AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA REPLICATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What is the first step of DNA Replication?
A
free nucleotides match with a template
B
DNA coils up tightly
C
DNA helicase unzips the DNA
D
DNA uncoils from its double helix shape
Explanation: 

Detailed explanation-1: -Replication occurs in three major steps: the opening of the double helix and separation of the DNA strands, the priming of the template strand, and the assembly of the new DNA segment. During separation, the two strands of the DNA double helix uncoil at a specific location called the origin.

Detailed explanation-2: -The first step in DNA replication is to ‘unzip’ the double helix structure of the DNA? molecule. This is carried out by an enzyme? called helicase which breaks the hydrogen bonds? holding the complementary? bases? of DNA together (A with T, C with G).

Detailed explanation-3: -The first step in DNA replication is to separate or unzip the two strands of the double helix. The enzyme in charge of this is called a helicase (because it unwinds the helix). The point where the double helix is opened up and the DNA is copied is called a replication fork.

Detailed explanation-4: -During DNA replication, DNA helicases unwind DNA at positions called origins where synthesis will be initiated. DNA helicase continues to unwind the DNA forming a structure called the replication fork, which is named for the forked appearance of the two strands of DNA as they are unzipped apart.

Detailed explanation-5: -In general, DNA is replicated by uncoiling of the helix, strand separation by breaking of the hydrogen bonds between the complementary strands, and synthesis of two new strands by complementary base pairing. Replication begins at a specific site in the DNA called the origin of replication.

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