DNA Structure and Replication Review Worksheet Answers
This document provides answers to common questions found in DNA structure and replication review worksheets. Remember that specific questions will vary depending on the worksheet, but this should cover many common themes. It's crucial to understand the concepts behind the answers, not just memorize them.
I. DNA Structure
1. What are the building blocks of DNA?
The building blocks of DNA are nucleotides. Each nucleotide consists of three parts: a deoxyribose sugar, a phosphate group, and a nitrogenous base.
2. What are the four nitrogenous bases found in DNA?
The four nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T).
3. Describe the base pairing rules in DNA.
Adenine (A) always pairs with thymine (T) through two hydrogen bonds, and guanine (G) always pairs with cytosine (C) through three hydrogen bonds. This is known as complementary base pairing.
4. What is the overall structure of a DNA molecule?
A DNA molecule is a double helix, resembling a twisted ladder. The sides of the ladder are formed by the sugar-phosphate backbone, while the rungs are formed by the paired nitrogenous bases.
5. What is meant by the term "antiparallel"?
The two strands of DNA are antiparallel, meaning they run in opposite directions. One strand runs 5' to 3', while the other runs 3' to 5'. The 5' and 3' refer to the carbon atoms on the deoxyribose sugar.
II. DNA Replication
1. What is DNA replication?
DNA replication is the process by which a double-stranded DNA molecule is copied to produce two identical DNA molecules. This is essential for cell division and inheritance of genetic information.
2. What is the role of DNA polymerase?
DNA polymerase is an enzyme that adds nucleotides to the growing DNA strand during replication. It also has a proofreading function, helping to ensure accuracy.
3. What is the role of helicase?
Helicase is an enzyme that unwinds the DNA double helix at the replication fork, separating the two strands so they can be copied.
4. What is the role of primase?
Primase is an enzyme that synthesizes short RNA primers, which provide a starting point for DNA polymerase to begin adding nucleotides.
5. What are Okazaki fragments?
Okazaki fragments are short, newly synthesized DNA fragments formed on the lagging strand during replication. This is because DNA polymerase can only add nucleotides in the 5' to 3' direction.
6. What is the role of DNA ligase?
DNA ligase is an enzyme that joins Okazaki fragments together to form a continuous DNA strand.
7. Explain the semiconservative model of DNA replication.
The semiconservative model states that each new DNA molecule consists of one original (parent) strand and one newly synthesized strand. This ensures that genetic information is accurately passed on during replication.
III. Further Review
To further solidify your understanding, consider reviewing diagrams of DNA replication, focusing on the roles of each enzyme. Try drawing the process step-by-step and labeling all the components. This will help you visualize and understand the complex process of DNA replication. Remember to consult your textbook or other learning resources if you need further clarification on any of these concepts.
