Molecular Basis of Inheritance Vocabulary Flashcards

Vocabulary practice flashcards generated from the Molecular Basis of Inheritance lecture notes, covering DNA structure, replication, transcription, translation, genetic code, and lac operon regulation.

Central Dogma

The principle stating that genetic information flows sequentially from DNA to RNA to Protein.

Nuclein

The original term given to DNA upon its discovery by Miescher in 1869.

Chargaff's Rules

The rule establishing that in DNA, adenine equals thymine ($A = T$) and guanine equals cytosine ($G = C$), meaning total purines equal total pyrimidines.

Hershey-Chase Experiment (1952)

The experiment conducted in 1952 that definitively proved DNA is the genetic material.

B-DNA Double Helix Model

The structural DNA model proposed by Watson & Crick in 1953, featuring two antiparallel polynucleotide chains ($5'\text{-}3'$ and $3'\text{-}5'$).

DNA Pitch and Diameter

Structural dimensions of B-form DNA, consisting of a diameter of $2\,\text{nm}$, a pitch of $3.4\,\text{nm}$, and $10\,\text{bp}$ per turn.

Helicase

An enzyme involved in DNA replication that unwinds the double-stranded DNA helix.

SSB Proteins

Single-strand binding proteins that prevent unwound single-stranded DNA from reannealing during replication.

Primase

An enzyme in DNA replication that synthesizes an RNA primer.

DNA Polymerase III

The primary enzyme responsible for synthesizing new DNA strands in the $5'\text{-}3'$ direction.

DNA Ligase

An enzyme that joins Okazaki fragments together on the lagging strand during DNA replication.

Leading Strand

The strand of DNA that undergoes continuous synthesis during DNA replication.

Lagging Strand

The strand of DNA that undergoes discontinuous synthesis during replication, resulting in Okazaki fragments.

Promoter

A specific sequence on DNA, such as a TATA box, where RNA polymerase binds to initiate transcription.

hnRNA

Heterogeneous nuclear RNA; the primary transcript produced in eukaryotic transcription prior to post-transcriptional processing.

Capping

An eukaryotic RNA processing step in which a 7-methyl guanosine cap is added to the $5'$ end of hnRNA.

Splicing

The process in eukaryotic RNA editing that involves the removal of non-coding introns and the ligation of coding exons.

Tailing

The addition of a Poly-A tail to the $3'$ end of eukaryotic hnRNA during post-transcriptional processing.

Triplet Code

The structural arrangement of the genetic code where a sequence of 3 nucleotides forms a single codon.

Unambiguous Genetic Code

The property of the genetic code specifying that one codon codes for strictly one amino acid.

Degenerate Genetic Code

The property of the genetic code wherein most amino acids are coded by more than one codon.

AUG Codon

The start codon in mRNA that codes for the amino acid Methionine (Met).

Stop Codons

The three non-coding codons—UAA, UAG, and UGA—that signal translation termination.

Initiator tRNA

The specialized tRNA carrying Methionine (Met) that binds to the ribosomal P site during translation initiation.

Translocation (Translation)

The step in translation elongation where the ribosome shifts along mRNA by one codon in the $5'\text{-}3'$ direction.

Lac Operon

A regulated gene system proposed by Jacob & Monod comprising a promoter (P), operator (O), structural genes (Z, Y, A), and a regulator gene (I).

Allolactose

The inducer molecule in the Lac Operon that binds to and inactivates the repressor protein when lactose is present, turning transcription ON.