DNA Replication - Lagging Strand

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Questions and Answers

What direction is the leading strand synthesized during DNA replication?

5' to 3' (correct)
3' to 5'
3' to 3'
5' to 5'

Which enzyme is responsible for initiating the Okazaki fragments on the lagging strand?

DNA polymerase I
DNA polymerase III
DNA ligase
Primase (correct)

What is the function of DNA ligase in the synthesis of the lagging strand?

It synthesizes DNA nucleotides
It connects Okazaki fragments (correct)
It creates RNA primers
It removes RNA primers

Which of the following statements about the lagging strand is correct?

<p>It is made up of shorter segments called Okazaki fragments. (C)</p> Signup and view all the answers

During DNA replication, which enzyme is responsible for replacing RNA primers with DNA nucleotides?

<p>DNA polymerase I (C)</p> Signup and view all the answers

Flashcards

Leading Strand

The continuous synthesis of DNA along the template strand in the 5' to 3' direction during replication. This synthesis is performed by the enzyme DNA polymerase III. It is the uninterrupted strand of replicated DNA.

Lagging Strand

The fragmented synthesis of a new DNA strand in the 5' to 3' direction, running against the replication fork. It is synthesized as short fragments that are later joined together.

Okazaki Fragments

Short, discontinuous segments of DNA on the lagging strand during replication. They are initiated by RNA primers and later joined by DNA ligase.

Primase

An enzyme involved in DNA replication that initiates new DNA strands by synthesizing short RNA primers for both leading and lagging strands.

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DNA polymerase I

An enzyme that removes RNA primers from the lagging strand and fills in the gaps with DNA nucleotides. It also proofreads for errors.

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Study Notes

DNA Replication - Lagging Strand

Lagging strand synthesis involves an alternating mix of RNA primers and new daughter DNA.
Fragments of daughter DNA are called Okazaki fragments.
Okazaki fragments are shown in the image as green boxes.
All RNA primers must be replaced with DNA.
DNA polymerase I removes RNA primers and replaces them with DNA (shown in pink box).
DNA polymerase I cannot complete the final covalent bond in the sugar-phosphate backbone.
DNA ligase completes the final bond between Okazaki fragments. DNA ligase is shown in the orange box.