Central Dogma & Nucleotide Chemistry
A mutation that reduces binding of RNA polymerase but leaves the coding region unchanged must occur in this functional sequence.
What is the promoter?
This is the most common biological form of DNA and features ~10 bp/turn in a right‑handed helix.
What is B‑DNA?
Heating DNA increases absorbance at 260 nm in a process known as this.
What is hyperchromicity?
Negative supercoiling facilitates this replication‑related process by reducing helix stability.
What is strand separation (unwinding)?
This amino acid disrupts α‑helices due to its rigid cyclic structure.
What is proline?
This structural difference between ribose and deoxyribose affects RNA’s chemical stability.
What is the presence of the 2'‑OH group?
Hoogsteen base pairs differ from Watson‑Crick pairs in this geometric detail.
What is altered hydrogen‑bonding orientation/rotation of the base?
DNA with higher GC content has a higher Tm because of this property of GC base pairs.
What is the presence of three hydrogen bonds?
These sequence motifs are required for formation of hairpins and cruciforms.
What are inverted repeats?
Hydrogen bonds in β‑sheets occur between these parts of the polypeptide.
What are backbone atoms of adjacent strands?
A nucleotide analog incorporated into DNA causes chain termination. This specific functional group must be missing.
What is the 3'‑OH?
This repair‑related process flips a base out of the helix to allow enzymatic access.
What is base flipping?
Spontaneous denaturation at lower temperatures occurs when this ionic condition is reduced.
What is low salt concentration (loss of electrostatic shielding)?
This topoisomerase relaxes supercoils without requiring ATP.
What is topoisomerase I?
This plot restricts φ/ψ angles due to steric hindrance.
What is the Ramachandran plot?
This type of tautomeric shift may cause adenine to pair with cytosine during replication.
What is the imino/enol tautomer formation?
Stacking interactions in DNA are stabilized primarily by this force rather than hydrogen bonding.
What are van der Waals/hydrophobic stacking interactions?
Chaotropic agents destabilize DNA by interfering with these two major stabilizing interactions.
What are hydrogen bonding and hydrophobic base stacking?
Gyrase inhibitors specifically block this essential cellular process in bacteria.
What is replication (and transcription due to altered topology)?
Cryo‑EM can visualize large flexible complexes more effectively than this classical structural method.
What is X‑ray crystallography?
In antimicrobial therapy, nucleoside analogs selectively inhibit pathogens because of this key biochemical difference in polymerase behavior.
What is differential recognition/incorporation of analogs by microbial polymerases?
This modified base regulates gene expression and contributes to controlled chromatin compaction.
What is 5‑methylcytosine?
Rapid cooling after denaturation prevents renaturation because it disrupts this necessary first step in re‑pairing strands.
What is initial proper base alignment?
Eukaryotic nucleosomes restrict transcription by influencing this feature of DNA accessibility.
What is chromatin compaction/limited access for transcription machinery?
Directed evolution improves protein properties by mimicking this natural biological mechanism.
What is selection on random mutation (natural selection)?