Questions and Answers
A new daughter strand of DNA is synthesized by what enzyme?
DNA polymerase
Free nucleotides are added to a growing daughter DNA strand by?
a reaction between the 3' hydroxyl of the growing strand and the 5' phosphate of the free nucleotides
Why is a primer necessary for DNA synthesis?
DNA polymerase requires an existing 3' hydroxyl to which it can add nucleotides.
What does DNA polymerization by DNA polymerase require?
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In which direction is a new strand of DNA synthesized?
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How many replication forks are there in each replication bubble?
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New strands of DNA grow from the 5' to 3' direction regardless of whether they are the leading or lagging strand.
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Lagging strand DNA synthesis is the replication fork, and the overall direction of lagging strand growth is the replication fork.
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The leading strand is synthesized in the direction and the lagging strand is synthesized in the direction.
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DNA polymerase III always adds nucleotides to which end of the growing strand?
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Which statement is true of DNA replication?
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An individual unit of replication is referred to as?
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Which description about prokaryotic versus eukaryotic DNA replication is not correct?
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Study Notes
DNA Synthesis
- DNA polymerase synthesizes new daughter strands of DNA.
- Free nucleotides are added to a growing DNA strand via a reaction between the 3' hydroxyl of the strand and the 5' phosphate of nucleotides.
- A primer is crucial for DNA synthesis as DNA polymerase needs an existing 3' hydroxyl to add nucleotides.
- DNA replication occurs in the 5' to 3' direction, with nucleotides added at the 3' end.
Leading and Lagging Strands
- Each replication fork has a leading and lagging strand; the leading strand is synthesized continuously from a single RNA primer.
- The leading strand grows in the same direction as the replication fork.
- The lagging strand consists of short Okazaki fragments, each requiring its own primer, and is synthesized discontinuously in the opposite direction of the replication fork.
- After replication, Okazaki fragments of the lagging strand are joined together.
Replication Bubble and Forks
- DNA replication is bidirectional, forming replication bubbles with two forks moving away from the origin of replication.
- When a bubble forms, one fork opens and moves left while the other moves right.
Direction of DNA Synthesis
- Both leading and lagging strands grow from the 5' to 3' direction.
- Newly synthesized strands require nucleotides to always be added to a free 3' hydroxyl end.
Okazaki Fragments and Lagging Strand Growth
- Lagging strand growth occurs in 5' to 3' direction, but overall growth is toward the replication fork.
- Upon completion, lagging strand fragments (Okazaki fragments) are linked together.
Role of DNA Polymerase III
- DNA polymerase III adds nucleotides specifically to the 3' end of the growing strand.
Characteristics of DNA Replication
- The lagging strand is characterized by being composed of Okazaki fragments.
- DNA replication is not continuous for the lagging strand but is continuous for the leading strand.
- Each individual unit of replication is referred to as a replicon.
Prokaryotic vs. Eukaryotic DNA Replication
- Recognize that certain statements about prokaryotic and eukaryotic DNA replication may vary, yet specifics are not detailed in the text provided.
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Description
Test your knowledge of key concepts in genetics with these flashcards focusing on DNA synthesis. Each card presents a critical question related to enzymes, nucleotides, and the role of primers in DNA replication. Challenge yourself and reinforce your understanding of genetic processes.
