Physics Class
summaries:
1. Each summary must be typed as a SINGLE paragraph with a 12 pt font and single-spaced with 1”
margins on all sides.
2. You must discuss EVERY topic of the chapter for the sections that are listed in the schedule. If you
leave out a topic, then you will get no credit no matter the length of your summary.
3. Each summary must be written entirely in your own words (No equations allowed!). Do not copy the
wording in the textbook or from any other source. Such acts are plagiarism and constitute academic
dishonesty; see http://www.utoledo.edu/policies/academic/undergraduate/pdfs/3364-71-04
Academic dishonesty.pdf. Optical character recognition and plagiarism software is ubiquitous and we
use it regularly. You will automatically fail the course if you are guilty of plagiarism to any degree.
4. The very first line will include your name, the chapter number and your recitation section number in the
following format:
Alex Newton Chapter 47 Summary Recitation 03
5. You will skip the second line and start your summary on the third line of the page. Write the entire
summary in a single paragraph. See the example summary at the end of the syllabus.
6. Your summary must contain at least 35 lines of text, covering every section of the entire chapter.
Absolutely no bullets or numbered lists are allowed! If your summary is acceptable, a check-mark will
be place on your quiz or exam. If not acceptable, then no check-mark will be place on the quiz/exam.
7. Only hard copies of each summary are accepted! You cannot submit them via email!
8. Print each summary at least one day before it is due so you don’t miss the deadline because of a printing
problem! You can submit chapter summaries early, if you wish.
9. Each summary must be submitted by 9:25:00 AM (as measured by my timepiece) on the day it is due.
Note that 9:25:01 AM is too late!
10. You must submit your chapter summary either on the table in MH 1005 on Friday morning or give it to
me directly. You are never allowed to submit your chapter summary in any other way.
11. All summaries must be on a SINGLE sheet of paper. If your summary is longer than one page, you can
also use the back of that single sheet of paper.
12. All summaries longer than a single sheet of paper will be thrown away and you will get no credit.
13. Attempting to submit a late chapter summary will result in a penalty (of -2 chapter summaries for each
late chapter summary attempted) to your extra credit score.
14. If you will miss class on a Friday because of an excused absence, you must turn in the summary before
its due date, except in the case of a documented emergency (such as illness).
15. Submitting acceptable summaries for all 16 chapters will result in your final exam score being increased
by 20% of your score. If you submit only some of the summaries, you will receive the appropriate
amount of extra credit (e.g., 9/16 of 20% if you submit 9 acceptable summaries).
16. As an example, if you did all the extra credit and received an 88 on the final, then your extra credit would
be 0.20 × 88 = 17.6, making your final exam score = 88 + 17.6 = 105.6.
17. All summaries must be given directly to me or turned in at the time of the quiz or exam. You can never
give your chapter summary to your TA, put it in my mailbox or slide it under my office door.
18. You can always submit chapter summaries to me early! I encourage you to do that.
On the next page is an example of the correct format for a chapter summary
Alex Newton Chapter 47 Summary Recitation # 3
This chapter discusses the factors which affect the conformation of the doublehelical
deoxyribonucleic acid (DNA) molecule. The conformation of the DNA molecule
is obviously of great importance to its biological function, as described in the
introduction of this chapter. Transcription, the process by which the genetic code is read
from a gene, involves the unwinding of the double helix into a flat structure vaguely
similar to a ladder. The two strands are separated and a single strand of messenger RNA
is created by base-pairing with the template strand. The details of the unwinding of the
double helix will depend on the initial geometry of the double helix. Consequently, it is
important to understand the factors which control the conformation of double-helical
DNA. These factors include the local charges of the DNA molecule, the nature of the
counterion, the Coulombic interaction, the hydrophobicity of the bases, the electrolytic
strength and water content of the environment and bonding with neighboring molecules.
The DNA molecule is composed hydrogen, carbon, nitrogen, oxygen and phosphorous
atoms. Since these atoms have different electronegativities, they do not “share” the
electrons of their covalent bonds equally. This causes atoms with a higher
electronegativity to have a net negative charge while atoms with a lower electronegativity
to have a net positive charge. These locally charged regions interact via the Coulombic
interactions, affecting the conformation of the molecule. Coulombic interactions are also
important since each basepair has a net charge of -2e. All of these Coulombic
interactions are affected by the local water content because of the very high dielectric
constant of water. This makes water a very effective screener of the Coulombic
interaction. Consequently, the water content of the sample can have very significant
affects on the conformation. Similarly, for DNA in solution, the electrolytic strength of
the solution can greatly alter the conformation. The four bases of DNA (adenine,
thymine, guanine and cytosine) are hydrophobic in nature. Consequently they are found
on the inside of the phosphodiester backbones composed of deoxyribose and phosphate
groups. This geometry minimizes interactions between the bases and water. Their base
pairing (A-T and G-C) permits for a smooth double helix since the two basepairs are
almost identical in size. If they were significantly different in size, the phosphodiester
backbone would not be a smooth helix. Van der Waals interactions between stacked
bases affect the temperature stability of the double helix. Hydrogen bonding between the
bases and between the DNA molecule and its local water of hydration also has significant
effects on the conformation of the DNA. Counterions are necessary for DNA to cancel
the -2e charge of each base pair. The various counterions (Na+ or K+, for instance) can
participate in electrostatic bonding between neighboring DNA molecules or molecules
(such as proteins) near the DNA molecules. Such bonding between neighboring DNA
molecules is relevant to our study of chromosomes in which the DNA is packed in a
highly condensed state. Histones (composed of proteins) are incorporated in the
chromosomes by having the DNA wrapped around the histones. These intermolecular
interactions (similar to the intermolecular interactions of solid DNA) are critical for
chromosome’s stability. Exactly how these interactions are modified during the
replication of a chromosome is currently a mystery to science.
