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Questions and Answers
What is the characteristic of A-DNA?
What type of DNA is formed when a third strand of DNA binds to a double helix?
What is the number of base pairs per turn in B-DNA?
What is the role of G-quadruplex DNA in cells?
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What is the effect of cisplatin binding to DNA?
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What is the characteristic of I-Motif DNA?
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What is the distance between base pairs in A-DNA?
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In what type of DNA does the double helix structure have a left-handed orientation?
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What is the characteristic feature of the double helix structure of B-DNA?
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What is the pitch (distance between turns) of the double helix structure of B-DNA?
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In which type of DNA is the distance between base pairs 0.38 nm?
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Study Notes
Alternative Forms of DNA
A-DNA, B-DNA, and Z-DNA
- A-DNA:
- Right-handed double helix
- Wider and shorter than B-DNA
- Found in dehydrated DNA or in the presence of certain ions
- B-DNA:
- Right-handed double helix
- Most common form of DNA in nature
- 10 base pairs per turn, pitch of 34 Å
- Z-DNA:
- Left-handed double helix
- Found in regions with high GC content
- 12 base pairs per turn, pitch of 45 Å
Triplex DNA
- Formed when a third strand of DNA binds to a double helix
- Can be parallel or antiparallel to the target DNA
- Stabilized by Hoogsteen or reverse Hoogsteen bonds
- Plays a role in gene regulation and DNA repair
G-quadruplex DNA
- Formed when four guanine bases come together
- Stabilized by hydrogen bonding and π-π stacking
- Found in telomeres, gene promoters, and untranslated regions
- Implicated in gene regulation, DNA repair, and cancer
Cisplatin-DNA Adducts
- Formed when cisplatin binds to DNA
- Causes intrastrand crosslinks and bending of the DNA
- Leads to inhibition of DNA replication and transcription
- Used as a chemotherapeutic agent in cancer treatment
I-Motif DNA
- Formed when cytosine-rich sequences come together
- Stabilized by hemiprotonated cytosine-cytosine+ pairs
- Found in promoter regions and plays a role in gene regulation
- Implicated in cancer and neurological disorders
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Description
Explore the different forms of DNA, including A-DNA, B-DNA, Z-DNA, triplex DNA, G-quadruplex DNA, cisplatin-DNA adducts, and I-motif DNA. Learn about their structures, characteristics, and roles in gene regulation and disease.
