DNA Replication Quiz
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the role of helicases during DNA replication?

  • They stabilize single-stranded DNA.
  • They untwist the double helix at the replication forks. (correct)
  • They add nucleotides to the new DNA strand.
  • They relieve the strain caused by twisting of the DNA.

    • What is the function of single-strand binding proteins in DNA replication?

  • They bind to and stabilize single-stranded DNA. (correct)
  • They synthesize RNA primers.
  • They destabilize double-stranded DNA.
  • They initiate the replication process.

    • Which enzyme is responsible for relieving the strain of twisting in the DNA double helix?

  • Helicase
  • Topoisomerase (correct)
  • DNA polymerase
  • Primase

    • What is the source of the initial nucleotide chain needed for DNA synthesis?

    <p>A short RNA primer</p> Signup and view all the answers

    What is the significance of the 3′ end of the RNA primer in DNA replication?

    <p>It marks the starting point for DNA polymerase to synthesize new DNA.</p> Signup and view all the answers

    What was the first evidence that DNA is the genetic material?

    <p>Transformation in bacteria</p> Signup and view all the answers

    What is the typical length of the completed RNA primer in DNA replication?

    <p>Five to ten nucleotides</p> Signup and view all the answers

    Which of the following is NOT a protein involved in the initiation of DNA replication?

    <p>Ligase</p> Signup and view all the answers

    What term describes the change in genotype and phenotype due to assimilation of foreign DNA?

    <p>Transformation</p> Signup and view all the answers

    Who were the researchers that confirmed DNA as the transforming substance in Griffith's experiment?

    <p>Avery, McCarty, and MacLeod</p> Signup and view all the answers

    During DNA replication, the replication fork forms a Y-shaped region. What occurs at this junction?

    <p>DNA strands are unwound and nucleotides are added.</p> Signup and view all the answers

    What type of viruses did studies reveal more evidence for DNA as the genetic material?

    <p>Bacteriophages</p> Signup and view all the answers

    What is the main component of a virus according to the evidence presented?

    <p>DNA or RNA with a protein coat</p> Signup and view all the answers

    Which experimental observation by Griffith led to his conclusion about the nature of the genetic material?

    <p>Live harmless bacteria transformed into pathogenic bacteria.</p> Signup and view all the answers

    Why were many biologists skeptical about DNA being the genetic material initially?

    <p>DNA's structure was not well understood.</p> Signup and view all the answers

    How do bacteriophages contribute to genetic understanding?

    <p>They are tools for molecular genetics research.</p> Signup and view all the answers

    What is the direction in which new DNA strands can elongate?

    <p>5′ to 3′</p> Signup and view all the answers

    Which of the following statements about DNA polymerases is correct?

    <p>They catalyze synthesis at the replication fork</p> Signup and view all the answers

    What are Okazaki fragments?

    <p>Short DNA segments synthesized on the lagging strand</p> Signup and view all the answers

    How do DNA polymerases add nucleotides to a growing strand?

    <p>To the free 3′ end</p> Signup and view all the answers

    What is the primary function of DNA ligase during DNA replication?

    <p>To join Okazaki fragments</p> Signup and view all the answers

    What is the approximate rate of elongation for DNA synthesis in human cells?

    <p>50 nucleotides per second</p> Signup and view all the answers

    What characterizes the leading strand during DNA replication?

    <p>It is synthesized in the 5′ to 3′ direction continuously</p> Signup and view all the answers

    Why must DNA polymerase work in the opposite direction on the lagging strand?

    <p>Because of the antiparallel structure of the DNA strand</p> Signup and view all the answers

    What is the primary purpose of DNA replication?

    <p>To ensure the resemblance of offspring to their parents</p> Signup and view all the answers

    What is the term used to describe the type of DNA replication where each strand serves as a template for a new strand?

    <p>Semiconservative replication</p> Signup and view all the answers

    How does DNA replication begin?

    <p>At origins of replication</p> Signup and view all the answers

    Which statement accurately describes the participation of enzymes in DNA replication?

    <p>Several enzymes and proteins are involved in replication</p> Signup and view all the answers

    Which characteristic of DNA replication is highlighted by its mechanism?

    <p>It is both fast and precise</p> Signup and view all the answers

    What structure is formed when DNA is combined with proteins in eukaryotic cells?

    <p>Chromatin</p> Signup and view all the answers

    Which proteins are primarily responsible for the DNA packing in interphase chromatin?

    <p>Histones</p> Signup and view all the answers

    What is the term for changes in chromatin condensation that affect gene expression?

    <p>Epigenetics</p> Signup and view all the answers

    Which of the following can induce epigenetic changes that may be inherited?

    <p>Environmental stressors</p> Signup and view all the answers

    How can a mother's diet during pregnancy affect her child?

    <p>It can impact the child's epigenetic profile.</p> Signup and view all the answers

    What is a potential effect of intergenerational trauma on descendants?

    <p>Increased susceptibility to mental health issues</p> Signup and view all the answers

    What happens to chromosomes in the nucleus?

    <p>They occupy specific areas.</p> Signup and view all the answers

    What is primarily affected by epigenetic changes?

    <p>Gene expression</p> Signup and view all the answers

    What is the role of a nuclease in nucleotide excision repair?

    <p>It cuts out and replaces damaged DNA stretches.</p> Signup and view all the answers

    What happens to DNA molecules during repeated rounds of replication?

    <p>They become shorter with uneven ends.</p> Signup and view all the answers

    Which of the following statements about telomeres is correct?

    <p>Telomeres are connected to aging.</p> Signup and view all the answers

    What is the significance of mutations in DNA?

    <p>They are the source of genetic variation for natural selection.</p> Signup and view all the answers

    How does DNA polymerase function in relation to the ends of linear DNA molecules?

    <p>It requires a 3′ end from a preexisting polynucleotide to add nucleotides.</p> Signup and view all the answers

    What type of DNA structure do most prokaryotes have?

    <p>Circular chromosomes</p> Signup and view all the answers

    Why is the error rate after DNA proofreading and repair described as 'not zero'?

    <p>Some mutations can remain undetected.</p> Signup and view all the answers

    What can cause DNA damage aside from replication errors?

    <p>Spontaneous changes</p> Signup and view all the answers

    Study Notes

    Chapter 16: The Molecular Basis of Inheritance

    • Learning Objectives:
      • Understand how DNA is the genetic material of cells/organisms.
      • Know the structural details of DNA.
      • Understand the process of DNA replication, including the enzymes and proteins involved.
      • Know the levels of chromosome structure.

    Concept 16.1: DNA is the Genetic Material- How Do We Know?

    • Early 20th century, identifying inheritance molecules was a challenge for biologists.
    • DNA's role in heredity was first discovered by studying bacteria and viruses that infect them.

    Evidence That DNA Can Transform Bacteria

    • In 1928, Frederick Griffith discovered bacterial transformation.
    • Griffith experimented with two bacterial strains: pathogenic (harmful) and harmless.
    • Mixing heat-killed pathogenic bacteria with harmless bacteria caused some of the harmless bacteria to become pathogenic.
    • This indicated a transfer of genetic material.

    Evidence That DNA Can Transform Bacteria

    • Oswald Avery, Maclyn McCarty, and Colin MacLeod identified DNA as the transforming substance.
    • Their work showed that DNA from pathogenic bacteria could transfer genetic traits to harmless bacteria, confirming DNA's role in heredity.
    • Many biologists were skeptical at first, mostly due to the limited knowledge about DNA.

    Evidence That Viral DNA Can Program Cells

    • More evidence from studies of viruses that infect bacteria (bacteriophages or phages).
    • Viruses are DNA (or sometimes RNA) enclosed in a protein coat.
    • Phages are widely used in molecular genetics research.

    Evidence That Viral DNA Can Program Cells

    • In 1952, Alfred Hershey and Martha Chase demonstrated that DNA, not protein, is the genetic material of a phage (bacteriophage T2).

    • They designed an experiment using bacteriophages, labeling either the protein coat or the DNA with radioactive isotopes.

    • Their findings proved that only the DNA entered the bacterial cell, thus transferring the genetic information.

    Concept 16.2: Structure of DNA

    • DNA is composed of four nucleotide pairs (A+T, C+G).
    • Phosphodiester bonds link nucleotides in a single strand.
    • DNA strands have polarity (5' and 3' ends).
    • Antiparallel DNA strands bond together with hydrogen bonds.

    DNA vs. RNA: Key Differences

    Feature DNA RNA
    Strandedness Double-stranded Mostly single-stranded
    Sugar Deoxyribose Ribose
    Bases Thymine (T) Uracil (U)
    Location Nucleus Cytosol
    Replication Replicated Transcribed
    Function Stores hereditary info Uses hereditary information to build proteins

    Figure 16.9 Base Pairing in DNA

    • Purines (A & G) have double C-N rings.
    • Pyrimidines (C, T, & U) have single C-N rings.
    • Bases pair specifically (A with T, and C with G).

    Building a Structural Model of DNA

    • X-ray crystallography, using X-ray diffraction, was crucial for understanding DNA structure.
    • Rosalind Franklin's X-ray diffraction images of DNA provided crucial data that enabled James Watson.
    • Watson and Crick then deduced that DNA is a double helix.

    Where are they now?

    • Rosalind Franklin died of cancer from X-ray exposure in 1958.
    • Watson, Wilkins, and Crick were awarded the Nobel Prize in 1962.
    • Wilkins, and Crick died during 2000s.

    Reviewing DNA Strx-Group Activity

    • Group A: Nucleotide components, nitrogenous bases, differences between deoxyribose and ribose sugar, and DNA vs. RNA differences.
    • Group B: DNA strand backbone molecules, phosphodiester linkages, antiparallel strands, bonds holding base pairs.

    Concept 16.2: DNA Replication and Repair

    • DNA replication is crucial for inheritance, ensuring faithful transmission of genetic information in cell division.
    • DNA replication occurs before mitosis.
    • Specific base pairing supports a possible copying mechanism.
    • DNA replication is the process of copying DNA.

    Figure 16.1b How Does DNA Replication Transmit Genetic Information?

    • DNA replication is the process of transmitting genetic information from parent to daughter cells during mitosis (and meiosis).
    • Replication begins at specific sites (origins of replication).
    • Replication proceeds in both directions from each site along the DNA.

    The Basic Principle: Base Pairing to a Template Strand

    • Each DNA strand acts as a template during replication.
    • DNA replication is semiconservative.

    DNA Replication: The Mechanism

    • DNA replication is rapid and accurate.
    • Many enzymes and proteins are involved.
    • Bacterial replication is better understood.

    Getting Started

    • Replication begins at origin(s) of replication, creating a replication bubble.
    • Chromosomes (eukaryotic) may have many origins of replication.
    • Replication progresses in both directions from each origin.

    Replication Initiation

    • Several proteins initiate replication.
    • Helicases untwist the double helix at replication forks, separating the strands.
    • Single-strand binding proteins stabilize single-stranded DNA.
    • Topoisomerase relieves the strain ahead of the replication forks.

    Synthesizing a New DNA Strand

    • DNA polymerases synthesize new DNA strands.
    • DNA polymerases require a primer.
    • A short RNA primer is synthesized by primase.

    Antiparallel Elongation

    • DNA polymerase only adds nucleotides to the free 3' end of a growing strand.
    • Leading strand is synthesized continuously.
    • Lagging strand is synthesized discontinuously in Okazaki fragments.

    Proofreading and Repairing DNA

    • DNA polymerase can proofread and repair errors.
    • Nucleotide excision repair removes and replaces damaged stretches of DNA.

    Evolutionary Significance of Altered DNA Nucleotides

    • Errors occur during DNA replication, but are usually corrected.
    • Sequence changes (mutations) are the source of genetic variation responsible for the appearance of new species.
    • Random mutations are the reason for evolution.

    Replicating the Ends of DNA Molecules

    • Linear DNA ends (telomeres) cannot be fully replicated by DNA polymerase.
    • Telomeres shorten during each replication cycle.
    • Telomerase, an enzyme, lengthens telomeres.

    Concept 16.3: Chromosome Structure

    • DNA is packaged into chromatin in eukaryotic cells.
    • Histones, proteins, are essential for DNA packing.
    • Chromatin undergoes different levels of condensation (organization) throughout the cell cycle.
    • Euchromatin and heterochromatin differ in their condensation levels.

    Environmental Factors

    • Environmental factors like famine, toxins, or extreme stress can cause epigenetic changes that can be passed to future generations.
    • Intergenerational trauma may cause epigenetic changes impacting mental health.
    • Maternal nutrition during pregnancy may affect the epigenetic profile of the fetus, influencing later health.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Campbell: Biology - Chapter 16 PDF

    Description

    Test your knowledge on the crucial processes involved in DNA replication. This quiz covers various enzymes, functions, and historical experiments that highlighted the role of DNA as genetic material. Dive into the specifics of each component involved in this essential biological process.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser