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General Biology: Gene Expression, Evolution, and Speciation

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  • What is transcription and where does it occur?

    Transcription is the process of copying DNA into mRNA. It occurs in the nucleus of eukaryotic cells.

  • What enzyme is key in transcription?

    RNA polymerase is the key enzyme that synthesizes mRNA from the DNA template during transcription.

  • What is the role of the promoter in transcription?

    The promoter is a DNA sequence where RNA polymerase and transcription factors bind to initiate transcription.

  • What is the TATA box?

    The TATA box is a DNA sequence in the promoter region that transcription factors bind to start transcription.

  • What are introns and exons?

    Introns are non-coding sequences removed during RNA splicing; exons are coding sequences joined to form mature mRNA.

  • What is RNA splicing and the role of the spliceosome?

    RNA splicing removes introns from pre-mRNA. The spliceosome is the complex that carries out this process.

  • What is alternative splicing?

    Alternative splicing allows a single gene to produce multiple protein variants by including or excluding different exons.

  • What is the triplet code, codon, and anticodon?

    The triplet code is a sequence of three nucleotides coding for an amino acid. A codon is the mRNA triplet; an anticodon is the complementary tRNA triplet.

  • What is the start codon and which amino acid does it code for?

    The start codon is AUG, which codes for the amino acid methionine.

  • Why is the genetic code said to be redundant?

    The genetic code is redundant because multiple codons can code for the same amino acid.

  • What is translation and where does it occur?

    Translation is the process of synthesizing proteins from mRNA. It occurs in the cytoplasm on ribosomes.

  • What is the role of tRNA in translation?

    tRNA molecules carry specific amino acids and have anticodons that pair with mRNA codons during translation.

  • What is the wobble position in a codon?

    The wobble position is the third nucleotide in a codon, allowing flexible base pairing and reducing the effect of mutations.

  • What is the function of aminoacyl-tRNA synthetase?

    Aminoacyl-tRNA synthetase attaches the correct amino acid to its corresponding tRNA.

  • What are the P, A, and E sites on a ribosome?

    The P site holds the tRNA with the growing polypeptide, the A site holds the incoming aminoacyl-tRNA, and the E site is where tRNA exits.

  • What are the three stages of translation?

    Initiation: ribosome assembles on mRNA; Elongation: amino acids are added; Termination: stop codon signals release of the polypeptide.

  • What is a point mutation?

    A point mutation is a change in a single nucleotide in DNA.

  • What is a silent mutation?

    A silent mutation changes a nucleotide but does not change the amino acid due to genetic code redundancy.

  • What is a missense mutation?

    A missense mutation changes a nucleotide and results in a different amino acid in the protein.

  • What is a nonsense mutation?

    A nonsense mutation changes a codon to a stop codon, prematurely terminating protein synthesis.

  • What are insertion and deletion mutations and their effect?

    Insertion or deletion mutations add or remove nucleotides, often causing frameshifts that disrupt protein function.

  • What is evolution?

    Evolution is the change in the genetic composition of a population over time.

  • Who wrote 'The Origin of Species' and what is its significance?

    Charles Darwin wrote The Origin of Species in 1859, proposing natural selection as the mechanism of evolution.

  • What is natural selection?

    Natural selection is the process where individuals with advantageous traits reproduce more successfully, leading to evolution.

  • What are homologous structures?

    Homologous structures are anatomical features shared by species due to common ancestry.

  • What is genetic drift?

    Genetic drift is a random change in allele frequencies in a population, especially in small populations.

  • What is gene flow?

    Gene flow is the transfer of alleles between populations through migration.

  • What is speciation?

    Speciation is the process by which new species arise from existing ones.

  • What is the difference between allopatric and sympatric speciation?

    Allopatric speciation occurs due to geographic isolation; sympatric speciation occurs without geographic separation.