Chapter 15: Information Flow: From DNA to RNA to Protein

Comprehensive vocabulary flashcards covering the molecular mechanisms of gene expression, transcription, RNA processing, translation, and genetic mutations based on Chapter 15 lecture slides.

Genotype

An organism's genetic makeup; the heritable information contained within the sequence of nucleotide bases in its DNA.

Phenotype

An organism's physical traits, which arise from the actions and functions of a wide variety of proteins.

Transcription

The transfer of genetic information from a DNA template strand into an RNA molecule.

Translation

The transfer of genetic information from an RNA molecule into a polypeptide (protein strand).

Triplet Code

The system of genetic instructions wherein flow of information from gene to protein is written as a series of non-overlapping, three-base words.

Codon

A three-base nucleotide sequence in DNA or RNA that specifies a particular amino acid or serves as a termination signal during protein synthesis.

Genetic Code

The universal set of rules converting nucleotide sequences in RNA to amino acid sequences, containing 64 triplets (61 coding for amino acids and 3 serving as stop codons).

RNA Polymerase

The primary transcription enzyme that links complementary RNA nucleotides along the DNA template strand by forming phosphodiester bonds.

Promoter

A specific nucleotide sequence in DNA situated at the beginning of a gene that signals the start of transcription and provides the binding site for RNA polymerase.

Transcription Initiation

The first phase of transcription, characterized by the attachment of RNA polymerase to the promoter and the synthesis of the initial RNA bases.

Transcription Elongation

The second phase of transcription, in which the newly forming RNA chain grows longer and peels away, allowing separated DNA strands to rewind behind it.

Terminator

A specific base sequence in the DNA template that signals the end of a gene, causing RNA polymerase to detach and release the newly synthesized RNA transcript.

Transcription Termination

The third and final phase of transcription, wherein RNA polymerase encounters a terminator sequence, detaches from the DNA, and releases the complete RNA transcript.

Gene

A region of chromosomal DNA that begins with a promoter sequence, ends with a terminator sequence, and directs the synthesis of a specific polypeptide.

Cap and Tail

Extra protective nucleotides added to the 5' and 3' ends of eukaryotic pre-mRNA that prevent degradation by cellular enzymes and help ribosomes recognize the mRNA.

Introns

Internal noncoding stretches of nucleotides within eukaryotic genes that interrupt coding sequences and are excised before translation.

Exons

The coding regions of a eukaryotic gene that are retained, expressed, and spliced together to produce the final mRNA coding sequence.

RNA Splicing

The post-transcriptional process in the eukaryotic nucleus where introns are removed and exons are joined into a continuous mRNA molecule.

Spliceosome

A nuclear molecular complex consisting of proteins and small RNAs that recognizes intron boundaries, cuts out introns, and splices exons together.

Messenger RNA (mRNA)

The type of ribonucleic acid transcribed from a gene that transports genetic information from the nucleus to the cytoplasm to direct polypeptide synthesis.

Transfer RNA (tRNA)

A specialized RNA interpreter (approximately 80 nucleotides long) that matches specific amino acids to their corresponding codons on the mRNA strand.

Anticodon

A specific three-base sequence on one loop of a tRNA molecule that base-pairs complementarily to an mRNA codon during translation.

Ribosome

A cytoplasmic organelle composed of ribosomal RNA (rRNA) and proteins, organized into large and small subunits, that coordinates translation and synthesizes polypeptides.

P Site (Peptidyl site)

A tRNA binding site on the large ribosomal subunit that holds the tRNA carrying the growing polypeptide chain.

A Site (Aminoacyl site)

A tRNA binding site on the large ribosomal subunit that receives the incoming tRNA carrying the next amino acid to be added to the chain.

Codon Recognition

The first step of translation elongation, during which the anticodon of an incoming tRNA carrying an amino acid base-pairs with the mRNA codon positioned in the A site.

Peptide Bond Formation

The second step of translation elongation, in which the ribosome catalyzes the transfer of the polypeptide from the P-site tRNA to the amino acid on the A-site tRNA.

Translocation (in Translation)

The third step of translation elongation, where the uncharged P-site tRNA exits and the ribosome moves the A-site tRNA carrying the growing chain to the P site.

Mutation

Any change occurring in the nucleotide sequence of a cell's DNA, ranging from single base-pair alterations to extensive chromosomal rearrangements.

Mutagen

A physical or chemical agent—such as high-energy radiation (X-rays, UV light) or chemicals in cigarette smoke—that causes mutations in DNA.

Carcinogen

An agent that causes cancer, often originating as a mutagen that alters critical growth-regulating genes.

Missense Mutation

A base substitution mutation involving a single nucleotide alteration that results in the coding of a different amino acid.

Nonsense Mutation

A base substitution mutation that converts an amino acid codon into a premature stop codon, leading to an abnormally truncated protein.

Frameshift Mutation

A mutation caused by the deletion or insertion of one or more nucleotides not divisible by three, which alters the triplet reading frame and typically yields a nonfunctional polypeptide.