DNA Structure and Function Concepts

The video tutorial covers the structure of DNA, starting with the basic components of nucleotides and the initial hypothesis that DNA was composed of equal amounts of four nucleotides. It then explains Chargaff's rule, which established that adenine pairs with thymine and guanine pairs with cytosine. The tutorial discusses Watson and Crick's development of the double helix model, supported by Franklin's X-ray crystallography. The concept of base pairing is introduced, explaining the structural integrity of DNA through hydrogen and covalent bonds.

What was the initial hypothesis about the composition of DNA?

• DNA is composed of random amounts of nucleotides.

• DNA is composed of equal amounts of four nucleotides.

• DNA is composed of only adenine and thymine.

• DNA is composed of only guanine and cytosine.

What did Chargaff discover about the proportions of nucleotides in DNA?

• All nucleotides are in equal proportions.

• Thymine equals guanine.

• Adenine equals thymine, and guanine equals cytosine.

• Adenine equals cytosine.

Who were the scientists that proposed the double helix model of DNA?

• Mendel and Darwin

• Watson and Crick

• Newton and Einstein

• Franklin and Chargaff

What did Watson and Crick propose about the location of the phosphate and sugar in the DNA model?

• They are randomly distributed.

• They are outside the double helix.

• They are not part of the DNA structure.

• They are inside the double helix.

What technique did Franklin use to support the double helix model?

• Ultrasound imaging

• Nuclear magnetic resonance

• X-ray crystallography

• Electron microscopy

What did Franklin's X-ray images suggest about the DNA structure?

• DNA is a triple helix.

• DNA is a double helix with even width.

• DNA is a single helix.

• DNA has an uneven width.

What is the significance of base pairing in DNA structure?

• It makes DNA unstable.

• It ensures equal width throughout the DNA.

• It allows DNA to be single-stranded.

• It prevents DNA from forming a helix.

Which bond holds the sugar and phosphate group together in DNA?

• Metallic bond

• Hydrogen bond

• Covalent bond

• Ionic bond

What is the role of hydrogen bonds in the DNA structure?

• They connect the sugar and phosphate backbone.

• They bind the nitrogenous bases together.

• They form the outer shell of DNA.

• They provide energy for DNA replication.

What is the relationship between purines and pyrimidines in DNA?

• Purines pair with purines.

• Pyrimidines pair with pyrimidines.

• Each pair consists of one purine and one pyrimidine.

• Purines and pyrimidines do not pair.