Homework Quiz 1: DNA and the Central Dogma
Name: Haley Culp
For each of the questions below, give the best answer. You may answer directly on the
document electronically and upload your document on Canvas. If you prefer, you may also print
and answer by hand writing, uploading a scanned copy to Canvas. (10 pts. each).
1. Consider the structure of a nucleotide. Which component(s) is/are important in connecting
another nucleotide in a growing DNA strand? Explain.
DNA polymerase is a vital component of adding nucleotides to the 3’ end of the
daughter strand. Before this can be done, telomerase is needed to elongate and prep
the strand for replication. In the case of the lagging strand, RNA primer is needed to
start replication
2. Again, consider the structure of a nucleotide. Which component is important in connecting a
two anti-parallel DNA strands together to form a DNA double-helix? Explain.
The nitrogenous bases account for the connection of the strands, as hydrogen bonds
form between them, whether it be adenine with thymine or guanine with cytosine.
3. A scientist tries to stop tumor progression by inhibiting DNA replication in tumor cells.
Specifically, the tumor cells are treated with a compound that blocks the function of DNA
replication helicase. If the amount of DNA in each cell during G1 is X, how much DNA would
you expect in each treated cell at the end of S phase? Assume the cell has not died (yet…).
Explain your answer, including why blocking helicase would result in this.
The same amount, X, would be expected. Helicase breaks the hydrogen bonds that
link the strands to allow for replication, so blocking its function would result in the
prevention of DNA replication.
For each statement in #4-8, mark whether it is true or false. If it is false, rewrite the statement so
it is completely correct.
4. DNA replication in humans occurs on one strand at a time throughout the cell cycle.
False. DNA replication in humans occurs during the S phase of the cell cycle, with
two new strands being synthesized at the same time.
5. DNA replication in humans results in daughter strands that contain one parental strand
of DNA and one newly synthesized strand of DNA.
True.
6. DNA replication requires RNA primase to establish RNA primers.
True.
7. Introns in mRNA contain only those sequences that are translated into proteins.
False. Exons in mRNA contain only those sequences that are translated into
proteins.
8. Mature mRNAs contain a 7-methyl guanine at the 3’ ends.
False. Mature mRNAs contain a poly-A-tail at the 3’ ends.
9. Consider the following sense strand DNA sequence: 5' GGAATC, what is the corresponding
mRNA sequence? Include the “direction” of your sequence.
3’ CCUUAG 5’
10. A single nucleotide change in a codon resulted in a sequence change from GAU to GUU.
Using the codon table on the next page, write out the two amino acids that correlated with
these two codons.
GAU
: Aspartate
GUU
: Valine
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