Exploring DNA Structure and Replication

The video tutorial covers AP Biology topics, starting with a warm-up on chromosome inheritance and nondisjunction. It then delves into the structure of DNA and RNA, highlighting the differences between them. The main focus is on DNA replication, explaining the roles of various enzymes and the processes involved in synthesizing new DNA strands. The tutorial also includes practice questions and discusses common misconceptions.

During which phase does nondisjunction occur, leading to an incorrect number of chromosomes in gametes?

• Interphase (S phase)

• Interphase (G1 or G2)

• Mitosis

• Meiosis I

What is the primary structural difference between DNA and RNA?

• DNA contains thymine, RNA contains uracil

• DNA is found only in the nucleus, RNA is found only in the cytoplasm

• DNA is single-stranded, RNA is double-stranded

• DNA has a ribose sugar, RNA has a deoxyribose sugar

Which nitrogenous base is found in RNA but not in DNA?

• Uracil

• Thymine

• Cytosine

• Adenine

What type of bond holds the nitrogenous bases together in a DNA molecule?

• Ionic bonds

• Covalent bonds

• Hydrogen bonds

• Metallic bonds

What is the role of helicase in DNA replication?

• Unwinds the DNA double helix

• Adds RNA primers

• Joins Okazaki fragments

• Synthesizes new DNA strands

In which direction is new DNA synthesized during replication?

• 5' to 3'

• Both directions simultaneously

• Randomly

• 3' to 5'

What is the function of DNA ligase during DNA replication?

• Joins Okazaki fragments

• Adds nucleotides to the growing strand

• Synthesizes RNA primers

• Unwinds the DNA strands

Which enzyme is responsible for adding nucleotides to the growing DNA strand?

• Helicase

• Topoisomerase

• DNA polymerase

• Primase

What is the purpose of proofreading during DNA replication?

• To unwind the DNA helix

• To add RNA primers

• To correct errors in base pairing

• To join Okazaki fragments

Which of the following statements best explains the movement of DNA fragments in a comet assay?

• DNA fragments move towards the negative pole

• DNA fragments move towards the positive pole

• DNA fragments move randomly

• DNA fragments remain stationary