Tutorial Questions Flashcards
Which one of the following statements about the sugar pucker impact on nucleic acid structure is true?
A. The ribose sugar has a 2’ and 3’ endo conformation which drives RNA to adopt a different structure than DNA
B. Deoxyribose is a
planar structure,
whereas ribose has a pucker, which
changes RNA and DNA polymer structures
C. When a carbon is “down” in a ring structure it is in the exo conformation
D. Sugar pucker is only possible when the carbohydrate is in the aldehyde
form
C. When a carbon is “down” in a ring structure it is in the exo conformation
Why don’t you find syn bonds in pyrimidine
bases within the DNA helix?
this is because steric hindrance between the oxygen on the pyrimidine base and the oxygen on the ribose/deoxyribose sugar
- carbonyl group on the pyrimidine and oxygen on sugar means they repel each other, cannot be facing on another
You isolate a new strain of bacteria (named302) and find that it has a genome
with 28% A. What percentage is G?
A. 28%
B. 14%
C. 22%
D. 44%
C. 22%
Describe the 4 differences between DNA and RNA nucleotides and how this impacts polymer structure
- DNA has 2’ endo sugar pucker while RNA has 3’ sugar pucker, means DNA has B form while RNA is in A form
- DNA is double stranded while RNA is single stranded, means there is anti-parallel double helix of DNA, and in RNA has intramolecular helix formations that are sequence dependent
- DNA has thymine while RNA has uracil, means that cytosine can undergo spontaneous deamination forming uracil, while thymine enables this to be recognized at damaged DNA
- DNA has a 3’ OH and 2’, RNA has 3’OH and 2’ OH, this makes RNA more reactive (more H-bond acceptors) and DNA more stable
You now wish to compare the stability of the 302 genome with the 303
genome which you’ve determined has a composition of 35% T. Is 302 more or
less stable than 302?
302 has less A-T bonds and more G-C bonds, so will have be more stable and have a higher Tm
Which one of the following is the largest
contributor to DNA double helix stability?
A. The hydrophobic effect
B. Metal ion stabilization
C. Base stacking forces
D. Hydrogen-bonds between bases
C. Base stacking forces
DNA is complementary
What is the complementary strand of:
5’-ACCTGGAATTG-3’
A. 5’ CAATTCCAGGT-3’
B. 5’ ACCTGGAATTG-3’
C. 5’ TGGACCTTAAC-3’
D. 5’ ACCUGGAAUUG-3’
A. 5’ CAATTCCAGGT-3’
Which one of the following molecules would you
predict would be synthesized at the lowest rate?
A. The tRNA that can be charged with Alanine
B. The rRNA that makes the large subunit of the ribosome
C. The mRNA that encodes for the protein MeCP2 (a protein that
binds to many regions within the genome)
D. Cannot predict given the information above
C. The mRNA that encodes for the protein MeCP2 (a protein that
binds to many regions within the genome)
You have a molecule that is a DNA-RNA hybrid and
subject it to heat denaturation. At a certain point Tm
the mixture is half annealed and half denatured.
A. This would have a higher Tm than a comparable solution of DNA
molecules (same length and base ID except T instead of U)
B. This would have a lower Tm than a comparable solution of DNA
molecules (same length and base ID except T instead of U)
C. This would have the same Tm as a comparable solution of DNA
molecules (same length and base ID except T instead of U)
D. Not given enough information in the question to solve this problem
A. This would have a higher Tm than a comparable solution of DNA
Which one of the following statements about
chromatin is true?
A. The majority of the chromatin found in a eukaryotic cell is in a 30
nm or larger higher order structure
B. The nucleosome makes up the fundamental unit of chromatin and
is made up of an octamer of histone proteins (4 copies of H2, and 4
copies of H3)
C. DNA associates with proteins via salt-bridge interactions
D. Chromatin is more rigid than naked DNA, but provides the cell with
an ability to regulate the genome through post-translational
C. DNA associates with proteins via salt-bridge interactions
Human cells have different sizes of nuclei,
depending on the cell type. Which one of the
following features would change in cells with small
nuclei?
A. Higher-order chromatin fibres, more 30 nm fibres to increase
compaction in the smaller cells
B. Fewer nuclear bodies
C. Ribosomes would be synthesized in the cytoplasm to make more
room in the smaller nuclei
D. Less space between chromatin fibres in the smaller nuclei
D. Less space between chromatin fibres in the smaller nuclei
Which of the following treatments would you
expect would be effective in treating progeria?
A. Over-expression of wild type Lamin A protein
B. Targeted degradation of the mRNA with the cryptic splice site
C. Gene therapy to replace the variant C with a wild type T
D. Low protein diet
B. Targeted degradation of the mRNA with the cryptic splice site
Most of the mechanistic discoveries in molecular biology were first discovered in Prokaryotes, why? (select 2)
A. Prokaryotes are single celled, and therefore easier to study
B. Prokaryotes don’t have a nucleus, and therefore have more
straightforward mechanisms driving information transfer
C. Prokaryotes have naked DNA, making them easier to study
D. Prokaryotes historically were easier to make and isolate mutants in,
so the functional consequences of missing a protein was feasible
E. Prokaryotes are cheaper to grow and culture, so make good models
for molecular biology
D. Prokaryotes historically were easier to make and isolate mutants in,
so the functional consequences of missing a protein was feasible
E. Prokaryotes are cheaper to grow and culture, so make good models
for molecular biology
T/F: The unique chemical information of the DNA double stranded helix is
constrained to the nitrogen-rich bases, yet the major and minor
grooves change how many bases in a particular region are easily
accessed is formed by the anti-parallel assembly of the two strands
within the double helix
True
T/F: In a dNTP where N is any of the bases A, G, C or T, the phosphate group
can be attached to either the 5’, 3’ or 2’ sugar positions, but is most
often found in the 5’ position in a biological system
False
