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Study guide test 2

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Termini in questo insieme (21)

  • Central dogma of molecular biology

    DNA is transcribed to mRNA, which is translated into protein that determines cellular function.

  • Inducible operon

    Genes are "off" with repressor bound to DNA; turned "on" when an inducer inactivates the repressor, allowing transcription.

  • Repressible operon

    Genes are "on" without repressor bound; turned "off" when a corepressor activates the repressor to bind DNA and block transcription.

  • DNA replication

    Process where DNA strands separate and serve as templates for new complementary strands, involving enzymes like helicase, DNA polymerase, and ligase.

  • Antiparallel strands in DNA

    Two DNA strands run in opposite directions: one 5' to 3', the other 3' to 5', allowing complementary base pairing.

  • Okazaki fragments

    Short DNA fragments synthesized discontinuously on the lagging strand during DNA replication, later joined by DNA ligase.

  • Transcription

    RNA polymerase synthesizes a complementary mRNA strand from the DNA template, starting at the promoter and ending at the terminator.

  • Translation

    mRNA codons are decoded by tRNA anticodons at the ribosome to assemble amino acids into a polypeptide chain.

  • Start and stop codons

    Translation begins at the start codon AUG and ends at stop codons UAA, UAG, UGA.

  • Polyribosome (polysome)

    Multiple ribosomes simultaneously translating a single mRNA molecule, increasing protein synthesis efficiency.

  • RNA processing in eukaryotes

    Introns are removed and exons spliced together by snRNPs to form mature mRNA before translation.

  • Operon structure

    Includes promoter, operator, structural genes, and regulatory gene controlling gene expression in prokaryotes.

  • Lac operon regulation

    In absence of lactose, repressor binds operator to block transcription; lactose (inducer) inactivates repressor allowing gene expression.

  • Trp operon regulation

    Operon is on by default; excess tryptophan (corepressor) activates repressor to bind operator and stop transcription.

  • Gene expression control: positive regulation

    cAMP binds CAP protein, which attaches to promoter to enhance transcription when glucose is scarce.

  • Mutation

    Permanent change in DNA sequence that can alter protein function and phenotype.

  • Types of mutations

    Include silent (neutral), missense (amino acid change), nonsense (stop codon), and frameshift (insertion/deletion).

  • Mutagens

    Agents like chemicals or radiation that increase mutation rates by damaging DNA or causing base substitutions.

  • DNA repair mechanisms

    Include photolyase for UV damage and nucleotide excision repair to remove and replace damaged DNA segments.

  • Horizontal gene transfer

    Transfer of genetic material between cells of the same generation via transformation, conjugation, or transduction.

  • Vertical gene transfer

    Transfer of genetic information from parent to offspring during cell division.