Nucleic Acids, Information Flow, and Mutations

Vocabulary practice flashcards covering nucleic acid structures, DNA replication, transcription, translation, the genetic code, and mutations based on the lecture transcript.

Transfer RNA (tRNA)

The smallest of the three types of RNA, whose function is to transfer or carry the correct amino acid to the site of protein synthesis.

Messenger RNA (mRNA)

A type of RNA of variable size that carries the genetic code from DNA as a sequence of nucleotide triplet codons to direct protein synthesis.

Ribosomal RNA (rRNA)

Long strands of RNA composed of hundreds of thousands of nucleotide residues that combine with mRNA and tRNA to form the multi-subunit platform where protein synthesis takes place.

Replication

The first step in information flow, involving the duplication of DNA before cell division by using existing DNA as a template to synthesize new DNA molecules.

Transcription

The second step in information flow, where portions of the primary structure of template DNA are mapped and copied to synthesize complementary RNA molecules.

Translation

The third step in information flow, in which the primary structure of mRNA (codons) is read to synthesize the primary structure of desired proteins.

Reverse transcription

A process found in certain viruses such as HIV where viral RNA is converted into viral DNA to allow information flow and viral protein synthesis.

Single-stranded binding proteins

Protective proteins that bind to unwound DNA single strands at the origin of replication to prevent them from being destroyed by cellular endonucleases.

DNA polymerase

The principal replication enzyme that binds to template DNA in the $3'$ to $5'$ direction, synthesizes daughter DNA in the $5'$ to $3'$ direction, and performs proofreading and repair.

Promoter site

The origin site where the double strands of DNA begin to separate during the process of transcription.

RNA polymerase

The transcription enzyme that binds to template DNA in the $3'$ to $5'$ direction and synthesizes an antiparallel RNA strand using ribonucleoside triphosphates (ATP, GTP, CTP, and UTP).

Gene

A specific portion of template DNA that is transcribed into RNA during transcription, unlike replication which copies the entire DNA strand.

Triplet codon

A series of three nucleotide bases on mRNA that specifies a particular amino acid during translation.

Start codon

The mRNA triplet codon AUG, which codes for the amino acid methionine and marks the beginning of protein synthesis.

Stop codons

The triplet codons UAA, UAG, and UGA, which are not associated with amino acids and signal the termination of translation.

Anticodon

A series of three bases carried by tRNA that is complementary to a triplet codon on mRNA, ensuring the correct amino acid is incorporated into the growing protein chain.

Synthase enzymes

Enzymes that correctly match and attach specific amino acids to their respective tRNA molecules.

Mutation

Any permanent change in the primary structure (nucleotide residue sequence) of DNA, which may involve base substitution, addition, or deletion.

Mutagens

Mutation-causing agents, including X-rays, ultraviolet (UV) radiation, nuclear radiation, and chemical agents such as oxidizing and reducing agents.

Carcinogens

Agents specifically defined as cancer-causing agents.