DNA Replication (text version)

Unzip DNA

Help Window:
The first step of replication is "unzipping" the DNA molecule. This will divide the molecule lengthwise.

Select Unzip to divide the molecule.

Description:
Selecting the "Unzip" button causes the DNA molecule to split lengthwise.

What Happened Window:
In a real cell, the molecule unwinds from spools made of protein, then untwists. (Here the molecule is already unwound and untwisted.) The DNA now resembles a ladder. Enzymes, special kinds of proteins, move up the ladder, breaking the rungs.

Match bases to make new DNA strand

Drag and drop from well:
A
G
C
T

Help Window:
DNA is made up of four types of bases: adenine (A), cytosine (C), guanine (G), and thymine (T). Each base has a complement -- another base that it can connect to. A complements T, and C complements G.

Drag bases from the left to their complementary bases on the DNA strands. Don't worry about the orientation of a base -- it will automatically flip, if it needs to, as it approaches the DNA strand.

Description:
Nucleotides are dragged from one area of the screen to the separated DNA strands.

What Happened Window
Well done. Replication is complete.

Our new DNA molecules consist of only a few base pairs. Not so with real DNA.

Each human chromosome, for example, contains millions of base pairs. All 46 human chromosomes contain 3 billion pairs.

If you haven't already done so, check out Protein Synthesis.

DNA Replication

All Wound Up

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