Molecular Biology: Transcription, Translation, and Genetics

Vocabulary flashcards covering transcription, eukaryotic pre-mRNA processing, RNA types, translation, ribosomes, genetics, and mutations based on the lecture transcript.

Central Dogma of Molecular Biology

The principle stating that genes (DNA) specify the sequences of mRNAs, which in turn specify the sequences of amino acids in proteins.

Transcription

The process by which cells make an mRNA copy of a gene.

Translation

The process by which the genetic information in mRNA is used by cellular machinery to produce proteins.

RNA Polymerase

The essential enzyme required for initiation, elongation, and termination stages of transcription that synthesizes an RNA strand complementary to the DNA template strand.

Transcription Factors

Additional proteins that aid RNA polymerase during the transcription process.

Promoter

The specific DNA sequence near a gene where RNA polymerase binds and begins transcription during initiation.

Template Strand

The single strand of DNA used by RNA polymerase during transcription to synthesize a complementary mRNA molecule.

Coding Strand

The DNA strand that is not transcribed, which is almost identical in sequence to the mRNA product except that RNA contains uracil (U) instead of thymine (T).

5' Cap

A special nucleotide added to the $5'$ end of eukaryotic pre-mRNA during transcription that protects it from hydrolytic enzymes and is recognized by translation initiation factors.

Poly-A Tail

A chain of about $200$ adenosines added to the $3'$ end of eukaryotic mRNA after transcription to protect against degradation and aid export to the cytoplasm.

Exons

Protein-coding sequences in eukaryotic genes that are expressed and joined together during mRNA splicing.

Introns

Intervening, non-coding sequences in eukaryotic genes that are precisely removed from pre-mRNA during splicing in the nucleus.

Splicing

The process in the eukaryotic nucleus that removes introns and reconnects exons to form a mature mRNA molecule.

Ribosomal RNA (rRNA)

RNA molecules that account for about $80\text{\%}$ of cellular RNA, interact with ribosomal proteins to build ribosomes, and catalyze the chemical reactions for protein synthesis.

Transfer RNA (tRNA)

Relatively short, folded RNA molecules that feature an exposed anti-codon and deliver specific covalently attached amino acids to the ribosome during translation.

Anti-codon

A sequence of three exposed nucleotides on a tRNA molecule that is complementary to a specific mRNA codon.

Codon

A three-nucleotide sequence in mRNA that defines a specific amino acid or a stop signal according to the genetic code.

Stop Codons

The three mRNA codons (UAA, UAG, UGA) that do not encode an amino acid and terminate protein synthesis.

Start Codon

The mRNA codon AUG near the $5'$ end that establishes the reading frame for protein synthesis and encodes methionine.

A Site

The compartment in the large ribosomal subunit where a newly arrived charged tRNA carrying an amino acid enters the ribosome complex.

P Site

The compartment in the large ribosomal subunit that holds the tRNA attached to the growing polypeptide chain.

E Site

The compartment in the large ribosomal subunit from which an uncharged tRNA departs the ribosome.

Gene

A specific DNA sequence that codes for a polypeptide.

Gene Locus

The physical location of a gene on a chromosome.

Alleles

Different versions of a gene that possess slightly different DNA sequences.

Genotype

The specific combination of alleles that an individual organism possesses.

Phenotype

The physical expression of an organism's alleles resulting from their interaction with the environment.

Homozygous

Describing an individual organism that possesses two identical copies of a specific allele.

Heterozygous

Describing an individual organism that possesses two different alleles for a specific gene.

Mutation

A change in the nucleotide sequence of DNA caused by DNA damage or mistakes during replication.