AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA REPLICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The separation of the two single strands of DNA creates a ‘Y’ shape?
A
enzyme
B
unzip
C
A replication fork
Explanation: 

Detailed explanation-1: -The separation of the two single strands of DNA creates a ‘Y’ shape called a replication ‘fork’. The two separated strands will act as templates for making the new strands of DNA. One of the strands is oriented in the 3’ to 5’ direction (towards the replication fork), this is the leading strand?.

Detailed explanation-2: -DNA replication takes place at a Y-shaped structure called a replication fork. A self-correcting DNA polymerase enzyme catalyzes nucleotide polymerization in a 5′-to-3′ direction, copying a DNA template strand with remarkable fidelity.

Detailed explanation-3: -Figure 9.10 A replication fork is formed by the opening of the origin of replication, and helicase separates the DNA strands. An RNA primer is synthesized, and is elongated by the DNA polymerase.

Detailed explanation-4: -The origin of replication is recognized by certain proteins that bind to this site. An enzyme called helicase unwinds the DNA by breaking the hydrogen bonds between the nitrogenous base pairs. ATP hydrolysis is required for this process. As the DNA opens up, Y-shaped structures called replication forks are formed.

Detailed explanation-5: -The replication fork is a structure that forms within the long helical DNA during DNA replication. It is created by helicases, which break the hydrogen bonds holding the two DNA strands together in the helix. The resulting structure has two branching “prongs", each one made up of a single strand of DNA.

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