Dna Structure And Function Worksheet Ap Biology Answer Guide

Why is DNA replication considered semiconservative ?

Hydrogen bonds hold the two strands together. Specifically, two hydrogen bonds form between A and T, and three hydrogen bonds form between G and C.

Compare and contrast the leading strand and the lagging strand .

What type of bond holds the two strands of DNA together? Why is this bond important for DNA replication? Dna Structure And Function Worksheet Ap Biology Answer

Let’s dive into the answers and explanations. Question 1: Draw and label a nucleotide. What are the three components?

| Enzyme | Function | |--------|----------| | | Unwinds and separates the double helix by breaking hydrogen bonds. | | DNA Polymerase III | Synthesizes new DNA strands by adding nucleotides to the 3’ end; also has 3’→5’ proofreading ability. | | Primase | Synthesizes a short RNA primer to provide a 3’-OH group for DNA polymerase to begin adding nucleotides. | | Ligase | Seals nicks (joins Okazaki fragments) on the lagging strand by forming phosphodiester bonds. | | Topoisomerase | Relieves supercoiling ahead of the replication fork to prevent DNA breakage. |

Hydrogen bonds are relatively weak, allowing the two strands to be easily “unzipped” by enzymes like helicase without breaking the covalent bonds (phosphodiester bonds) within each strand. This allows each strand to serve as a template. Why is DNA replication considered semiconservative

Understanding DNA structure and function is the cornerstone of molecular biology and a critical topic for the AP Biology exam. This post provides a comprehensive answer key for a typical AP Biology worksheet on DNA, including detailed explanations to help you understand why each answer is correct.

The complementary strand is: 3’-TAAGCTCG-5’

Semiconservative replication means that each new DNA double helix contains one original (parental) strand and one newly synthesized daughter strand . This was proven by the Meselson-Stahl experiment using isotopic nitrogen (¹⁵N and ¹⁴N). Compare and contrast the leading strand and the

What is the Central Dogma of molecular biology?

| Feature | Leading Strand | Lagging Strand | |---------|----------------|----------------| | Direction of synthesis | Continuous 5’→3’ | Discontinuous 5’→3’ (Okazaki fragments) | | Requires multiple primers | No (one primer needed) | Yes (many primers needed) | | Template strand orientation | 3’→5’ (toward replication fork) | 5’→3’ (away from replication fork) |

| Purines (two rings) | Pyrimidines (one ring) | |---------------------|------------------------| | Adenine (A) | Cytosine (C) | | Guanine (G) | Thymine (T) | | (Also Uracil in RNA)| |

The purine-to-pyrimidine ratio is always 1:1 in a double-stranded DNA molecule (Chargaff’s rule). Part 2: DNA Function (Replication & Central Dogma) Question 5: Explain the role of the following enzymes in DNA replication: