Molecular Biology: Central Dogma & Griffith's Experiments
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Molecular Biology: Central Dogma & Griffith's Experiments

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Questions and Answers

What name did Griffith give to the process in which type R bacteria were transformed into type S bacteria?

  • Transformation (correct)
  • Translocation
  • Transmutation
  • Translation

    • In the experiments by Avery, MacLeod, and McCarty, which macromolecule was found to be responsible for the transformation of R bacteria to S bacteria?

  • Carbohydrates
  • DNA (correct)
  • Proteins
  • RNA

    • What was the outcome when DNA extract was treated with DNase?

  • Proteins were eliminated
  • Transformation ceased (correct)
  • Transformation still occurred
  • Only RNA was affected

    • Which macromolecules were known constituents of living cells at the time of Avery, MacLeod, and McCarty's experiments?

    <p>DNA, RNA, proteins, and carbohydrates</p> Signup and view all the answers

    What was the primary goal of Avery, MacLeod, and McCarty's experiments?

    <p>To identify the genetic material</p> Signup and view all the answers

    What does Chargaff's rule state about the composition of DNA bases?

    <p>Percent of adenine equals percent of thymine</p> Signup and view all the answers

    Which species provides the highest average percentage of a specific measurement in the provided data?

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

    What impact did Chargaff's observations have on the field of genetics?

    <p>They were relevant to Watson and Crick's DNA structure elucidation.</p> Signup and view all the answers

    What was one of the key findings from the measurements taken from different tissues?

    <p>Base compositions were similar within the same species.</p> Signup and view all the answers

    Which of the following organisms exhibits the lowest measured percentage in the provided data?

    <p>S.pneumoniae</p> Signup and view all the answers

    What is the primary structural unit of both DNA and RNA?

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

    Which component differentiates RNA nucleotides from DNA nucleotides?

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

    What type of bond links nucleotides within a DNA strand?

    <p>Covalent bond</p> Signup and view all the answers

    What is the term for the connection between the 5' carbon of one nucleotide and the 3' carbon of another?

    <p>Phosphodiester linkage</p> Signup and view all the answers

    In what direction does a DNA strand run?

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

    What forms the backbone of a DNA strand?

    <p>Sugars and phosphates</p> Signup and view all the answers

    What is included in the structure of a nucleotide?

    <p>A phosphate group and a sugar</p> Signup and view all the answers

    Which type of sugar is found in DNA nucleotides?

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

    Which of the following properties is NOT required for the genetic material?

    <p>Transmitted from environmental sources</p> Signup and view all the answers

    In Griffith's experiments, what did the type S strain of Streptococcus pneumoniae produce?

    <p>Smooth colonies due to polysaccharide capsule</p> Signup and view all the answers

    What was a key question to ask when learning about new molecules?

    <p>Is it DNA, RNA, or protein?</p> Signup and view all the answers

    What type of colonies does the type R strain of Streptococcus pneumoniae produce?

    <p>Rough colonies due to no capsule</p> Signup and view all the answers

    Which option is an essential role of genetic material?

    <p>Contain information to build the organism</p> Signup and view all the answers

    What is a critical characteristic of genetic material regarding variation?

    <p>It must be capable of changes contributing to phenotypic variation</p> Signup and view all the answers

    What was a major finding of Griffith's studies on S.pneumoniae?

    <p>Type R can be converted into type S under certain conditions</p> Signup and view all the answers

    Which distinguishes the smooth colonies of type S from the rough colonies of type R?

    <p>Type S's secretion of a polysaccharide capsule</p> Signup and view all the answers

    How many nucleotides are approximately present in each strand per complete 360° turn of the DNA helix?

    <p>10.0</p> Signup and view all the answers

    What type of bonding occurs between adenine and thymine in the DNA structure?

    <p>Two hydrogen bonds</p> Signup and view all the answers

    Which of the following correctly describes the primary structure of RNA?

    <p>RNA uses Ribose with a 2’ OH group</p> Signup and view all the answers

    What stabilizes the DNA double helix structure?

    <p>Both hydrogen bonding and base stacking</p> Signup and view all the answers

    In which groove of the DNA double helix might proteins interact with specific base sequences?

    <p>Both the major and minor grooves</p> Signup and view all the answers

    During RNA synthesis, how many strands of DNA are used as a template?

    <p>One strand</p> Signup and view all the answers

    Which nucleotide is used in RNA instead of Thymine?

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

    What type of strength does base stacking provide to the DNA structure?

    <p>Hydrophobic strength</p> Signup and view all the answers

    Study Notes

    Molecular Biology

    • The Central Dogma of Biology: DNA -> RNA -> Protein
    • Life is possible due to the proper interactions and functions of molecules
    • The role of the genetic material:
      • Information: It must contain the information necessary to make an entire organism
      • Transmission: It must be passed from parent to offspring
      • Replication: It must be copied in order to be passed from parent to offspring
      • Variation: It must be capable of changes to account for the known phenotypic variation in each species

    Frederick Griffith and Streptococcus pneumoniae

    • Studied a bacterium (pneumococci) now known as Streptococcus pneumoniae
    • Two strains of S. pneumoniae
      • Type S  Smooth: Secrete a polysaccharide capsule that protects the bacterium from the immune system of animals and produces smooth colonies on solid media
      • Type R  Rough: Unable to secrete a capsule and produces colonies with a rough appearance

    Griffith’s Experiments on Genetic Transformation

    • Griffith’s experiments were conducted using two strains of S.pneumoniae: type S and type R
    • Griffith concluded that substance from dead type S bacteria was transforming type R bacteria into type S
    • This process was called transformation
    • The substance that allowed this to happen was termed the transforming principle.

    The Experiments of Avery, MacLeod and McCarty

    • These experiments sought to identify the genetic material
    • Cell extracts from type S cells were purified and only DNA was able to convert type R bacteria into type S
    • Treatment with RNase or protease did not eliminate transformation; treatment with DNase did

    DNA Structure

    • DNA contains two polynucleotide chains oriented antiparallel to each other
    • The two strands are held together by hydrogen bonds between complementary bases
    • There are two asymmetrical grooves on the outside of the helix: Major groove and Minor groove
    • Certain proteins can bind within these grooves and thus interact with a particular sequence of bases

    RNA Structure

    • RNA uses Uracil as a base, instead of Thymine
    • RNA uses Ribose with 2’ OH, instead of Deoxyribose
    • RNA strands are typically several hundred to several thousand nucleotides in length
    • Only one of the two strands of DNA is used as a template in RNA synthesis

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    Description

    This quiz explores key concepts in molecular biology, focusing on the Central Dogma, which outlines the flow of genetic information from DNA to RNA to protein. It also covers Frederick Griffith's experiments with Streptococcus pneumoniae, highlighting the differences between its two strains and the implications for genetic transformation. Test your understanding of these fundamental topics in biology.

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