DNA Polymerization, Replication Fork Machinery, and PCR Mechanics

Vocabulary flashcards covering key concepts from DNA synthesis directionality, replication fork enzymes, mutation statistics, and the mechanism of Polymerase Chain Reaction (PCR).

DNA Polymerization Directionality

The process of DNA synthesis occurring exclusively in the $5'\text{-to-}3'$ direction, where the $5'$-phosphate of an incoming nucleotide monomer is added to the $3'\text{-OH}$ group of deoxyribose.

Leading Strand

The newly synthesized DNA strand that is replicated continuously in a single piece along the template.

Lagging Strand

The newly synthesized DNA strand that must be replicated discontinuously in many separate pieces due to $5'\text{-to-}3'$ synthesis constraints.

Telomeres

The specialized ends of linear eukaryotic chromosomes that require unique replication mechanisms.

Primer

A small piece of complementary RNA (or DNA) required by DNA polymerases to initiate the replication process.

Helicase

An enzyme that unwinds parental double-stranded DNA at replication forks.

Single-strand binding protein (SSB)

A protein that binds to and stabilizes single-stranded DNA so it can serve as a template during replication.

Topoisomerase

An enzyme that relieves overwinding (supercoiling) ahead of replication forks by breaking, swiveling, and rejoining DNA strands.

Replication Mutation Rate

The measured rate of base incorporation mistakes, given as $1.1 \times 10^{-8}/\text{base/gen.}$, resulting in approximately $34$ novel mutations per person: $\approx 2(1.1 \times 10^{-8})(3.1 \times 10^9) = 34$.

Pleiotropic Effects

The phenomena where single genetic mutations produce large, widespread effects on several distinct traits.

Armand Marie Leroi

The author of the book 'Mutants', referenced regarding human genetic variations and biological mechanisms.

Polymerase Chain Reaction (PCR)

A laboratory technique used to exponentially amplify specific target DNA sequences, requiring prior knowledge of the genomic sequence.

Denaturation (PCR)

The initial step of a PCR cycle where high temperatures ($\sim 95^\circ\text{C}$) cause DNA 'melting' to separate double strands into single strands.

Annealing (PCR)

The second step of a PCR cycle where reaction temperatures are lowered ($\sim 55^\circ\text{C}$) to allow primers to bind to complementary sequence targets.

Extension (PCR)

The third step of a PCR cycle where DNA polymerase synthesizes new strands by adding nucleotides, effectively doubling the number of target molecules.