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Vocabulary flashcards covering key terms from the lecture on protein synthesis, gene expression, and mutations.
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DNA
The hereditary molecule housed in the nucleus that carries genetic information.
Chromosome
Tightly packed DNA structure containing many genes.
Gene
A sequence of DNA that codes for a single protein.
Genome
All the genetic information of an organism.
Transcription
Process of copying DNA into an RNA strand.
RNA Processing
Eukaryotic modification of pre-mRNA by capping, tailing, and splicing to produce mature mRNA.
Translation
Decoding mRNA to build a polypeptide chain in the cytoplasm.
Central Dogma
Flow of genetic information: DNA → RNA → Protein.
RNA
Ribonucleic acid; usually single-stranded and contains ribose and uracil.
Messenger RNA (mRNA)
RNA copy that carries genetic instructions from nucleus to ribosome.
Transfer RNA (tRNA)
RNA that delivers specific amino acids to the ribosome during translation.
Ribosomal RNA (rRNA)
RNA that combines with proteins to form ribosomes and catalyze protein synthesis.
Promoter
DNA sequence where transcription factors and RNA polymerase bind to start transcription.
Transcription Factor
Protein that regulates transcription by helping RNA polymerase bind to the promoter.
RNA Polymerase
Enzyme that synthesizes RNA using a DNA template.
Template Strand
DNA strand used by RNA polymerase to build complementary RNA.
Codon
Three-nucleotide mRNA sequence that specifies an amino acid or stop signal.
Anticodon
Three bases on tRNA complementary to an mRNA codon.
Genetic Code
Set of rules by which codons specify amino acids; universal and redundant.
Start Codon
AUG; signals beginning of translation and codes for methionine.
Stop Codon
UAA, UAG, or UGA; signals termination of translation.
Ribosome
rRNA-protein complex where translation occurs; has large and small subunits.
A Site
Acceptor site on ribosome where incoming charged tRNA binds.
P Site
Peptide site on ribosome holding the growing polypeptide chain.
E Site
Exit site where empty tRNA leaves the ribosome.
Initiation (Transcription)
Binding of transcription factors and RNA polymerase to promoter to begin RNA synthesis.
Elongation (Transcription)
RNA polymerase adds RNA nucleotides in the 5′→3′ direction.
Termination (Transcription)
RNA polymerase recognizes stop sequence and releases newly made RNA.
Initiation (Translation)
Small ribosomal subunit, mRNA, and initiator tRNA assemble at the start codon.
Elongation (Translation)
Sequential addition of amino acids as ribosome moves along mRNA.
Termination (Translation)
Release factor binds to stop codon, freeing polypeptide and disassembling ribosome.
Intron
Non-coding RNA segment removed during RNA processing.
Exon
Coding RNA segment retained in mature mRNA.
Spliceosome
Enzyme complex that removes introns and joins exons.
5′ Cap
Modified guanine added to 5′ end of mRNA to aid ribosome binding.
Poly-A Tail
String of ~150 adenines added to 3′ end of mRNA for stability and export.
Point Mutation
Single base substitution in DNA.
Silent Mutation
Point mutation that changes a codon to a synonym, leaving amino acid unchanged.
Missense Mutation
Point mutation that replaces one amino acid with another in the protein.
Nonsense Mutation
Point mutation creating a premature stop codon.
Frameshift Mutation
Insertion or deletion altering the reading frame of a gene.
Sickle Cell Anemia
Disease caused by a non-conservative missense mutation in the β-globin gene.
Cystic Fibrosis
Autosomal recessive disorder often due to frameshift mutations in a chloride ion channel gene.
Fragile X Syndrome
Genetic disorder caused by CGG repeat insertions on the X-chromosome leading to frameshifts.
Thymine Dimer
Covalent linkage of adjacent thymines induced by UV light, potentially causing mutations.
Ames Test
Bacterial assay used to identify chemical mutagens via reversion to histidine synthesis.
Somatic Mutation
DNA change in non-reproductive cells; not inherited but can lead to cancer.
Germ-Line Mutation
Mutation in eggs or sperm that can be passed to offspring.
Teratology
Study of congenital malformations and their causes.
Redundancy (in Genetic Code)
Feature where most amino acids are encoded by multiple codons, protecting against mutations.