I. INTRODUCTION
Molecular biology fundamentally relies on understanding macromolecular structures like
proteins, tRNA, and DNA, which are essential for a various cellular function. Creating paper
models is one method of visualizing and comprehending the complex three-dimensional structure
of these molecules.
Amino acid chains, which make up proteins, fold into particular shapes that create functional
domains that are in charge of signaling, molecular recognition, and enzymatic activity. Protein
domains are stable in structure parts of proteins that are frequently linked to specific biological
processes. Cellular function depends on their stability and the right folding, and misfolding can
lead from illnesses like Alzheimer’s and cystic fibrosis.
Similarly, tRNA is essential to translation because it makes sure that amino acids are
accurately incorporated into developing polypeptides. During protein synthesis, its cloverleaf
secondary structure folds into an L-shaped three-dimensional conformation, allowing appropriate
interaction with the ribosome. Its efficiency and fidelity are further improved by interactions with
aminoacyl-tRNA synthetases and modifications to tRNA bases.
DNA is a double-helical molecule made up of nucleotide base pairs that serves as the genetic
information carrier. Stability and precise transcription and replication are ensured by the helical
structure and complimentary base pairing. Gene regulation and cellular function are influenced
by structural changes including supercoiling, methylation, and DNA packing into chromatin. It is
often challenging to visualize these complex biomolecular structures with only two-dimensional
representations. Creating three-dimensional paper models makes studying molecular structures
more realistic and interesting.
Students can gain a better understanding of the spatial
arrangements, folding patterns, and functional interactions of proteins, tRNA, and DNA by
physically creating these models.
Therefore, the purpose of this laboratory activity Is to use templates from the RCSB Protein
Data Bank (PDB) to create accurate three-dimensional paper models of DNA, tRNA, and protein
domains.
II. OBJECTIVES
The primary objectives of this laboratory experiment are:
1. To create accurate three-dimensional paper models of protein domains, tRNA, and
DNA using given templates from the RCSB PDB to better spatial comprehension
of molecular structures.
2. Explain the structural elements and roles that DNA, tRNA, and protein domains
play in biological processes.
3. Compare the structural and functional differences among protein domains, tRNA,
and DNA, explaining how their three-dimensional conformations contribute to
their biological roles.
III. MATERIALS AND METHODS
Materials
•
Printed templates from RCSB PDB for protein domains, tRNA, and DNA.
•
Scissors or precision cutting tool.
•
Glue or double-sided tape.
•
Colored pencils or markers.
•
Ruler for precise folding.
Methods
General Preparation:
•
Templates were printed on sturdy cardstock paper to ensure durability.
•
Folding and cutting instructions from the RCSB PDB website were reviewed.
•
Colored pencils or markers were used to highlight key structural features.
A. Protein Domain Models:
A.a. Protein Domain Model 1: TIM BARREL/ALPHA-BETA BARREL
Materials: Eight alpha helices (prepared from two printed sheets) and eight beta strands
(prepared from one printed sheet) were used. One beta strand was unused.
Procedure:
Step 1: Component Preparation
Eight alpha helices and eight beta strands were obtained by printing two and one sheets of
paper, respectively.
Step 2: N- and C-Termini Designation
The N-terminus was marked on the bottom of the upward-facing arrow of one beta strand,
designating it as the first element. The C-terminus was marked on the extending loop of one
alpha helix, which was reserved for final assembly.
Step 3: Parallel Beta Sheet Cluster Assembly
A parallel beta sheet cluster was constructed to simplify the assembly of the TIM barrel fold.
The N-terminus-marked beta strand was used to initiate the assembly. Subsequent beta
strands were aligned side-by-side, aligning the arrow tip of each strand with the arrow base
of the preceding strand, and secured with tape. This process continued until all eight beta
strands were assembled.
Step 4: First Alpha Helix Integration
An alpha helix was positioned such that the colored side of its adjoined loop faced upward.
It was placed approximately 0.25 inches below the loop of the first (leftmost) beta strand and
taped in place. The helix was then manipulated so that its gray extending loop, representing
the polymer chain, connected to the next beta strand.
Step 5: Remaining Helix Integration
The remaining alpha helices were added sequentially, following the method described in Step
4. The alpha helix marked with the C-terminus was added last, positioned over the beta sheet.
Step 6: Beta Barrel Closure
The two exposed edges of the beta sheet cluster were taped together, aligning the arrow tip of
the final beta strand with the arrow base of the N-terminal beta strand, completing the barrel
structure.
A.b. Protein Domain Model 2: Beta Sandwich/Nanobody
Materials: Nine beta strands (obtained by cutting a single printed sheet) were used.
Procedure:
Step 1: Component Preparation
Nine beta strands were prepared by cutting a printed sheet along the solid black lines.
Step 2: First Beta Hairpin Construction
Two beta strands were aligned in an antiparallel orientation (one arrow up, one arrow down)
and taped together along their sides. The loop of the upward-facing strand was bent at a 45degree angle approximately one-third of its height, folded over the bottom of the adjacent
strand’s arrow, and taped in place.
Step 3: First Hairpin Marking
The hairpin was oriented with the bent loop facing upward. The N-terminus was marked on
the bottom of the leftmost arrow. The number “1” was marked on the bottom of the extending
loop of the adjacent strand, and the letter “B” was marked on the middle of the right edge.
Step 4: Second Hairpin Construction and Marking
A second beta hairpin was constructed as in Step 2. The leftmost arrow was oriented upward.
The number “3” was marked on the extending loop of the leftmost strand, “B” on the left
edge, and “2” on the top of the rightmost arrow.
Step 5: Third Hairpin Construction and Marking
Two beta strands were aligned side-by-side (left strand arrow down, right strand arrow up)
and taped. The extending loop of the right strand was folded to create a hairpin, as in Step 2.
The C-terminus was marked on the bottom of the extending loop of the left strand, “3” was
marked on the bottom of the right arrow, and “A” was marked on the right side of the right
arrow.
Step 6: Fourth Beta Sheet Construction and Marking
Three beta strands were aligned side-by-side in an arrow down | arrow up | arrow down
pattern and taped. The extending loop of the middle strand was folded to the left to create a
hairpin, and the loop of the leftmost strand was folded to create a hairpin connecting it to the
middle strand. The number “1” was marked on the top of the leftmost arrow and “A” on its
side. The number “2” was marked on the bottom of the extending loop of the rightmost
strand.
Step 7: Cluster Connection
The loops marked “1” were taped together, as were the loops marked “2” and “3,” connecting
the hairpin clusters.
Step 8: Sandwich Fold Assembly
The sides of the clusters marked “A” were aligned and taped together, followed by the
alignment and taping of the sides marked “B,” completing the beta sandwich fold.
A.c. Protein Domain Model 3: ABA SANDWICH/ROSSMANN FOLD
Materials: Four alpha helices (constructed from one printed sheet) and six beta strands
(obtained by cutting one printed sheet; three strands were unused) were used.
Procedure:
Step 1: Component Preparation
Four alpha helices were constructed from a single printed sheet. Six beta strands were
prepared by cutting a printed sheet; three strands were discarded.
Step 2: N- and C-Termini Designation
Two beta strands were oriented with their arrows pointing upward. The N-terminus was
marked on the bottom of one arrow, and the C-terminus was marked on the top of the
extending loop of the other.
Step 3: Initial Helix-Strand Chain Assembly
Two chains were assembled, each consisting of an alternating sequence of beta strands and
alpha helices. The first chain began with the N-terminus strand, and the second chain ended
with the C-terminus strand. The primary chain representation lines were aligned during
taping.
Step 4: First Beta Strand Cluster Assembly (Initiation)
The N-terminus strand was flipped to its uncolored side and laid flat. The adjacent helix was
positioned such that its loop was bent over and then under the strand. The next strand in the
sequence was aligned and taped to the right of the N-terminal strand.
Step 5: First Beta Strand Cluster Assembly (Completion)
Step 4 was repeated, incorporating the second helix and the final beta strand to complete the
first cluster.
Step 6: Second Beta Strand Cluster Assembly (Initiation)
The second chain was oriented with its arrows upward, the C-terminus strand at the end. The
first beta strand was laid flat, colored side up. The loop extending from the beta strand was
bent over, and then the loop from the helix was bent under to align the next beta strand,
which was taped to the right of the first.
Step 7: Second Beta Strand Cluster Assembly (Completion)
Step 6 was repeated, incorporating the second helix and final beta strand to complete the
second cluster.
Step 8: Beta Sheet Connection
The two beta strand clusters were aligned and taped together, with the N-terminus cluster on
the left and the C-terminus cluster on the right, both colored sides facing upward, forming a
three-layered alpha-beta-alpha sandwich structure.
Step 9: Beta Sheet Twisting
The beta sheet was oriented with its arrows pointing upward. It was folded diagonally from
the bottom left to the bottom right.
Step 10: Final Loop Connection
The beta sheet was oriented with arrows upward. The extending loop from the leftmost beta
strand was taped to the fourth helix from the right, completing the polymer chain.
B. tRNA Model:
1. The tRNA model template was cut along the provided lines.
2. The template was folded to create the cloverleaf secondary structure.
3. The folds were secured using glue or tape.
4. The anticodon loop, acceptor stem, and D- and T-loops were correctly oriented.
C. DNA Model:
1. The DNA model template was cut along the provided lines.
2. The paper was folded to create a double-helix shape.
3. Complementary base pairs were attached using adhesive glue or tape.
4. The assembled structure was gently twisted to represent the helical nature of DNA.
IV. DATA ANALYSIS AND DISCUSSION
The following table compares the three-dimensional structures from the RCSB PDB with the
corresponding paper models constructed using RCSB PDB templates:
RCSB PDB 3D Models
Constructed Paper Models
Protein Domain Model 1:
TIM Barrel/Alpha-Beta
Barrel
Protein Domain Model 2:
Beta Sandwich/Nanobody
Protein Domain Model 3:
ABA Sandwich/
Rossmann Fold
tRNA Model
DNA Model
Figure 1. Comparison of RCSB PDB 3D Models and Constructed Paper Models
Analysis of Results
Protein Domains
The distinctive parallel beta-sheet core surrounded by alpha-helices was accurately
depicted by the TIM barrel model. The antiparallel arrangement of beta-sheets was
effectively proved via the beta-sandwich model. The alternating arrangement of
alpha-helices and Beta-sheets was well illustrated using the Rossmann fold model.
tRNA
The secondary structure of cloverleaf and its L-shaped folding were accurately
represented by the tRNA model. Functional elements (anticodon loop, acceptor
stem, and D and T loops) were positioned properly.
DNA
The complimentary base pairing and double helix structure were accurately
represented in the DNA model. The model's twisting provided an actual
representation of DNA's helix structure.
Guide Questions
Protein Domains:
• How do the secondary structures (alpha helices and beta sheets) contribute to the overall
stability of protein domains?
-
Alpha helices and beta sheets, primarily through hydrogen bonding, contribute to protein
domain stability by forming a stable helical structure in alpha helices and strands in beta
sheets. Hydrogen connections between the polypeptide chain’s backbone atoms maintain
these structures, ensuring the protein’s overall integrity and structure. Each backbone N-H
group in an alpha helix forms a hydrogen bond with the amino acid’s C=O group four
residues earlier, causing the polypeptide chain to coil into a spiral. The helical structure is
stabilized by this hydrogen bonding pattern, which makes it a common and reliable
component of protein domains. In order to produce a sheet-like structure, beta sheets are
made up of beta strands connected laterally by two or three backbone hydrogen bonds.
Hydrogen bonds are formed between the carbonyl oxygen of one strand and the amide
hydrogen of an adjacent strand, and the strands can be orientated either parallel or
antiparallel. The beta sheet structure is stabilized by this extensive hydrogen bonding
network, which contributes to the protein domain’s overall stability. (Khan Academy, n.d.)
• What roles do protein domains play in cellular functions and interactions with other molecules?
-
Protein domains are crucial structural components that provide proteins their variety of
roles and ability to interact with other molecules. According to Klug et al. (2016), these
domains are typically sequences of 50 to 300 amino acids that fold into stable, independent
structures, and they often correspond to specific functional roles. For example, a protein
may have a catalytic domain that is responsible for enzyme activity, or a binding domain
that allows the protein to interact with DNA, other proteins, or small molecules be thought
of as modular components that allow a single protein to perform multiple functions, making
them highly versatile in cellular processes.
Additionally, prot has multiple domains, each of which is in charge of a distinct function.
Because of their modular structure, proteins are more complicated and versatile, allowing
them to carry out various kinds of functions based on the specific cellular context. (Klug
et al., 2016)
• How can mutations in protein domains impact their function and lead to diseases?
-
Protein domain mutations can have a significant impact on how well protein’s function and
may result in several kinds of diseases. Disease-causing mutations frequently cause
changes to the protein’s structure network, which may cause problems with its normal
function. The interactions between amino acid residues may be affected by these mutations,
which may cause modifications in the protein’s 3D structure. These modifications to the
structure may affect the stability, binding affinity, or enzymatic activity of the protein,
which may ultimately result in the development of disease. In conclusion, protein domain
mutations can cause functional deficiencies and the onset of a variety of diseases by
disrupting the intricate network of interactions that make up the protein structure. (Prabantu
et al., 2021).
• How do protein domains facilitate enzyme activity and specificity?
-
Protein domains are distinct structural components found in proteins that are essential for
facilitating the specificity and enzyme activity. The active site of the enzyme, where
substrates bind and undergo chemical reactions, is frequently found in these domains. The
enzyme’s specificity is determined by the particular arrangement of amino acids within
these domains, which determines its capacity to recognize and interact with specific
substrates. Additionally, an enzyme’s specificity and activity can be affected by the
structure of its multiple domains. Furthermore, the activity of enzymes may be affected by
the structure of protein domains. The activity, specificity, and regulation of caspases are
influenced by the particular arrangement of their protein structures. (Lewis, T. & Stone, W.
2023).
• What factors influence the folding and stability of protein domains?
-
Protein folding is a very sensitive process that is affected by many different types of
external factors, including: temperature, pH, electric and magnetic fields, chemicals,
molecule crowding, and space constraints. The capacity of proteins to fold into their proper
functional forms is influenced by several factors. Protein stability is affected by extreme
temperatures, which can cause them to unfold or denature. Proteins can also be denatured
by chemical denaturants, mechanical pressures, and extremely high or low pH. Proteins
become random coils when denaturation occurs, losing their tertiary and secondary
structures. Certain proteins have the ability to refold under specific circumstances, even if
denaturation is not always reversible. Certain cells have chaperones or heat shock proteins
that shield the cell’s proteins from heat denaturation. Proteins need chaperones to fold and
stay folded in extremely hot or cold conditions. (Cheriyedath, 2019).
• How do different environmental conditions affect protein domain structures?
-
The structure of the protein could be affected by different external conditions, such as
temperature, water, and salt ions. For example, water is a typical factor, although the water
environment has been confirmed to have a profound impact on the structure and dynamic
properties of keratin like swelling or hydrogen bonds network. (Yin, C., et al., 2023).
• How does domain swapping influence protein evolution?
-
Domain swapping is a well-known phenomenon in structural biology, which can be
described as one sequence having two folds. It is believed to play an important role in the
mechanism of oligomerization in the evolutionary pathway of some proteins. (Kundu, S.
& Jernigan, R. L., 2004).
• What experimental techniques are used to study protein domains?
-
Nuclear magnetic resonance (NMR) spectroscopy has been widely used for many years to
analyze the structure of small molecules. This technique is now also increasingly applied
to the study of small proteins or protein domains. (Alberts, B. et al., 2002).
• How do post-translational modifications affect protein domain functionality?
-
Post-translational modifications (PTMs) can occur on specific amino acids localized within
regulatory domains of target proteins, which control a protein’s stability. These regions,
called degrons, are often controlled by PTMs, which act as signals to expedite protein
degradation (PTM-activated degrons) or to forestall degradation and stabilize a protein
(PTM-inactivated degrons). (Lee, J. M. et al., 2023).
• How do protein-protein interactions rely on domain specificity?
-
Proteins bind to each other through a combination of hydrophobic bonding, van der Waals
forces, and salt bridges at specific binding domains on each protein. These domains can be
small binding clefts or large surfaces and can be just a few peptides long or span hundreds
of amino acids. (Thermo Fisher Scientific, n.d.).
• What is the significance of intrinsically disordered regions in proteins?
-
Proteins can be intrinsically disordered fully (IDP) or have disordered regions (IDR). They
provide plasticity and reversibility in binding, essential for cell signalling. (Chakrabarti, P.,
& Chakravarty, D., 2022).
• How do chaperones assist in protein domain folding?
-
Chaperones are proteins that aid in the proper folding of other proteins by facilitating their
assembly without being a part of the resulting complex. These proteins merely act as
catalysts and do not add any information required for the folding process. (The Protein
Man, 2020).
• How does the hydrophobic effect influence protein domain formation?
-
When amino acids form new hydrogen bonds, van der Waals and other electrostatic
interactions it results in releasing heat, while breaking these bonds with water results in
absorbing heat. Therefore, the relative amount of bond formation to bond breakage in the
unfolded and folded states will determine ΔH. However, the basis of the hydrophobic effect
(collapse) is an increase in the entropy of protein-associated water and is the most
important driving force in protein folding. (Stollar, E. J., & Smith, D. P., 2020).
• How do computational models help predict protein domain structures?
-
Computational algorithms and tools have made significant improvements in the field of
structural modeling. Protein structure prediction methods include comparative modeling
(homology modeling), threading, and ab initio approach. Several tools and software have
been developed for the 3D modeling of proteins. (Jabeen, A., & Ranganathan, S., 2019).
• How can engineered protein domains be applied in biotechnology and medicine?
-
Protein engineering is also used in biotechnology to create proteins with new or improved
functions. For example, enzymes can be engineered to be more stable, active, or specific,
making them valuable tools for industrial processes, such as biofuel production and
chemical synthesis. Similarly, engineered antibodies can be used for diagnostic and
therapeutic applications, such as detecting and treating cancer. (Rosing, J., 2023).
tRNA:
• How does the structure of tRNA enable it to efficiently carry out its function in translation?
-
Two regions of unpaired nucleotides situated at either end of the L-shaped molecule is
crucial to the function of tRNA in protein synthesis. One of these regions forms the
anticodon, a set of three consecutive nucleotides that pairs with the complementary codon
in an mRNA molecule. The other is a short single-stranded region at the 3′ end of the
molecule; this is the site where the amino acid that matches the codon is attached to the
tRNA. (Alberts, B. et al., 2002).
• Why is the L-shaped three-dimensional conformation of tRNA important for ribosome
interaction?
-
Confirmational flexibility of L-shaped structure of tRNA, along with confirmational
changes and rearrangements of the ribosomes, respectively provide variety of tRNA
binding states and ability of ribosome to bind to tRNA hybrid states. (Parvathy, S. T. et al.,
2022).
• How can modifications to tRNA bases affect its function in protein synthesis?
-
Mechanically, tRNA modifications impact the tRNA’s affinity for tRNA ribonuclease and
its activity. tRNA modifications influence interrelated physiological functions, including
protein synthesis, stemness, and cellular stress response, by regulating tRFs biogenesis.
(Wang, L., & Ling, S., 2023).
• What role does the anticodon loop play in translation accuracy?
-
In particular, modifications in the anticodon stem-loop (ASL), located near the site of
tRNA:mRNA interaction, can play key roles in ensuring protein homeostasis and accurate
translation. (Smith, T. J., Giles, R. N., & Koutmou, K. S, 2024).
• How does the aminoacylation of tRNA ensure correct protein synthesis?
-
The aminoacylation of tRNA ensures accurate protein synthesis by attaching the correct
amino acid to its corresponding tRNA, a process catalyzed by aminoacyl-tRNA synthetases
(AARSs). These enzymes recognize specific tRNAs and amino acids based on structural
and sequence features, ensuring high fidelity. Additionally, some AARSs have
proofreading mechanisms that remove incorrectly attached amino acids, preventing
translation errors. This precise pairing ensures that the genetic code is correctly translated
into functional proteins. (Hopper, A. K., & Shaheen, H. H., 2008).
• How do tRNA synthetases contribute to translation fidelity?
-
The synthetase ensures that the right amino acid pairs up with the right tRNA. Once the
aminoacyl-tRNA has been synthesized, the amino acid part makes no contribution to
accurate translation of the mRNA. Instead, this is achieved by the codon recognition
through base pairing via anticodon of aminoacyl-tRNA. (Shen, C. H., 2023).
• How do different tRNA isoacceptors contribute to genetic code redundancy?
-
Spencer, P. S., & Barral, J. M., (2012). “Genetic code redundancy and its influence on the
encoded polypeptides”. National Library of Medicine.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3962081/
• What role does tRNA play in stress response mechanisms?
-
Metchener, M. M., Begley, T. J., & Dedon, P. C., (2023). Molecular Coping Mechanisms:
Reprogramming tRNAs To Regulate Codon-Biased Translation of Stress Response
Proteins. Accounts of Chemical Research.
https://pubs.acs.org/doi/full/10.1021/acs.accounts.3c00572
• How do viral infections manipulate tRNA functions?
-
Nune, A. et al., (2020). “Emerging Roles of tRNAs in RNA Virus Infections – PubMed”.
https://pubmed.ncbi.nlm.nih.gov/32505636/
• How does mitochondrial tRNA differ from cytoplasmic tRNA?
-
Buck, C. A., & Nass, M. M., (1968). “Differences between mitochondrial and
cytoplasmic transfer RNA and aminoacyl transfer RNA synthetases from rat liver”.
National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC225158/
• How do mutations in tRNA genes affect human diseases?
-
Abbott, J. A. et al., (2014). “Transfer RNA and human disease”. National Library of
Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC4042891/
• What role does tRNA play in non-canonical translation mechanisms?
-
Su, Z. et al., (2021). Non-canonical roles of tRNAs: tRNA fragments and beyond.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7686126/
• How can tRNA be used in synthetic biology and genetic engineering?
-
Khran, N. et al., (2020). Engineering aminoacyl-tRNA synthetases for use in synthetic
biology. National Library of Medicine. https://pubmed.ncbi.nlm.nih.gov/33837709/
• How does tRNA abundance affect cellular translation rates?
-
Davyt, M. et al., (2023). Effect of mRNA/tRNA mutations on translation speed:
Implications for human diseases. Journal of Biological Chemistry.
https://www.sciencedirect.com/science/article/pii/S0021925823021178
• How do ribosomal interactions regulate tRNA selection?
-
Khade, P., & Joseph, S., (2011).” Functional Interactions by Transfer RNAs in the
Ribosome”. National Library of Medicine.
https://pmc.ncbi.nlm.nih.gov/articles/PMC2795042/
DNA:
• How does the double-helix structure of DNA contribute to its stability and replication
accuracy?
-
Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular
biology of the cell (4th ed.). Garland Science.
https://www.ncbi.nlm.nih.gov/books/NBK21054/
• What is the significance of complementary base pairing in genetic information storage and
transmission?
-
Chemistry LibreTexts. (n.d.). 19.4: Replication and Expression of Genetic Information.
Chemistry LibreTexts. https://chem.libretexts.org/Courses/Mount_Aloysius_College
• How do structural variations in DNA, such as supercoiling, impact gene expression and cellular
function?
-
Martis, S. B., et al. (2019). DNA supercoiling: An ancestral regulator of gene expression
in pathogenic bacteria? National Library of Medicine.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6700405/
• How do histones influence DNA packaging and gene accessibility?
-
Genemod, (2024). “What Are Histones? Understanding Their Role in Gene Expression”.
Genemod. https://genemod.net/blog/what-are-histones-understanding-their-role-in-geneexpression.
• How does DNA methylation impact gene expression?
-
Moore, L. D., Le, T., & Fan, Guoping., (2012). DNA Methylation and Its Basic Function.
Neuropsychopharmacology https://www.nature.com/articles/npp2012112
• What role do telomeres play in chromosomal stability?
-
Lee, J. & Pellegrini, M. V., (2022). Biochemistry, Telomere and Telomerase. National
Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK576429/
• How do DNA mutations lead to genetic disorders?
-
Cleveland clinic, (n.d.). “What Is a Genetic Mutation? Definition & Types”. Cleveland
clinic. https://my.clevelandclinic.org/health/body/23095-genetic-mutations-in-humans
• How does DNA recombination contribute to genetic diversity?
-
Clancy, S. (2008). Genetic recombination. Nature Education.
https://www.nature.com/scitable/topicpage/genetic-recombination-514/
• How do repair mechanisms correct DNA damage?
-
Cooper, G. M. (2000). The cell: A molecular approach (2nd ed.). National Library of
Medicine. https://www.ncbi.nlm.nih.gov/books/NBK9900/
• What is the significance of alternative DNA structures such as Z-DNA?
-
Potaman, V. N., & Sinden, R. R. (2013). DNA: Alternative conformations and biology. In
Madame Curie Bioscience Database [Internet]. Landes Bioscience.
https://www.ncbi.nlm.nih.gov/books/NBK6545/
• How do epigenetic modifications alter DNA function?
-
Al Aboud, N. M., Tupper, C., & Jialal, I. (2023). Genetics, epigenetic mechanism.
StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK532999/
• How does RNA interact with DNA in transcription regulation?
-
Khan Academy. (n.d.). Transcription: An overview of DNA transcription. Khan Academy.
https://www.khanacademy.org/science/ap-biology/gene-expression-andregulation/transcription-and-rna-processing/a/overview-of-transcription
• How do CRISPR systems utilize DNA recognition for gene editing?
-
National Library of Medicine. (n.d.). What are genome editing and CRISPR-Cas9?
MedlinePlus Genetics.
https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/
• How does DNA topology affect replication and transcription?
-
Demidov, V. (2002). DNA topology. Trends in Biotechnology. ScienceDirect.
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/dnatopology
• How do external factors like radiation and chemicals alter DNA integrity?
-
Brown, T. A. (2002). Genomes (2nd ed.). Wiley-Liss. Chapter 14, Mutation, repair, and
recombination. https://www.ncbi.nlm.nih.gov/books/NBK21114/
V. CONCLUSION
In constructing paper models, we were able to visualize and understand
the complex structures of Protein domains, tRNA, and DNA. These
models helped in showing how molecular interactions and folding
support their biological roles. The protein domain models showed how
proteins fold and interact in biological systems by accurately replicating
important structural elements such the beta sandwich, Rossmann fold,
and TIM barrel. The tRNA model successfully shown its L-shaped
folding and cloverleaf secondary structure, emphasizing its function in
translation. The DNA model made it simpler to understand how genetic
information is stored and replicated by clearly showing the double-helix
shape and complementary base pairing.
In summary, constructing these models offered an authentic learning
opportunity that enhanced understanding of the structure and functional
interactions of these proteins. This approach improves molecular
biology learning by transforming abstract concepts into interactive,
practical tools.
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