Skip to main content
Back

DNA Structure and Replication - General Biology

Control buttons has been changed to "navigation" mode.
1/31
  • What are the two chemical components of chromosomes?
    DNA and proteins.
  • Define transformation in genetics.
    The process by which genetic material is transferred from one organism to another.
  • What did Hershey and Chase demonstrate about DNA?
    Only the DNA of a phage enters an E. coli cell, proving DNA is the genetic material.
  • What are Chargaff’s rules?
    In DNA, adenine pairs with thymine and guanine pairs with cytosine in equal amounts.
  • Who discovered the first molecular model of DNA?
    Watson and Crick, who shared the 1962 Nobel Prize for the discovery.
  • What was Rosalind Franklin’s contribution to DNA structure discovery?
    She produced X-ray diffraction images that revealed the double helix structure.
  • How does the DNA double helix explain Chargaff’s rules?
    Base pairing between purines and pyrimidines ensures equal amounts of A-T and G-C.
  • What does antiparallel mean in DNA strands?
    The two DNA strands run in opposite directions: one 5ʹ to 3ʹ, the other 3ʹ to 5ʹ.
  • Name the five nitrogenous bases and their types.
    Purines: adenine, guanine; Pyrimidines: thymine, cytosine, uracil.
  • Which DNA base pairs with adenine?
    Thymine.
  • Which DNA base pairs with guanine?
    Cytosine.
  • What is the significance of 5ʹ and 3ʹ ends in nucleotides?
    They indicate the direction of the sugar-phosphate backbone; DNA synthesis occurs 5ʹ to 3ʹ.
  • What is the semiconservative model of DNA replication?
    Each new DNA molecule has one old strand and one newly synthesized strand.
  • What are origins of replication?
    Specific sites where DNA replication begins.
  • How is eukaryotic DNA replication sped up?
    By having multiple origins of replication on linear chromosomes.
  • Difference between leading and lagging strands?
    Leading strand is synthesized continuously; lagging strand is synthesized in Okazaki fragments.
  • Why can new DNA strands only be synthesized in one direction?
    DNA polymerase adds nucleotides only to the 3ʹ end, synthesizing 5ʹ to 3ʹ.
  • What are Okazaki fragments?
    Short DNA fragments synthesized on the lagging strand.
  • Which enzyme joins Okazaki fragments?
    DNA ligase.
  • Role of helicase in DNA replication?
    Unwinds and separates the DNA strands.
  • Role of single-strand binding proteins (SSBP)?
    Stabilize unwound DNA strands to prevent reannealing.
  • Role of primase?
    Synthesizes RNA primers to start DNA synthesis.
  • Role of DNA polymerase III?
    Adds DNA nucleotides to the new strand.
  • Role of topoisomerase?
    Relieves strain caused by unwinding DNA.
  • Role of DNA polymerase I?
    Removes RNA primers and replaces them with DNA nucleotides.
  • What is proofreading in DNA replication?
    DNA polymerase checks and corrects errors during synthesis.
  • What are telomeres?
    Protective DNA sequences at chromosome ends that prevent loss of genes.
  • What is telomere erosion and its significance?
    Shortening of telomeres with each cell division, linked to aging.
  • Which cells produce telomerase?
    Germ cells, stem cells, and some cancer cells produce telomerase to maintain telomeres.
  • What is the polymerase chain reaction (PCR)?
    A technique to amplify specific DNA sequences rapidly.
  • What is Cas9 in CRISPR technology?
    An enzyme that cuts DNA at specific sites for gene editing.