UNIVERSITY OF TECHNOLOGY, JAMAICA
FACULTY OF SCIENCE AND SPORTS
SEMESTER 1: Tutorial 4
DATE: September 29, 2010
GROUP: DMD
MODULE: Cell and Molecular Biology
1. A eukaryotic structural gene has two introns and three exons:
5’-exon1-intron1-exon2-intron2-exon3-3’
The GU at the 5’ end of intron2 has been mutated so it is no longer recognized. What
would the mature mRNA look like in the wild type and in the mutant?
Wild type:
Mutant:
2. The base composition of a virus was found to be 11% A, 32% G, 18% U and 39% C.
i.
It this a DNA or RNA virus? How can you tell?
ii. Is it single-stranded or double-stranded? How can you tell?
3. Describe the function of each of the following in transcription: promoter, RNA
polymerase, transcription factors, stem loop structure followed by a string of U’s, rho
protein, AAUAAA sequence.
4. A geneticist isolates a gene that contains five exons. She then isolates the mature
mRNA produced by this gene. After making the DNA single stranded, she mixes
thesingle-stranded DNA and RNA. Some of the single-stranded DNA hybridizes (pairs)
with the complementary mRNA. Draw a picture of what the DNA-RNA hybrids would
look like under and electron microscope. Keep the drawing simple (i.e. a single line for
DNA and for RNA). Hint: think about how DNA and RNA might pair and where the
complementary bases are.
5. Can transcription and translation be coupled (occur in the same compartment) in a eukaryotic
cell? Why or why not? In E. coli? Why or why not?
3
H uridine is a ribonucleotide in which uracil is radioactively labeled.
a. When this label is applied to eukaryotic cells growing in a culture dish, it is first seen in
the nucleus. What process is this molecular tag labeling?
b. When cells are observed at a later time after the labeling, the 3H uridine is in the
cytoplasm associated with ribosomes. What process is this molecular tag now labeling?
5. Complete the following table: Label the 5’ and 3’ ends of DNA and RNA and the
amino and carboxyl ends of the protein. Assume it is read left to right and the columns
represent transcriptional and translational alignments. (a copy of the codon table is on the
last page of this exam)
DNA
double helix
mRNA
tRNA
anticodon
Amino acid
C
C
T
U
A
G
C
G
A
A
TRP
1.
DNA replication is semi-conservative, what does this mean? If DNA replication were
conservative, where would the DNA band in the centrifuge tube be after one round of
DNA replication in the Messelson Stahl experiment?
2.
Diagram the process of semi conservative replication of DNA by drawing the
replication fork and indicating important enzymes, proteins, and other
components involved in this process. Provide a one sentence description of the
function of each component
3.
DNA replication is bi-directional. What would the replication bubble look like if
replication was unidirectional? What is the start site for DNA replication?
4.
How are the primers replaced at the end of replication in eukaryotic organisms?
5.
Why do some mutations affect protein structure and function that can result in
disease whereas other mutations have no significant effects on protein structure
and function?
6. What type of mutation is AGAGCCGAGGA --> AGAGCGAGGA?
A. deletion B. inversion C. frameshift
D. insertion E. point mutation
7. Outline some differences between replication in prokaryotes and eukaryotes.
8. A DNA copy of a sequence of DNA is synthesized during
A. replication. B. transcription. C. translation.
D. transformation. E. none of these choices are true
9. DNA replication along the 3' --> 5' template strand
A. is continuous. B. is discontinuous.
C. cannot occur. D. forms a lagging strand.
E. must loop the DNA
References
http://www.colorado.edu/MCDB/MCDB1150/Fall06/ExamFourPracticeQuestionsFall06.
doc
http://www.csuchico.edu/~jbell/Biol207/final.html