D1.1.2 Semi-conservative nature of DNA replication Flashcards
(19 cards)
Why is DNA replication described as semi-conservative?
Each new DNA molecule consists of one original (parental) strand and one newly synthesized strand.
Which bases pair together in DNA?
Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).
What is a replication fork?
A replication fork is the Y-shaped region where the DNA strands are separated and replication occurs.
What was the purpose of the Meselson-Stahl experiment?
To provide evidence for the semi-conservative model of DNA replication.
What happens if a nucleotide with the wrong base is introduced during replication?
Hydrogen bonding will not occur, and the nucleotide will be rejected.
What stabilizes the DNA structure during replication?
Hydrogen bonds between complementary bases stabilize the DNA structure.
What role does complementary base pairing play in DNA replication?
It ensures that new strands are accurate copies of the original strands.
What enzyme is responsible for adding nucleotides during DNA replication?
DNA polymerase.
Give an analogy for DNA replication.
DNA replication is like photocopying a book, where each copy contains one original page and one new page.
What are the specific pairing rules for DNA bases?
A pairs with T (2 hydrogen bonds) and C pairs with G (3 hydrogen bonds).
What is the difference between semi-conservative and conservative replication?
In semi-conservative replication, each daughter DNA molecule contains one original strand. In conservative replication, the original DNA molecule remains intact while a completely new molecule is synthesized.
What were the results of the Meselson-Stahl experiment after two generations?
Two bands appeared: one of intermediate density and one of light density, confirming the semi-conservative model.
What is the proofreading function of DNA polymerase?
DNA polymerase identifies and corrects mismatched bases during replication.
What method did the Meselson-Stahl experiment use to analyze DNA?
Centrifugation in a density gradient to separate DNA based on its weight.
How does semi-conservative replication contribute to evolutionary stability?
It minimizes errors in DNA replication, preserving genetic information across generations.
What is the biological significance of semi-conservative DNA replication?
It ensures genetic continuity, minimizes errors, and allows for adaptability through occasional mutations.
What is the role of helicase in DNA replication?
Helicase unwinds the double helix and separates the two strands, creating a replication fork.
Why is the accuracy of DNA replication important?
High accuracy minimizes mutations, which is essential for basic cell functions like protein synthesis.
What were the results of the Meselson-Stahl experiment after one generation?
A single band of intermediate density was observed, indicating each DNA molecule contained one heavy strand and one light strand.
