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Regulationand
Reproduction
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Class
Date
Structure of DNA and RNA
Deoxyribonucleic acid (DNA) and bonucIeic acid (ANA) are two
of the cell’s most Important molecules. These
nucleic acids have a complex three-dimensional structure that enab
les them to direct protein synthesis in the cell.
• Study the structure of the DNA and RNA molecules
shown below. Fill in the missing labels. Then com
plete
the chart and answer the questions.
DNA
RNA
Name
Sugar
Basea
Number of Nudeotide Strands
iDNA
FINA
1. The two DNA strands twist around each other. This is called a__
_________________
2. The repeating units of
make the
backbone of DNA and RNA.
3. in a DNA molecule, the nitrogen bases of one strand attach to the nitro
gen bases of the other by
following the___________________ rule. The bases are held toge
ther by
4. A strand of DNA contains the following bases: ATCOACT. What will
be the bases on the complementary
DNA strand?
will be the bases on the complementary NA
strand?
5. Part of the DNA molecule shown above is starting to unwind. What two
cellular activities could this be
thestartof?
Copyflght 01985 by D.C. Head and Company
12
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Table 34—1. SlmiIarttI
and Diffran S.tw..n DNA and RNA
RNA
DNA
.
Ri pint
Deoxynlxse present
Phospbonc acid present
Ademne
—
The pres
Uracil present
GaI2rnne
jxeseut
cprent
-.
De
•—-
Single s*xand
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c
4
Ee
i
in nidei
4
Moves out aE nucIe
4