Protein Synthesis & DNA Mutations – Key Vocabulary

This set of vocabulary flashcards covers the major terms and concepts from the lecture on protein synthesis, gene expression, and DNA mutations, providing a comprehensive review for exam preparation.

DNA

Deoxyribonucleic acid; double-stranded hereditary molecule that stores genetic information in the nucleus.

Chromosome

Tightly packed DNA structure containing many genes.

Gene

Sequence of DNA nucleotides that codes for a single protein.

Genome

All the genetic information of an organism.

Central Dogma

Flow of genetic information: DNA → RNA → Protein.

Transcription

Process of copying DNA into RNA.

RNA Processing

Modifications that convert pre-mRNA into mature mRNA (capping, tailing, splicing).

Translation

Decoding mRNA to synthesize a polypeptide chain.

Messenger RNA (mRNA)

RNA copy of DNA that carries the genetic code to the ribosome.

Transfer RNA (tRNA)

RNA that delivers specific amino acids to the ribosome using its anticodon.

Ribosomal RNA (rRNA)

RNA that combines with proteins to form ribosomes, the site of translation.

Promoter

DNA sequence where transcription factors and RNA polymerase bind to start transcription.

Transcription Factors

Proteins that regulate transcription by assisting RNA polymerase binding.

RNA Polymerase

Enzyme that synthesizes RNA from the DNA template strand.

Template Strand

DNA strand used by RNA polymerase to assemble complementary RNA.

Codon

Three-nucleotide mRNA sequence that specifies an amino acid.

Anticodon

Three-nucleotide sequence on tRNA complementary to an mRNA codon.

Genetic Code

Set of codon–amino acid correspondences; universal and redundant.

Start Codon

AUG; signals initiation of translation and codes for methionine.

Stop Codon

UAA, UAG, or UGA; signal termination of translation.

Redundancy (of the code)

Feature where multiple codons specify the same amino acid, providing mutation protection.

Ribosome

rRNA–protein complex that coordinates translation.

A Site

Ribosomal site where incoming tRNA binds during elongation.

P Site

Ribosomal site holding the growing polypeptide-bearing tRNA.

E Site

Ribosomal exit site for spent tRNA.

Peptide Bond

Covalent bond linking amino acids in a polypeptide.

Polypeptide

Chain of amino acids; folds to become a functional protein.

5′ Cap

Modified guanine added to the 5′ end of mRNA to aid ribosome binding.

Poly-A Tail

Series of adenines added to 3′ end of mRNA to prevent degradation.

Intron

Non-coding sequence removed from pre-mRNA.

Exon

Coding sequence retained in mature mRNA.

Spliceosome

Enzyme complex that excises introns and ligates exons.

Pre-mRNA

Initial RNA transcript containing introns and exons.

Mature mRNA

Processed RNA consisting only of exons, capped and tailed.

Release Factor

Protein that recognizes stop codon and releases the completed polypeptide.

Large Ribosomal Subunit

Upper ribosome component housing A, P, and E sites.

Small Ribosomal Subunit

Lower ribosome component that binds mRNA first.

Glycoprotein

Protein with covalently attached sugar chains added in ER or Golgi.

Endoplasmic Reticulum (ER)

Organelle where membrane or secreted proteins are translocated and folded.

Golgi Apparatus

Organelle that modifies, sorts, and ships proteins to final destinations.

Mutation

Permanent change in DNA sequence.

Point Mutation

Single-base substitution in DNA.

Silent Mutation

Point mutation that does not alter the encoded amino acid.

Missense Mutation

Point mutation changing one amino acid in the protein.

Nonsense Mutation

Point mutation converting codon to premature stop codon.

Conservative vs. Non-conservative

Missense change to similar (conservative) or dissimilar (non-conservative) amino acid.

Frameshift Mutation

Insertion or deletion altering the reading frame of mRNA.

Sickle-Cell Disease

Disorder from non-conservative missense mutation in β-globin gene.

Cystic Fibrosis

Inherited disease often caused by frameshift mutations in chloride channel gene.

Thymine Dimer

UV-induced covalent link between adjacent thymines causing DNA distortion.

Ames Test

Bacterial assay that detects mutagenic chemicals via reversion mutations.

Somatic Mutation

DNA change in non-reproductive cells; not heritable but may lead to cancer.

Germ-line Mutation

DNA change in gametes; heritable and can affect offspring phenotypes.

Teratology

Study of congenital malformations and their causes.