AP BIo 6.2 - DNA Replication

DNA Replication

the process by which a DNA molecule is copied; also called DNA synthesis

Antiparallel

strands of DNA run in opposite directions

Semiconservative process

one strand of DNA serves as the template for a new strand of complementary DNA.

Replication fork

a Y shaped region where the parental strands of DNA are being unwound

Helicase

enzymes that "unzip" or untwist the DNA double helix at the replication forks, separating the two strands of DNA

Single Strand Binding (SSB) Proteins

Bind to the unpaired DNA strands keeping them from re-connecting

Topoisomerase

relaxes supercoiling in front of the replication fork

Primer

The initial nucleotide chain that is produced during DNA synthesis is actually a short stretch of RNA

DNA Primase

creates the RNA primer, starts a complementary RNA chain from a single RNA nucleotide, adding more RNA nucleotides one at a time, using the parental DNA strand as a template

DNA polymerase

The main enzyme that builds a new DNA strand by adding nucleotides

Leading strand

Strand that continuously adds nucleotides to the new complementary strand as the replication fork progresses

Lagging Strand

The strand that DNA polymerase builds moving away from the replication fork, Synthesized discontinuosly as a series of segments

Okazaki fragments

Series of segments that are 1000-2000 nucleotides long. Made due to the discontinuous building of the lagging strand.

DNA Ligase

joins the backbones of all the Okazaki fragments and replaced primers into a continuous DNA strand

S-Phase

When DNA replication occurs

Sister Chromatids

The result of DNA replication is chromosomes with 2_________________ attached with a centromere.

The direction the DNA polymerase works

5' to 3'

Origin of replication

Site where the replication of a DNA molecule begins.

Speed that DNA is copied at

50 nucleotides/second

Number of mistakes that are made by DNA polymerase

fewer than 1 in a billion