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WorksheetsFinal Exam (DNA)
Total questions: 118
Worksheet time: 59mins
Griffith’s transformation experiment data supported the idea that the DNA transferred led to what result?
The formation of the double helix structure
A pathogenic strain of bacteria
Dideoxy chain termination
The concept of semiconservative replication.
Prior to the Watson-Crick discoveries, Chargaff developed rules indicating that DNA was comprised of how many different molecules/monomers?
2
6
4
3
Chargaff discovered that two specific DNA monomers were always present in equal amounts, leading to the conclusion that the monomers must be doing what?
Forming enzymatic activity
Carrying negative charges
Forming pairs
Being replaced by Uracil.
Which component of a DNA monomer carries a negative charge and is located in the DNA backbone?
Deoxyribose sugar
The base molecule
Purine
Phosphate group
Which sugar forms part of the backbone of a DNA molecule?
Ribose sugar
Glucose sugar
Deoxyribose sugar
Fructose sugar
Which group of DNA bases contains a single ring structure?
Purines (Guanine and Adenine)
Pyrimidines (Cytosine and Thymine)
Purines (Cytosine and Thymine)
All four bases
Which type of base contains a double ring structure?
Pyrimidines
Purines
Deoxyriboses
Phosphates
A purine will always pair with a pyrimidine in the double helix. What does this pairing rule maintain?
An equal distance between either strand of DNA
The strength of the hydrogen bonds
The negative charge of the backbone
The directionality of the strands
In RNA, which DNA base is replaced by Uracil (U)?
Guanine
Cytosine
Adenine
Thymine
RNA is typically found as what kind of structure?
A single stranded molecule
Triple helix
Double-stranded molecule
Circular molecule
The invention of which technology was essential in finally providing the ability to view DNA and understand its structure?
Electron microscopy
Dideoxy chain termination
X-ray crystallography
Gel electrophoresis
Which scientists were granted the Nobel Peace Prize for their discovery and description of the structure of DNA?
Chargaff and Griffith
James Watson, Francis Crick and Maurice Wilkins
Mendel and Sanger
Kunkel and Rosalind
The Sanger method of DNA sequencing relies on which mechanism?
Harnessing the power of diffusion
Dideoxy chain termination
Separating fragments based on charge
Using UV light to visualize dyes
Gel electrophoresis separates fragments of DNA or RNA based on what primary physical characteristic?
Charge density
Nucleotide sequence
Size
Amount of negative charge
What is frequently included in gel electrophoresis as a reference point?
A sample loaded with dye only
A “ladder” of a sample containing fragments of known sizes
The primer sequence
A sample that is negatively charged
ukaryotic cells house their linear chromosomes within which membrane-bound structure?
Nucleus
Nucleoid
Cytoplasm
Telomere
Prokaryotic cells have a singular circular chromosome found within the cytoplasm in an area known as the:
Nucleus
Nucleoid
Telomere
Euchromatin
How does the circular chromosome in prokaryotic cells achieve greater compaction to form the visible nucleoid?
It associates with histone proteins.
It remains linear
It super-coils around itself
It is cleaved into linear fragments
What allows the large DNA molecule in eukaryotes to remain dynamic, despite exhibiting multiple levels of organization?
The continuous presence of telomerase
DNA organizational structures must be able to change for transcription
The singular origin of replication
The presence of a nucleoid
Which type of chromatin represents areas of genes that are actively transcribed?
Heterochromatin
Histochromatin
Euchromatin
Centromeric chromatin
Where is heterochromatin typically located on eukaryotic chromosomes?
In the regions that are actively transcribed
In the nucleus but outside the nucleolus
Near the centromere and telomeres
In the cytoplasm
During which phase of the cell cycle does DNA synthesis occur?
G1 phase
G2 phase
M phase
S phase
Which base pairs with Guanine in the DNA double helix?
Thymine
Adenine
Cytosine
Uracil
The complimentary pairing of DNA strands led to the discovery that either strand could serve as what?
A promoter
A centromere
A template for replication
An enzyme
DNA replication is described as semiconservative because of which process?
Both parental strands remain joined after replication
One of each parental strand is used as a template for a new “daughter strand.”
It conserves energy during synthesis
It only happens once in the cell cycle
Using one original parental strand as a template during replication results in what benefit?
Faster replication rate
Additional quality control for higher fidelity
Shorter DNA molecules
Circular chromosome structure
What is the location where the DNA replication process will start?
Nucleoid
Telomere
Origin of replication (ORI)
Centromere
What is the primary function of the enzyme Topoisomerase during DNA replication?
To prevent overwinding of DNA
To synthesize the RNA primer
To add new nucleotides in the 5'—3' direction.
To remove the RNA primer
Which enzyme helps to open up the DNA helix during replication by breaking the hydrogen bonds?
Primase
Topoisomerase
Helicase
DNA Ligase
Primase synthesizes the RNA primer, which is necessary for what subsequent event?
For Helicase to unwind the DNA
For DNA Ligase to seal gaps
For Topoisomerase to function
For DNA pol to start synthesis of a new DNA strand
Which enzyme is the main one that synthesizes DNA by adding nucleotides in the 5’—3’ direction?
DNA Pol I
Primase
DNA Pol II
DNA Ligase
Nucleoside triphosphates (NTPs) serve as nucleotide monomers and also contain what essential component for the synthesis reaction?
Template strand
The energy
High fidelity enzymes
The RNA primer
Which enzyme is responsible for removing the RNA primer and replacing it with DNA (exonuclease activity)?
DNA Pol II
Helicase
DNA Pol I
Primase
The lagging strand is replicated in pieces known as:
Telomeres
Okazaki fragments
Primer sequences
Origin of replication
Which enzyme joins the fragments on the lagging strand together to form a continuous strand?
Helicase
. DNA Pol II
DNA Pol I
DNA ligase
Compared to prokaryotes, how many origins of replication (ORIs) do eukaryotic chromosomes typically have?
Single
Two
Multiple
None
What is the approximate rate of replication in prokaryotes?
50-100 nucleotides/second
1000 nucleotides/second
500 nucleotides/second
10 nucleotides/second
What structural difference between prokaryotic and eukaryotic chromosomes means prokaryotes require fewer enzymes for DNA replication?
Prokaryotic DNA is linear
Prokaryotes lack telomerase
Prokaryotic chromosomes are circular
Eukaryotes have multiple ORIs
What is the noncoding, repeating region at the ends of eukaryotic chromosomes that prevents the loss of vital genes?
Centromeres
Nucleosomes
ORIs
Telomeres
Which enzyme adds repeated regions to the end of chromosomes, extending the template strand?
DNA Pol II
Primase
DNA Pol I
Telomerase
How does DNA Pol I contribute to high fidelity during replication?
It seals the gaps between fragments
It has proof-reading capabilities
It adds the RNA primer
It prevents overwinding
When mismatches occur during DNA replication, what immediate physical effect is seen on the newly formed double helix?
It distorts the newly formed double helix
It is cleaved by Helicase
It automatically causes a frameshift
It triggers the action of Telomerase
What repair mechanism is particularly important for fixing UV-induced Thymine dimers?
Mismatch repair
Semiconservative replication
Nucleotide excision repair
Proof-reading activity of DNA Pol I
Nucleotide excision repair is necessary to fix damage to DNA occurring at what time?
Only during S phase
At times other than replication
Only in prokaryotes
Only in the leading strand
A genetic mutation defined by a single nucleotide change is known as a:
Frameshift mutation
Missense mutation
Deletion mutation
Point mutation
What is the result of a missense mutation?
The subsequent amino acid remains the same
Change in nucleotide results in changing the subsequent amino acid
Termination of translation prematurely
Altering all subsequent codons
A nonsense mutation is defined by what outcome?
Change in nucleotide results in changing the subsequent amino acid
Termination of translation prematurely
Change in nucleotide does not result in changing the subsequent amino acid
Altering all subsequent codons
Which category of mutation results in altering all subsequent codons in the sequence?
Missense mutation
Nonsense mutation
Point mutation
Frameshift mutations
What type of frameshift mutation involves adding one or more nucleotides, altering all following codons?
Deletion
Insertion
Missense
Point
In gel electrophoresis, what is used along with UV light to visualize the separated DNA or RNA samples?
Electricity
Buffer solutions
Dyes
Dideoxy chain terminators
Human nature discusses gene drives as potential application of CRISPR. What is a gene drive used for?
Increasing DNA replication efficiency
Spreading a genetic trait rapidly through a population
Preventing gene expression
Reversing cellular aging
One major ethical concern raised in the film involves the creation of what?
Artificial Organs
Human cloning centers
Designer babies
Automated laboratories
The documentary suggests that CRISPR could potentially eliminate which type of disease?
Infectious disease only
Genetically inherited disorders
Age-related diseases exclusively
Psychological Illnesses
What is CRISPR, and how does the documentary explain its discovery and development for a general audience?
A type of cancer therapy discovered by accident during surgery
A gene-editing tool based on a bacterial immune system that scientists adapted for precise DNA editing
A method of cloning mammals using embryonic stem cells
A form of artificial intelligence used for predicting genetic diseases
How does Human Nature portray the potential medical benefits of CRISPR, such as treating genetic diseases like sickle-cell anemia?
It shows CRISPR could potentially cure inherited disorders by correcting mutations
It argues CRISPR is too risky for all medical use
It claims CRISPR will replace all medications within ten years
It states CRISPR can only be used on plants, not humans
What ethical dilemmas arise from the possibility of editing the human germline?
Whether CRISPR should be used on animals
Whether CRISPR should replace vaccines
If CRISPR will make humans stronger athletes
Concerns about permanent changes passed to future generations and who gets to decide these changes
How do the film’s interviewees differ in their viewpoints on germline editing?
All scientists agree it should be used immediately
Some support cautious exploration while others warn against irreversible societal consequences
Everyone interviewed strongly opposes germline editing
Only non-scientists support germline editing
How does the documentary address “designer babies,” and what questions does it raise about human enhancement versus therapy?
It questions whether CRISPR should be used only to treat disease or also to enhance traits like intelligence or appearance
It claims designer babies are already common
It shows designer babies being safely created in a U.S. lab
It states enhancements are safer than therapies
In what ways does the film highlight the social implications of unequal access to CRISPR-based technologies?
It argues all genetic technologies will be free in the future
It claims CRISPR will eliminate all inequality
It shows only wealthy nations rejecting CRISPR
It warns that unequal access could widen socioeconomic gaps and create genetic inequality
How do scientists in the documentary balance enthusiasm for CRISPR’s potential with caution about unintended consequences?
By acknowledging its promise while stressing unknown risks, especially off-target effects and long-term impacts
By recommending CRISPR be used without further testing
By claiming unintended consequences are impossible
By replacing all existing gene therapies with CRISPR immediately
What real-world case studies (such as He Jiankui’s edited embryos) are discussed, and how are they used to illustrate the need for regulation?
They show successful unregulated CRISPR use that should be expanded
They show governments encouraging CRISPR baby research
They demonstrate why all genetic research should stop
They highlight the dangers of unsupervised human germline editing and the global disagreement about ethical guidelines
What predictions do the documentary’s experts make about the future of CRISPR?
CRISPR will have no medical applications
CRISPR will instantly solve global hunger
CRISPR has enormous potential but its future depends on ethical, social, and regulatory decisions
CRISPR will be banned worldwide
After watching the documentary, what responsibilities do scientists, governments, and society have in deciding how CRISPR should be used?
All groups must participate in creating transparent, ethical guidelines for safe and fair use
No oversight is needed
Only private companies should control CRISPR
Only scientists should make decisions
According to Human Nature, what inspired the scientific breakthrough that led to CRISPR gene editing?
A discovery made while studying volcanic rocks
Research on how bacteria defend themselves from viral infection
An attempt to clone extinct animals
A failed experiment with gene therapy in mice
In the documentary, what does the young sickle-cell patient’s story illustrate?
The human motivation behind developing gene-editing therapies
The limitations of CRISPR in treating blood diseases
That CRISPR is not useful for inherited diseases
That gene editing is mainly cosmetic
What concern is raised about altering traits like intelligence or behavior using CRISPR?
These traits are simple and controlled by a single gene
Editing intelligence has no ethical implications
CRISPR has already perfected enhancement methods
Complex traits involve many genes and environmental factors, making editing unpredictable
How does the film describe the difference between somatic and germline editing?
Somatic editing affects only the treated person; germline editing affects future generations
Germline editing is temporary while somatic editing is permanent
Somatic editing is illegal everywhere
Germline editing treats only cancer
What global challenge does the film suggest must be addressed before CRISPR is widely used?
Reducing lab costs
Teaching CRISPR to non-scientists
Developing universal international regulations and ethical standards
Building more DNA sequencing machines
What does the Central Dogma describe?
How DNA is translated directly into protein
How RNA makes DNA
The flow of information from DNA → RNA → protein
How proteins replicate themselves
The genetic code is described as “universal and degenerate.” What does “degenerate” refer to?
Codons decay over time
Several codons can code for the same amino acid
Codons are unstable during transcription
Some codons produce no amino acids
What is the start codon in most mRNA sequences?
UAA
UGA
AUG
CAG
Which of the following is a nonsense (stop) codon?
UUC
AUG
GUG
UAA
What is the role of a promoter in transcription?
It is the DNA sequence where RNA polymerase binds to begin transcription
It binds ribosomes to start translation
It cuts introns out of the mRNA
It attaches amino acids to tRNAs
Prokaryotic promoters are characterized by what feature?
A G-C rich region at +50bp
A-T rich regions at −10 and −35 bp upstream
A TATA box at −80bp
A poly-A tail at the beginning of the gene
What is the transcription bubble?
The region of ribosome assembly
A pocket of RNA polymerase active sites
Locally unwound DNA where transcription occurs
A protective cap placed on mRNA
Which termination mechanism in prokaryotes depends on a hairpin loop?
Rho-dependent termination
Rho-independent termination
Sigma factor termination
Ribosomal termination
Why can prokaryotes produce proteins rapidly?
They translate mRNA before transcription is finished
They have multiple nuclei
Their ribosomes do not require tRNAs
Their mRNA has no codons
What is the function of RNA polymerase II in eukaryotes?
It transcribes tRNA only
It adds amino acids to tRNAs
It assembles ribosomal proteins
It transcribes mRNA
What does the TATA box do in eukaryotic promoters?
Signals where ribosomes attach
Provides a binding site for tRNAs
Terminates transcription
Helps establish the transcription initiation site
Which promoter element is essential for binding transcription factors in eukaryotes?
Octamer box
CAAT box
Poly-A tail
Shine-Dalgarno sequence
What is the role of the FACT complex?
Splices introns out of mRNA
Helps ribosomes locate the start codon
Disassembles and reassembles nucleosomes during transcription
Exports RNA through nuclear pores
What modification is added to the 5’ end of eukaryotic mRNA?
Poly-A tail
Introns
7-methylguanosine cap
TATA signal
What are introns?
Intervening sequences removed before export
Coding regions of mRNA
Untranslated regions at the 5' end
RNA that forms ribosomes
What are tRNAs used for?
Translating mRNA codons into amino acids
Editing DNA sequences
Stabilizing the nuclear membrane
Transporting ribosomes
What is the function of aminoacyl tRNA synthetases?
Remove introns from mRNA
Charge tRNAs with the correct amino acids
Synthesize rRNA
Form peptide bonds in the ribosome
Which ribosomal site holds the tRNA carrying the growing polypeptide chain?
A-site
C-site
E-site
P-site
What provides the energy for shifting the mRNA through the ribosome?
ATP
GTP
NADH
FADH₂
What happens during translation termination?
RNA polymerase stops copying DNA
Exons are removed
The ribosome begins reading a new mRNA
A release factor detaches the polypeptide from the ribosome
What do chaperone proteins do?
Build ribosomes
Fold newly formed polypeptides
Transport mRNA out of the nucleus
Insert introns into RNA
What is the purpose of a signal sequence in a protein?
Directs the protein to the correct cellular location
Begins transcription
Prevents tRNA binding
Removes introns
What do ribosomes read during protein synthesis?
DNA
mRNA
tRNA
rRNA
Why must DNA be transcribed into mRNA?
mRNA is more stable than DNA
DNA cannot enter the nucleus
Transcription replaces translation
Ribosomes can only read RNA
Which enzyme performs transcription in prokaryotes?
RNA polymerase III
Helicase
RNA polymerase with 5 subunits
DNA polymerase
What is Rho in transcription?
A protein that initiates translation
A protein that attaches amino acids to tRNA
A protein that terminates transcription by interacting with RNA polymerase
A ribosomal subunit
What structure forms during Rho-independent termination?
A tRNA-amino acid bond
A stem-loop (hairpin) in mRNA
A peptide bond
A ribosomal cap
What is a polyribosome?
Multiple RNA polymerases working on one gene
A ribosome inside the nucleus
Many ribosomes translating the same mRNA at once
A mutated ribosome
How many RNA polymerases do eukaryotes use?
One
Two
Three
Four
Which eukaryotic RNA polymerase makes rRNA?
RNA pol I
RNA pol II
RNA pol III
RNA pol IV
Which promoter element may appear multiple times to increase transcription efficiency?
TATA box
CAAT box
Sigma factor
Octamer box
Basal transcription factors in eukaryotes begin with which letters?
RNA
TATA
TFII
Rho-I
What does RNA pol II produce?
tRNA
mRNA
rRNA
DNA
What is the purpose of the 5′ cap?
To splice introns
To help ribosomes recognize mRNA
To add amino acids
To initiate DNA replication
What does the poly-A tail do?
Initiates transcription
Regulates translation initiation
Protects mRNA and serves as an export tag
Forms peptide bonds
Where are tRNAs and rRNAs processed?
Nucleolus
Cytosol
Rough ER
Golgi apparatus
What is an anticodon?
Three nucleotides in mRNA
A DNA binding site
Three amino acids in a protein
A three-nucleotide sequence on tRNA
What is required for tRNA to be “charged”?
Introns
Poly-A binding proteins
Ribosomal subunits
Aminoacyl tRNA synthetase
Which ribosomal site receives the incoming aminoacyl tRNA?
P-site
A-site
E-site
Z-site
Which direction is mRNA shifted through the ribosome?
3′ → 5′
5′ → 3′
Randomly
Depends on the codon
Which molecule provides energy for translation elongation?
GTP
ATP
NAD+
FAD
What event marks translation initiation?
The first intron is removed
mRNA binds to the small ribosomal subunit
RNA polymerase binds the promoter
A release factor enters the ribosome
Which factor ends translation?
Sigma factor
Rho protein
A release factor
RNA polymerase
What are exons?
Noncoding sequences that are removed
Coding sequences that remain in mRNA
Regions added during transcription
rRNA components
What is the biological role of tRNA?
Copy DNA into RNA
Connect amino acids to ribosomes
Cap the mRNA
Translate codons into amino acids
What is the purpose of mRNA splicing?
Remove introns and join exons
Assemble ribosomes
Add codons to the sequence
Charge tRNAs
Which sequence helps direct a protein to its correct location?
CAAT box
Signal sequence
Anticodon
Hairpin loop
What do chaperone proteins assist with?
Protein folding
DNA replication
rRNA synthesis
Introns removal
What part of the translation complex initially binds mRNA?
Large ribosomal subunit
RNA polymerase
Small ribosomal subunit
Release factor
What is the genetic code organized into?
Groups of three nucleotides called codons
Regions called promoters
Pairs of introns
Segments called operons
