AP Biology 11
DNA Replication and Protein Synthesis
Concept 2: Analyzing the processes of DNA Replication (Ch 16)
Name:___________________
Date:____________________
Block:_____
Complete the following questions to help you understand Concept 2.
1) Define the following terms:
Term
DNA ligase
DNA polymerase I
DNA polymerase III
double helix
helicase
lagging strand
Definition
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of
the 3’ end of a new DNA fragment to the 5’ end of a growing chain
An enzyme that catalyzes the elongation of new DNA at a replication fork by the
addition of nucleotides to an existing chain – DNA pol I specifically catalyzes the
removal of RNA nucleotides from the 5’ end of the RNA primer and replaces them
with DNA nucleotides
An enzyme that catalyzes the elongation of new DNA at a replication fork by the
addition of nucleotides to an existing chain – DNA pol III specifically catalyzes the
addition of nucleotides to the 3’ end of a pre-existing DNA strand or RNA primer
The form of native DNA, referring to its two adjacent polynucleotide strands
would into a spiral shape
An enzyme that untwists the double helix of DNA at the replication forks
origin of replication
A discontinuously synthesized DNA strand that elongates in a direction away
from the replication fork
The new continuous complimentary DNA strand synthesized along the template
strand in the mandatory 5’ to 3’ direction
The cellular process that used special enzymes to fix incorrectly paired
nucleotides
A team on enzymes that hydrolyze DNA and RNA into their component
nucleotides
The process of removing and then replacing a damaged segment of DNA using
the undamaged strand as a guide
Fragments of the lagging strand of synthesizing DNA, about 100-200 nucleotides
long. They are joined together by the enzyme ligase
Sites where the replication of a DNA molecule begins
primase
An enzyme that joins RNA nucleotides to make the primer
primer
An already existing RNA chain bound to a template DNA to which DNA
nucleotides are added during DNA synthesis
A Y-shaped region on a replicating DNA molecule where new stands are growing
leading strand
mismatch repair
nuclease
nucleotide excision
repair
Okazaki fragment
replication fork
semiconservative
model
single strand binding
protein (SSBP)
telomerase
Type of DNA replication in which the replicated double helix consists of one old
strand, derived from the old molecule, and one newly made strand
During DNA replication, molecules line up along the unpaired DNA strands,
holding them apart while the DNA strands serve as templates for the synthesis of
complimentary strands of DNA
An enzyme that catalyzes the lengthening of telomeres. The enzyme includes a
molecule of RNA that serves as a template for new telomere segments
telomere
topoisomerase
The protective structure at the end of a eukaryotic chromosome. Specifically, the
tandomly repetitive DNA at the end of the chromosome’s DNA molecule
Helps relieve the strain from the twisting of DNA strands in front of helicase
2) Compare DNA and RNA by filling out the following chart:
DNA
(deoxyribonucleic acid)
RNA
(ribonucleic acid)
deoxyribose
ribose
adenine
thymine
guanine
cytosine
adenine
uracil
guanine
cytosine
2 strands (in a double helix)
1 strand
To contain genetic information
To relay the information from the
genetic code for protein synthesis
Sugar
Types of Bases
# of Strands
Function
3) List the three components of a nucleotide.
Phosphate – Sugar – Nitrogen Base
4) Explain what is meant by 5' and 3' ends of the nucleotide.
5’ end is the exposed phosphate end (attached to the 5th carbon of the
sugar)
3’ end is the exposed “OH” of the sugar (attached to the 3 rd carbon of
the sugar)
5) Who built the first model of DNA and shared the 1962 Nobel Prize for
discovery of its structure?
James Watson and Francis Crick
6) Distinguish between the structure of pyrimidines and purines. Explain
why cytosine binds only to guanine.
Pyrimidines (C, T, U) are single-ringed, whereas purines (A, G) are double-ringed.
Cytosine forms 3 hydrogen bonds with guanine (and only guanine). (Also, A forms 2 hydrogen bonds
with only T, or U for RNA)
7) Given that the DNA of a certain fly species consists of 27.3% adenine and 22.5% guanine, what would
be the percentages of thymine and cytosine?
Since A pairs with T and G pairs with C, there would be 27.3% thymine and 22.5% cytosine.
8) What do we mean when we say the two strands of DNA are antiparallel?
The two strands are oriented in opposite directions from one another.
5’----------------------- 3’
3’-----------------------5’
9) Name the five nitrogenous bases, and put a checkmark in the correct column for each base. Also
indicate if the base is found in DNA (D), RNA (R), or both (B).
10) During DNA Replication, the leading stand is synthesized towards the replication fork while the lagging
strand is synthesized away from the replication fork. This is because the new nucleotide can only be
added in the 5’ to 3’ direction.
11) Label the following figures. Include 3' and 5' strands, RNA primer, primase, SSBP, topoisomerase,
helicase, leading strand, lagging strand, DNA pol I, DNA pol III, DNA ligase, parental DNA, and newDNA.
12) Put it all together! Make a detailed list of the steps that occur in the synthesis of a new strand of DNA.
Use Holtzclaw and Campbell, but make sure to put it into your own words!