CHAPTER 7

• What is the direction of the lagging strand during DNA replication?

  3’ to 5’ direction
• How is the lagging strand synthesized during DNA replication?


  It is synthesized discontinuously in fragments.
• What are Okazaki fragments?


  Short DNA segments synthesized on the lagging strand.
• What enzyme joins Okazaki fragments together?


  DNA ligase
• What is the process of DNA transcription?


  It is the copying of genetic information from DNA to RNA.
• What is ribosomal RNA (rRNA) primarily responsible for?


  It is a crucial component of ribosomes.
• What role does rRNA play in protein synthesis?


  It ensures proper alignment of mRNA and tRNA and catalyzes peptide bond formation.
• What is the function of messenger RNA (mRNA)?


  It carries genetic instructions from DNA to ribosomes.
• How does mRNA dictate the sequence of amino acids in a protein?


  Through its codons, which are three-nucleotide sequences.
• What is the role of transfer RNA (tRNA) in protein synthesis?


  It decodes genetic information carried by mRNA.
• What is the significance of the anticodon region in tRNA?


  It binds to complementary codons on the mRNA strand.
• What type of ribosomes do prokaryotes have?


  70S ribosomes
• What is a start codon in mRNA?


  It is the first codon that codes for methionine.
• What is a stop codon in mRNA?


  It signals the end of protein synthesis.
• What are sense codons?


  Codons that code for an amino acid.
• What are nonsense codons?


  Codons that do not code for any amino acid.
• What is feedback inhibition in metabolism?


  It is a regulatory mechanism that inhibits enzyme activity.
• What are constitutive enzymes?


  Enzymes synthesized continuously regardless of nutrient availability.
• What are inducible enzymes?


  Enzymes that are synthesized in response to the presence of a substrate.
• What is enzyme induction?


  It is the process that turns on the transcription of genes.
• What is an inducer?


  A substance that induces transcription of a gene.
• What is repression in gene regulation?


  It inhibits gene expression and decreases enzyme synthesis.
• Who proposed the operon theory?


  François Jacob and Jacques Monod
• What is an operon?


  A sequence of closely associated genes that regulate enzyme production.
• What is the role of structural genes in an operon?


  They carry information for the synthesis of specific proteins.
• What is a promoter in DNA?


  The region where RNA polymerase initiates transcription.
• What is the function of the lac operon?


  It regulates the metabolism of lactose in bacteria.
• What happens when lactose is present in relation to the lac operon?


  The repressor protein changes conformation and allows transcription.
• What is a mutation?


  Heritable changes in the sequence of nucleotides in DNA.
• What is a point mutation?


  A mutation involving base substitution at a specific location in a gene.
• What is a missense mutation?


  A base substitution that results in amino acid substitution in a protein.
• What is a nonsense mutation?


  A base substitution that creates a stop codon in mRNA.
• What is a frameshift mutation?


  A mutation involving deletion or insertion of bases that shifts the reading frame.
• What is an insertion mutation?


  A mutation that adds a piece of DNA, changing the number of bases in a gene.
• What is a deletion mutation?


  A mutation that removes a piece of DNA, changing the number of bases in a gene.
• What is a spontaneous mutation?


  A mutation that occurs without any known agent causing changes in DNA.
• What is an induced mutation?


  A mutation produced by agents called mutagens.
• What is transformation in bacteria?


  It is the transfer of "naked" DNA from one bacterium to another.
• What does it mean for a cell to be competent?


  It can take up and incorporate donor DNA.
• What is the significance of the early stationary phase in transformation?


  Cells producing surface structures that bind and take up extracellular DNA are competent.