DNA Structure and Replication Concepts

The video tutorial covers the structure of DNA, explaining its components like nucleotides, which consist of a phosphate group, a sugar, and a nitrogen base. It discusses Chargaff's rules, highlighting the equal ratios of adenine to thymine and cytosine to guanine. The discovery of DNA's double helix structure by Watson and Crick, aided by Rosalind Franklin's x-ray crystallography, is detailed. The process of DNA replication is explained, emphasizing the role of enzymes like DNA helicase and DNA polymerase, and the concept of semi-conservative replication.

What are the three main components of a nucleotide?

• Phosphate group, ribose sugar, amino acid

• Phosphate group, five-carbon sugar, nitrogen base

• Phosphate group, glucose, nitrogen base

• Phosphate group, deoxyribose sugar, lipid

According to Chargaff's rules, if a DNA sample contains 20% adenine, what percentage of thymine should it contain?

• 20%

• 10%

• 30%

• 40%

Who used X-ray crystallography to help discover the structure of DNA?

• Erwin Chargaff

• Francis Crick

• Rosalind Franklin

• James Watson

What is the shape of the DNA structure discovered by Watson and Crick?

• Single strand

• Double helix

• Quadruple helix

• Triple helix

In the DNA double helix, what type of bonds hold the nitrogen bases together?

• Hydrogen bonds

• Covalent bonds

• Metallic bonds

• Ionic bonds

Which part of the DNA structure is referred to as the 'backbone'?

• Amino acids

• Hydrogen bonds

• Phosphate and sugar

• Nitrogen bases

What is the role of DNA helicase in replication?

• To unzip the DNA double helix

• To repair DNA mutations

• To join nucleotides together

• To synthesize new DNA strands

What does 'semi-conservative' mean in the context of DNA replication?

• Each new DNA molecule is identical to the original

• Each new DNA molecule has two old strands

• Each new DNA molecule has one old and one new strand

• Each new DNA molecule has two new strands

Which enzyme is responsible for adding complementary nucleotides during DNA replication?

• DNA helicase

• DNA ligase

• DNA polymerase

• RNA polymerase

Why is it important for DNA to replicate before cell division?

• To create genetic diversity

• To produce energy for the cell

• To repair damaged DNA

• To ensure each new cell has a complete set of DNA