Protein Synthesis. Scientists call this the:. DNA. DNA. Central Dogma of Biology!. RNA. RNA. Protein. Protein. Part 1: DNA Structure and Replication. What is DNA?. DNA = D eoxyribo n ucleic A cid
Central Dogma of Biology!
The “parent” molecule has two complementary strands of DNA.
Each is base paired by hydrogen bonding with its specific partner:
A with T
G with C
The first step in replication is the separation of the two strands. This is done by the enzyme helicase. Helicase unwinds the two strands and then breaks up the hydrogen bonds in the middle.
Each exposed parental strand now serves as a template that determines the order of the bases along a new complementary strand.
Free floating nucleotides in the nucleus will add on to each exposed strand, forming two new molecules of DNA. This process is performed by the enzyme DNA polymerase. DNA polymerase adds the bases in the correct order, and also “proof-reads” the strands as it makes the new one.
A will pair with a T. T will pair with an A.
G will pair with a C. C will pair with a G.
The nucleotides are connected to form the sugar-phosphate backbones of the new strands. This is done by the enzyme ligase, which is like a “glue.”
Each daughter DNA molecule consists of one parental strand and one new strand.
This model of replication is called semi-conservative replication. This is due to the fact that each new molecule has one old strand and one new strand. This ensures that each molecule of DNA is accurate.