The Discovery of DNA Structure and Chargaff's Rules Quiz

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Questions and Answers

What is the primary function of DNA replication?

To create new DNA molecules for energy production

To regulate gene expression in the cell

To produce proteins for cellular functions

To transmit genetic information from parent cells to daughter cells and from generation to generation (correct)

What is the structure of a chromosome?

A protein molecule with attached nucleotides

A double-stranded RNA molecule

A single-stranded DNA sequence

A DNA molecule packed together with proteins (correct)

Who proposed the double-helical structure of DNA?

Rosalind Franklin

Barbara McClintock

James Watson and Francis Crick (correct)

Gregor Mendel

What does DNA carry as genetic information?

All genes and genetic information Signup and view all the answers

Who initially considered proteins as stronger candidates for the genetic material?

Oswald Avery Signup and view all the answers

What did Frederick Griffith's 1928 experiment demonstrate?

Transformation phenomenon Signup and view all the answers

Who confirmed that DNA is the genetic material of the phage T2?

Alfred Hershey Signup and view all the answers

What do bacteriophages infect?

Bacteria Signup and view all the answers

What did the experiments with T2 phage and E. coli provide crucial evidence for?

DNA as the genetic material Signup and view all the answers

What does DNA replication begin with on a chromosome?

Replication bubbles Signup and view all the answers

What is composed almost entirely of DNA and protein?

Bacteriophages Signup and view all the answers

What provides additional evidence that DNA is the genetic material?

Experiments with bacteriophages Signup and view all the answers

What did the process of DNA replication and chromosome condensation lead to the formation of?

Duplicated and condensed chromosomes Signup and view all the answers

What is the genetic material that is routinely manipulated in laboratories today?

DNA Signup and view all the answers

What did the Hershey-Chase experiment conclude about the genetic material of phage T2?

DNA, not protein, functions as the genetic material Signup and view all the answers

What did radioactive sulfur label in the Hershey-Chase experiment?

Protein Signup and view all the answers

What did radioactive phosphorus label in the Hershey-Chase experiment?

DNA Signup and view all the answers

What did Erwin Chargaff's analysis of base composition of DNA show?

Molecular diversity among species Signup and view all the answers

What did Erwin Chargaff observe about the base composition of DNA from different species?

The number of adenines approximately equaled the number of thymines Signup and view all the answers

What was the main contribution of Chargaff's work to the understanding of DNA as the genetic material?

Provided evidence for DNA as the genetic material Signup and view all the answers

What did the Hershey-Chase experiment and Chargaff's observations contribute to?

Understanding DNA as the genetic material Signup and view all the answers

What is DNA a polymer of?

Nucleotides Signup and view all the answers

What was labeled with radioactive sulfur in the Hershey-Chase experiment?

Protein of the phage Signup and view all the answers

What was the significance of the Hershey-Chase experiment and Chargaff's work?

Establishing DNA as the molecule carrying genetic information Signup and view all the answers

What did the Hershey-Chase experiment involve labeling T2 phages with?

Radioactive sulfur for protein and radioactive phosphorus for DNA Signup and view all the answers

Where was the radioactivity found when DNA was labeled in the Hershey-Chase experiment?

Inside the cells Signup and view all the answers

What type of bonds hold the nucleotides in a DNA strand together?

Covalent sugar-phosphate bonds Signup and view all the answers

What is the structure of the sugar-phosphate backbones in the DNA molecule?

They are on the outside of the DNA molecule Signup and view all the answers

How many layers of base pairs are there in each full turn of the DNA double helix?

Ten layers Signup and view all the answers

What is the diameter of the DNA double helix when a purine is paired with a pyrimidine?

Uniform diameter Signup and view all the answers

What is the difference in structure between the two ends of a DNA strand?

One end has a 3¿ end and the other has a 5¿ end Signup and view all the answers

What is the shape of the DNA double helix?

Double-stranded helix Signup and view all the answers

What is the pattern of base equivalences known as?

Chargaff’s rule Signup and view all the answers

What holds the two DNA strands together in the double helix?

Hydrogen bonds between bases Signup and view all the answers

What is the role of nitrogenous bases in the DNA double helix?

Hidden in the interior, akin to a rope ladder with rigid rungs Signup and view all the answers

What is the result of pairing a purine with a pyrimidine in the DNA double helix?

Uniform diameter for the double helix Signup and view all the answers

What dictates the specific combinations of nitrogenous bases in the DNA double helix?

Base-pairing rules Signup and view all the answers

What confirms that the amounts of adenine and thymine are equal in DNA?

Modern DNA sequencing techniques Signup and view all the answers

Who were the first scientists to come up with the complete answer about the DNA structure?

James Watson and Francis Crick Signup and view all the answers

What did Chargaff's rules state about the DNA base composition?

The percentages of A and T bases are roughly equal, as are those of G and C bases. Signup and view all the answers

What did Chargaff's data from experiments provide?

Approximate values for each type of nucleotide in DNA. Signup and view all the answers

Who confirmed the helical shape of DNA through images produced by X-ray crystallography?

Rosalind Franklin Signup and view all the answers

What did Chargaff's rules remain unexplained until?

The discovery of the double helix. Signup and view all the answers

Who noticed a pattern in the base composition of nucleotides from different species?

Erwin Chargaff Signup and view all the answers

What did DNA structure research begin with?

Watson and Crick's collaboration at Cambridge University. Signup and view all the answers

What did Chargaff's rules attribute the equal percentages of A and T bases to?

Complementary base pairing between A and T in the DNA double helix. Signup and view all the answers

What did Chargaff and his co-workers do to analyze DNA in their experiments?

Extracted DNA from species and chemically analyzed it. Signup and view all the answers

What did the table provide data for, and how were Chargaff's rules utilized?

The table provided base distribution data for species, and Chargaff's rules were applied to predict unknown values. Signup and view all the answers

Who were among the scientists working on the three-dimensional structure of DNA?

Maurice Wilkins and Rosalind Franklin Signup and view all the answers

Study Notes

Discovery of DNA Structure and Chargaff's Rules

Chargaff's rules: DNA base composition varies between species, and the percentages of A and T bases are roughly equal, as are those of G and C bases.
Chargaff's rules remained unexplained until the discovery of the double helix.
The structure of DNA could account for its role in inheritance.
Linus Pauling, Maurice Wilkins, and Rosalind Franklin were among the scientists working on the three-dimensional structure of DNA.
James Watson and Francis Crick were the first to come up with the complete answer about the DNA structure.
DNA structure research began with Watson and Crick's collaboration at Cambridge University.
Erwin Chargaff and his co-workers noticed a pattern in the base composition of nucleotides from different species.
Chargaff's rules are due to complementary base pairing between A and T and between C and G in the DNA double helix.
In Chargaff’s experiments, DNA was extracted from species, hydrolyzed to break apart nucleotides, and then chemically analyzed.
Chargaff's data from experiments provided approximate values for each type of nucleotide.
Images produced by X-ray crystallography, like the one by Rosalind Franklin, confirmed the helical shape of DNA.
The table provides base distribution data for species, and Chargaff's rules can be applied to predict unknown values.

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Description

Test your knowledge of the discovery of DNA structure and Chargaff's rules with this quiz. Explore the contributions of scientists like Watson, Crick, Chargaff, and Franklin, and learn about the key findings that led to the understanding of DNA's double helix structure and base composition.