Name
Date
Period
DNA & Replication Worksheet
1.
Write out the complete name for DNA:
2.
A nucleotide is made of three parts: a
nitrogen containing
base
phosphate group, a five carbon sugar and a
In a single strand of DNA, the phosphate group binds to the
4.
The 5' end of a single DNA strand contains a free
5.
phosphate
Label these three parts on the diagram to the right:
3.
contains a free
N base
deoxyribonucleic acid
sugar of the next group.
phosphate, while the 3' end
sugar
OH.
DNA was not thought to be the genetic blueprint originally; instead many scientists hypothesized that
protein contained the genetic code and blueprint of life. (They were later proven wrong.)
6.
Purines have two rings, and pyrimidines have
7.
Chargaff's rule states that the DNA of any species contains equal amounts of
also equal amounts of guanine &
8.
adenine & thymine and
cytosine.
Wilkinsand Franklin studied the structure of DNA using
the shape of the molecule was a
9.
one ring.
x-ray crystallography and determined that
helix.
James Watson and Francis Crick amended Franklin and Wilkin's conclusions and determined that the shape of
the molecule was instead a
double helix.
10. Name the scientist(s) responsible for each of the following discoveries.
Griffith
Chargraff
Hershey & Chase
Franklin (& Wilkins)
Watson & Crick
Bacterial transformation
The base-pair rule
DNA was the hereditary material of viruses
The shape of DNA was a helix
The shape of DNA was a double helix
11. In DNA, thymine is complementary to
adenine ; cytosine is complementary to guanine.
12. In a strand of DNA, the percentage of thymine is 30%. What is the percentage of cytosine in the same DNA
strand? 20%
13. The figure below shows DNA replicating. In the space provided, describe what is occurring.
DNA unwinds
Helicase splits apart
helix
Daughter strands are
formed using
complementary base
pairing
DNA polymerase adds
DNA nucleotides
The DNA of the daughter
strands winds together with
its parent strand
14. Number the steps of DNA replication in the correct order (1, 2, 3)
2
1
3
Daughter strands are formed using complementary base pairing.
DNA unwinds
The DNA of the daughter strands winds with together with its parent strand.
15. Why is DNA replication called "semi-conservative"?
½ is old, ½ is new
sugar
16. What enzyme unwinds or unzips the parent strand? helicase
17. What enzyme binds fragments of DNA on the lagging strand?
18. DNA polymerase builds the DNA daughter strand in the
phosphate
ligase
5’ to
3’ direction.
3’
5’
T
19. On the diagram:
Label the 3' and 5' ends.
Circle a nucleotide.
Label the sugar and phosphate.
Label the bases that are not already labeled
A
C
20. The two sides of the DNA helix are held together by
hydrogen bonds- between nitrogen bases
(covalent bonds – between the sugars and
phosphates in the backbone)
A
T
21. In your own words, explain why the discovery that DNA was the
molecule of heredity was an important discovery.
C
G
3’
G
5’