Analytical Cytology: Methods for Studying Cellular Form and Function

By Robert C. Mellors | Go to book overview

CHAPTER 9 X-ray Diffraction Techniques and Their Application to the Study of Biomolecular Structures

GERALD OSTER, PH.D. Polytechnic Institute of Brooklyn, New York, N.Y.


Introduction

The molecular morphology of materials of biological significance is determined by a long deductive process utilizing data obtained by a variety of physical methods. Perhaps the most direct method of the visualization of biomolecular structures is that of electron microscopy, which is treated elsewhere in this volume. The electron microscope suffers, however, in its inability in practice to resolve structural elements smaller than about 30 A (one angstrom, A, equals 10-8 cm). In proteins, for example, the interatomic distances in the polypeptide chain are of the order of 1.5 A and, hence, can be resolved only by rays having wavelengths of the same magnitude. All forms of matter scatter x-rays. If, as is usually the case, the material is periodic on a molecular level, then monochromatic x-rays of wavelength of, say, 1.54 A (the so-called copper Kα radiation) will be diffracted. From the diffraction pattern, the structure of the scattering material can, in principle, be deduced. Even if this material is not periodic, the resultant diffuse scattering can be used to deduce the disposition of the scattering elements. X-ray diffraction techniques have an additional feature not possessed by electron microscopy, in that the former method can be applied to determination of structures of gels and concentrated solutions of macromolecules.

The diffraction pattern may, in some cases, be extremely elaborate. For example, crystalline proteins may show an x-ray diagram containing more than a thousand spots. For this reason, other physical techniques, such as visible-light birefringence and infrared dichroism, are frequently employed in conjunction with the x-ray studies. This infor-

-9/1-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Analytical Cytology: Methods for Studying Cellular Form and Function
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
/ 32

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.