Lecture 1/27/25 Flashcards
What is the favorable position for DNA bases within the same strand?
Stacked inside the double helix to maximize hydrophobic interactions.
What can put them in an unfavorable condition?
Disruptions like high temperature, pH changes, or chemical denaturation.
What are Chargaff Ratios?
A = T and G = C in DNA; total purines equal total pyrimidines.
Does DNA base composition vary by age, nutrition, or tissue type?
No, DNA composition remains constant within a species.
How can a kidney cell and lung cell have the same DNA but different functions?
Gene expression differences regulate specialized cell functions.
What is a major and minor groove in DNA?
Unequal spacing between backbones; major groove is where proteins bind more often.
What happens in the major groove?
Protein interactions, including transcription factor binding.
What is DNA annealing?
Reformation of complementary DNA strands after denaturation.
How do we differentiate between replication and transcription polymerases?
Replication polymerases copy the genome; transcription polymerases synthesize RNA.
What is a hairpin structure?
A single-stranded sequence that folds back on itself due to complementary base pairing.
What is a cruciform structure?
A double-stranded version of a hairpin, forming a cross shape.
What is a palindrome in DNA?
A sequence that reads the same forward and backward on opposite strands.
How are palindromes used by restriction endonucleases?
They serve as recognition sites for precise DNA cutting.
Example of a DNA palindrome?
GAATTC (complementary strand: CTTAAG).
Why don’t palindromes or mirror repeats form hairpins or cruciforms?
Palindromes involve both strands, while mirror repeats are on a single strand.
What is DNA recombination?
Exchange of genetic material between DNA molecules.
Define mitosis and meiosis.
Mitosis creates identical diploid cells; meiosis creates haploid gametes with genetic variation.
