Bio 183
Constructing Powerful Sentences And Paragraphs
From: Hofmann A.H. Scientific Writing and Communication.
GOAL: authors should guide and influence readers.
7.
Establish importance.
Word location within a sentence, if considered carefully, can help authors to guide and influence
readers. The format and structure authors use to present information will lead the reader to interpret it
as important or less important. To decide on the best placement of words within a sentence, it is crucial
that authors establish importance. In general, the end position in a sentence is more emphasized than
the beginning position, and the main clause is more emphasized than the dependent clause.
Consider the following four versions of a sentence:
Example
a
Although vitamin B6 seems to reduce the risk of macular degeneration, it
may have some side effects.
b
Vitamin B6 reduces the risk of macular degeneration, but it may have
some side effects.
c
Taking vitamin B6 may have some side effects, but vitamin B6 also
reduces macular degeneration.
d
Although taking vitamin B6 has some side effects, vitamin B6 reduces
macular degeneration.
If readers were to vote on the impact of each sentence, the percent of readers that would recommend
taking vitamin B6 then would be:
Sentence
a
b
c
d
news in main clause
negative
positive
negative
positive
news in end position
negative
negative
positive
positive
percent that recommend
vitamin B6 (%)
30
40
60
70
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8.
Place old, familiar, and short information at the beginning of a
sentence in the topic position.
9.
Place new, complex, or long information at the end of a sentence in
the stress position.
Readers expect to see old information that links backward at the beginning of a sentence (or paragraph)
and new information at the end of a sentence (or paragraph) where it is more emphasized. If it is
placed where most readers expect to find it, information is interpreted more easily and more uniformly.
Above all, writing “flows’ much better if the information is linked through word location, such as when
the information at the end position of a sentence is placed at the beginning, or topic position, of the
next sentence, as in the following example.
Example
Macular degeneration is affected by diet. One of the diet components that influences
the progression of macular degeneration is vitamin B6. Although vitamin B6 seems to reduce
the risk of macular degeneration, it may have some side effects.
10.
Get to the subject of the main sentence quickly and make it short and specific. If
possible, use central characters and topics as subjects.
Readers understand a sentence more easily if the subject of it is readily available. When a sentence is
started with several words before its subject/topic, readers have a hard time to see what the sentence is
about. Avoid such long introductory phrases and subjects.

Example
Because high resolution EM methods can show fine details of oligomeric
proteins or complexes such as ribosomes, these methods may show where
nucleic acid strands are located.
☺
Revised
High resolution EM methods may show where nucleic acid strands are located
because these methods can show fine details of oligomeric proteins or complexes
such as ribosomes.
Readers also prefer to see characters as their subjects. Most readers prefer central characters to be life
characters rather than abstract terms. However, concepts can also serve as central characters if the
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corresponding verb describes an action.

Example
The reason for rejection on the part of the biochemists was that the focus
of the paper was too broad.
☺
Revised
The biochemists rejected the paper because it was too broad.
11.
Place the verb immediately after the subject and avoid interruptions
between verb and object.
Readers expect grammatical subjects to be followed immediately by the verb as information is more
easily interpreted if it is not obstructed. Anything of length that intervenes between subject and verb is
read as an interruption, and therefore as something of lesser importance.

Example
Dengue virus, a Flavivirus belonging to the family Flaviviridae, which includes
over 60 known human pathogens such as those causing yellow fever, Japanese
encephalitis, tick-borne encephalitis, Saint Louis encephalitis, and West Nile
encephalitis, is classified into four different serotypes, types 1, 2, 3, and 4.
This sentence obstructs the reader, because the grammatical subject ("Dengue virus") is separated from
its verb ("is classified") by 31 words.
Often an interruption can be moved to the beginning or the end of a sentence, depending on
whether it is connected to old or new information in the sentence. At other times, the author should
consider splitting the information into two sentences.
☺
Revised A
Dengue virus is a Flavivirus belonging to the family Flaviviridae, which
includes over 60 known human pathogens such as those causing yellow fever,
Japanese encephalitis, tick-borne encephalitis, Saint Louis encephalitis, and
West Nile encephalitis. It is classified into four different serotypes, types 1, 2, 3,
and 4.
☺
Revised B
Dengue virus is classified into four different serotypes, types 1, 2, 3, and 4.
Readers also like to get past the verb to the object of a sentence quickly. Thus, authors should avoid
any interruptions between verb and object by placing interrupting passages either at the beginning or at
the end of the sentence.

Example
We have appended, to determine if deoxyribozymes can similarly be
activated by effector molecules, an anti-adenosine aptamer to a selected
deoxyribozyme ligase.
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☺
Revised
14.
To determine if deoxyribozymes can similarly be activated by effector
molecules, we have appended an anti-adenosine aptamer to a selected
deoxyribozyme ligase.
Use past tense for observations, completed actions, and specific conclusions.
Many scientific authors seem to be confused about when to use past tense and present tense. Many are
also unsure if past tense and present tense can be mixed in the same paragraph or sentence. Generally,
you should use the past tense for observations, completed actions, and specific conclusions.
☺
Example
15.
The IV caused local irritation in 53% of the patients.
Use the present tense for generalizations and statements of general validity.
Use the present tense for generalizations and statements of general validity.
☺
Example
Most regions where this problem arises belong to category X.
A sentence can also have mixed tenses, as is apparent in the next example:
☺
Example
Sultan observed that certain species of bacteria respond to light stimuli.
Here, the experiment has been completed. “Observed” is therefore written in past tense. “Respond”,
however, is present tense because this part of the sentence is still true and considered established
knowledge because it has been published.
16.
Write short sentences. Aim for one main idea in a sentence.
Short sentences are easier to understand than long sentences. Aim for sentences with an average
number of words of about 15-20. Short, simple sentences tend to emphasis the idea contained in them.
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However, using only short sentences does not result in strong writing. Some sentences will be long to
communicate complex ideas.
Make sure your sentences do not contain more than one main idea and that they do not wander.
Subordinate less important information and omit unimportant information. Consider breaking
subordinate sentences into separate sentences.

Example
(79 words)
Skin swaps were cultured at the time of the removal of the
catheter from seven patients with catheter-related bloodstream infection and in
five of these cases (71%) the culture yielded bacteria of the same species with a
DNA fingerprint pattern similar to that of the isolates from the catheter and the
blood, whereas a different organism grew from skin cultures in the other two
patients (29%), suggesting that catheter infection may have originated from
contamination of the catheter hub.
☺
Revised
Skin swaps were cultured at the time of the removal of the catheter from seven
patients with catheter-related bloodstream infection. In five of these cases (71%)
the culture yielded bacteria of the same species with a DNA fingerprint pattern
similar to that of the isolates from the catheter and the blood. However, a
different organism grew from skin cultures in the other two patients (29%).
These observations suggest that catheter infection may have originated from
contamination of the catheter hub.
Also note that single clause sentences have more weight, and thus more importance, than multi-clause
sentences.

Example
It is generally accepted in the field of medicine that rheumatic fever is an
autoimmune disease.
☺
Revised
Rheumatic fever is an autoimmune disease.
23.
Organize your paragraphs.
Sentences within a paragraph are not put together randomly. They need to be logically organized and
positioned. There are two important positions in a paragraph: the first sentence and the last sentence.
Usually, the first sentence introduces the topic of the paragraph, whereas the last sentence may be used
to summarize, draw a conclusion, or emphasize something of importance. Both of these positions are
known as power positions.
The first position in a paragraph (or section) is considered more powerful than the last position
because it gives the reader a direction of where the paragraph is going. Within the first and the last
sentence of the paragraph, the psychological geography of the sentence structure is particularly
important. The beginning of the sentences should describe familiar information, while the stress
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position within these sentences should highlight significant words to be emphasized.
!
24.
Use a topic sentence to provide an overview of the
paragraph.
A well written paragraph generally gives an overview first and then goes into detail. The topic
sentence states the central topic or message of the paragraph and guides the reader into the paragraph.
The end or stress position of the topic sentence highlights the topics that the author wants readers to
follow in the rest of the paragraph. Although the topic sentence may appear anywhere in the
paragraph, it is usually the first sentence, that is, the first power position. A topic sentence may also
contain a transition from the previous paragraph or section. The details found in the remaining
sentences are organized logically and consistently to explain the message provided by the topic
sentence.
☺
Example
There are at least three classes of theories in which (in contrast to MFL) the self
energy has strong momentum dependence: (i) Theories that involve strongly
momentum-dependent couplings such as antiferromagnetic spin fluctuation
exchange (10). (ii) Theories based on breaking of translational symmetry, such as
stripe or charge-density wave scenarios (11, 12). (iii) Theories based on an
extension from one to two dimensions of anomalous non-Fermi liquid behavior
as described in the Luttinger liquid formulation (13). In the first theory, coupling
involving an excitation whose spectrum is peaked in one part of the Brillouin
zone necessarily leads to a momentum-dependent self energy. In the second
theory, the breaking of translation invariance also results in momentum
dependence of all quantities. The third theory, the Luttinger liquid, has no
analytic dependence of the spectral function on momentum, that is on k-kF, at =
0 it is the same as the  dependence at k=kFF (14). Thus, should the new ARPES
results prove robust, these three classes of theories would require important
modifications.
The topic of the above paragraph is “Three classes of theories.” The pattern of organization, that is the
order of the remaining sentences is not random, but proceeds from least to most important and follows
the list of theories provided.
25.
Use consistent order.
To keep paragraphs organized authors also need to pay attention to keeping a consistent order of topics.
Parallelism helps locate information in paragraphs, sections, and chapters. If you list items in a topic
sentence and then describe them in the remaining sentences at the paragraph level, keep the same order.
Avoid interrupting the order of your items by filling in with other information. Also, do not add any
items not mentioned in the topic sentence.
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☺
Example
28.
In response to a foreign macromolecule, five different immunoglobulins can be
synthesized: IgG, IgM, IgA, IgE, or IgD. IgG is the main immunoglobulin in
serum. IgM is the first class to appear following exposure to an antigen. IgA is
the major class in external secretions, such as saliva, tears, and mucus. Thus, IgA
serves as a first line of defense against bacterial and viral antigens. IgA is
transported across epithelial cells from the blood side to the extracellular side by
a specific receptor. IgE protects against parasites. The role of IgD is not known.
Use key terms to create continuity. Repeat them exactly and link
them.
Readers consider a paragraph to be coherent if they can quickly find the topic of each sentence and if
they see how the topics are a related set of ideas. Thus, a coherent paragraph needs to consist of a
series of sentences that lead logically from one to the next. Cohesion is achieved not only through the
use of word location but also through key terms and transitions.
Key terms are words or short phrases used to identify important ideas in a sentence, a
paragraph, and the paper as a whole. Usually, key terms are used to identify your main points in the
topic sentence. Repeating and linking terms ensures that the topic of the work cannot be missed and
that relationships between topics are clear.
Key terms should not be changed. If you deliberately repeat key terms, your main points are
emphasized and you create continuity. If a key term is not repeated exactly and instead another term is
used, it may be difficult to see the relationship between the two terms.

Example
The dynamic binding capacity of a protein on chromatographic resins depends
largely on flow rate. For large molecules such as proteins, the shape of the
breakthrough curve may vary considerably as linear velocity is changed.
Especially readers unfamiliar with this particular topic may not know that “flow rate” and “linear
velocity” mean the same thing. Readers may be confused when two different terms are used.
☺
Revised
The dynamic binding capacity of a protein on chromatographic resins depends
largely on flow rate. For large molecules such as proteins, the shape of the
breakthrough curve may vary considerably as the flow rate is changed.
When you need to shift from a category term to a more specific term or the other way around, key
terms should be linked so continuity is not lost and the paragraph stays coherent. To link key terms,
use the category term to define the specific term.
☺
Example
Infectious diseases related to travel may be caused by gram-positive organisms.
One such organism, Staphylococcus aureus, can cause cellulitis, purulent
arthritis, and suppurative lymphadenitis.
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29.
Use transitions to indicate logical relationships between sentences.
When word location and key terms alone are not sufficient to link sentences within a paragraph or
section, transitions need to be used. Transitions ensure that the reader not only understands what each
sentence says, but also how the sentences are logically related to the story. Common transitions
include words, phrases, or even sentences. Transitions should be placed at the beginning of a sentence
for strongest continuity and are usually set off by a comma.

Example
We determined whether the increased endotoxin susceptibility of AUF1-/- mice is
due to deregulation of pro-inflammatory cytokine expression. We measured the
serum TNF level in AUF1-/- mice after LPS challenge.
In this example the logical relationship between sentence 1 and 2 is not clear because a transition is
missing. Once the transition is added in, the relationship between the two sentences becomes obvious.
☺
Revised
30.
We determined whether the increased endotoxin susceptibility of AUF1-/- mice is
due to deregulation of pro-inflammatory cytokine expression. For this purpose,
we measured the serum TNF level in AUF1-/- mice after LPS challenge.
Make your writing concise.
A well written paragraph needs to be concise. If you need to condense a passage, this often needs to be
done in combination with other techniques:
1)
Emphasize important information
2)
De-emphasize or omit less important information
3)
Replace or omit words and phrases
Establishing Importance
As a first step in condensing, you need to decide what is important, what is less important, and what is
unimportant information in your manuscript. The next steps then are to emphasize the important
information, de-emphasize the less important information, and omit the unimportant information.
Important information needs to be highlighted by placing it into a power position and/or by signalling
it, such as “Most importantly,…” or “The key finding of this study was….”. Less important
information can be de-emphasized by subordinating it. This can be done for example by placing it in a
subordinate clause. Unimportant information adds nothing but clutter and distracts the reader. It
should be omitted. De-emphasizing or omitting less important information is probably the most
important technique in condensing.
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Summary of Writing Principles
1. Write with the reader in mind.
2. Use precise words.
3. Use simple words.
4. Omit unnecessary words and phrases.
5. Avoid too many abbreviations.
6. Use correct terminology and nomenclature.
7. Establish importance.
8. Place old, familiar, and short information at the beginning of a sentence in the topic
position.
9. Place new, complex, or long information at the end of a sentence in the stress position.
10. Get to the subject of the main sentence quickly and make it short and specific. If possible,
use central characters and topics as subjects.
11. Place the verb immediately after the subject and avoid interruptions between verb and
object
12. Use the first person.
13. Use the active voice.
14. Use past tense for observations, completed actions, and specific conclusions.
15. Use the present tense for generalizations and statements of general validity
16. Write short sentences. Aim for one main idea in a sentence.
17. Use active verbs.
18. Avoid noun clusters.
19. Use clear pronouns.
20. Use correct parallel form. If possible, arrange ideas in a list to read from shorter to
longer.
21. Avoid faulty comparisons.
22. Avoid errors in spelling, punctuation, and grammar.
23. Organize your paragraphs
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24. Use a topic sentence to provide an overview of the paragraph. Arrange the details in the
remaining sentences.
25. Use consistent order.
26. Use consistent point of view (same subject for different sentences within a paragraph.)
27. Make your sentences cohesive.
28. Use key terms to create continuity. Repeat key terms exactly and early, and link them.
29. Use transitions to indicate logical relationships between sentences.
30. Make your writing concise.
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