DNA as the Genetic Material
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Questions and Answers

The Hershey-Chase experiment confirmed that DNA, not ______ or protein, is the genetic material.

RNA

Bacteriophages are composed of ______ and protein.

DNA

In the Hershey-Chase experiment, DNA was labeled with ______.

32P

The transforming principle was first described by ______ in 1928.

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

In the DNA structure, the sugar component for DNA is ______.

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

James D. Watson and Francis H. Crick proposed the ______ Model of DNA in 1953.

<p>Double Helix</p> Signup and view all the answers

Avery's work in 1944 concluded that ______ is the transforming substance.

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

The nitrogenous bases in DNA include adenine, guanine, cytosine, and ______.

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

Frederick Griffith conducted transformation experiments using two strains of Streptococcus pneumoniae, namely type ______ and type R.

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

______ proposed the double-helix model of DNA in 1953.

<p>Watson and Crick</p> Signup and view all the answers

In 1928, Griffith’s experiments led to the conclusion that something from the dead type S transformed type ______ into type S.

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

Erwin Chargaff's studies indicated that double-stranded DNA consists of ~50% ______ and ~50% pyrimidines.

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

The unknown substance that Griffith called the ______ was later understood to be DNA.

<p>transforming principle</p> Signup and view all the answers

According to Chargaff’s rules, the amount of ______ is equal to the amount of thymine.

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

Oswald Avery performed experiments in ______ to determine the chemical identity of the transforming principle.

<p>1944</p> Signup and view all the answers

In the search for genetic material, it is essential for it to be a stable source of ______.

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

X-ray diffraction studies by Rosalind Franklin and Maurice Wilkins concluded that DNA is a ______ structure.

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

Hershey and Chase conducted their famous experiment in ______ to confirm DNA as the genetic material.

<p>1953</p> Signup and view all the answers

The Nobel Prize ceremony in 1962 recognized ______, Watson, and others for their contributions to the discovery of DNA.

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

The double helix model of DNA was built based on ______ rules.

<p>Chargaff’s</p> Signup and view all the answers

According to Erwin Schrodinger, genes must be ______ because they can change over time but are also stable.

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

Homo sapiens have a G and C content of approximately ______%.

<p>37.5</p> Signup and view all the answers

The discovery of the DNA structure exemplifies the importance of ______ research.

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

Memories may be passed down through generations in ______, which can influence phobias.

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

Double-stranded DNA consists of ~50% purines (A, G) and ~50% ______ (T, C).

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

According to Chargaff's rules, the amount of A is equal to the amount of ______.

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

Rosalind Franklin and Maurice Wilkins conducted X-ray diffraction studies that concluded DNA is a ______ structure.

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

The discovery of the DNA structure was made possible by knowledge from chemists, biologists, physicists, and ______.

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

The percentage of GC content varies from organism to ______.

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

In the DNA structure, the two strands are held together by ______ bonds between the nitrogenous bases.

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

The model building for DNA suggested that base pairing is in agreement with ______ rules.

<p>Chargaff's</p> Signup and view all the answers

The significant debate around the DNA discovery in 2023 raises questions about how ______ should we be with our data.

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

The process of transforming type R bacteria into type S was termed ______.

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

Frederick Griffith worked with two strains of ______ pneumoniae in his transformation experiments.

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

In 1944, Oswald Avery identified the ______ as the substance responsible for transformation.

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

Erwin Schrödinger suggested that genes must be ______ because they can be stable yet change over time.

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

The 1953 proposal of the double-helix model of DNA was made by ______ and Crick.

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

In the context of DNA, the stable source of information must have the ability to ______ accurately.

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

The hereditary information in chromosomes was shown to be composed of ______ and nucleic acids.

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

The first demonstration of RNA as viral genetic material occurred in ______.

<p>1956</p> Signup and view all the answers

The Hershey-Chase experiment used the T2 bacteriophage to confirm that ______ is the genetic material.

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

Bacteriophage T2 was labeled with ______ to track the DNA.

<p>32P</p> Signup and view all the answers

In the structure of DNA, the sugar component is known as ______.

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

The nitrogenous base thymine is present in ______ but is replaced by uracil in RNA.

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

The two types of nitrogenous bases are ______ and pyrimidines.

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

James Watson and Francis Crick proposed the ______ Model of DNA structure.

<p>Double Helix</p> Signup and view all the answers

Avery’s experiments in 1944 demonstrated that ______ serves as the transforming substance.

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

Frederick Griffith’s transformation experiments involved type R and type ______ strains of Streptococcus pneumoniae.

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

What percentage of GC content is found in Zea mays?

<p>49.1%</p> Signup and view all the answers

Which of the following statements aligns with Chargaff's rules?

<p>The amount of guanine is equal to the amount of cytosine.</p> Signup and view all the answers

What type of research is highlighted as being crucial in the discovery of DNA structure?

<p>Multidisciplinary research</p> Signup and view all the answers

What was the key finding from the X-ray diffraction studies conducted by Rosalind Franklin and Maurice Wilkins?

<p>DNA is a helical structure.</p> Signup and view all the answers

What percentage of thymine is present in Homo sapiens?

<p>31.5%</p> Signup and view all the answers

In the context of DNA, what significance does the 0.34 nm regularity represent?

<p>The distance between nucleotide pairs.</p> Signup and view all the answers

What is the approximate percentage of GC content in Drosophila?

<p>45.0%</p> Signup and view all the answers

What aspect of scientific research does the debate surrounding the discovery of DNA structure in 2023 emphasize?

<p>The necessity of open data sharing.</p> Signup and view all the answers

What was the main conclusion of the Hershey-Chase experiment?

<p>DNA, not RNA or protein, is the genetic material.</p> Signup and view all the answers

Which type of labeling was used in the Hershey-Chase experiment for DNA and protein respectively?

<p>32P for DNA and 35S for protein.</p> Signup and view all the answers

Which of the following components is found in RNA but not in DNA?

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

What did Avery demonstrate in 1944 regarding genetic material?

<p>DNA is the transforming substance responsible for heredity.</p> Signup and view all the answers

What type of virus is a bacteriophage characterized as?

<p>A virus that replicates inside bacterial cells.</p> Signup and view all the answers

Which of the following best describes the structure of DNA?

<p>A double helix composed of nucleotides.</p> Signup and view all the answers

What did Gierer & Schramm, and Fraenkel-Conrat & Singer conclude about RNA?

<p>RNA serves as genetic material for some viruses.</p> Signup and view all the answers

Which statement about the components of a nucleotide is correct?

<p>Nucleotides consist of a sugar, nitrogenous base, and phosphate group.</p> Signup and view all the answers

What was the key conclusion from Frederick Griffith's experiments with Streptococcus pneumoniae?

<p>A substance from dead type S transformed type R into type S.</p> Signup and view all the answers

Which experiment was pivotal in establishing DNA as the genetic material in 1944?

<p>Avery’s Transformation Experiment</p> Signup and view all the answers

What characteristic is essential for a stable genetic material?

<p>Stability over long periods</p> Signup and view all the answers

Erwin Schrödinger's perspective on genes emphasized that they must be what?

<p>Stable yet capable of changing.</p> Signup and view all the answers

What was a common misconception about the genetic material before the discovery of DNA's role?

<p>DNA is too simple to be the genetic material.</p> Signup and view all the answers

What major advance did Watson and Crick make in 1953 regarding DNA?

<p>They proposed the three-dimensional structure of DNA.</p> Signup and view all the answers

In the context of DNA, what does the term 'transformation' specifically refer to?

<p>The process of genetic alteration from one bacterial strain to another.</p> Signup and view all the answers

What is NOT a criterion for identifying a stable source of genetic information?

<p>Inducement of immediate changes</p> Signup and view all the answers

What conclusion did Griffith reach about the relationship between type S and type R strains of Streptococcus pneumoniae?

<p>Type S can transform type R into type S.</p> Signup and view all the answers

Which characteristic was NOT identified as a requirement for genetic material in the content?

<p>High complexity of structure</p> Signup and view all the answers

What did Oswald Avery use to treat cell extracts in his transformation experiments?

<p>DNase, RNase, and protease</p> Signup and view all the answers

According to Schrodinger, what is a fundamental property of genes?

<p>They can be stable over time and change occasionally.</p> Signup and view all the answers

What was a primary reason scientists initially believed proteins were the genetic material instead of DNA?

<p>Proteins were believed to be more chemically complex.</p> Signup and view all the answers

In what year did Watson and Crick propose the double-helix model of DNA?

<p>1953</p> Signup and view all the answers

What aspect of DNA structure contributed to the initial skepticism regarding its role as genetic material?

<p>It was thought to be chemically simplistic.</p> Signup and view all the answers

Which of the following was shown in 1900 concerning chromosomes?

<p>They contain hereditary information.</p> Signup and view all the answers

What was the main conclusion derived from the Hershey-Chase Experiment?

<p>DNA, not RNA or protein, is the genetic material.</p> Signup and view all the answers

Which component of the T2 bacteriophage was labeled with phosphorus in the Hershey-Chase experiment?

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

How did Hershey and Chase confirm that DNA is the genetic material?

<p>By demonstrating that labeled DNA entered the bacteria.</p> Signup and view all the answers

Which of the following is a common misconception about phage composition in the context of the Hershey-Chase experiment?

<p>Bacteriophages contain both DNA and protein.</p> Signup and view all the answers

In terms of genetic material, what did Gierer & Schramm establish in relation to certain viruses?

<p>Some viruses utilize RNA as their genetic material.</p> Signup and view all the answers

Which of the following correctly identifies a key component of the structure of DNA?

<p>Deoxyribose sugar in the backbone.</p> Signup and view all the answers

What significant role does the phosphate group play in the structure of DNA?

<p>It is part of the sugar-phosphate backbone.</p> Signup and view all the answers

Which experiment was pivotal in establishing DNA as the transforming substance prior to the Hershey-Chase experiment?

<p>Avery's experiments.</p> Signup and view all the answers

Which organism has the highest percentage of GC content?

<p>Zea mays</p> Signup and view all the answers

What is the significance of Chargaff's rules in the study of DNA?

<p>They confirm the pairing of bases in double-stranded DNA.</p> Signup and view all the answers

What is one of the major contributions of Rosalind Franklin and Maurice Wilkins to DNA research?

<p>They conducted X-ray diffraction studies revealing DNA's helical structure.</p> Signup and view all the answers

What aspect of DNA's structure is highlighted by the distinct regularities observed in X-ray diffraction studies?

<p>The spacing between base pairs and helical turns is regular.</p> Signup and view all the answers

What do the findings about the percentage of A and T, as well as G and C, imply for double-stranded DNA?

<p>This pairing reflects a fundamental property of all organisms.</p> Signup and view all the answers

In the context of current scientific debates regarding DNA research, what aspect is emphasized?

<p>The need for collaborative research among traditional disciplines.</p> Signup and view all the answers

Which statement best characterizes the shared nature of DNA across different species?

<p>DNA sharing can explain evolutionary relationships among species.</p> Signup and view all the answers

According to the findings presented, what can explain variations in the percentage of AT and GC content among different species?

<p>Diverse evolutionary adaptations leading to unique genetic profiles.</p> Signup and view all the answers

What is the primary conclusion from the Hershey-Chase experiment?

<p>DNA, not RNA or protein, is the genetic material.</p> Signup and view all the answers

Which component was used to label the DNA during the Hershey-Chase experiment?

<p>32P</p> Signup and view all the answers

In the context of the structure of nucleotides, which nitrogenous base is exclusive to RNA?

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

Which two types of components make up the structure of DNA?

<p>Sugar and phosphate groups</p> Signup and view all the answers

What did Avery's 1944 experiments reveal about DNA?

<p>DNA is the transforming substance.</p> Signup and view all the answers

Why did Hershey and Chase label the protein with 35S in their experiment?

<p>To demonstrate that proteins do not enter bacteria.</p> Signup and view all the answers

What is the significance of the pentose sugar component in DNA?

<p>It defines whether the nucleic acid is DNA or RNA.</p> Signup and view all the answers

Who are the scientists credited with proposing the double helix model of DNA?

<p>Watson and Crick</p> Signup and view all the answers

What was the main conclusion of Frederick Griffith's transformation experiments?

<p>An unknown substance was responsible for transforming type R into type S.</p> Signup and view all the answers

Which of the following was NOT a criterion for identifying DNA as genetic material?

<p>Ability to form RNA</p> Signup and view all the answers

In Oswald Avery's Transformation Experiment, which enzyme was used to treat the cell extract from type S cells?

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

Which scientist first suggested that genes must be molecules in his 1944 publication?

<p>Erwin Schrödinger</p> Signup and view all the answers

Which of the following statements about the strains of Streptococcus pneumoniae is accurate?

<p>Type S produces smooth colonies on solid media.</p> Signup and view all the answers

What was revealed by Griffith's Transformation Experiment regarding the existence of a genetic material?

<p>Transformation can occur between bacterial strains.</p> Signup and view all the answers

What did scientists initially believe to be the genetic material before DNA was recognized?

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

Which base pairing rule is established by Chargaff's findings?

<p>Adenine pairs with Thymine.</p> Signup and view all the answers

What conclusion was drawn from X-ray diffraction studies about the structure of DNA?

<p>DNA has a helical structure.</p> Signup and view all the answers

Which organism has the highest percentage of GC content according to the examples provided?

<p>Zea mays</p> Signup and view all the answers

What important aspect of research does the discovery of DNA structure highlight?

<p>The significance of multidisciplinary collaboration.</p> Signup and view all the answers

What percentage of adenine is found in Homo sapiens according to the provided information?

<p>31.5%</p> Signup and view all the answers

What does Chargaff’s rule state about the relationship between purines and pyrimidines in double-stranded DNA?

<p>Purines and pyrimidines are approximately equal in amount.</p> Signup and view all the answers

Which nitrogenous base pairs with guanine in DNA?

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

Study Notes

Learning Objectives

  • Students will understand the experiments that led to the discovery of DNA's role as genetic material
  • Students will know the experiments (Griffith's, Avery's, Hershey-Chase) leading to DNA's discovery.
  • Students will grasp the chemical composition and structure of DNA.

Who Discovered DNA?

  • The discovery of DNA was a collaborative effort spanning many scientists' work over a long time. Several landmark experiments highlighted the pivotal nature of DNA as the genetic material
  • Key experimenters' names are associated with particular milestones

Timeline of Events

  • 1890: Weismann proposed that a substance in cell nuclei controls development.
  • 1900: Chromosomes were identified as containing hereditary material, composed of protein and nucleic acids.
  • 1928: Griffith's transformation experiment
  • 1944: Avery's transformation experiment
  • 1953: Hershey-Chase bacteriophage experiment
  • 1953: Watson and Crick proposed the double-helix model of DNA
  • 1956: RNA was demonstrated to be the genetic material in some viruses.

Search for the Genetic Material

  • Key criteria for the genetic material:
    • Stable source of information
    • Ability to accurately replicate
    • Ability to change (produce variation)
    • Transformation

Griffith's Transformation Experiment (1928)

  • Two strains of Streptococcus pneumoniae:
    • S (smooth): secretes a polysaccharide capsule, produces smooth colonies on solid media, virulent.
    • R (rough): unable to secrete a capsule, colonies with a rough appearance, avirulent.
  • Griffith injected mice with different combinations of S and R strains:
    • Living S strain killed the mice
    • Living R strain did not kill the mice
    • Heat-killed S strain did not kill the mice
    • Mixture of heat-killed S and living R strains killed the mice
  • Living R bacteria were transformed into S bacteria by transferring some material from the dead S cells.

Avery's Transformation Experiment (1944)

  • Refined Griffith's experiment, trying to identify the transforming principle.
  • Removed lipids and sugars from heat-killed S cells.
  • Used enzymes to selectively destroy proteins, RNA, and DNA in the extract.
  • Only treating the sample with DNAse prevented the transformation
  • Concluded that DNA was the transforming principle.

Hershey-Chase Bacteriophage Experiment (1953)

  • Used bacteriophage T2.
  • Labeled bacteriophage DNA with radioactive phosphorus (32P) and bacteriophage protein with radioactive sulfur (35S).
  • Bacteriophages infected bacteria.
  • After infection, bacteria were separated from the bacteriophages, and radioactivity within the bacteria was measured.
  • DNA, labeled with 32P, was found inside the bacteria
  • Protein, labeled with 35S, remained outside the bacteria.
  • Confirmed DNA as the genetic material.

DNA Structure

  • 1953: James Watson and Francis Crick proposed the double-helix model.
  • Key idea: Watson and Crick found that the chemical structure of DNA suggested a specific arrangement of base pairs along the DNA strands -Crucial for DNA's role in replication.

DNA Structure (Continued)

  • Key components:
    • Pentose sugar (deoxyribose in DNA, ribose in RNA)
    • Nitrogenous bases (adenine, guanine, cytosine, thymine in DNA; uracil in RNA)
    • Phosphate group.
  • Base pairing (Chargaff's rules):
    • Adenine (A) pairs with thymine (T)
    • Guanine (G) pairs with cytosine (C)
  • Double helix structure and its dimensions -X-ray diffraction data of Rosalind Franklin and Maurice Wilkins played a critical role
  • The double helix form confirmed that DNA contained information

Significance of Early Experiments and the 1953 work.

  • The conclusions were groundbreaking and showed that the structure of DNA was important to its function
  • The findings clarified the physical basis for inheritance and laid the foundation for furthering discoveries in molecular biology.

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DNA as the Genetic Material PDF

Description

This quiz explores the crucial experiments that led to the understanding of DNA as the genetic material, including Griffith's, Avery's, and Hershey-Chase's pivotal studies. Students will also learn about the chemical composition and structure of DNA through its historical context and timeline of discoveries. Test your knowledge on the key figures and experiments in the history of genetics.

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