useful to compare and contrast source C with source B? Having read and considered sources A, B, and C, can you infer something else - D (not a source, but your own idea)?

Because a synthesis is based on two or more sources, you will need to be selective when choosing information from each. It would be neither possible nor desirable, for instance, to discuss in a ten-page paper on the battle of Wounded Knee every point that the authors of two books make about their subject. What you as a writer must do is select the ideas and information from each source that best allow you to achieve your purpose.

PURPOSE
Your purpose in reading source materials and then in drawing upon them to write your own material is often reflected in the wording of an assignment. For example, your assignment may ask that you evaluate a text, argue a position on a topic, explain cause and effect relationships, or compare and contrast items. While you might use the same sources in writing an argumentative essay as your classmate uses in writing a comparison/contrast essay, you will make different uses of those sources based on the different purposes of the assignments. What you find worthy of detailed analysis in Source A may be mentioned only in passing by your classmate.

USING YOUR SOURCES
Your purpose determines not only what parts of your sources you will use but also how you will relate them to one another. Since the very essence of synthesis is the combining of information and ideas, you must have some basis on which to combine them. Some relationships among the material in you sources must make them worth sythesizing. It follows that the better able you are to discover such relationships, the better able you will be to use your sources in writing syntheses. Your purpose in writing (based on your assignment) will determine how you relate your source materials to one another. Your purpose in writing determines which sources you use, which parts of them you use, at which points in your essay you use them, and in what manner you relate them to one another.


TWO TYPES OF SYNTHESES

THE EXPLANATORY SYNTHESIS: An explanatory synthesis helps readers to understand a topic. Writers explain when they divide a subject into its component parts and present them to the reader in a clear and orderly fashion. Explanations may entail descriptions that re-create in words some object, place, event, sequence of events, or state of affairs. The purpose in writing an explanatory essay is not to argue a particular point, but rather to present the facts in a reasonably objective manner. The explanatory synthesis does not go much beyond what is obvious from a careful reading of the sources. You will not be writing explanatory synthesis essays in this course. However, at times your argumentative synthesis essays will include sections that are explanatory in nature.

THE ARGUMENT SYNTHESIS: The purpose of an argument synthesis is for you to present your own point of view - supported, of course, by relevant facts, drawn from sources, and presented in a logical manner. The thesis of an argumentative essay is debatable. It makes a proposition about which reasonable people could disagree, and any two writers working with the same source materials could conceive of and support other, opposite theses.


STANDARDS FOR SYNTHESIS ESSAYS

1. Remember that you are using your sources to support your ideas and claims, not the other way around.

2. Keep in mind that original thought and insightful analysis are required for a 4.0, 3.5, or 3.0 paper; 2.5 and below evaluations tend not to present original ideas.

3. A 4.0, 3.5, or 3.0 paper will create a "dialogue" between the essay author's ideas and her sources, and also among the sources themselves. 2.5 and below evaluations will often summarize one point at a time, with the essay author's idea stated at the end. If you imagine a synthesis essay as a room in which the synthesis writer is joined by the authors of her/his sources, the 4.0, 3.5, or 3.0 essay has everyone engaged in conversation or debate, with everyone commenting on (or arguing against) each other's ideas directly. In the 2.5 and below essay, each person in the room stands up in turn, gives a speech, and sits down, with little or no question and answer period in between or afterward.

4. Take special care to address your audience in an appropriate manner. Make sure you establish your credibility on the subject and that you provide sufficient information to make your argument (thesis) convincing.

5. Organize your paper logically:
A. State your thesis clearly and make sure that it reflects the focus of your essay.
B. Make sure your main points are clearly stated (use topic sentences), and connect each point to your thesis as explicitly as possible.
C. Divide paragraphs logically.
D. Provide appropriate transitions both within and between paragraphs.
6. Develop each main idea thoroughly. Use specific examples and source materials appropriately as support. Be sure to integrate source materials smoothly into your own writing using attribution phrases and transitions. Also be sure to avoid unnecessary repetition (repetition is often an organization problem).

7. Select words precisely. When in doubt, use a dictionary!

8. Make sure sentences are clear and unambiguous. Avoid passive voice. Double-check to see that sentences are adequately varied in length and style, and that there are no fragments or run-ons. Also proofread carefully to correct any other sentence errors.

9. Proofread carefully to identify and correct mechanical errors, such as errors in plurals or possessives, subject-verb agreement, shifts in verb tense or person ("you"), comma errors, spelling errors, and so on.

10. Quadruple check your MLA documentation. Are your parenthetical citations correct? Is your Works Cited list correct according to MLA style, and does it include all sources cited in your essay?

11. Be sure to give your essay a descriptive and attention-getting title (NOT "Synthesis," for goodness sake!!!).

12. Make sure your essay is formatted correctly and posted to your web site correctly.


HOW TO WRITE SYNTHESIS ESSAYS

  1. Consider your purpose in writing. Read the topic assignment carefully. What are you trying to accomplish in your essay? How will this purpose shape the way you approach your sources?
  2. Select and carefully read your sources, according to your purpose. Re-read the sources, mentally summarizing each. Identify those aspects or parts of your sources that will help you in fulfilling your purpose. When rereading, label or underline the passages for main ideas, key terms, and any details you want to use in the synthesis.
  3. Formulate a thesis. Your thesis is the main idea that you want to present in your synthesis. It must be expressed as a complete sentence and include a statement of the topic and your assertion about that topic. Sometimes the thesis is the first sentence, but more often it is the final sentence of the first paragraph.
  4. Decide how you will use your source material and take notes. How will the information and the ideas in your sources help you to fulfill your purpose? Re-read your sources and write down the information from your sources that will best develop and support your thesis.
  5. Develop and organizational plan, according to your thesis. (See Techniques for Developing Synthesis Essays immediately below.) How will you arrange your material? It is not necessary to prepare a formal outline, but you should have some plan in mind that will indicate the order in which you will present your material and that will indicate the relationships among your sources.
  6. Write the first draft of your synthesis, following your organizational plan. Be flexible with your plan, however, and allow yourself room to incorporate new ideas you discover as you write. As you discover and incorporate new ideas, re-read your work frequently to ensure that your thesis still accounts for what follows and that what follows still logically supports your thesis.
  7. Document your sources. Use MLA-style in-text citations and a Works Cited list to credit your sources for all material you quote, paraphrase, or summarize. For example, if I wanted to note in my essay the difference between name-calling and argumentum ad hominem as personal forms of attack, I would credit the article on "Politics: The Art of Bamboozling" fromWARAC by offering a citation that includes the author's last name and the exact page number where she discussed this notion (Cross 302). At the end of the essay, I would have a complete bibliographic citation for the "Politics" article.
  8. Revise your synthesis. Insert transitional words and phrases where necessary. Integrate all quotations so they flow smoothly within your own sentences. Use attribution phrases to distinguish between your sources' ideas and your own ideas. Make sure the essay reads smoothly, logically, and clearly from beginning to end. Check for grammatical correctness, punctuation, and spelling.

TECHNIQUES FOR DEVELOPING SYNTHESIS ESSAYS

SUMMARY: The simplest - and least sophisticated - way of organizing a synthesis essay is to summarize your most relevant sources, one after the other, but generally with the most important source(s) last. The problem with this approach is that it reveals little or no independent thought on your part. Its main virtue is that it at least grounds your paper in relevant and specific evidence.

Summary can be useful - and sophisticated - if handled judiciously, selectively, and in combination with other techniques. At some time you may need to summarize a crucial source in some detail. At another point, you may wish to summarize a key section or paragraph of a source in a single sentence. Try to anticipate what your reader needs to know at any given point of your paper in order to comprehend or appreciate fully the point you are making.

EXAMPLE OR ILLUSTRATION: At one or more points in your paper, you may wish to refer to a particularly illuminating example or illustration from your source material. You might paraphrase this example (i.e., recount it, in some detail, in your own words), summarize it, or quote it directly from your source. In all these cases, of course, you would properly credit your source.

TWO (OR MORE) REASONS: The "two reasons" approach can be an extremely effective method of development. You simply state your thesis, then offer reasons why the statement is true, supported by evidence from your sources. You can advance as many reasons for the truth of your thesis as needed; but save the most important reason(s) for last, because the end of the paper is what will remain most clearly in the reader's mind.

STRAWMAN: When you use the strawman technique, you present an argument against your thesis, but immediately afterward you show that this argument is weak or flawed. The advantage of this technique is that you demonstrate your awareness of the other side of the argument and show that you are prepared to answer it. The strawman argument first presents an introduction and thesis, then the main opposing argument, a refutation of the opposing argument, and finally a positive argument.

CONCESSION: Like the strawman, the concession technique presents the opposing viewpoint, but it does not proceed to demolish the opposition. Instead, it concedes that the opposition has a valid point but that, even so, the positive argument is the stronger one. This method is particularly valuable when you know your reader holds the opposing view.

COMPARISON AND CONTRAST: Comparison and contrast techniques enable you to examine two subjects (or sources) in terms of one another. When you compare, you consider similarities. When you contrast, you consider differences. By comparing and contrasting, you perform a multifaceted analysis that often suggests subtleties that otherwise might not have come to your attention.

To organize a comparison/contrast analysis, you must carefully read sources in order to discover significant criteria for analysis. A criterion is a specific point to which both of your authors refer and about which they may agree or disagree. The best criteria are those that allow you not only to account for obvious similarities and differences between sources but also to plumb deeper, to more subtle and significant similarities and differences. There are two basic formulas for comparison/contrast analysis:

 BY SOURCE
 BY CRITERIA
I. Introduce essay, state thesis I. Introduce essay, state thesis
II. Summarize passage A II. Introduce Criterion 1
  A. View on Criterion I  A. Passage A's viewpoint
  B. View on Criterion 2  B. Passage B's viewpoint
III. Summarize passage BIII. Introduce Criterion 2
  A. View on Criterion 1  A. Passage A's viewpoint
  B. View on Criterion 2  B. Passage B's viewpoint
IV. Discussion and conclusionIV. Discussion and conclusion

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Hemoglobin: Structure, Function and its Properties

  • Marcello Malpighi described the RBCs in 1665.
  • Felix Hope Seyler in 1862 isolated pure Hemoglobin.
  • Christian Bohr in 1904 discovered that hemoglobin is the transporter of oxygen.
  • In 1912 Kutster established the structure of hemoglobin.
  • Hans Fischer synthesized heme in laboratory in 1920 (Nobel prize, 1930).
  • In 1945, Linus Pauling (Nobel prize, 1954) described abnormal hemoglobins.
  • Max Perutz (Nobel Prize, 1962) studied the 3D structure of Hemoglobin.

Table of Contents

What is Hemoglobin?

Hemoglobin is a globular heme protein in vertebrate red blood cells and in the plasma of many invertebrates that carries oxygen and carbon dioxide; heme group binds oxygen and carbon dioxide and as well as imparts red color to the blood; also spelt as hemoglobin.

Introduction of Hemoglobin Protein:

  • Red colored conjugated protein (made up of heme and Globin) present inside the RBC
  • Normal Hb% in adult male is 14 to 16 gm.
  • Approximately 6.25 gm of Hb are synthesized and destroyed every day.
  • Heme structure does not vary from species to species.
  • It is the basic protein globin that varies in amino acid composition and sequence in different species.
  • Globin is rich in Histidine and lysine.

Importance:

  • Hb binds O2 transports O2 and delivers the same to tissues.
  • Hb binds CO2, a waste product of metabolism.
  • 2-3 BPG,produced in RBC by Rapport-Leubering shunt stabilizes Hb conformation at quaternary level and enhances dissociation of O2 from Hb at tissue site.
  • Cyanide combines with methamoglobin to form cyanomethemoglobin which is non-toxic.
  • Study of Hb structure gives an insight into the molecular basis of hemoglobinopathies.

Structure of Hemoglobin:

  • Heme is iron porphyrin compound. Porphyrin is a tetrapyrrole structure.
  • Ferrous iron occupies the center of the porphyrin ring and establishes linkages with all the four nitrogens of all the pyrrole rings.
  • It is also linked to nitrogen of imidazole ring of histidine present in globin part.
  • Globin part is made of four polypeptide chains, to identical α-chains and two identical β-chains in normal adult hemoglobin.
  • Each chain contains a “heme” in the so called ‘heme pocket’. So one Hb molecule possess four heme units.
  • Hb molecule contains hydrophobic amino acids inside and hydrophilic ones on the surface.
  • Heme pockets of α-subunits are of just adequate size to give entry to an O2 molecule. Entry f O2 into heme pockets of β-subunits is blocked by a valine residue.
  • Varieties of normal human Hb are
    • Hb-A1 (two α-chains and β-chains)
    • HbF (two α-chains and ¥-chains)
    • Hb-A2 (two α-chains and delta-chains)
    • Embyonic Hb (two α-chains and €-chains)
    • Hb-A3 (Altered from Hb-A found in old red cells)
    • HbA1C (Glycosylated Hb, present in concentration of 3-5% of total Hb). In diabetes mellitus it is increased to 6 to 15%.

Hemoglobin derivatives:

  • Hemin (Hematin hydrochloride)
  • Hemochromogen
  • Hematoidin
  • Methemoglobin (Oxidation product of Hb; produced by drugs like nitrites, phenacetin, sulphonamide drugs; lack of enzymes like methamoglobin reductase, diaphorase-I, HbM.
  • Toxic effects of Met Hb are : cyanosis, fatigue, tachycardia, tachypnea, depression.
  • Methemalbumin: (Combination of hematin with albumin),not present in normal adult blood, when present indicates intravascular hemolysis, detected by Schumm’s test.

Combination of Hb with gases:

  • Oxyhemoglobin: (loose and reversible combination with O2); 1.34ml O2 combines with each gm of Hb.
    • One mole of Hb can maximally combine with four mols of O2. Partial pressure of O2 favors oxygenation.
    • Partial pressure of CO2 favors dissociation. Acidosis favors liberation of O2.
    • Oxygenated Hb is in relaxed state i.e, ‘R’ state. R state characterized by removal of valine residue from heme pocket of β-subunit; broken salt bridges; can not bind BPG; FFe++ comes in plane of porphyrin ring; Heme-Heme interaction increases te affinity to O2; Histidines ofβ-chains release protons (H+).
  • Deoxygenated Hb: In “T” form i.e. Taut form, salt bridges plenty and intact, valine residue covers heme pocket of β-chain and does not allow entry of O2; can bind BPG; F++ out of the plane of porphyrin ring; low affinity to O2; β-chain histidine residue protonated (H+ added).
  • Carboxyhemoglobin (Hb+ carbo monoxide): Firmer combination, not reversible, affinity of Hb to CO in 210 times more than )2; inhibits cytochrome oxidase of electron transport chain.
  • Carbamino Hb (Hb + CO2):
  • Sulfhaemoglobin: Greenish pigment; formed when H2S reacts with Oxy-Hb, seen in severe constipation, certain types of bacteria.

Abnormal Haemoglobins:

More than 30 abnormal types descries, differentiated by their characteristic electrophoretic mobilities, generally transmitted; are due to single mutant gene; Two types –

  • Due to mutation of structural gene. E.g: HbS, HbM, HbC, HbD (Punjab) etc.
  • Due to mutation in regulator gene. E.g: Thalassemias.
  • Detection by Finger Printing techniques and Hybridization

Effects of abnormal Hb:

  • Changed Red cell morphology
  • Haemolytic anemia, Jaundice
  • Methamoglobinemia
  • High O2 affinity E.g:Hb chesapea ke, Hb-Rainier
  • Interfere with mRNA formation e.g.: Hb constant spring

HbS:

In both β-chains glutamic acid in 6th position is replaced by Valine. This results in increase of viscosity and precipitation of HbS. Hence the crescent or sickle shaped RBC of more fragile nature. However such RBCs show increased resistance to malaria but more vulnerable to salmonella infections.

Thalassemias:

  • α-chain Thalassemia: Synthesis of α-chains are replaced. E.g.: HbH (β4) and Hb-Barts (¥4).
  • β-chain Thalassemia (Thalassemia major): Synthesis of β-chain is repressed. As a result increased synthesis of HbA2 or HbF.

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