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AP Biology
Saturday Study Session 2
Information Transfer
Student Packet
Session 3 – Modern Genetics
Multiple Choice Questions
1) DNA replication is the process of making an exact copy of an existing DNA molecule during the S
phase of Interphase in the cell cycle. Which of the following does NOT occur during DNA
replication?
A) Complimentary base pairing between the constructed complimentary strand and the template
DNA molecule.
B) Polymerization of the new complimentary strand in the 3’  5’ direction.
C) Unwinding of the parent double helix to form two template molecules that will serve as guides
for constructing the complimentary strand.
D) The use of RNA primers to start the formation of short pieces of DNA that will eventually be
connected together using the enzyme ligase.
2) DNA polymerase can act as a “proofreader” during the DNA replication process. Some mutations
to an existing DNA molecule can occur, by environmental sources such as radiation. Cells will try
to correct these abnormalities by utilizing nucleotide excision repair. What is the correct sequence
for the following events in excision repair?
1) DNA Polymerase adds correct bases by 5’ 3’ replication
2) Damaged bases are recognized
3) DNA ligase seals the new strand to existing DNA
4) Part of a single strand is excised
A)
B)
C)
D)
2, 4, 1, 3
1, 2, 3, 4
3, 4, 2, 1
4, 2, 3, 1
3) Polymerase Chain Reaction (PCR) is a process utilized everyday in education, scientific research
and legal cases. Polymerase Chain Reaction serves what purpose?
A) PCR is utilized to sequence existing DNA molecules for comparing nucleotide sequences
between organism.
B) PCR is used for transcribing specific gene sequences.
C) PCR utilization is for amplifying small quantities of DNA molecules to large workable samples.
D) PCR ultilization is used during the creation of transformed prokaryotes to aid in the
bioremediation of environments.
4) Messenger RNA serves as a “messenger” between the safety of the nucleus and the harsh
cytoplasmic environment where ribosomes are located. The ribosomes use the mRNA molecule to
synthesis proteins by the process of translation. An mRNA has the sequence 5’ –AUGAAAUCCUAG 3’. What is the template DNA strand for this generating this mRNA sequence?
A)
B)
C)
D)
5’ – TACTTTAGGATC – 3’
5’ – ATGAAATCCTAG – 3’
5’ – TACAAATCCTAG – 3’
5’ – CTAGGATTTCAT – 3’
5) Gene expression for a phenotypic trait is accomplished through protein synthesis. Which
statement about translation is NOT true?
A)
B)
C)
D)
An mRNA molecule can be translated by only one ribosome at a time.
The same genetic code operates in all living organisms and organelles.
The mRNA molecule is translated using three nucleotide sequences called codons.
tRNA molecules deliver free amino acids from the cytoplasm to the A site of a ribosome.
6) Prokaryotes genomes are structural different than eukaryotic genomes in that they do not possess
nucleotide sequences referred to as introns. The regulatory mechanisms for gene expression can
also be different. One such regulatory mechanism in prokaryotes is the operon. Which of the
following statements about the lac operon is NOT true?
A) When lactose binds to the repressor, the repressor changes shape and can no longer bind to
the operator.
B) When lactose binds to the operator, transcription is stimulated.
C) When the repressor binds to the operator, transcription is inhibited.
D) The repressor protein has binding sites for DNA and lactose.
Math Grid In
Using the provided gel electrophoresis of a plasmid, determine the number of base pairs that exist on the
plasmid.
Perform calculations here:
Short Free Response
1) Mutations are rare. Most of the time, if a mutation occurs, it is harmful to that cell or organism.
Sometimes mutations can be beneficial though. There are two types of mutations that can occur in
the process of Protein Synthesis – point mutations and reading frame mutations. Explain what has
occurred to a DNA molecule, in terms of the mutation, and describe the outcome of that mutation
as it relates to the structure of a protein’s amino acid sequence.
2) A research scientist is wanting to alter a bacterial genome to allow it to synthesize the humane
hormone known as Human Growth hormone. The bacteria’s ability to produce human growth
hormone will greatly reduce the cost to a patient who suffers from Pituitary dwarfism, usually
associated with a genetic condition where the person cannot produce the hormone in their body.
Describe the procedural process the scientist will perform to get the gene for human growth
hormone to combine with a bacterial plasmid for insertion.
Long Free Response
The diagram below shows a segment of DNA with a total length of 4,900 base pairs. The arrows indicate
reaction sites for two restriction enzymes (enzyme X and enzyme Y).
.
.
.
(A) Explain how the principles of gel electrophoresis allow for the separation of DNA fragments.
(B) Describe the results you would expect from the electrophoretic separation of fragments from
the following treatments of the DNA segment above. Assume that the digestions occurred under
appropriate conditions and went to completion. I. DNA digested with only enzyme X II. DNA
digested with only enzyme Y III. DNA digested with enzyme X and enzyme Y combined IV.
Undigested DNA
(C) Explain both of the following. (1) The mechanism of action of restriction enzymes (2) The
different results you would expect if a mutation occurred at the recognition site for enzyme Y.