Molecular Biology B: DNA Transcription and Translation

Vocabulary flashcards covering the molecular mechanisms of DNA replication, transcription, translation, RNA processing, and their clinical applications in dental genetics and tooth development.

Central Dogma

The core framework of molecular biology describing the flow of genetic information: DNA is replicated or copied into RNA via transcription, and RNA is translated into protein.

Transcription

The enzymatic process occurring in the nucleus of human cells where genetic information from a DNA template strand is copied to produce a complementary RNA strand.

Translation

The process taking place on ribosomes in the cytoplasm where an mRNA sequence is read codon-by-codon to assemble amino acids into a polypeptide chain.

Ribosomal RNA (rRNA)

A major functional category of RNA that combines with proteins to construct the physical and catalytic structure of the ribosome.

Messenger RNA (mRNA)

A type of RNA synthesized in the cell nucleus that carries the transcribed coding instructions of DNA out to the ribosomes for protein synthesis.

Transfer RNA (tRNA)

An RNA molecule bearing a specific anticodon that delivers corresponding amino acids one by one to the growing polypeptide chain at the ribosome.

Helicase

The enzyme that unwinds and separates the parent double-stranded DNA helix ahead of the replication machinery.

RNA Primase

A specialized RNA polymerase that initiates DNA replication by creating a short RNA primer to provide a free end for DNA polymerase to extend.

Okazaki Fragments

Short, discontinuous segments of synthesized DNA formed along the lagging strand template during DNA replication.

TATA Box

A conserved promoter DNA sequence positioned approximately $25\,\text{bp}$ upstream of the transcription start site where transcription factors assemble.

RNA Polymerase II

The eukaryotic enzyme complex that binds to promoter regions downstream of transcription factors to synthesize pre-mRNA.

Introns

Non-coding sequences located within pre-mRNA transcripts that are removed by splicing and absent from mature mRNA.

Exons

The coding nucleotide segments of a pre-mRNA transcript that are retained and spliced together during RNA processing to form mature mRNA.

$$5'\text{ Cap}$$

A modified guanine nucleotide added to the $5'$ end of eukaryotic pre-mRNA during processing to protect against degradation and facilitate translation.

$$3'\text{ Poly-A Tail}$$

A repetitive stretch of adenine nucleotides appended to the $3'$ end of eukaryotic pre-mRNA during post-transcriptional processing to ensure stability and nuclear export.

Aminoacyl tRNA Synthetase

An enzyme that attaches a specific amino acid to its corresponding tRNA via an ester bond using energy supplied by ATP.

Codon

A consecutive sequence of three nucleotides on an mRNA strand that specifies a single amino acid or signals translation termination.

Anticodon

A three-nucleotide sequence found on a tRNA molecule that base-pairs complementarily with a specific codon on mRNA during translation.

Start Codon

The mRNA triplet codon AUG, which marks the initiation site of translation and codes for the amino acid methionine (Met).

Stop Codons

The three mRNA triplet codons—UAA, UAG, and UGA—that do not encode an amino acid and instead trigger release factors to terminate translation.

Amelogenesis Imperfecta

A hereditary dental condition caused by mutations in genes such as AMELX and ENAM, leading to defective enamel matrix formation, weak or thin enamel, and hypersensitivity.

Dentine Sialophosphoprotein (DSPP)

A critical matrix protein secreted by odontoblasts that plays an essential role in dentine matrix formation and mineralization.

Dentinogenesis Imperfecta

A genetic condition caused by pathogenic variants in the DSPP gene that disrupts dentine formation, causing teeth to appear opalescent and susceptible to fracture and wear.

RUNX2

A transcriptional regulator that contributes critically to skeletal development as well as tooth and craniofacial morphogenesis.

COL6 Deficiency

A collagen defect that impairs fibrillogenesis in the periodontal ligament (PDL), reducing tissue integrity and exacerbating periodontal destruction.