DNA replication

Flashcards reviewing key concepts, enzymes, and processes involved in DNA replication, based on lecture notes by Earl Yoon.

Name five individuals (or their work) involved in discovering the double helix structure of DNA.

Erwin Chargaff, Maurice Wilkins, Rosalind Franklin, James Watson, and Francis Crick.

Describe the semiconservative model of DNA replication.

Each strand of the parent DNA serves as a template for a new strand, resulting in hybrid DNA molecules (original + new).

What is the difference in DNA replication between prokaryotic and eukaryotic organisms?

Prokaryotes have circular genomes with one origin of replication. Eukaryotes have linear chromosomes with multiple origins of replication.

Name the enzymes involved in DNA replication.

Helicase, single-strand DNA binding proteins, topoisomerase, primase, DNA polymerase III, DNA polymerase I, and DNA ligase.

What is the function of Helicase?

Separates the two DNA strands (unwinds the DNA helix).

What is the function of single-strand DNA binding proteins?

Holds the two parent DNA strands apart.

What is the function of Topoisomerase?

Cuts and swivels DNA to relieve coiling tension (relaxes positive supercoils).

What is the function of DNA Primase?

Synthesizes RNA primer sequence to initiate DNA synthesis.

What is the function of DNA Polymerase III?

Synthesizes the new DNA strand by adding nucleotides.

What is the function of DNA Polymerase I?

Removes RNA primers and replaces them with new DNA.

What is the function of DNA Ligase?

Forms covalent bonds between DNA fragments to make the new DNA strand continuous.

In what direction does DNA synthesis occur?

DNA synthesis only occurs in the 5’ to 3’ direction.

What is the leading strand?

The new DNA strand that elongates towards the replication fork in a continuous manner.

What is the lagging strand?

The new DNA strand that elongates away from the replication fork in a discontinuous manner.

What are Okazaki fragments?

Short DNA fragments (100-200 nucleotides long in eukaryotes) synthesized on the lagging strand.

At what site does DNA replication begin?

Origin of replication (ori)

What are the ingredients required for DNA replication?

Parent DNA molecule, proteins/enzymes, and deoxyribonucleoside triphosphates (dNTPs).