Unit 8 - Gene Expression (DNA Replication)

3 types of DNA replication

conservative, dispersive, and semiconservative

DNA Replication is ___

the process in which a cella entire DNA is copied

when does DNA replication happen

S phase

Semiconservative replication

results in 2 copies, one old strand and one new

Conservative replication

leaves 2 original DNA strands in a double helix and makes 2 new strands

Dispersive replication

makes 2 new strands of DNA containing both old + new material

When did the Meselson-Stahl experiment take place

1958

how many strands in a DNA model

two strands

DNA replication is a ______ process

semiconservative

what is a main part of DNA replication

enzymes

Helicase

Unwinds the DNA molecule and cuts H⁺ bonds between strands creating a replication fork

Single stranded binding proteins

prevents strands from reattaching

Topoisomerase

prevents overwinding ahead of the replication fork

Primase

lays down RNA primers for DNA polymerase

DNA polymerase 3

adds complementary bases to the 3’ end of the existing DNA strand. Also checks for errors and fixes them.

The leading strand

made continuously in a line

the lagging strand

made in sections called Okazaki Fragments

DNA polymerase 1

Adds bases where RNA primers were removed

Ligase

glues the okazaki fragments together